By Jessica Lewis

1. Skeletal system

Functions:

The Skeletal System serves many important functions. It provides the shape and form for our bodies. It also supports, protects allows our bodies to move, allows our bodies to function, produces blood for the body, and also store minerals.

Functions: cont.

Many vital organs are protected by the skeletal system. One example is the brain, it is protected by the skull while the lungs and heart are protected by the ribcage. Our bodies function because there is an interaction between our muscles and skeletal system. Muscles are connected to the bone by tendons. Now, bones are connected to each other by ligaments . Muscles which cause movement of a joint are connected to two different bones and contract to pull them together. An example would be the contraction of the biceps and a relaxation of the triceps. Blood cells are produced by the marrow located in some bones. Around 2.6 million red blood cells are produced every second by the bone marrow to replace the ones that have become worn out and destroyed by the liver. Bones serve as a storage area for minerals such as calcium and phosphorus. When an excess is present in the blood, buildup will occur within the bones. When the supply of these minerals that is with in the blood is low, it is withdrawn from the bones and is replenished.

Divisions of the Skeleton: Axial: Appendicular:

This consists of bones that form an axis of the body and protect the organs of the head, neck and trunk. It also supports these organs. These bones protect the:

1. The Skull

2. The Sternum

3. The Ribs

4. The Vertebral Column

This skeleton is composed of bones that anchor the appendages to the axial skeleton. The organs that are involved with this are:

1.The Upper Extremities

2.The Lower Extremities

3.The Shoulder Girdle

4.The Pelvic Girdle

The Skull:

Your skull provides the framework for most of your sensory organs, such as eyes, ears, tongue, nose, and some skin. Your skull is made up of 22 cranial or facial bones, plus the three in each ear. As a baby you have more. Most are fixed joints separated by cartilage as a baby, but fuse together a later as you grow. Once fused, they are locked together, forming an immovable joints, called a suture-sound.

The Backbone:

The backbone, or vertebral or spinal column, though called a "bone", is really a flexible structure made of 26 bones. As a baby, you have 33 vertebrae, or back bones, but the lower four fuse to form the coccyx-sound, and the next lower five fuse to become the sacrum. The backbone serves several important functions itself. It provides structure from which all other upper body structures branch, and it protects the spinal nerve, which is the "highway" that all the information your brain sends to your body travels. The backbone is approximately 70 cm, long and is separated into five regions.

The Thorax:

The thorax is basically your chest, comprising your breast bone and ribs. Your breast bone, or sternum-sound, is around 6 inches (15 cm) tall, spanning about half the length of your ribs. The twelve ribs form the cage of your chest. One of the primary necessities of the ribs is to protect your heart and lungs. Your top seven ribs are called true ribs because they connected to the sternum. The next four ribs are called false ribs because they attach to the sternum so indirectly if at all. If they do not connect to the sternum, they do connect to upper cartilage for support. The last two ribs are called floating ribs because they do not connect to anywhere.

Types of Bone:

Long Bones: Short Bones:

The long bones are longer then they are wide and they work as a lever. The bones of the upper extremities are where these bones could be found. The upper extremities are the humerus, tibia, femur, ulna, metacarpals ect.

Short bones are a cubed like and short. You can find them in wrists and ankles.

Types of Bone: cont.

Flat Bones: Irregular Bones:

Flat bones have more of a broad service and are used to protect organs and attachments of muscles. For example the rib cage, cranial bones, and the bones of shoulder girdle.

Irregular bones are the bones that do not fall into any of the other categories. They all vary in size and shape and some can be found in the skull.

Bone Composition:

Bones are composed of tissue that may take one of two forms. Compact or spongy. Compact bone is very hard and dense and forms sort of a protective shield around the exterior of the bone.

Bone Composition: cont.

Spongy bone is inside of the bone and has a lot of holes that reside within it. You can find spongy bone in most all bones. The bone tissue is made up of several kinds of bone cells that are imbedded in sort of a web or inorganic salts like calcium. This gives the bon e strength and collagenous fibers allow the bone to be fexible.

2. Muscular System

Function:

The main role of the muscular system is to provide movement.  Muscles work in pairs to move limbs and provide the organism with mobility.  Muscles also control the movement of materials through some organs, such as the stomach and intestine, and the heart and circulatory system.

Muscle Tissues

Cardiac Muscle:

The cardiac muscles is the muscle of the heart itself. The cardiac muscle is the tissue that makes up the wall of the heart called the mydocardium. Also like the skeletal muscles, the cardiac muscle is striated and contracts through the sliding filament method. However it is different from other types of muscles because it forms branching fibers. Unlike the skeletal muscles, the cardiac muscle is attached together instead of been attach to a bone.

Skeletal Muscle:

The skeletal muscle makes up about 40 % of an adults body weight. It has stripe-like markings, or striations. The skeletal muscles is composed of long muscle fibers. Each of these muscles fiber is a cell which contains several nuclei. The nervous system controls the contraction of the muscle. Many of the skeletal muscle contractions are automatic. However we still can control the action of the skeletal muscle. And it is because of this reason that the skeletal muscle is also called voluntary muscle.

Smooth Muscle:

Much of our internal organs is made up of smooth muscles. They are found in the urinary bladder, gallbladder, arteries, and veins. Also the digestive tract is made up of smooth muscle as well. The smooth muscles are controlled by the nervous system and hormones. We cannot consciously control the smooth muscle that is why they are often called involuntary muscles.

Major Skeletal Muscles:

Facial: Neck: In the facial are one finds all the

muscles which move the face. Orbicularis oculi-sound are the two muscles that move the eye are. Frontalis-sound and Temporalis-sound are the two muscles which move the forehead and sides of your head. Zygomaticus-sound ands Masseter-sound are the two muscle that work in conjunction to move your jaw and upper lip area. Orbicularis oris-sound is the muscle which moves your lips

The neck area is almost entirely moved by the sternohyoid-sound and Sternocleidomastoid-sound. These muscles allow the neck to move your head left and right. They work with the platysma muscle to control how far you can move your head left and right. What allows your head to move up and down is the trapeziums'-sound. The trapezius is so large that it extend down to the shoulder and thorax area. The trapezius is a good example of how some muscles are named by their shape. the trapeziums looks just like a trapezoid.

