PHYSIOLOGY OF EXERCISE

Ch. 28Option BPg 298

Muscles and MovementCh. 25 pg 264

Muscles and Movement

The movement in humans involves bones, ligaments, muscles, tendons and nerves.

Bones Provide anchorage for

muscles Act as levers,

changing size and direction of forces

Provide support for the body and protection to internal organs

Blood cell formation Metabolism of

calcium and other minerals.

Ligaments

Tough cords or sheets of tissue

Connect bones together Cover joints and

connections between bones.

Flexible to allow certain movement

Almost inelastic to prevent movement outside normal range of a joint and prevent dislocation

Muscles

Attach to bones and provide forces to change position of bones and the body.

Work in antagonistic pairs

Tendons

Tough cords or straps of tissue Connect muscles to bones Help to anchor muscles to bone and to

transmit forces generated by contraction of muscles.

Joints

These are the points where bones meet. There are many types of joints according to their movement, ex: fixed, ball and socket, pivot and hinge joints.

Joint’s structure:

Cartilage: though, smooth tissue that covers regions of the bone. Prevents contact between bones and absorbs shocks.

Synovial lubricates the joint and helps to prevent friction

Capsule: though ligamentous covering to the joint. Seals the joint, holds the synovial fluid and prevents dislocation.

Biceps and triceps: muscles connected to the humerus.

The striated muscle Muscle used for

movement – skeletal muscle.

Other types of muscle are smooth and cardiac.

Striated muscle is composed of bundles and muscle fibres

A sarcolema surrounds each muscle fibre

The striated muscle

Within each muscle fibre, there are many parallel elongated structures called myofibrils.

Between each myofibril are large numbers of mitochondria

Each muscle fibre contains many nuclei and a specialized E. R. called sarcoplasmic reticulum.

The striated muscle

Myofibrils consist of an alternating series of light and dark bands. In the center of each light band is a disk-shaped structure called the Z line. A part between one Z line and the other is called a sarcomere, the functional unit of a myofibril

The striated muscle

Two filaments compose myofibrils: thin actin and thick myosin filaments.

Actin filaments are attached to the Z line.

Myosin filaments are between actin filaments in the center of the sarcomere.

One myosin filament is surrounded by six actin filaments.

Together they form cross bridges during contraction shortening the length of the muscle fibre.

Questions

What is the role of ligaments in the elbow joint?

A. Attach biceps to radius

B. Reduce friction between humerus, ulna and radius

C. Hold humerus, ulna and radius in proper alignment

D. Secrete synovial fluid

The diagram below shows part of a muscle fibre. What parts are labelled I and II?

 I II

The unit between one Z-line and the next is termed:

A. Sarcomere B. MyofibrilC. Sarcoplasmic reticulumD. Sarcolemma

Distinguish between each of the following word pairs:

Hinge joint and pivot joint Radius and humerus Hip and knee joint Actin and myosin ADP and ATP Ligament and tendon Extension and flexion

Pysiology of Exercise

Muscles and Cellular Respiration

Muscles need to be supplied with oxygen for aerobic cell respiration and to get rid of the carbon dioxide. The pulmonary system plays an important role during exercise.

Exercise is physical activity, such as walking, running or swimming.

It involves muscle contraction which requires ATP.

In order for the lungs to provide oxygen and release carbon dioxide, concentration gradients must be maintained.

This is achieved when the blood returns to the lungs with less oxygen and more carbon dioxide than the air outside.

During exercise, more oxygen is needed; this is accomplished by increasing the tidal volume and ventilation rate.

Training and the Pulmonary System.-

Training is a program of exercise designed to develop a particular type of fitness. Athletes use training to improve their performance. Training changes both ventilation rate and vital capacity.

The maximum ventilation rate during exercise can increase by about 10% due to strengthening of muscles used in ventilation (diaphragm and intercostals muscles)

The ventilation rate at rest can drop by about 10 to 15 %. Because the efficiency of gas exchange is increased.

Vital capacity may increase, but only about 5%, this is referred to the lung capacity

Aerobic cell respiration and muscle fibers.-

Muscle fibers produce ATP to provide the energy for muscle contraction in three ways: aerobic cell respiration, anaerobic cell respiration and creatine phosphate.

Aerobic cell respiration and muscle fibers.-

AEROBIC RESPIRATION:

VO2 is the volume of oxygen that is absorbed by the body per minute and supplied to the tissues. As the intensity of the exercise increases, so does the VO2 until it reaches a maximum capacity, this is the VO2max, the maximum rate at which oxygen can be absorbed by the body and supplied to tissues.

