THE MUSCULAR

SYSTEM Module #6 – To Understand the Structure and Function of

Muscles

YOUR AMAZING MUSCULAR SYSTEM:

You have about 650 muscles in your body.

There are over 150 just in your head and neck!

Your muscles make up 50% of your body weight.

Muscle tissue is three times more efficient at burning calories than fat.

Your muscle cells produce enough heat every day to boil almost 2 pints of water for an hour.

Your tireless heart beats more than 4500 times each hour.

Smile! You've just used about 30 muscles. Muscles control your eyelids, nostrils and brow. They work together to show the slightest change in your emotions.

MUSCLES ARE IMPORTANT BECAUSE

THEY…

Hold your organs in place

Hold your bones together so

that you can move

Help you chew your food

Open and close your eyelids

Pump your blood

Allow you to move and

exercise

Enable you to have good

posture

TYPES OF MUSCLES

THE MAJOR MUSCLES AND

ACTIONS

MUSCLE FIBER TYPES

WHAT HAPPENS DURING

EXERCISE

HOW MUSCLES WORK

TYPES OF CONTRACTION

POSTURE

MUSCLES

THE THREE TYPES OF MUSCLE

1. Cardiac Muscle (Heart)

2. Smooth or Involuntary Muscle

3. Skeletal/Striped or Voluntary Muscle

BASIC FEATURES OF A SKELETAL MUSCLE

Muscle attachments Most skeletal muscles run

from one bone to another

They are under our conscious control

We use them to run, jump, walk

One bone will move – other bone remains fixed

Origin – less movable attachment

Insertion – more movable attachment

THE MAJOR SKELETAL MUSCLES

Abdominals (4)

Quadriceps (4)

Hamstrings (3)

Gluteals (3)

Pectorals

Anterior Tibialis

Gastrocnemius

Lattissimus Dorsi

Trapezius

Deltoid

Triceps

Biceps

MUSCLE MAIN ACTION Deltoid

Biceps

Abdominals

Quadriceps

Pectorals

Latissimus Dorsi

Trapezius

Triceps

Gluteals

Hamstrings

Gastrocnemius

Anterior Tibialis

Raises your arm sideways at the shoulder

Bends your arm at the elbow

Pull in your abdomen, Flex your trunk so you can bend forward.

Straighten your leg at the knee and keep it straight when you stand

Raises your arm at the shoulder. Draws it across your chest.

Pulls your arm down at the shoulder. Draws it behind your back.

Holds and rotates your shoulders. Moves your head back and sideways.

Straightens your arm at the elbow

Pulls your leg back at the hip. Raise it sideways at the hip. Gluteus Maximus is the largest muscle in body.

Bend your leg at the knee

Straightens the ankle joint, so you can stand on your toes.

Works opposite of the gastrocnemius to pull foot towards knee

MUSCLES MUST WORK IN PAIRS:

Muscles can only contract: If one muscle contracts to bring bones together, another muscle must contract to bring the bones apart (a bicep /tricep contraction, to bend the arm)

We need large numbers of pairs of muscles to work together in different ways for even simple body movements.

Our muscles take on different roles depending on the movement they are to perform.

ANTAGONISTIC MUSCLES: THEY WORK IN PAIRS

MUSCLE ATTACHMENTS: TENDONS ATTACH

MUSCLES TO BONE

SMOOTH OR INVOLUNTARY MUSCLES

These muscles work automatically – they are not under our conscious control.

They fatigue..but very slowly

Found in the digestive system: stomach, esophagus, intestines, control digestion

Found in the respiratory system: lungs, diaphragm, control breathing

Found in urinary system: bladder, controls urination

CARDIAC MUSCLE

Cardiac is a special type of involuntary muscle

It is only found in the heart

It works automatically but under constant

nervous system and chemical control.

Contractions of the heart muscle pump blood

throughout the body and account for the heart

beat

Healthy cardiac muscle never fatigues or else…

HOW DO OUR MUSCLES WORK?