Major Skeletal Muscles:cont.

Shoulder: Arm: A group of muscles all work

together to move the whole shoulder area. This group takes into account the trapezius-sound, deltoid-sound, infraspinatus-sound, teres major-sound, and the rhomboid major-sound. The rhomboid major is called so because its shaped like the geometric shape of a rhombus. Along with the help of the ball and socket joint-hyperlink in your shoulder, these group of muscles allow your arm to throw a softball, pick things over your head, and give your arms a good strecth early in the morning.

Most known amongst teenage weight lifters is the arm area. The famous bicep brachii-sound is the muscle that allows you to bring your forearm close to your body and form a huge ball of muscle which catches a lot of attention amongst weight lifters. The tricep brachii-sound and brachialis-sound are the two other muscles located in the arm region.

Major Skeletal Muscles:cont. Forearm: Thorax: A majority of the muscle in the

forearm help control a part of the arm. Amongst these is the Berachiodialis major-sound, palmaris longus-sound, and Flexor carpi radialis-sound. The name of the flexor carpi radialis is a good example of how muscles are named by their function and location. This muscle is named carpi because of the bones that it helps move, the carples. Also, the name of radialis is made by the bone that its attached to, the radius.

The thorax is the set of muscles which carrying your head, arms, stomach, and any other upper body areas. These muscles are the trapezius-sound and latissimus dorsi-sound. Usually, the majority of the muscles of the thorax can be damaged easily is one dose not stretch before exercise, or lifts a heave load.

Major Skeletal Muscles:cont. Abdomen: Hip:

The abdominal area consists of the muscles that allows you to bend down and move your waist from side to side. The interanal oblique-sound and external oblique-sound are the muscles that move your body from left to right. The Transversus abdominus-sound and Rectus abdominus-sound, along with the trapezius-sound an latissimus dorsi-sound allow you to bend down and grab objects.

Only two muscles make up the hip area. These are the gluteus medius-sound and gluteus maximus-sound. Probably the laziest muscles in the whole system the gluteus set of muscles are used only to sit down on.

Major Skeletal Muscles:cont. Pelvis/ Thigh: Leg: An overlapping of muscles is what makes

this area so firm. The pelvis area is usually referred to as the upper part of the leg. Muscles like the pectineus-sound and illiopsoas-sound , which help support the upper leg area are known as pelvic muscles. Thigh muscles are very rich in capillaries and support the whole body. The upper thigh muscles are abductor longus-sound, Gracilis-sound, Sartorius-sound, and Tensor fasciae latea. The lower thigh muscles are rectus femoris-sound, vastus lateralis-sound and medialis-sound. Located in the back of your leg are the hamstrings-sound. These muscles help you run, jump, and walk!

Helping the thigh region support the body is the Leg region. These muscles like the Gastrocnemius-sound, soleus-sound, porenius longus-sound, and Tibialis anterior-sound absorb the impact when one walks and runs. they also give beter cordination for moving. the thigh region trust the body forward while the leg region coordinates where it should be thrusted and where it should stand.

3. Circulatory system

Function:

The main role of the circulatory system is to transport nutrients, gases (such as oxygen and CO2), hormones and wastes through the body.

Parts of The Circulatory System

1. The Heart2. The Blood3. The Blood Cells

The Heart:

The heart beats about 3 BILLION times during an average lifetime. It is a muscle about the size of your fist. The heart is located in the center of your chest slightly to the left. It's job is to pump your blood and keep the blood moving throughout your body.

The Blood:

The blood is an amazing substance that is constantly flowing through our bodies.

Your blood is pumped by your heart.

Your blood travels through thousands of miles of blood vessels right within your own body.

Your blood carries nutrients, water, oxygen and waste products to and from your body cells.

A young person has about a gallon of blood. An adult has about 5 quarts.

Your blood is not just a red liquid but rather is made up of liquids, solids and small amounts of oxygen and carbon dioxide.

The Blood Cells:

Red Blood Cells: White Blood Cells:

They are responsible for carrying oxygen and carbon dioxide. Red Blood Cells pick up oxygen in the lungs and transport it to all the body cells. After delivering the oxygen to the cells it gathers up the carbon dioxide and transports it back to the lungs where it is removed.

White Blood Cells help the body fight off germs. White Blood Cells attack and destroy germs when they enter the body. When you have an infection your body will produce more White Blood Cells to help fight an infection.

The Blood Cells: cont.

Platelets: Platelets are blood cells that

help stop bleeding. When we cut ourselves we have broken a blood vessel and the blood leaks out. In order to plug up the holes where the blood is leaking from the platelets start to stick to the opening of the damaged blood vessels. As the platelets stick to the opening of the damaged vessel they attract more platelets, fibers and other blood cells to help form a plug to seal the broken blood vessel.

The Blood Vessels:

1. Arteries2. Capillaries3. Veins 4. Plasma

Arteries and Veins:

Arteries are blood vessels that carry oxygen rich blood AWAY from the heart.

Veins carry blood back to your heart

Capillaries:

Capillaries are tiny blood vessels as thin or thinner than the hairs on your head. Capillaries connect arteries to veins. Food substances(nutrients), oxygen and wastes pass in and out of your blood through the capillary walls.

Plasma:

Plasma is the liquid part of the blood. Approximately half of your blood is made of plasma. The plasma carries the blood cells and other components throughout the body. Plasma is made in the liver.

4. Nervous system

Function:

The main role of the nervous system is to relay electrical signals through the body.  The nervous system directs behaviour and movement and, along with the endocrine system, controls physiological processes such as digestion, circulation, etc.

