BPK 105 Study Guide - Midterm Guide: Adrenal Medulla, Hypotension, Sympathetic Nervous System
27 Apr 2018
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Module 6 - Review Questions - Part 5
11. Compare and contrast the roles and control of release of hormones from the two
regions of the adrenal gland. Provide two detailed examples of different classes of
hormones from the adrenal cortex and their effects (do not describe androgens). [8
marks]
Adrenal Medulla: principle hormone is epinephrine (and norepinephrine), which are both
released in response to stimuli from the sympathetic division of the ANS (stress and low blood
glucose also stimulate). Hormones bind to membrane bound receptors in target tissues. Effects:
increased breakdown of glycogen to glucose in liver, glucose release in blood & release of fatty
acids from fat cells. Glucose and fatty acids are energy sources for maintaining the body's
increasing rate of metabolism. Increase heart rate and blood pressure, stimulation of smooth
muscle in walls of arteries supplying internal organs and skin, but not supplying skeletal muscle.
Blood flow to organs and skin decreases as do functions. Blood flow to muscle increases.
Adrenal cortex: secretes 3 classes of steroid hormones: mineralocorticoids, glucocorticoids,
androgens. 1st class from outer layer of adrenal cortex, helps regulate blood volume and blood
levels of K+ Na+ (aldosterone)
Adrenal Glands
The adrenal glands are two small glands located superior to each kidney (figure 10.18a
; table
10.2). Each adrenal gland has an inner part, called the adrenal medulla (marrow, or middle),
and an outer part, called the adrenal cortex (bark, or outer). The adrenal medulla and the
adrenal cortex function as separate endocrine glands.
Adrenal Medulla
- The principal hormone released from the adrenal medulla is epinephrine, or adrenaline
- Small amounts of norepinephrine are also released. The adrenal medulla releases
epinephrine and norepinephrine in response to stimulation by the sympathetic nervous
system, which becomes most active when a person is excited or physically active (figure
10.19).
- These hormones bind to membrane-bound recep- tors in their target tissues.
- Stress and low blood glucose levels can also cause increased sympathetic stimulation of
the adrenal medulla.
- Epinephrine and norepinephrine are referred to as the fight-or-flight hormones because
of their role in preparing the body for vigorous physical activity. The major effects of the
hor- mones released from the adrenal medulla are
1. Increases in the breakdown of glycogen to glucose in the liver, the release of the
glucose into the blood, and the release of fatty acids from adipose tissue. The glucose
and fatty acids serve as energy sources to maintain the body’s increased rate of
metabolism.
Document Summary
Module 6 - review questions - part 5: compare and contrast the roles and control of release of hormones from the two regions of the adrenal gland. Provide two detailed examples of different classes of hormones from the adrenal cortex and their effects (do not describe androgens). Adrenal medulla: principle hormone is epinephrine (and norepinephrine), which are both released in response to stimuli from the sympathetic division of the ans (stress and low blood glucose also stimulate). Hormones bind to membrane bound receptors in target tissues. Effects: increased breakdown of glycogen to glucose in liver, glucose release in blood & release of fatty acids from fat cells. Glucose and fatty acids are energy sources for maintaining the body"s increasing rate of metabolism. Increase heart rate and blood pressure, stimulation of smooth muscle in walls of arteries supplying internal organs and skin, but not supplying skeletal muscle. Blood flow to organs and skin decreases as do functions.
