Maintaining an Internal Balance and
The Importance of Excreting Wastes
Part A: Short Answer
1. How do “goosebumps” help protect against rapid cooling?
2. What behavioural adjustments affect thermoregulation?
3. What is ADH and where is it produced? Where is ADH stored?
4. Where is the thirst center located?
5. What is deamination?
Part B: Multiple Choice
1. Nitrogen wastes from the breakdown of proteins and amino acids are removed from the body by the
a) conversion of ammonia to urea in the liver and filtration by the kidney;
b) conversion of ammonia to urea in the kidney and filtration by the kidney;
c) conversion of urea to ammonia in the liver and secretion by the kidney;
d) conversion of urea to ammonia in the kidney and secretion by the kidney;
e) conversion of nitrogen to ammonia in the liver and secretion by the kidney.
2. After a severe cut to the skin, the production of urine temporarily decreases. This can be explained by the drop in blood pressure, which causes
a) the release of aldesterone, which increases K+ reabsorption in the nephron, leading to decreased water reabsorption;
b) the release of ADH, which increases water reabsorption in the nephron;
c) the release of aldesterone, which increases Na+ reabsorption in the nephron, leading to increased water reaabsorption
d) the release of ADH, which decreases water reabsorption in the nephron;
e) the release of aldesterone, which increases Na+ reabsorption in the nephron, leading to decreased water reabsorption.
3. An increase in blood pressure in the glomerulas would cause
a) an increase in filtration and increase in urine output;
b) a decrease in filtration and decrease in urine output;
c) no effect on urine output;
d) a decrease in filtration and increase in urine output;
e) an increase in filtration and decrease in urine output.
4. A rapid increase in external temperature would be followed by which homeostatic adjustment in humans?
a) an increase in urine production and decrease in heart rate;
b) decreased blood flow to the arms and shivering;
c) an increase in blood flow to the arms and an increase in perspiration;
d) the formation of “goosebumps” and shivering;
e) an increased heart rate and decreased blood flow to the arms.
5. Concentrated urine is produced when ADH is
a) abundant and the loop of Henle is impermeable to water;
b) lacking and the loop of Henle is permeable to water;
c) lacking and the collecting duct is impermeable to water;
d) abundant and the collecting duct is permeable to water;
e) unchanged and the nephron is impermeable to water.
Chemical Systems Maintain Homeostasis
1. What are target tissues or organs?
2. What is cyclic adenosine monophosphate (cyclic AMP)?
3. How does insulin regulate blood sugar levels?
4. How does glucagon regulate blood sugar levels?
7. How does thyroxine affect blood sugar?
8. Why would the removal of the parathyroid glands lead to tetany?
9. What are prostaglandins?
10. Why would a marathon runner be unlikely to take growth hormone or
11. Why is it difficult to detect banned drugs like growth hormone and
How Nerve Signals Maintain Homeostasis
Part A: Short Answers
1. Differentiate between the peripheral nervous system (PNS) and the
central nervous system (CNS).
2. Differentiate between sensory neurons and motor neurons.
Part B: Matching
Match the following words with the correct function:
a) part of the neuron; an extension of cytoplasm that carries nerve impulses away from dendrites
b) nerve impulses caused by the reversal of charge across a nerve membrane
c) motor nerves, not under conscious control, designed to maintain homeostasis
d) a neurotransmitter that permits the transmission of an action potential across a synapse
e) carries information about the environment to the brain
f) a reflex that makes adjustments for near and distant objects
g) the time required before another action potential can be produced
1. What is the primary function of the myelin sheath?
a) to conduct active transport of potassium ions;
b) to carry wastes from the axon;
c) to regulate the diffusion of sodium ions across the synapse;
d) to increase the speed at which nerve impulses travel;
e) to supply nutrients to the axon.
2. A person suffers a stroke that results in a loss of speech, difficulty
in using the right arm, and an inability to solve mathematical equations. Which
area of the brain was damaged?
a) left cerebellum;
b) left cerebral hemisphere;
c) medulla oblongata;
d) right cerebral hemisphere;
e) right cerebellum;
3. What makes it possible for an impulse to move from one neuron to an
a) Neurotransmitters are released from the dendrites of one neuron and
diffuse to the axon terminal of the adjacent neuron;
b) Dendrites of one neuron always touch the axon of the adjacent neuron;
c) Cerebrospinal fluids are released from the axon terminal of one neuron
and diffuse to the axons of the adjacent neuron;
d) The axon of one neuron always touches the axon of the adjacent neuron;
e) Neurotransmitters are released from the axon terminal of one neuron
and diffuse to the dendrites of the adjacent neuron.