The Peripheral Nervous System:

The nervous system is made up of nerve cells or neurons that are "wired" together throughout the body, somewhat like communication system. Neurons carry messages in the form of an electrical impulses. The messages move from one neuron to another to keep the body functioning.

Neurons have a limited ability to repair themselves. Unlike other body tissues, they cannot also be repaired if damaged due to injury or disease.

Central Nervous System: "Brain, Spinal Cord &

Senses" The brain keeps the body in order. It helps to control all of the body systems and organs, keeping them working like they should. The brain also allows us to think, feel, remember and imagine. In general, the brain is what makes us behave as human beings.

The brain communicates with the rest of the body through the spinal cord and the nerves. They tell the brain what is going on in the body at all times. This system also gives instructions to all parts of the body about what to do and when to do it.

Central Nervous System: cont.

Nerves divide many times as they leave the spinal cord so that they may reach all parts of the body. The thickest nerve is 1 inch thick and the thinnest is thinner than a human hair. Each nerve is a bundle of hundreds or thousands of neurons (nerve cells). The spinal cord runs down a tunnel of holes in your backbone or spine. The bones protect it from damage. The cord is a thick bundle of nerves, connecting your brain to the rest of your body.

Central Nervous System: cont. There are five main senses - touch,

smell, taste, hearing and sight. These are the external sensory system, because they tell you about the world outside your body. Your senses tell you what is happening in the outside world. Your body's sense organs constantly send signals about what is happening outside and inside it to your control center - the brain.

The cerebrum is part of the forebrain. The cerebral cortex is the outer layer of the cerebrum. Certain areas of the cerebral cortex are involved with certain functions.

Sensory areas such as touch, smell, taste, hearing and sight receive messages from the skin, nose, mouth, ears and eyes. We feel, taste, hear and see when these messages are received by the sensory parts of the brain.

The Endocrine System:

There is another system that works with the brain and nerves to keep the body in order. This is the endocrine or hormone system. It controls the rate we grow, our feelings of hunger, our body temperature, and more. Glands are organs that run the endocrine system. The pituitary gland, the pancreas, ovaries or testes the thyroid gland, the parathyroid gland, and the adrenal glands are organs that run the endocrine system.

Neurons:

Dendrite: Dendrites are short, thick branched

extensions which extend like the roots of a tree over other neurons or body cells. The dendrites all branch off dendritic spines, which in turn branch of the cell body. Dendrites are the receptive sites of the neurons. Here, the neurons receive electric messages from other neurons or body cells. The site where one dendrite meets another neuron's impulse is called the synapse. Usually, neurons have hundreds of dendrite extensions. These extensions are spread over a large area, giving the neuron better reception of signals. Some dendrites are specialized for the accumulation of information. These cells are finer than other dendrites and found near the brain.

Also called the perikaryon-sound or soma-sound, the cell body contains a spherical nucleus with a nucleolus and lots of cytoplasm. Like many cells, the neuron cell body of the neuron contains the usual cellular particles or organells-sound, except centrioles-sound. Centrioles are the basis by which cells are able to divide and form new cells. Because the neurons lack centrioles , they are unable to divide and reproduce themselves. Therefore, if one should damage nerves, then they are not able to be replaced. Nevertheless, neurons do have specialized hardworking endoplasmic reticulum-sound (ER), which help transport proteins and molecules at high speeds due to the fact that neurons work at lightning speeds. Also, the neurofibrils, bundles of micro filaments and micro tubules, which are important in intracellular transport, are seen through the body. A pigment called lipofuscin, which is yellow-brown, is one of the many pigments believed to be in the neuron.

Neurons: cont.

The axon is a long cylindrical tube, with the same consistent diameter, which runs through the body for long or short lengths. For example, the axon of your neuron controlling your toe, extends all the way from the lumbar back area. The axon branches off a cone shaped region of the cell body called the axon hillock-sound Axons diameters differ in many parts of the body, but the ruel is the thicker the axon, the more message it transmits through the neurons. The main purpose of the axon is to send impulses away from the cell body to neuron dendrite or other body cells called effecter cells-sound. A nerve impulse travels from a dendrite, to the cell body, and down the axon to thousands of branches called telondria which connect at a synapse to dendrites from other neurons. Once the impulse reaches the synapse, neurotransmitters, chemicals, which excite or calm effecter or neurons, diffuse into the extra cellular space and reach the dendrite, once again turning into an impulse. Protecting and insulating electric fibers from one another is the myelin sheath. It is a whitish, fatty, segmented sheath which covers the majority of nerve fibers and helps transmit nerve impulses faster. Throught the axon of the neuron, cells which protect the neuron envelope . These cells forms slope like structures with indents in between them called a Node of Ranvier-sound. The myelin sheath is exceedingly important because one can lose control of your muscles due to the uncoordinated fibers of an axon without myelin sheath

Nose:

The olfactory or smell action is The olfactory or smell action is quite simple. Once the smell of quite simple. Once the smell of food has reached your nose, food has reached your nose, which is lined with hairs, it which is lined with hairs, it travels to an olfactory bulb, a travels to an olfactory bulb, a set of sensory nerves. The set of sensory nerves. The nerve impulses travel through nerve impulses travel through the olfactory tract, around, in a the olfactory tract, around, in a circular way, the thalamus, and circular way, the thalamus, and finally to the smell sensory finally to the smell sensory cortex of your brain, located cortex of your brain, located between your eye and ear, between your eye and ear, where it is interpreted to be where it is interpreted to be understood and memorized by understood and memorized by the body.the body.

Eye:

Seeing is one of the most pleasing senses of the nervous system. This cherished action primarily conducted by the lens, which magnifies a seen image, vitreous disc, which bends and rotates an image against he retina, which translates the image and light by a set of cells. The retina is at the back of the eye ball where rods and cones structures along with other cells and tissues covert the image into nerve impulses which are transmitted along the optic nerve to the brain where it is kept for memory.

