Regulation and Homeostasis in the

Human Body:

Overview

How do Humans and other complex mammals maintain homeostasis? They must carry out all needed life functions in a coordinated way.

What does our species need to accomplish?

Growth Repair of injuries

Get energy Get building materials

Get rid of waste

Keep away disease

Respond to changing environment

Reproduce

Eleven Body Systems work together to maintain homeostasis and carry out these tasks:

1. Nervous System 2. Endocrine System

3. Lymphatic System 4. Circulatory System

5. Respiratory System 6. Digestive System

7. Excretory System 8. Skeletal System

9. Muscular System 10. Integumentary System

11. Reproductive System

1. Nervous System:

Structures: Brain, Spinal Cord, Peripheral Nerves, Neurons (Cells of nervous system)

Functions: Coordinates the body’s response to changes to internal and external environment

2. Endocrine System – Hormone System

Structures: Glands - Hypothalmus, pituitary, thyroid, parathyroids, adrenals, pancreas, ovaries (in females), testes (in males)

Functions: Produce Hormones. Controls growth, development, metabolism, and reproduction

3. Lymphatic System – Immune System

Structures: White blood cells, thymus, spleen, lymph nodes, lymph vessels

Function: Helps protect the body from disease; collects fluid lost from blood vessels; returns the fluid to the circulatory system

4. Circulatory System

Structures: Heart, Blood vessels, blood

Functions: Brings oxygen, nutrients, and hormones to cells; fights infection; regulates body temperature

5. Respiratory System

Structures: Nose, pharynx, larynx, trachea, bronchi, bronchioles, lungs

Functions: Provides oxygen needed for cellular respiration and removes carbon dioxide from body

6. Digestive System

Structures: Mouth, pharynx, larynx, esophagus, stomach, liver, pancreas, small and large intestines,

Function: Breaks down foods into simple molecules that can be used by the body for respiration and building cells

7. Excretory System

Structures: Skin, lungs, kidneys (nephrons), ureters, urinary bladder, urethra

Functions: Removes waste products of metabolism from the body

8. Skeletal System

Structures: Bones, cartilage, ligaments, tendons

Functions: Supports the body; protects internal organs; allows movement; stores mineral reserves; provides a site for blood formation

9. Muscular System

Structures: Skeletal muscle, smooth muscle, cardiac muscle

Function: Works with skeletal system to produce voluntary movement; helps circulate blood and move food through the digestive system

10. Integumentary System (Skin)

Structures: Skin, Hair, Nails, Sweat and Oil Glands

Functions: Serves as a barrier against infection and injury; Helps to regulate temperature; Protects against UV light

Structures:

Female- Uterus, Fallopian tubes, ovary, cervical canal, cervix, vagina

Male – Penis, Vas Deferens, Prostate, Epididymis, Testes, Scrotal Sac, Seminal Vesicle

Function: Produces reproductive cells; in females nurtures and protects developing embryo

11. Reproductive System

Support and Motion

Functions of the SKELETAL AND MUSCULAR SYSTEM

How does the human body move from place to place and have the ability to run, blink or build things?

These things are all made possible by the skeletal and muscular systems.

Skull

Sternum

Ribs

Vertebral column

Metatarsals

Metacarpals

Phalanges

ClavicleScapula

Humerus

RadiusPelvisUlnaCarpals

Femur

Patella

FibulaTibiaTarsals

Phalanges

A. Skeletal System

There are 206 bones in the adult human body. These bones provide a system of supports and levers on which muscles can produce movement

Figure 36-3 The Structure of BoneBones are a solid network of living cells and protein fibers that are surrounded by calcium deposits. Bones contain blood vessels and cavities containing marrow. Red marrow produces red blood cells, white blood cells and platelets

Bone Marrow

Ball-and-Socket Joint

Hinge Joint

Pivot Joint

Saddle Joint

Clavicle

Figure 36-4 Freely Movable Joints and Their Movements

Section 36-1

Joints are places where one bone attaches to another. Each type of joint is designed to allow movement without damaging the other bones. Joints in the skull allow no movement, joints in the spine allow a small amount of movement and those shown below allow movement in one or more directions.

