STUDY POINTS HANDOUT Chapter 10 (KEY)

BIOL 2401 STUDY POINTS HANDOUT Chapter 10 (KEY)

1. What structures shown releases calcium ions to trigger muscle contraction?

The sarcoplasmic reticulum releases calcium ions to trigger muscle contraction.

2. Which proteins are present in the A band? In the I band?

A bands contain myosin, actin, troponin, tropomyosin,

3. Which of the following is the smallest: muscle fiber, thick filament, or myofibril? Which is the largest?

The following are arranged from smallest to largest: thick filament, myofibril, muscle fiber.

4. What happens to the I band and H zone as muscle contract? Do the lengths of the thick and thin filaments change?

The I bands and H zones disappear during muscle contraction; the lengths of the thin and thick filaments do not change.

5. What part of the sarcolemma contains acetylcholine receptors?

The part of the sarcolemma that contains acetylcholine receptors is the motor end plate.

6. Where inside a skeletal muscle fiber does glycolysis occur? Where does cellular respiration occur?

Glycolysis, exchange of phosphate between creatine phosphate and ADP, and glycogen breakdown occur in the cytosol. Oxidation of pyhruvic acid, amino acids, and fatty acids (aerobic cellular respiration) occurs in mitochondria.

7. Critical Thinking: Polio is a disease caused by a virus that can attack the somatic motor neurons in the central nervous system. Individuals who suffer from polio can develop muscle weakness and atrophy. In a certain percentage of cases, the individuals may die due to respiratory paralysis. Relate your knowledge of how muscle fibers function to the symptoms exhibited by infected individuals.

Destruction of the somatic motor neurons to skeletal muscle fibers will result in a loss of stimujlation to the skeletal muscles. When not stimulated on a regular basis, a muscle begins to lose its muscle tone. Through lack of use, the muscle fibers will weaken, begin to decrease in size, and can be replaced by fibrouf connective tissue, resulting in a type of denervation atrophy. A lack of stimulation of the breathing muscles (especially the diaphragm) from motor neurons can result in inability of the breathing muscles to contract, thus causing respiratory paralysis and possibly death of the individual from respiratory failure.