Tongue:

A set of microscopic buds on the tongue divide everything you eat and drink into four kinds of taste: bitter, sour, salty, and sweet. These buds have taste pores, which convert the taste into a nerve impulse and sends the impulse to the brain by a sensory nerve fiber. Upon receiving the message, your brain classifies the different kinds of taste. This is how you can refer the taste of one kind of food to another.

Ear:

Most people only relate the ear drum or tympanic membrane as the only structure in the ear. However, this is not true. The cartilage over the cell ear is called the auricle. This area serves as a protective member to guard the inner ear where the famous ear drum is located. The typmanic membrane is divided into two layers. One that goes to the pharynx and the other is a mucus membrane. By putting pressure of both membranes is the only way the ear drum receives sound. Once the sound or sound wave has entered the drum, it goes to a large structure called the cochlea. In this snail like structure, the sound waves are divided into pitches. The vibration of the pitches in the cochlea are measured by the Corti. This organ transmits the vibrational information to a nerve, which sends it to the brain for interpretation and memory.

5. Respiratory system

Function:

The main role of the respiratory system is to provide gas exchange between the blood and the environment.  Primarily, oxygen is absorbed from the atmosphere into the body and carbon dioxide is expelled from the body.

Nose and Nasal Cavity:

As you inhale, small specks of dirt are trapped by many tiny hairs in your nose. This cleans the air. The hairs stop the dirt from going further in your body. The moist inside surface in your nose traps even smaller pieces of dirt. The nasal cavity, the air passage behind the nose, plays an important role in breathing. The nasal cavity is divided into a right and left passageway. The tissue that covers the wall of your nasal cavity contains many blood vessels. Heat from the blood in the vessels helps warm the air as you breath. Moisture is added to the air you breath by special cells in the walls of the nasal cavity. The air is warmed and moistened before it reaches your lungs.

Windpipe and Bronchial Tree:

The windpipe joins the upper respiratory tract to the lungs. The bottom of the trachea splits into two branches called bronchi. One enters the right lung and one goes to the left lung.

The bronchial tree's job is to spread the air from the trachea over a very wide area as quickly as possible. The air passing through the windpipe divides into two branches. These divide into twigs called bronchioles. These twigs open into little bags called alveoli. The alveoli gives our lungs a huge surface for absorbing oxygen from the air.

Lungs:

The lungs are protected by our ribs. The lungs are the pickup place for oxygen and the drop off place for carbon dioxide. The lungs are always working, breathing in oxygen and breathing out carbon dioxide.

Blood is pumped into the lungs from the heart through the pulmonary arteries. Blood with oxygen leaves the lungs through the pulmonary veins and travels to the heart. Oxygen is the fuel that makes all the body processes run.

The Pharynx:

The pharynx, most commonly known as the throat, serves duel purposes. Not only does it move the air into your lungs, but it also moves food into your stomach. About five inches long, the pharynx is separated into three distinct regions, chosen by location and function: the nasopharynx, the oropharynx, and the laryngopharynx.

The Larynx:

Also known as the voice box, the pharynx is what allows you to speak. The larynx has an inlet at the top that allows substances to pass through it or not. When food is being swallowed, the inlet is closed, forcing food into the stomach. When air is being breathed, the inlet is wide open so that air can enter your lungs. With the exception of the epiglottis, all larynx cartilage is hyaline cartilage. The Adam's apple is really the laryngeal prominence, where the curved disc shaped thyroid cartilage bond.

The Trachea:

The trachea, or windpipe connects the larynx to the bronchi. This organ differs from others in the neck in that it is flexible, stretching to be between four and five inches long, and about one inch in diameter. The trachea is lined with mucous called the mucociliary escalator, which represents the mucous and cilia and carry the foreign substances up to be swallowed. The trachea is made up of between 16 and 20 cartilage rings in the shape of a "C". Because the trachea is so flexible and twistable, without these cartilage rings, it would collapse under the partial vacuum formed when inhaling. The open part of the "C" shape is covered with the Trachealis muscle, which can stretch itself to prevent tracheal tearing when swallowing large things. When you cough, the muscle also contracts to force air out at a faster speed to dislodge food or other foreign objects stuck.

The Bronchi:

The trachea branches off into two main bronchi, your left and right primary bronchi, which lead to the left and right lung respectively. Your right lung is slightly wider, shorter, and taller that the left, which makes it more vulnerable to foreign invasion. At this point in breathing, the air has been moistened, purified and warmed.Each bronchi enters its lung and begins on a series of branches, called the bronchial or respiratory tree. The first of these branches is the lobar (secondary) branch. On the left, there are two lobar branches, while on the right, there are three. Each lobar branches into one lobe. The next branch is called the segmental (tertiary) branch. Each branch continues to branch into smaller and smaller bronchioles. The final branch is called the terminal bronchioles. These bronchioles are smaller than 0.5 mm in diameter.

Respiratory Zone:

Respiration begins when the terminal bronchioles lead into the respiratory bronchioles. These bronchioles are covered with thin-skinned air sacs that allow for gasses to pass through them. These sacs, which contain alveoli, are called alveolar sacs, and are at the end of alveolar ducts. The alveoli are very small curves in the sac walls. Your lung has many millions of alveoli, which gives your lungs an incredible surface area for gas exchange. Though fairly impossible to measure exactly, that surface area is approximated to 70 - 80 square meters, or a square between eight and nine meters on each side!

The Pleurae:

The Pleurae is a thin, double-layered tissue which lines the walls of the lungs and heart. Due to the fact that it produces pleural fluid, the pleurae helps the lungs to glide easily against the rib-lining tissues, the thoracic wall, when the lungs take in air. Also, the pleural is essential to breathing because it serves as potential space. This important function helps the lungs form a vacuum which sucks in air from the atmosphere. In addition, its capability to stretch and divide the lungs into two compartments, a lower lung and a upper lung, allows other organs to move without interfering with respiration.