Knee

Elbow

Muscle

Tendon

Femur

PatellaBursaLigament

Cartilage

Fat

Fibula

Tibia

Knee JointSection 36-1

Ligaments are a tough connective tissue that attach bones to bones

Tendons are connective tissue which attach bones and muscles to allow bones to move

B. The Muscular System

More than 40% of the average human is muscle. Muscles are involved in both voluntary actions and involuntary actions. Three types of muscles cells are:

•Skeletal – Attached to bones for voluntary actions and controlled by the central nervous system

•Smooth – Found in the digestive tract and the blood vessels to move food and blood. Control involuntary actions (you do not decide for them to work)

•Cardiac – Heart muscle cells are involuntary.

Figure 36-7 Skeletal Muscle Structure

Section 36-2Skeletal muscles are made up of clusters of filaments of proteins known as actin and myosin which control muscle contraction and relaxation

Figure 36-8 Muscle Contraction

During Muscle contraction Actin filaments slide over myosin filaments shrinking the muscle

Energy for muscle contraction is supplied by ATP

Nervous system cells known as motor neurons are attached to skeletal muscle cells to control the voluntary movement.

Threadlike Nerve or neuron

Axon or junction

Movement

MovementBiceps

(relaxed)

Triceps (contracted)

Biceps (contracted)

Triceps (relaxed)

Figure 36-11 Opposing Muscle Pairs

Section 36-2Skeletal muscles work in opposing pairs. When one muscle contracts, the other relaxes.

How does the human body take in required nutrients and get rid of wastes?

The Digestive and Excretory Systems are responsible for bringing in food and getting rid of the leftovers.

Nutrition and Waste Removal

Food supplies the raw materials for building molecules your body needs, such as:

• enzymes

• Lipids in cell membranes

• DNA

Food contains 45 substances your body needs but cannot manufacture.

Overview of Nutrients

The nutrients your body needs are water, carbohydrates, fats, proteins, vitamins and minerals.

WATER – Most of the bodies reactions take place in water. Humans need an average of 1 liter of water a day. Dehydration causes many problems throughout the body.

CARBOHYDRATES – Sugars and starches are used by the body to provide the simple sugars needed for Respiration (energy)

FATS- Deposits of fats protect body organs, insulate the body and store energy, make up cell membranes and coat the nervous system cells

PROTEINS – Supply the raw materials for growth and repair in the form of enzymes

VITAMINS – Organic molecules that work with enzymes to control body processes.

MINERALS – Inorganic nutrients that are needed in small amounts. Calcium is needed to build bones, Iron is needed for red blood cells.

Fats

Sugars

Food Guide PyramidA Balanced Diet

C. The Digestive System

Pharynx

Esophagus

Liver

Gallbladder

Rectum

Mouth

Salivary Glands

StomachPancreas behind stomach

Large Intestine

Small Intestine

The Process of Digestion: The path of food

Each organ of the digestive system helps convert foods into simpler molecules that can be absorbed and used by the cells of the body.

Teeth – Cut, Crush and tear food

Salivary glands – Moisten food to make it easier to chew and pass through the system, enzymes break down starches

Esophagus – Tube from mouth to stomach connected by Pharynx. Works by contraction of the smooth muscles known as peristalsis.

Stomach – Muscular sac that churns and mixes food with acid

Section 38-2

As food leaves the stomach it travels into the small intestine through the doudenum, and it mixes with with enzymes and digestive fluids from the liver, gallbladder and pancreas.

Liver

Gallbladder

Doudenum

Bile Duct

Pancreas

. Chemicals from the pancreas breakdown carbohydrates, proteins, lipids and nucleic acids. In addition chemicals from the pancreas produce substances which neutralize stomach acid.

If the acid travels too far without being neutralized it will change the shape of enzymes and cause problems in the body.

The Liver makes bile which acts like a detergent to break down fat. The gall bladder is a storage area for the bile

Small Intestine

Villus

Section 38-2

The small intestine absorbs nutrients from the digestive systems and transfers many of the nutrients to the circulatory system. The small intestine is lined with small fingerlike projections known as villi which designed to have a large surface area for this task.

