health course chapter 11

Section 11.1 Your Skeletal System

Your skeletal system has five main roles.Functions of the Skeletal System

• provides support• protects internal organs• allows your body to move• stores and produces materials that your body

needs


• Your skeleton is made up of all the bones inyour body.

Support and Protection

• Your skeleton gives your body its basic shape and provides the support that you need.

• Many bones of the skeletal system protect internal organs.


In coordination with your muscular and nervous systems, your skeletal system allows you to move.

Movement


• Your bones store essential substances which are released when other parts of the body need them.

Storage and Production of Materials

• Some bones also produce blood cells.


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The Skeletal System1) Sternum (breastbone)

2) Vertebral column (backbone)

3) Carpals

4) Metacarpals

5) Phalanges

6) Tarsals

7) Metatarsals

8) Phalanges

9) Clavicle (collarbone)

10) Scapula (shoulder blade)

11) Humerus

12) Ribs

13) Radius

14) Ulna

15) Pelvic girdle

16) Femur

17) Patella

18) Fibula

19) Tibia

Skull


• Your skeletal system is made up of just over 200 bones.

Bones and Joints

• A place in your body where two or more of your bones come together is called a joint.


• Your bones are living structures that undergo change throughout your life.

Development of Bones

• Cartilage is a tough supportive tissue that is softer and more flexible than bone.

• By young adulthood, most of this cartilage is replaced by bone in a process called ossification (ahs uh fih KAY shun).

• In a process called ossification minerals, such as calcium and phosphorus, are deposited within the cartilage, making it hard.


• Bone consists of two different types of tissue—compact bone and spongy bone.

Structure of Bones

• Another type of tissue called marrow fills the spaces in bones.

• There are two types of marrow—red and yellow.


Compact BoneCompact bone makes up theouter layer of all bones. Althoughit looks dense and solid, It is fullof holes for nerves and blood vessels.

Spongy BoneSpongy bone contains flatand needlelike structuresthat resist stress. Red bonemarrow may fill the openspaces in some bones.

Central CavityCentral cavities in long bones usually containyellow bone marrow (fat).

Outer MembraneAn outer membranecovers most of a long bone.The inner portion of a membrane contains cells that build up and breakdown bone.


• Joints allow for movement and protect bones from friction and force.

Joints

• Bones are held together at joints by strong, fibrous bands called ligaments.


Ball-and-Socket JointA ball-and-socket joint allows movementin all directions. Your shoulders and hipsare ball-and-socket joints.

Hinge JointHinge joints allow bending and straightening movements.Your knees and elbows are hinge joints.

Gliding JointGliding joints allowmovement in many directions as the bones slide along each other. Your wrists and ankles contain gliding joints.

Pivot JointA pivot joint connects yourhead to the first vertebra inyour backbone. It allows youto turn your head from side to side.


Active Art: The Skeletal and Muscular Systems

Click on the screen above to launch the Active Art.


• A combination of eating well, exercising, and avoiding injuries contributes to lifelong bone andjoint health.

Keeping Healthy

• Regular medical checkups can help detect skeletal system problems.


• Adequate intake of calcium and phosphorus will help your bones grow to their maximum size and strength.

Eating Well

• Osteoporosis is a condition in which the bones become weak and break easily.

• Other nutrients that are important for bone health include potassium, magnesium, and vitamins A, C, and D.


• Another way to build strong bones and prevent osteoporosis is to get plenty of weight-bearing exercise.

Exercising

• Activities in which the bones support the entire weight of your body help your bones grow strong and dense.


• A fracture is a break in a bone.Avoiding Bone Injuries

• You can protect your bones from fractures.

• When participating in a physical activity, wear appropriate safety equipment, such as helmets and pads.

• Always wear a seat belt when traveling in a vehicle.


Proper warm-up and stretching exercises are important to help prevent joint injuries.

Avoiding Joint Injuries

• Sprains A sprain is an overstretched or torn ligament.

• Dislocations In a dislocation, the ends of the bones in a joint are forced out of their normal positions.