6. Digestive system

Function:

The main role of the digestive system is to breakdown and absorb nutrients that are necessary for growth and maintenance.

Mouth and Teeth:

During the process of chewing, food is shredded and ground. Powerful muscles move the mandible, or lower jaw, while the food is chewed. The front teeth cut the food and the back teeth grind the food.

There are three main parts to the tooth: the root, the neck and the crown. The root is the part inside the jaw. The neck is a narrow connection between the root and the crown. The crown of the tooth is above the gum.

First teeth come in between 6 and 8 months. By age 6, baby teeth are gradually replaced by permanent teeth. There are 32 permanent teeth.

When food is being chewed, saliva is squirted into the mouth. Saliva helps to soften the food. It contains an enzyme that helps break down the starch in the food.

After chewing, the food is swallowed and passes down the esophagus to the stomach. The esophagus is about ten inches long. The tongue helps push the food to the back of the mouth, and the muscles in the esophagus move the food down the tube.

Food Travel:

The muscles in the stomach move, which helps break down the food. The stomach is protected from the acid by a lining. From the stomach, the food pulp is sent to the small intestine. Food leaves the stomach a little bit at a time.

The small intestine is the final place for digestion. Measuring about twenty feet in length, the small intestine is one inch in diameter. Digestive juices released in the small intestine finish breaking down the food.

The food is moved along the small intestine in a squeezing motion known as peristalsis. This motion is much the same as squeezing a tube of toothpaste. All of this movement causes the noise when we say our stomach is "growling."

Lining the small intestine are millions of fingers called villi. These absorb the chemicals that we need from the food into the body. It is at this point the food is actually in the body.

Waste products and food that are not absorbed in the small intestine pass into the large intestine. This waste material is called feces. The large intestine is only five feet long but is larger in diameter than the small intestine. The large intestine includes the colon.

In the large intestine, feces are formed from water, undigested food and bacteria. Water is absorbed back into the body so the waste material becomes more solid as it travels through the colon. It may take as long as twenty hours for food to pass completely through the large intestine.

Gall Bladder, Pancreasand Liver

The pancreas is an elongated gland that is below the stomach. It produces pancreatic juice that contains digestive enzymes. The pancreas also secrets insulin into the blood. Insulin is needed to allow glucose or sugar from food to get into the bloodstream. People who cannot produce insulin are diabetics.

Gall Bladder, Pancreas and Liver: cont.

The largest gland in the body is the liver. It is on the right side of the body underneath the ribs. It weighs about three pounds and is eight inches long. The liver stores a form of glucose called glycogen. Vitamin A is manufactured in the liver. Bile which is needed to breakdown fat, is made in the liver. This organ is also where alcohol, drugs, bacteria and old blood cells are broken down and removed from the body. Damage to the liver can be serious because this organ is extremely necessary to life.

Gall Bladder, Pancreas and Liver: cont. The gallbladder is a

small sac on the underside of the right lobe of the liver. It stores bile that is made by the liver. Bile travels from the liver through the hepatic ducts to the gallbladder. It holds about two ounces of bile. Bile is needed to breakdown the fat that is in food.

Small Intestine:

The small intestine is the longest organ of the digestive tract. It is divided up indiscriminately into three sections: the duodenum, the jejunum, and the ilium.

Duodenum:

This is the place where the ultimate destruction of food digestion reaches its completion and where the acidity of chyme is nullified. The nutrients in the food eaten many hours ago have almost been diminished to molecules small enough to be absorbed through the intestinal walls into the bloodstream. Carbohydrates are diminished into simpler sugars; proteins to amino acids; and fats to fatty acids and glycerol. Enzymes are secreted by the walls of the duodenum and unite with the bile (essential for the digestion and absorption of tenacious fatty materials) and pancreatic enzymes in the duodenum.

Jejunum:

Peristalsis pushes the nutrient liquid out of the duodenum into the first reaches of the jejunum. A greater number of villi , microscopic, hair like structures, begin to absorb amino acids , sugars, fatty acids and glycerol from the digested contents of the small intestine, and starts them on their way to other parts of the body. This part of the small intestine executes a digestive operation so that what is passed on to the large intestine is a thin watery substance almost completely devoid of nutrients.

Ilium:

This is the place which is about a third of the small intestine. The greatest number of the estimated five or six million villi in the small intestine are found along the ilium making it the main absorption locale of the gastrointestinal tract. The villi here are always in a fretful movement: oscillating, pulsating, lengthening, shortening, growing narrower then wider, extorting every particle of nutrient.

7. Excretory system

Function:

The main role of the excretory system is to filter out cellular wastes, toxins and excess water or nutrients from the circulatory system. This system includes the kidneys, bladder and tubes. These organs control the amount of water and salts that are absorbed back into the blood and what is taken out as waste. This system also acts as a filtering mechanism for the blood.

Kidneys:

The kidneys are a filter for the blood. The body has two kidneys located in the middle of the back at about the location of your elbows. Blood is pumped from the heart to the kidneys to be cleaned. Each kidney has about 1000 nephrons that act as filters. As the blood goes into a nephron, everything that is dissolved in the blood (waste products, food) is pushed out of the blood into small tubules. As these things travel through the tubule, the water and anything else the body needs goes back into the blood. The rest of the waste products keep moving through the tubule into the urethra. The urethra is the tube that leads to the bladder. The cleaned blood leaves the kidney and travels throughout the body.

Bladder:

The bladder is where urine is stored to be released from the body. It can hold between one half to two cups of urine before it needs to be emptied. About 96% of urine is water. It also contains some waste salts and a substance called urea. Urea is made during the breakdown of proteins in your liver. Urea may also leave your body in sweat. If urea builds up in your body, it is a sign that your kidneys are not working properly. Kidney failure can be fatal if it is not treated quickly.

