Advanced Physiology: Homework #2
1. Based on your study of lung anatomy, into which lung would a foreign object that’s small
enough to pass into a primary bronchus most likely become lodged and block air movement?
It would become lodged in the left lung because it has two secondary bronchi and is
smaller than the right lung.
2. Predict what would occur with the following scenarios regarding muscle physiology:
a. How would a drug that interferes with cross-bridge formation affect muscle contraction?
Cross- bridge formation is when the myosin head binds to the myosin binding site. If
there was no cross-bridge formation, there would be no actual muscle contraction
because no power stroke occurred in which the myosin head pulls the actin chain past
itself and ADP is released and ATP hydrolysis occurs immediately so that the myosin
head is cocked.
b. What would you expect to happen to a resting skeletal muscle if the sarcolemma suddenly
became very permeable to calcium ions?
Increased permeability of the sarcolemma to Ca2+ would lead to an increased intracellular
concentration of Ca2+ and a greater degree of contraction
c. What would happen to a muscle if the motor end plate did not contain acetylcholinesterase?
An acetylcholinesterase inhibitor is a chemical that inhibits the cholinesterase enzyme
from breaking down acetylcholine, increasing both the level and duration of action of the
neurotransmitter acetylcholine so the strength of a muscle contraction would be higher and
last longer.
3. After attending a Fourth of July fireworks extravaganza, Celia Ringer finds it difficult to hear
normal conversation because of a constant and high pitched ringing in her ears.
a. What is this condition called?
Tinnitus
b. Which specific area of the cochlea is involved with this condition?
The organ of Corti houses the hair cells called cilia which trigger the production of nerve
impulses. These nerve impulses are transmitted through the cochlear nerve to the brain.
c. Why is it difficult for Ms. Ringer to hear normal conversation?
Exposure to loud noises can easily bend and damage the tiny hairs in the inner ear. If
hairs are damaged, the cells may send out random electrical impulses. The impulses are
received by the brain and incorrectly interpreted.