Myoglobin is used to store oxygen in some muscle fibers. It releases oxygen during periods of intense exercise allowing aerobic respiration to continue for longer periods of time. The reserves of myoglobin are limited, and after they are finished, the body has to find other supplies of oxygen. These other sources are: aerobic respiration and creatine phosphate.

Aerobic respiration can either use fat or carbohydrate as a substrate. Carbohydrates are metabolized faster than fat.

Risks and benefits of EPO and blood transfusions.-

Human blood varies in the relative amounts of cells and plasma.

This can be measured calculating the packed cell volume (PCV) from the blood contents that have been centrifugated.

Some athletes try to increase their PCV artificially. One method is using erythropoietin (EPO), a naturally occurring hormone that stimulates the production of red blood cells.

Other method is to transfuse blood into the athlete.

Both of these methods increase performance in endurance events involving intense exercise. However, this also causes increases in the risk of strokes and heart attacks as a result of blood clot formation.

Anaerobic cell respiration in muscle fibers.-

Anaerobic respiration is used to provide ATP during intense exercise when oxygen cannot be supplied rapidly enough.

Only glucose can be used as a substrate, and lactate is produced as a toxic waste product that accumulates in muscles and blood.

It can only occur in short periods of time.

The lactate has to be converted back to pyruvate, which requires oxygen.

The oxygen needed to convert lactate into pyruvate is called oxygen debt. In order to repay it, the body needs to continue deep ventilation after vigorous exercise.

Creatine Phosphate.-

Creatine phosphate + ADP creating + ATP

This is also an anerobic reaction. Muscle fibers only contain enough creatine phosphate for ATP to be produced for 8 – 10 seconds during vigorous exercise. During rest, ATP has to be used to remake the creatine phosphate.

Some athletes take creatine phosphate as a dietary supplement to try to increase their performance in high intensity exercise, but there is no evidence if improve while there is evidence of increased fluid retention.

Fast and slow muscle fibers.-

Striated muscle fibers vary in their structure and activity. There are two main types of muscle fibers: fast and slow. Slow muscle fibers are also called type I and fast are called type II. Proportions vary depending on the person.

Fast and slow muscle fibers.-

Slow muscle fibers Fast muscle fibers

- Excellent body supply, many blood capillaries - Moderate blood supply

- Large amounts of myoglobin (intense red color)

- Little myoglobin (pale in color)

- Many mitochondria (rich in oxidative enzymes)

- Few mitochondria (rich in enzymes for glycolysis)

- Large aerobic capacity - Contract more rapidly

- Strength is moderate - Great strength

- Contain some glycogen but mostly rely on respiratory substances supplied by the blood system during exercise.

- Contain larger stores of glycogen as a fast source of glucose.

- Very high stamina - Low stamina (rapid accumulation of lactate)

- Moderate intensity exercise promotes its development.

- High intensity exercise promotes its development.

Fitness

is specific for every particular activity. Training can improve fitness, especially by improving pulmonary and cardiovascular function, but there may also be an inherited element.

Fitness can be assessed in various ways. Two types of measure are speed and stamina: Speed is the rate at which a movement is

performed Stamina is the ability to continue an exercise for a

long time.

Injuries.-

Muscles and joints are both vulnerable to injury. Five injuries are described: Sprains: injuries to the joints, result in pain and disability,

involve stretching and damage to the ligaments of the joint, with pain and swelling.

Torn ligaments are caused by severe sprains, strong enough to tear ligaments. Surgery is sometimes required.

Joint dislocation is movement of the bones at a joint beyond their normal range. Ligaments are thorn in the process, so the bones may become dislocated.

Torn muscles are due to excessive muscle exertion. Produces a sharp pain and sometimes also snapping sensation.

Inter-vertebral disc damage, caused by a soft pulpy core of an inter-vertebral disc to bulge out through the side wall. The bulge often presses the spinal nerve with consequent pain in the area served by the nerve.

Warming up.-

involves stretching or gentle exercise. Reasons for warming up include: Venous return to the heart may increase, allowing the

heart rate to rise Blood flow to muscles may increase, supplying more

oxygen and allowing the rate of aerobic cell respiration to rise.

Muscles may become warmer. More vigorous and rapid muscle contractions and

improved performance. Mental preparation for competition Causes adrenaline to be secreted, preparing the body

for physical activity. Prevents injuries in muscles, tendons and ligaments.

Performance-enhancing substances.-

many substances have been used to try to enhance performance in sport.

Some are effective legal and safe.

Others are ineffective or have been banned.

Once case is the use of anabolic steroids, a group of chemical substances, related to testosterone, which can cause tissue growth and increase strength. Some harmful side effects include: in woman irregular periods, in men decreases in size of the testes and low sperm counts; liver diseases, psychological effects including emotional problems, increase in injuries such as torn muscles and tendons.

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