Liver:

The liver acts as a filter for the blood that passes through it. The liver removes amino acids that don't need to be in your body. The excess amino acids are broken down so that they form the urea which is excreted in the urine. The liver can also change hemoglobin from worn-out red blood cells into substances that are useful to the body. In addition, the liver can change any poisonous toxins that have collected in the blood into harmless substances.

Skin:

Excretion by definition is passive and deals with metabolic wastes as filtered by the kidneys. Though the sweat may contain a trace amount of metabolic wastes, sweating is an active process of secretion not excretion, specifically for temperature control and pheromone release. Therefore, its role as a part of the excretory system is minimal at best. Specifically, the skin secretes a fluid waste called sweat.

Defecation:

Organisms eliminate solid, semisolid or liquid waste material (feces) from the digestive tract via the anus during the process of defecation. Waves of muscular contraction known as peristalsis in the walls of the colon move fecal matter through the digestive tract towards the rectum. Undigested food may also be expelled this way; this process is called egestion.

Ureter:

In human anatomy, the ureters are muscular ducts that propel urine from the kidneys to the urinary bladder. In the adult, the ureters are usually 25–30 cm (10–12 in) long. In humans, the ureters arise from the renal pelvis on the medial aspect of each kidney before descending towards the bladder on the front of the psoa major muscle. The ureters cross the pelvic brim near the bifurcation of the iliac arteries (which they run over). This "pelviureteric junction" is a common site for the impaction of kidney stones (the other being the uteterovesical valve). The ureters run posteroinferiorly on the lateral walls of the pelvis. They then curve anteriormedially to enter the bladder through the back, at the vesicoureteric junction, running within the wall of the bladder for a few centimeters. The backflow of urine is prevented by valves known as ureterovesical valves. In the female, the ureters pass through the mesometrium on the way to the urinary bladder.

Urinary Bladder:

The urinary bladder is the organ that collects urine excreted by the kidneys prior to disposal by urination. A hollow muscular, and distensible (or elastic) organ, the bladder sits on the pelvic floor. Urine enters the bladder via the ureters and exits via the urethra. Embryologically, the bladder is derived from the urogenital sinus and, it is initially continuous with the allantois. In males, the base of the bladder lies between the rectum and the pubic symphysis. It is superior to the prostate, and separated from the rectum by the rectovesical excavation. In females, the bladder sits inferior to the uterus and anterior to the vagina. It is separated from the uterus by the vesicouterine excavation. In infants and young children, the urinary bladder is in the abdomen even when empty.

Urethra:

In anatomy, the urethra is a tube which connects the urinary bladder to the outside of the body. The urethra has an excretory function in both sexes to pass urine to the outside, and also a reproductive function in the male, as a passage for semen during sexual activity.

The external urethral sphincter is a striated muscle that allows voluntary control over urine.

8. Endocrine System

Function:

The main role of the endocrine system is to relay chemical messages through the body.  In conjunction with the nervous system, these chemical messages help control physiological processes such as nutrient absorption, growth, etc.

Major Glands That Make Up The Endocrine System

hypothalamus pituitary gland thyroid parathyroid's adrenal glands pineal body reproductive glands

(which include the ovaries and testes)

Hypothalamus:

It is a collection of specialized cells that is located in the lower central part of the brain, is the main link between the endocrine and nervous systems. Nerve cells in the hypothalamus control the pituitary gland by producing chemicals that either stimulate or suppress hormone secretions from the pituitary

Pituitary:

Located at the base of the brain just beneath the hypothalamus, is considered the most important part of the endocrine system. It's often called the "master gland" because it makes hormones that control several other endocrine glands.

The production and secretion of pituitary hormones can be influenced by factors such as emotions and changes in the seasons. To accomplish this, the hypothalamus provides information sensed by the brain (such as environmental temperature, light exposure patterns, and feelings) to the pituitary.

The tiny pituitary is divided into two parts: the anterior lobe and the posterior lobe. The anterior lobe regulates the activity of the thyroid, adrenals, and reproductive glands. The anterior lobe produces hormones such as:

growth hormone, which stimulates the growth of bone and other body tissues and plays a role in the body's handling of nutrients and minerals

prolactin , which activates milk production in women who are breastfeeding

Thyrotrophic, which stimulates the thyroid gland to produce thyroid hormones

Corticotrophin, which stimulates the adrenal gland to produce certain hormones

The pituitary also secretes endorphins, chemicals that act on the nervous system and reduce feelings of pain. In addition, the pituitary secretes hormones that signal the reproductive organs to make sex hormones. The pituitary gland also controls ovulation and the menstrual cycle in women.

The posterior lobe of the pituitary releases antidiuretic hormone, which helps control the balance of water in the body. The posterior lobe also produces oxytocin, which triggers the contractions of the uterus in a woman having a baby.

Thyroid:

The thyroid located in the front part of the lower neck, is shaped like a bow tie or butterfly and produces the thyroid hormones and triiodothyronine. These hormones control the rate at which cells burn fuels from food to produce energy.

The production and release of thyroid hormones is controlled by thyrotropin, which is secreted by the pituitary gland. The more thyroid hormone there is in a person's bloodstream, the faster chemical reactions occur in the body.

Parathyroid’s:

Attached to the thyroid are four tiny glands that function together called the parathyroids. They release parathyroid hormone, which regulates the level of calcium in the blood with the help of calcitonin, which is produced in the thyroid.

Adrenal Glands:

The adrenal glands have two parts, each of which produces a set of hormones and has a different function:

1. The outer part, the adrenal cortex, produces hormones called corticosteroids that influence or regulate salt and water balance in the body, the body's response to stress, metabolism, the immune system, and sexual development and function.

2. The inner part, the adrenal medulla, produces catecholamines, such as epinephrine. Also called adrenaline, epinephrine increases blood pressure and heart rate when the body experiences stress.