Large intestine (Colon)

Food that enters the large intestine is nutrient-free. Usable nutrients have been absorbed leaving water and undigestible substances. The large intestine removes water from the waste. Once water is eliminated the solid waste passes out of the body through the rectum.

The appendix is located just below the entry to the large intestine. In many animals it

helps digest difficult materials such as cellulose. In humans the appendix is not used for any purpose

in digestion. When it gets infected it is removed.

D. Excretory System:

In the process of obtaining nutrients and carrying out chemical reactions the human body produces wastes (CO2, Urea, Salts). If some of these wastes are not removed they could threaten homeostasis. Excess chemicals that are not toxic also need to be removed.

The skin, lungs and kidneys all function to get rid of excess or harmful products

produced in the body.

Kidney Nephron

Section 38-3

Kidneys contain millions of small filters called nephrons, which filter your entire blood supply every 45 minutes. Filtration takes place because blood pressure forces water, salt, glucose, amino acids and urea into structures known as Bowman’s capsules. (Protein and Blood are too large to enter)

Bowman’s Capsule

Processes of osmosis and active transport filter the useful materials from the waste (urine). Substances your body needs to keep are returned to the blood stream. Substances your body needs to get rid of are passed from the renal tubes to the urinary bladder.

Kidney

Urinary Bladder

Ureter

Urethra

Vein Artery

Other important parts of the bodies excretory system

•The skin excretes excess water and salts

•The lungs excrete carbon dioxide produced from respiration

Both of these body organs serves multiple functions

in the human body.

Section 37-3

Figure 37-13 The Respiratory System

Bronchi branch to air sacs known as aveoli where gas exchange occurs

The Respiratory System links to the Circulatory System to provide cells with oxygen and remove carbon dioxide

Alveoli

Bronchiole

Capillary

Section 37-3

Gas Exchange in the lungs occurs through the process of

DIFFUSION

High concentration of oxygen (O2) moves out of lungs into blood to balance concentration. CO2 does the opposite (moves from blood to lungs)

Air inhaled

Diaphragm

Rib cage rises

Air exhaled

Diaphragm

Rib cage lowers

InhalationExhalation

Section 37-3

Figure 37-15 The Mechanics of BreathingThe Lungs are only air sacs. In order for them to move they must work together with a muscle known as the Diaphragm

Breathing is not an entirely voluntary process. While you have control of breathing so that you can briefly hold your breath or blow up a balloon, your body will not allow you not to breathe. The brain has control over the diaphragm if the level of carbon dioxide in the blood rises to high.

The circulatory system works together with several other body systems to bring needed supplies to cells which cannot move. The circulatory system is a delivery system that consists of the following:

• The Heart

• Blood Vessels

• Blood

The Heart: The heart is about the size of a clenched fist. On average the heart contracts about 72 times a minute, pumping about 70 milliliters of blood with each contraction.

The entire circulatory system including Heart has structures which prevent oxygen rich blood and oxygen poor blood from mixing. All blood is really red but oxygen poor blood is shown as blue in pictures for ease.

The heart has four main chambers with valves that separate each to prevent backflow

Left Ventricle

Left Atrium

Pulmonary Artery

Oxygen poor blood to lungs

The heart acts as two pumps. One for sending oxygen poor blood to the lungs and the other for sending oxygen rich blood to the body.

The heart’s contractions are controlled by a small group of cardiac muscle cells known as the sinoatrial node. These are the pacemakers of the heart. These cells send an electrical message from the atrium to the ventricles to contract

Sinoatrial Node

Atrioventricular node

Conducting

Fibers

Blood moves through 3 different types of vessels:

Arteries – Carry oxygen rich blood away from the heart

Capillaries – Tiny vessels only one cell thick. Bring oxygen and nutrients to the cells. Remove waste products.

Veins – Carry blood back to the heart with wastes

ARTERY VEIN

CAPILLARIES

Blood Pressure:

When the heart contracts it produces pressure in the arteries. The force of the blood on the arteries is known as blood pressure. Blood pressure decreases when the heart relaxes but it does not disappear. The difference between the two pressures is what is measured when you go to the doctor and have your blood pressure checked.