• Torn Cartilage Serious damage to the cartilage between the bones in a joint is known as torn cartilage.

• Overuse Injuries When an activity is performed too often or too strenuously, joints may become irritated and inflamed.


• A doctor can advise you on how to prevent serious injury or recommend other professionals who can help you.

Medical Checkups

• A nurse or doctor may check your spine for scoliosis (skoh lee OH sis), an abnormal curvature of the spine.

Section 11.2 Your Muscular System

• Muscles move your eyes as you read.The Muscles in Your Body

• Muscles in your chest allow you to breathe.• Muscles in your heart pump your blood. • Every time your body moves, muscles are at work.


Your body has three types of muscle tissue that perform different functions.

Types of Muscle

• Smooth muscle is involuntary muscle that causes movements within your body.

• Cardiac muscle is involuntary muscle that is found only in the heart.

• Skeletal muscles are the muscles that you control to do activities, such as walk or play a musical instrument. A thick strand of tissue called a tendon attaches a muscle to a bone.


• All muscles do work by contracting, or becoming shorter and thicker.

How Muscles Work

• Many skeletal muscles work in pairs.• One muscle in the pair contracts to move the

bone in one direction.• Then, the other muscle in the pair contracts to

move the bone back.


Muscle Pairs

Biceps contracted

Biceps relaxedTriceps relaxed

Triceps contracted


• Even when a skeletal muscle is not contracting to cause movement, a few of its individual muscle fibers are still contracting.

Muscle Tone

• Contractions tense and firm the muscle.• This slight tension is called muscle tone.• Muscles that cannot contract due to injury, or are not

used often, will weaken and shrink, a condition known as atrophy.


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The Muscular System

1) Frontalis

2) Temporalis

3) Trapezius

4) Deltoid

5) Pectoralis major

6) Sartorius

7) Tibialis anterior

8) Biceps

9) Triceps

10) External oblique

11) Rectus abdominus

12) Quadriceps muscles

13) Gastrocnemius


• You can maintain a healthy muscular system by regularly participating in different types of exercise.

Keeping Healthy

• To help prevent injuries, exercise sessions should include a warm-up and cool-down period.


• Some types of exercise increase a muscle’s endurance—how long it can contract without tiring.

Working Your Muscles

• Other exercises make individual fibers grow, which causes the muscles to thicken and increase in strength.

• Anabolic steroids are artificial forms of the male hormone testosterone.


• Strains A muscle strain, or a pulled muscle, is a painful injury that may happen when muscles are overworked or stretched too much or too quickly.

Avoiding Muscle Injuries

• Tendonitis Overuse of tendons may lead to painful swelling and irritation called tendonitis (ten duh NY tis).

• Prevent injuries• regular strengthening and stretching exercises • vary your exercise routine • warm up and cool down • stop exercising if you feel a sharp or sudden pain


• A muscle cramp is a strong, uncontrolled muscle contraction.

Preventing Muscle Cramps

• To relieve a cramp, try massaging the affected area and exercising the limb gently.

• Stretching and drinking plenty of water before and during exercise can help you avoid muscle cramps.

Section 11.3 Your Nervous System

• Your nervous system receives information about what is going on inside and outside of your body.

What Is the Nervous System?

• Then it processes the information and forms a response to it.

• The basic unit of the nervous system is a type of cell called a neuron (NOOR ahn).


• Neurons carry messages, or impulses, from one part of your body to another.

Neuron Structure

• A neuron has three basic parts.• dendrites• a cell body• an axon


• Sensory Neurons Information about your external and internal environment is gathered by sensory neurons through your sense organs or other parts of your body.

Types of Neurons

• Interneurons Located only in the brain and spinal cord, interneurons pass impulses from one neuron to another.

• Motor Neurons Motor neurons send nerve impulses to muscles and glands.


Neuron StructureDendriteDendrites carry nerve impulses toward a neuron’s cell body.

Cell BodyThe cell body controlsthe cell’s basic functions.

AxonImpulses travel alongaxons toward other cells.

Myelin SheathSome axons are coveredby a myelin sheaththat increases the speedof an impulse.

