Question

18. Norman is an amateur body builder with a huge

collection of weight lifting equipment in his basement. His

little sister Venus tried to lift the 100-lb barbel- it didn't

budge. Norman lifted the same barbell over his head, held

it there and then lowered it back to the ground. Venus

was very impressed with her big brother. What were the

types of muscle contractions performed by Norman?

a. isotonic concentric contractions

b. isotonic eccentric contraction

c. isometric contractions

d. all of the above

19. Which physiological response is an example of positive

feedback?

a. an increase in the concentration of glucose in the blood

stimulates the pancreas to secrete insulin, a hormone that

lowers blood glucose concentration

b. a high concentration of carbon dioxide in the blood

causes deeper, more rapid breathing which expels CO2.

c. stimulation of a nerve cell causes sodium ions to leak

into the cell and the sodium influx triggers the inward

leaking of even more sodium.

d. the pituitary gland secretes a hormone called TSH

which stimulates the thyroid gland to secrete another

hormone called thyroxine. A high concentration of

thyroxine suppresses the pituitary’s secretion of TSH.

20. Weakening of skeletal muscles in myasthenia gravis is

caused by:

a. decreased calcium ions diffusing into the muscle fibers

b. decreased number of acetylcholine receptors

c. increased parathyroid hormone production

d. increased osteoclastic activity

Answer 1

18,d,all of the above

Three muscle contraction takes place when they lifting the weight as the foundation for strength and hypertrophy..These all the strongest type of contraction your body can able to actively moving.

19,c, stimulation of a nerve cell causes sodium ions to leak into the cell and the sodium influx trigger the inward leading of even more sodium..

Leaking of more sodium causes illness that is a positive feedback happened due to physiological response..

20, B, decreased number of acetylcholine receptors.

Due to damage to the neuromuscular membrane reduces the effect of the neurotransmitter substance acetylcholine responsible for nerve cells and muscles..This results in muscle weakness.