The average adult’s blood pressure is 120/80.

Blood

The Human body contains 4 to 6 liters of blood, which is about 8% of the total body mass. Blood is made up of a number of types of cells and substances:

55% Plasma – mostly water with dissolved gases, salts, nutrients, enzymes, hormones, waste products and plasma proteins.

45% Cells – Red Blood cells, White Blood Cells, and platelets.

Whole Blood Sample

Plasma

Sample Placed in Centrifuge

Blood Sample That Has Been Centrifuged

Cells

Red blood cells transport oxygen on an iron containing protein called hemoglobin. They are shaped like flat disks so that they have maximum surface area and don’t get caught in the blood vessels.

Your body produces red blood cells in bone marrow and each one circulates for about 120 days. RBC’s are destroyed by the liver and the spleen.

Mature red blood cells do not have a nucleus.

Platelets and plasma proteins work together to make sure that too much blood is not lost.

1. Injured blood vessel

2. Platelets clump at site and release Thrombin

3. Fibrin forms from Thrombin and clot stops blood loss

White Blood cells (also known as Leukocytes) are also produced in the bone marrow but do not have hemoglobin for carrying oxygen. They contain nuclei and live anywhere from a few days to a few months. They carry out an entirely different function than the Red Blood Cells.

White blood cells are the army of the

circulatory system. They attack

foreign substances or organisms.

Normally the body contains 700 times more red blood cells than white blood cells.

The body can increase the number of white blood cells on demand if the body is threatened by a foreign invader. Doctors often test for increased White Blood Cell levels to check your health

Thymus

Thoracic

Duct

Spleen

Heart

Superior Vena

Cava

Lymph Nodes

Lymph Vessels

F. The Lymphatic system collects fluid that leaks into body tissues and returns it to the circulatory system.

Lymph nodes are also filters that collect invaders that cause disease.

G. The Integumentary system or Skin is the bodies largest organ. It serves many purposes and overlaps with many of the body systems.

• Serves as a barrier against infection and injury

• Helps regulate body temperature

• removes excess salts and water

• Protects internal cells from UV radiation

• Serves as one link between the nervous system and the environment (receives information on pressure, temperature, pain)

The skin is made of 2 main layers

1. Epidermis – Outer layer of skin which comes in contact with environment.

•The outermost layer is coated in dead cells.

•The inner epidermis rapidly divides to produce a constant supply of new cells, constantly pushing old cells to the top.

• As skin cells are forced upward they flatten and organelles disappear and they form a layer of waterproof covering

2. Dermis – Inner layer of the skin containing blood vessels, nerve endings, sweat glands, oil glands, sense organs, hair follicles.

Epidermis

Dermis

Hair and Nails are made up of a substance known as keratin. They are both used to protect the skin from damage:

• Fingernails and toe nails protect the tips of your toes and fingers

•Hair on your head protects from UV rays

•Eyelashes, Nose Hair and Ear Hair prevent dirt and other particles from entering the body.

REGULATION of the HUMAN BODY

How does the Human Body Control (Regulate) all these body systems and make them work together?

Electrical Impulses from the Nervous System

Chemical Hormones from the Endocrine System

The Nervous System:The nervous system is the number one communication center of the body. The basic cell type that carries the communications is a network of neurons that transmit electrical impulses.

Axon terminals

Nodes

Myelin Sheath

Cell Body

Nucleus

Dendrites

NEURON CELL

Electrical Impulses depend on the movement of negatively charged electrons compared with the positively charged ions across a cell membrane

Once and impulse begins it moves along the axon in the direction of the impulse. To pass between neurons the impulse must be sent across a gap known as a synapse which sends the message from one neuron to the other.

When the impulse reaches the end of the axon it transfers its impulse to another cell by releasing chemicals known as neurotransmitters which pass the message across the synapse.

Synapse

The nervous system is divided into two divisions:

• The Central Nervous System (CNS)– Responsible for relaying messages, processing and analyzing information.