SynapseThe junction betweenan axon and anothercell is a synapse. Chemicals called neurotransmitters passthe impulse from the sending neuron to thereceiving cell.


• The nervous system consists of two major divisions—the central nervous system and the peripheral nervous system.

Central Nervous System

• The central nervous system is the control center of the body. It includes the brain and spinal cord.

• The peripheral nervous system includes all the other parts of the nervous system.


• The cerebrum consists of several specialized regions that receive messages from sense organs, and control movement, memory, communication, and reasoning.

The Brain

• The cerebellum (sehr uh BEL um) coordinates your body’s movements and helps you keep your balance.

• The brain stem consists of three structures—the midbrain, pons, and medulla. These structures control many of your body’s involuntary actions.


• The spinal cord is a thick column of nerve tissue that links the brain to most of the nerves in the peripheral nervous system.

The Spinal Cord

• The spinal cord extends from the brain down the back.

• Spinal nerves are part of the peripheral nervous system.


• An automatic response to your environment is called a reflex.

Reflexes

• In some reflex actions, the actions of the skeletal muscles are controlled by the spinal cord only—not the brain.

• Reflexes help protect your body from harm because they enable you to react very quickly.


A Reflex ActionSensory neurons in yourhand send impulsesto your spinal cord.

Neurons in your spinalcord process the information and send commands directlyto motor neurons that control muscles in your arm and hand.

Your muscles contract andyou quickly withdraw your hand.

Meanwhile, messages of pain travelto the brain. Shortly after your arm moves, you feel pain.


• The peripheral nervous system includes the network of nerves that links the rest of your body to your brain and spinal cord.

Peripheral Nervous System

• The peripheral nervous system carries information to the central nervous system, and then carries responses from the central nervous system to the rest of the body.


• Some nerves in the sensory division carry information about your outside environment from your ears, eyes, and other sense organs.

Sensory Division

• Other sensory nerves carry information about internal body conditions such as blood pressure and heart rate.


• Somatic Nervous System Motor nerves in the somatic nervous system carry signals that control voluntary actions.

Motor Division

• Autonomic Nervous System Motor nerves in the autonomic nervous system regulate actions that happen automatically.


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1) Brain

2) Spinal cord

3) Peripheral nerves


• Rest, good nutrition, and daily exercise can help keep your nervous system functioning properly.

Keeping Healthy

• The most important step you can take to care for your nervous system is to protect it from injury.


• A bruiselike injury to the brain is known as a concussion.

Avoiding Head Injuries

• A coma is a prolonged period of deep unconsciousness.

• Head injuries can be avoided.• Wear a helmet when you play contact sports.• Fasten your seat belt.• Before diving into water be sure that it is deep

enough and that there are no underwater hazards.

• Avoid drugs and alcohol.


• Paralysis is the loss of the ability to move and feel some part of the body.

Avoiding Spinal Cord Injuries

• Spinal cord injuries can be avoided• Fasten your seat belt.• Take care when diving.• Avoid drugs and alcohol.


• Individual peripheral nerves also can be injured. Avoiding Nerve Injuries

• To help prevent carpal tunnel syndrome and similar nerve injuries, it is important to take breaks from repetitive motions and to maintain good posture.


• Nervous system infections are rare because its tissues are well protected.

Preventing Infections

• Meningitis (men in JY tis) causes inflammation of the membranes surrounding the brain and spinal cord.

• The most serious form of meningitis can be prevented with a vaccine.

• A bite from an infected animal can transmit rabies, an infection of the central nervous system.

• Avoid contact with animals that act sick or behave strangely.


• Sudden, uncontrolled nerve impulses in the brain can lead to a seizure.

Living with Epilepsy

• People with a disorder called epilepsy are prone to seizures.

• Epileptic seizures include facial twitching, loss of awareness, and muscle spasms.


• The most common problem of the nervous system that people experience are headaches.

Preventing Headaches

• Proper diet, exercise, and sleep can help prevent headaches.

• If you can identify certain foods or odors that trigger headaches, you may be able to avoid those triggers.

health course chapter 11

Education