Pineal:

The pineal body, also called the pineal gland, is located in the middle of the brain. It secretes melatonin, a hormone that may help regulate when you sleep at night and when you wake in the morning.

Reproductive Glands:

The gonads are the main source of sex hormones. Most people don't realize it, but both guys and girls have gonads.

In guys the male gonads, or testes, are located in the scrotum. They secrete hormones called androgens , the most important of which is testosterone. These hormones tell a guy's body when it's time to make the changes associated with puberty like penis and height growth, deepening voice, and growth in facial and pubic hair. Working with hormones from the pituitary gland, testosterone also tells a guy's body when it's time to produce sperm in the testes.

A girl's gonads, the ovaries are located in her pelvis. They produce eggs and secrete the female hormones estrogen and progesterone. Estrogen is involved when a girl begins to go through puberty. During puberty, a girl will experience breast growth, will begin to accumulate body fat around the hips and thighs, and will have a growth spurt. Estrogen and progesterone are also involved in the regulation of a girl's menstrual cycle. These hormones also play a role in pregnancy.

Although the endocrine glands are the body's main hormone producers, some other organs not in the endocrine system — such as the brain, heart, lungs, kidneys, liver, and skin — also produce and release hormones.

The pancreas is also part of the body's hormone-secreting system, even though it is also associated with the digestive system because it produces and secretes digestive enzymes. The pancreas produces (in addition to others) two important hormones, insulin and glucagon. They work together to maintain a steady level of glucose, or sugar, in the blood and to keep the body supplied with fuel to produce and maintain stores of energy.

What Does the Endocrine System Do?

Once a hormone is secreted, it travels from the endocrine gland that produced it through the bloodstream to the cells designed to receive its message. These cells are called target cells. Along the way to the target cells, special proteins bind to some of the hormones. These proteins act as carriers that control the amount of hormone that is available for the cells to use.

The target cells have receptors that latch onto only specific hormones, and each hormone has its own receptor, so that each hormone will communicate only with specific target cells that have receptors for that hormone. When the hormone reaches its target cell, it locks onto the cell's specific receptors and these hormone-receptor combinations transmit chemical instructions to the inner workings of the cell.

When hormone levels reach a certain normal amount, the endocrine system helps the body to keep that level of hormone in the blood. For example, if the thyroid gland has secreted the right amount of thyroid hormones into the blood, the pituitary gland senses the normal levels of thyroid hormone in the bloodstream. Then the pituitary gland adjusts its release of thyrotropin, the hormone that stimulates the thyroid gland to produce thyroid hormones.

Another example of this process is parathyroid hormone. Parathyroid hormone increases the level of calcium in the blood. When the blood calcium level rises, the parathyroid glands sense the change and reduce their secretion of parathyroid hormone. This turnoff process is called a negative feedback system

9. Reproductive system

Function:

The main role of the reproductive system is to manufacture cells that allow reproduction.  In the male, sperm are created to inseminate egg cells produced in the female.

Asexual Reproduction:

Fission, budding, fragmentation, and the formation of rhizomes and stolons are some of the mechanisms that allow organisms to reproduce asexually. The hydra produces buds; starfish can regenerate an entire body from a fragment of the original body. Asexual reproduction allows an organism to rapidly produce many offspring without the time and resources committed to courtship, finding a mate, and mating. The lack of genetic variability in asexually reproducing populations can be detrimental when environmental conditions (for which all the clones are so well adapted) change quickly.

Sexual Reproduction:

In sexual reproduction new individuals are produced by the fusion of haploid gametes to form a diploid zygote. Sperm are male gametes, ova (ovum singular) are female gametes. Meiosis produces cells that are genetically distinct from each other; fertilization is the fusion of two such distinctive cells that produces a unique new combination of alleles, thus increasing variation on which natural selection can operate.

Rotifers will reproduce asexually when conditions are favorable by having females produce eggs by mitosis. When conditions deteriorate, rotifers will reproduce sexually and encase their zygotes inside a resistant shell. Once conditions improve, these eggs hatch into diploid individuals. Rotifers thus use sexual reproduction as way to survive a deteriorating environment.

Sexual reproduction offers the benefit of generating genetic variation among offspring, which enhances the chances of the population's survival. Costs of this process include the need for two individuals to mate, courtship rituals, as well as a number of basic mechanisms described later.

Human Reproduction and Development:

Human reproduction employs internal fertilization, and depends on the integrated action of hormones, the nervous system, and the reproductive system. Gonads are sex organs that produce gametes. Male gonads are the testes, which produce sperm and male sex hormones. Female gonads are the ovaries, which produce eggs (ova) and female sex hormones.

The Male Reproductive System: Testes are suspended

outside the abdominal cavity by the scrotum, a pouch of skin that keeps the testes close or far from the body at an optimal temperature for sperm development. Somniferous tubules are inside each testis, and are where sperm are produced by meiosis.

Male Sex Hormones:

The anterior pituitary produces follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Action of LH is controlled by the gonadotropin-releasing hormone (GnRH). LH stimulates cells in the seminiferous tubules to secrete testosterone, which has a role in sperm production and developing male secondary sex characteristics. FSH acts on cells to help in sperm maturation. Negative feedback by testosterone controls the actions of GnRH.

Sexual Structures:

Sperm pass through the vas deferens and connect to a short ejaculatory duct that connects to the urethra. The urethra passes through the penis and opens to the outside. Secretions from the seminal vesicles add fructose and prostaglandins to sperm as they pass. The prostate gland secretes a milky alkaline fluid. The bulbourethral gland secretes a mucus-like fluid that provides lubrication for intercourse. Sperm and secretions make up semen.