• The Peripheral Nervous System – Receives information from the environment and relays commands from the CNS to the organs and glands

The brain is the main switching area of the central nervous system.

Cerebrum – Responsible for voluntary activities of the body (Intelligence, learning and judgement)

Cerebellum – Coordinates muscle movement

Brain Stem – Consists of the pons and the medulla oblongata. Pass message between brain and body

Thalamus – Connects messages from the sense organs to the Cerebrum

Hypothalamus - Controll center for hunger, thirst, anger and body temperature.

Cerebrum

Thalamus

Hypothalamus

Pituitary Gland

Pineal Gland

Cerebellum

Spinal CordPons

Medulla oblongata

The Brain

The Endocrine System

Sends messages throughout the body by way of chemicals known as hormones. Hormones travel throughout the bloodstream to target cells which contain matching receptors.

Hormone

Receptor

If a cell does not have a specific receptor the hormone will not affect the cell.

Responses to hormones take longer and last longer than nervous system messages.

Hormones can take minutes, hours or days to influence cells.

Examples of functions controlled by hormones:

Growth, Metabolism, Sleep, Reaction to stress, Reproduction.

The Endocrine System works through a FEEDBACK system. Glands of the Endocrine system determine the level of a hormone in the blood and then changes the rate of hormone production or sends out the opposite hormone to counteract excess amounts of hormone.

Examples of Feedback mechanisms:

Control of insulin/sugar levels in blood

Hypothalamus can measure water level in blood and sends out hormones that tell the kidneys to conserve water.

Room temperature increases

Thermostat senses temperature change and switches on heating system

Thermostat senses temperature change and switches off heating system

Room temperature decreases

Section 35-1

Example of Feedback Loop

Beta cells release insulin into the blood

Body cells absorb glucose

Blood glucose level decreases

Homeostasis: Normal blood glucose level

Blood glucose level decreases

Alpha cells release glucagon into blood

Liver converts glycogen to glucose

Blood glucose level increases

Blood glucose level increases

Liver converts glycogen to glucose

Feedback Actions of Insulin and Glucagon

Important Glands and Hormones of the Human Body

Gland Hormone Function

Pineal Melatonin Controls sleep and wake cycle

Thyroid Thyroxine Controls appetite and metabolism

Adrenal Adrenaline Deals with stressful situations

Thymus Thymosin T-cell development (fight diseases)

Ovary Estrogen Female reproduction

Testis Testosterone Male reproduction

Hypothalamus

Pituitary

Parathyroids

Thymus

Adrenal Glands

Pineal Gland

Thyroid

Pancreas

Ovary (female)

Testis (male)

K. The Reproductive System

Functions to make new individuals by producing, storing and releasing specialized sex cells known as gametes.

Cells from the male reproductive system, known as sperm, must fuse with cells of the female reproductive system, known as eggs.

Reproduction in both males and females is regulated by hormones.

•In males - Testosterone is produced by the testes. It is required for sperm production and development of male physical characteristics.

•In females - Estrogen and progesterone are female hormones produced by the ovaries. Estrogen is required for the development of eggs

and female physical characteristics. Progesterone prepare the uterus for the arrival of

a developing embryo.

Neither males or females are capable of producing active reproductive cells until puberty, which is a period of sexual maturation.

Puberty begins when the hypothalmus signals the pituitary to produce increased levels of hormones that affect the sex organs (gonads). The hormones are follicle stimulating hormone (FSH) and luteinizing hormone (LH).

In both the male and female reproductive system sex cells are produced by the process of Meiosis.

Meiosis involves producing a cell with only 1 copy of each chromosome (haploid nuclei). When the egg and sperm fuse, a cell with two copies of each chromosome is created. Every cell in the new individual has two copies of each chromosome (diploid nuclei).