There are three main types of muscular contraction:

Isotonic and concentric: muscles shorten as they contract,

the ends of the muscle move closer together (like in a

biceps during a pull up), most sport moves are this type of

contraction

Isotonic and eccentric : muscles lengthen as they contract,

the ends move farther apart, (like the biceps when lowering

down from a pull up), plyometrics

Isometric: muscles stay the same length when contracting,

there is no movement, (like your shoulders in a tug of war),

in sporting events the stabilizing muscles hold parts of the

body steady as other parts move

HOW ARE MUSCLES ATTACHED TO BONES?

Muscles are usually attached to 2 or more

different bones

The muscle fibers end in s strong, white fibrous

cord called a tendon

This anchors the tendon strongly and spreads

the force of the contraction

Tendons attach muscle to bone

Ligaments attach bone to bone

MUSCLE FIBER TYPES:

There are two different types of muscle fibers:

Slow Twitch: have a very good oxygen supply, work for a long

time without fatigue, are not as strong as fast twitch, take

longer to contract, are used in all types of exercise (especially

aerobic activities).

Fast Twitch: do not have a good oxygen supply, tire

very quickly, are stronger than slow twitch, are used in

powerful, fast, movements, are used in high intensity exercise,

used in anaerobic activities

MIXTURE OF MUSCLE FIBERS:

Every muscle contains a mixture of fast and slow twitch muscle fibers, but…

The mixture is different in every muscle, for example the gastrocnemius muscle contains a lot of fast twitch fibers so standing on your toes is tiring.

The mixture is also unique to each individual. Some distance runners have 80% slow twitch while some power lifters have 80% fast twitch.

WHAT DOES THIS MEAN FOR SPORTS

PERFORMANCE?

The more fast twitch fibers you have the more

you are suited for sports requiring bursts of

strength and power.

Consider two sprinters X and Y. They both are

the same age, weight and fitness level. X has

75% fast twitch fibers in his legs and Y only has

55%. Physiologically, X is suited better for

sprinting than Y.

MUSCLE FIBERS AND SPORT

If we jog slowly, only a few of our slow twitch fibers contract to move our legs. When we increase our speed we use more slow twitch fibers. As we run faster our fast twitch fibers also start to contract to help out. More and more fibers will start to contract as we run even faster. At our top speed all or our fast twitch and slow twitch fibers will be working.

Our muscle change based on activity:

Muscle hypertrophy – the muscle increases

in size with resistance training

Muscle atrophy – muscle decreases in size

(“Use it or lose it”) when it is not used

MUSCLE TONE: Even when a muscle is relaxed, a small number of fibers are

contracted – enough to keep the muscle taut but not enough to cause movement.

This partial state of contraction is referred to as “muscle tone”. Without muscle tone you would not be able to stand up straight.

To maintain muscle tone without getting tired, groups of muscles take turns in contracting. They

work in relays.

Poor muscle tone leads to poor posture.

Exercise improves muscle tone – it makes

the fibers thicker so they may contract

stronger.

WHAT HAPPENS TO OUR MUSCLES AS WE

EXERCISE?

There is an increased flow of blood to the working muscles.

Muscles take up more oxygen from the blood.

The muscles contract more often and more quickly.

More of the muscle fibers contract

There is a rise in the temperature of the muscle

Waste products such as carbon dioxide and lactic acid build up in the muscles, these products lead to tiredness and cramps

Stores of muscle glucose are expended

Our ability to continue exercising may be affected

Overuse of muscles can lead to soreness, strains and stress fractures.

QUESTIONS???? 1. How many muscles do you have in your body? (1 point)

2. List 4 different functions of your muscles. (2 points )

3. Explain the 3 types of muscles. A minimum of 4 sentences for each type. (12 points)

4. List four major muscle groups and the action they create. (8 points)

5. Explain how muscles work in pairs. (2 points)

6. List and describe the 3 types of muscular contraction. Give an example of each type of contraction (not the ones listed). (6 points)

7. Describe the two types of muscle fibers. What sports would be suitable for each type? List at least three per type. (5 points)

8. How do muscles change based on activity? (2 points)

9. What is muscle tone? How does it affect us on a daily basis? (2 points)

10. List and explain 3 actions that occur when are muscles are being exercised. (3 points)

43 points possible