Sport Science physiology 144 self-made practice test. Can be used to test yourself on work fro tests. Contains questions and answers. Made using notes from lecture slides, textbook and class notes. Made in 2017.
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Physiology 144 Practice Test (MEMO)
1. Name and describe the three muscle tissue types.
There are three types of muscle tissues.
• Cardiac muscle – forms the walls of the heart, striated, involuntary, contract at a
steady rate
• Smooth muscle – forms the walls of hollow visceral organs, no striations,
voluntary, contract at a slow and sustained rate
• Skeletal muscle – forms smoother contours of the body, striated, voluntary,
contract rapidly with great force for short periods.
2. What are the functions of skeletal muscle?
Skeletal muscle has 4 functions: to produce movement, to maintain posture, to stabilize
joints and to generate heat (energy from contractions)
3. Describe the structure of a muscle.
The structure of a muscle from inner layer to outer layer is:
• Muscle fiber (muscle cell)
• Each surrounded by endomysium
• Group of muscle fibers forms a fascicle
• Fasicle surrounded by perimysium
• Group of fascicles forms a muscle
• Surrounded by epimysium
• Muscles ends in a tendon
• Tendon attached to bone
4. Describe the structure of a muscle fiber.
Muscle fibers have multiple nuclei. The nuclei are pushed to the sides of the cell by the
myofibrils. Myofibrils are chains of contractile fibers called sarcomeres. Sarcomeres are the
functional unit of muscles. Sarcomeres are made of myofilaments. There are two protein
myofilaments: Actin and Myosin. Actin is the thin band that attaches to the Z line of the
sarcomere. Myosin is the fat/thick band which contains ATPase enzymes for contraction
energy.
5. Name and describe the four properties of skeletal muscle.
Four properties:
• Irritability – ability to receive and respond to stimulus
• Contractibility – ability to forcibly shorten
• Extensibility – ability to be stretched
• Elasticity – ability to recoil and return to resting length
6. Describe the nervous set up for muscle stimulation.
One neuron and all the muscle fibers that it stimulates is called a motor unit. The point
where the sarcolemma (membrane) meets the axon terminal is called the neuromuscular
junction. The specific neurotransmitter for skeletal muscle contraction is called acetylcholine
(Ach).
7. How is a contraction stimulated? (excitation)
• The nerve impulse reaches the axon terminal
• Calcium is released into the terminal
, • Calcium stimulates the release of acetylcholine by exocytosis
• Ach diffuses across the synaptic cleft and attaches to receptors
• Depolarization occurs
• An action potential is generated
• The muscle is stimulated to contract
• Ach then broken into acetic acid and choline by acetylcholinesterase (enzyme)
• This ends the stimulation
8. Describe the Sliding Filament Theory.
During a contraction, the actin (thin) and myosin (thick) bands move closer together. This
means that the H zone shortens, the I band shortens BUT the A band stays the same. There
are two other proteins in the sarcomere: troponin and tropomyosin. Troponin sits on top of
the tropomyosin which covers the actin binding site. In order for a contraction to occur, the
binding site must be uncovered.
• Muscle is stimulated (excitation)
• Calcium (sarcoplasmic reticulum) is released into the cytoplasm
• Calcium stimulates the troponin to pull the tropomyosin away from the actin binding
site.
• This allows actin and myosin to bind
• Myosin pulls the actin toward the M line
• The Z lines move closer together, invoking a contraction
• When the action potential (stimulation) ends, calcium is reabsorbed
• The muscle then relaxes and returns to its original length
9. Give three functions of ATP in muscle contraction.
ATP is used to help bind actin and myosin, to split actin and myosin and to return the
calcium to the sarcoplasmic reticulum by active transport.
10. Name and describe the three types of muscle contraction.
Isotonic contraction – sliding of the myofilaments is successful, muscle shortens
Isometric contraction – tension in the muscle builds, muscles doesn’t shorten
Eccentric contraction - unbinding of myofilaments, muscles lengthens
11. Describe three ways that muscles get energy for contractions.
ATP molecule bonds are hydrolysed which releases energy. ATP is the only source of energy
for skeletal muscles. Very little ATP is stored in the muscles. It must be generated in one of
three ways:
1. Phosphorylation of ADP by Creatine Phosphate - ADP and CP interact which
causes a high-energy phosphate group to transfer to ADP. ATP is then
regenerated. This energy supply is soon exhausted.
2. Aerobic respiration – Glucose is broken down into carbon dioxide and water. As
bonds break, energy is released which is captured by ATP. Involves the use of
oxygen, rich energy supply that acts slowly. Best for light exercise.
3. Anaerobic respiration – involves the process of glycolysis (glucose broken down
into pyruvic acid and small amounts of energy). Pyruvic acid is converted into
lactic acid. It uses a large amount of glucose for a small ATP harvest but it is very
fast.
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