The Male Reproductive System

Urinary Bladder

Vas deferens

Pubic Bone

Urethra

PenisEpididymis

Testis

Scrotum

Seminal Vesicle

ProstateRectum

Bulbourethral gland

Sperm development:

1. Sperm are made from special cells in testes that undergo the process of meiosis.

2. Once sperm mature they move through a tube known as the vas deferens upward from the scrotal sacs into the abdomen into the seminal vesicle. The sperm mixes with seminal fluid to form semen. Between 50 and 130 million sperm are present in one milliliter of semen. The seminal vesicle merges with the urethra (also connected to the urinary bladder)

3. During sexual excitement the nervous system of the male contracts the glands of the reproductive tract. The release of semen is controlled by the autonomic nervous system so it is not entirely voluntary. The male reproductive system is designed to deliver sperm into the female reproductive system.

The Female Reproductive SystemSection 39-3

Fallopian TubeOvary

Uterus

Urinary Bladder

Pubic Bone

Urethra

Cervix

Rectum

Vagina

1. The ovaries produce one mature ova or egg per month. Females are born with 400,000 immature eggs which are stored in follicles. The follicle assist in the maturing process of an egg from each ovary once a month based on a signal from the FSH hormone.

2. When the egg matures the follicle breaks open releasing the egg into the fallopian tube. A process known as ovulation. Fertilization occurs in the fallopian tube if sperm is present.

3. The fallopian tube connects to the uterus which is a cavity designed to protect and nourish a developing embryo.

4. If fertilized egg enters the uterus it is implanted into the lining of the uterus and the embryo develops. If fertilization does not occur the egg is discharged out of the body along with the uterus lining through a canal known as the vagina. Known as MENSTRUATION

5. The endocrine system controls the cycle of events surrounding ovulation through a feedback mechanism that can signal the presence of a fertilized egg. While the egg is maturing and preparing for release the uterus is preparing for a fertilized egg by building up the lining of the uterus. A new lining must be created each month to prepare for nourishing the embryo.

The Menstrual Cycle

Meiosis I

Section 11-4

Figure 11-15 Meiosis

Meiosis I

Section 11-4

Figure 11-15 Meiosis

Meiosis I

Meiosis I

Section 11-4

Figure 11-15 Meiosis

Meiosis I

Section 11-4

Figure 11-15 Meiosis

Meiosis I

Section 11-4

Figure 11-15 Meiosis

Meiosis I

Meiosis II

Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.

Prophase II Metaphase II Anaphase II Telophase IIThe chromosomes line up in a similar way to the metaphase stage of mitosis.

The sister chromatids separate and move toward opposite ends of the cell.

Meiosis II results in four haploid (N) daughter cells.

Section 11-4

Figure 11-17 Meiosis II

Meiosis II

Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.

Prophase II Metaphase II Anaphase II Telophase IIThe chromosomes line up in a similar way to the metaphase stage of mitosis.

The sister chromatids separate and move toward opposite ends of the cell.

Meiosis II results in four haploid (N) daughter cells.

Section 11-4

Figure 11-17 Meiosis II

Meiosis II

Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.

Prophase II Metaphase II Anaphase II Telophase IIThe chromosomes line up in a similar way to the metaphase stage of mitosis.

The sister chromatids separate and move toward opposite ends of the cell.

Meiosis II results in four haploid (N) daughter cells.

Section 11-4

Figure 11-17 Meiosis II

Meiosis II

Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.

Prophase II Metaphase II Anaphase II Telophase IIThe chromosomes line up in a similar way to the metaphase stage of mitosis.

The sister chromatids separate and move toward opposite ends of the cell.

Meiosis II results in four haploid (N) daughter cells.

Section 11-4

Figure 11-17 Meiosis II

Meiosis II

Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.

Prophase II Metaphase II Anaphase II Telophase IIThe chromosomes line up in a similar way to the metaphase stage of mitosis.

The sister chromatids separate and move toward opposite ends of the cell.

Meiosis II results in four haploid (N) daughter cells.

Section 11-4

Figure 11-17 Meiosis II

Meiosis II

Prophase II Metaphase II Anaphase II Telophase II

Section 11-4

Figure 11-17 Meiosis II

Meiosis produces specialized cells known as gametes

Each gamete must contain only half the number of chromosomes that the parent has. The gamete gets a mixture of chromosomes from the parent cells.