The Female Reproductive System:

The female gonads, ovaries, are located within the lower abdominal cavity. The ovary contains many follicles composed of a developing egg surrounded by an outer layer of follicle cells. Each egg begins oogenesisas a primary oocyte. At birth each female carries a lifetime supply of developing oocytes, each of which is in Prophase I. A developing egg (secondary oocyte) is released each month from puberty until menopause, a total of 400-500 eggs.

Ovarian Cycles:

After puberty the ovary cycles between a follicular phase (maturing follicles) and a luteal phase (presence of the corpus luteum). These cyclic phases are interrupted only by pregnancy and continue until menopause, when reproductive capability ends. The ovarian cycle lasts usually 28 days. During the first phase, the oocyte matures within a follicle. At midpoint of the cycle, the oocyte is released from the ovary in a process known as ovulation. Following ovulation the follicle forms a corpus luteum which synthesizes and prepares hormones to prepare the uterus for pregnancy. The secondary oocyte passes into the oviduct (fallopian tube or uterine tube). The oviduct is connected to the uterus

Hormones and Female Cycles: The ovarian cycle is

hormonally regulated in two phases. The follicle secretes estrogen before ovulation; the corpus luteum secretes both estrogen and progesterone after ovulation. Hormones from the hypothalamus and anterior pituitary control the ovarian cycle. The ovarian cycle covers events in the ovary; the menstrual cycle occurs in the uterus.

10. Lymphatic/Immune System

Function:

The main role of the immune system is to destroy and remove invading microbes and viruses from the body.  The lymphatic system also removes fat and excess fluids from the blood. 

The Inflammatory Response:

The Inflammatory Response is a defensive action which takes into account fluids, hormones, and cells. Some apparent symptoms relating to this response are redness, heat, swelling, and pain. Once pathogens have seeped into the blood stream, hostile chemicals like prostaglandins, kinins, histamines, lymphokins cause vasodilation, a dilation of the blood vessels, which allows blood to rush into the damaged area. This amounts to a feel of congestion inside your vessels and causes a burning sensation and redness. These chemicals provoke clotting factors and antibodies to amass in the area, irritating nearby nerves, thus, causing the pain. Adding to the pain would be the damaging secretion of the bacterial toxins. Nevertheless, the hormones, in a process called chemotaxis, act like homing signals to the defensive cells of the system, which latently arrive in the scene to breach the pathogenic invasion. To further help the clogging agents, nuetrophils cling to the skin surface one after another, forming chains which sow the damaged area. One common effect of the inflammatory response is that of puss. By releasing lysosomal enzymes, nuetrophils kill large portions of the invading armies but destroy themselves in the process. This mass killing of both pathogens and cells amounts to a creamy like fluid called puss.

Interferon:

Interferon is a family of small proteins which are manufactured by an infected cell and helps inhibit viruses from entering other healthy cells. Once a cell has been infected by some virus, it releases interferon, which binds to the membranes of other immune cells, such as phagocites. As the interferon binds to these cells, viruses are incapable of dividing within these cells.

The three kinds of interferon have somewhat similar effects on immune cells. In addition to their anti-viral effects, interferon activate macrophages, natural killers, and decrease cell division. Alpha [a] interferon is produced by leukocytes. Beta [ß] which is produced by fibroblasts. And, Gamma [l] is fabricated by lymphocytes.

Natural Killers:

Natural Killers are a unique set of cells which kill virus infested and cancer cells by a process called lysis. This involves the use of proteins called compliment. This arrow like strand of proteins allows the natural killer to drain all the cellular fluid in the cell. The process is similar to cutting yourself and letting all your blood drain out. Since bacteria can replace it's membrane just like we can replace our skin, the natural killers' compliment has a protein called C9 which keeps the membrane hole open. This ensures the full drainage of the cellular fluid. Mainly, lysis and the nonspecific ability to destroy all diseased cells spontaneously gives Natural Killers' their name.

Phagocytosis:

Phagocytosis is the cellular action of "eating". This mechanism is mostly used by immune cells called macrophages and nuetrophils to destroy pathogens and disease infested cells. The cell grabs any bacteria or diseased cell with its flowing extensions like if it were a blob engulfing its victim. After the bacteria is ingested in a food vacuole, a ball of highly acidic enzymes called a lysozyme, inside the cell begins, to digest it. To further impose harm on the surrounding pathogens, the neutrophil secretes a deadly chemical somewhat similar to household bleach. Unfortunately, upon secreting the chemical, the nuetrophil can not live in such an environment and dies along with the other pathogens.

Saliva:

Saliva in your mouth contains an enzyme called lysozyme which kills bacteria. Any pathogen upon entering the mouth will meet not only the sugar digesting enzyme called alamalze , which will produce some harm, but, also lysozyme.

Nostrils:

Your nostrils lead to your lungs where the warm environment would allow pathogens to grow. However, the mucous covered hairs of the nose trap these invaders. If pathogens get past the nose, then the ciliated trachea, the wind pipe, trap these organisms and sweep them to the top of the trachea, where it is met by your mouth..

Skin:

Your skin will keep most pathogens from entering, at least while it is healthy, because it has a very thick layer of fat and dead skin cells which block any intruder from entering the body. Also, it secrets acidic chemicals that kill many pathogens. In fact, the vaginal secretions of adult female have so high acidic levels that they kill pathogens near the skin on contact.

Fever:

Fever is an abnormally high increase of body temperature in response to pathogen invasion. Body temperature is regulated by a section of the brain called the hypothalamus . Normal temperature is set by the hypothalamus at 37°C (98.6°F). If pathogens should enter the body, then macrophages, which would be fighting the invaders, secret chemicals called pyrogens.

BIBLIOGRAPHY:

http://library.thinkquest.org/2935/Natures_Best/Nat_Best_Low_Level/skeletal_page.L.html

http://www.google.com

http://www2.estrellamountain.edu/faculty/farabee/biobk/BioBookREPROD.html 

http://library.thinkquest.org/5777/ner1.htm

http://www.wikipedia.com

http://www.wikispaces.com