Section 4

Question 1

Where are the adrenal glands located, and how are they structured in terms of endocrine organs?

Answer 1

The adrenal glands are small and located at the top of the kidneys. They are essentially two endocrine organs, with outer layers called the cortex and inner layer called the medulla.

Question 2

What do the outer layers of the adrenal glands secrete, and what are they called?

Answer 2

The outer layers of the adrenal glands secrete several steroid hormones and are called the cortex.

Question 3

What does the inner layer of the adrenal gland secrete, and what is it called?

Answer 3

The inner layer of the adrenal gland secretes catecholamines and is called the medulla.

Question 4

How can the adrenal cortex be divided, and what are the three distinct zones?

Answer 4

The adrenal cortex can be divided into three distinct zones: the zona glomerulosa, the zona fasciculata, and the zona reticularis.

Question 5

What is the precursor molecule for the hormones produced in the adrenal cortex, and what are these hormones based on?

Answer 5

The precursor molecule for the hormones produced in the adrenal cortex is cholesterol, and these hormones are all steroid hormones.

Question 6

What are the three main categories of adrenal cortex hormones?

Answer 6

Mineralocorticoids: Influence mineral (electrolyte) balance, mainly produced in the zona glomerulosa.

Glucocorticoids: Play a role in glucose, lipid, and protein metabolism, mainly produced in the zona fasciculata and the zona reticularis.

Sex Hormones: Produced in lower quantities in the zona fasciculata and the zona reticularis, identical or similar to those produced in the gonads.

Question 7

What are mineralocorticoids, and where are they produced?

Answer 7

Mineralocorticoids are a class of corticosteroids produced in the adrenal cortex. They influence salt and water balances in the body and are essential for life.

Question 8

What is the major mineralocorticoid, and what is its role?

Answer 8

The major mineralocorticoid is aldosterone, which plays an essential role in electrolyte balance, particularly sodium conservation in the kidney, salivary glands, sweat glands, and colon.

Question 9

What is the consequence of the absence of mineralocorticoids, and how quickly can it lead to death?

Answer 9

In the absence of mineralocorticoids, a person could die as quickly as in a matter of days due to circulatory shock, a condition where blood pressure decreases to the point that adequate blood flow to tissues is compromised.

Question 10

What are the two primary stimuli for aldosterone secretion?

Answer 10

1. Activation of the renin-angiotensin-aldosterone system in response to reduced Na+ and a fall in blood pressure.
2. Direct stimulation of the adrenal cortex by increased K+ concentration.

Question 11

What is the primary glucocorticoid, and what is its major role?

Answer 11

The primary glucocorticoid is cortisol, and it plays a major role in metabolism and has other important functions.

Question 12

What are some of the major metabolic effects of cortisol?

Answer 12

1. Stimulates gluconeogenesis in the liver, producing glucose from non-carbohydrate precursors like amino acids.
2. Stimulates protein degradation in muscle to obtain amino acids.
3. Inhibits glucose uptake by most tissues, excluding the brain.
4. Breaks down lipid stores (lipolysis) to mobilize free fatty acids as a fuel source.

Question 13

How does cortisol contribute to the adaptation to stress?

Answer 13

Cortisol plays a key role in the adaptation to stress, possibly by causing a shift away from protein and fat stores while increasing carbohydrate stores. This ensures increased availability of glucose for adequate brain activity during times of fasting and provides building blocks for wound repair.

Question 14

Describe the negative feedback regulation involved in cortisol secretion.

Answer 14

Cortisol secretion is under negative feedback regulation involving the hypothalamus and anterior pituitary. The hypothalamus releases corticotropin-releasing hormone (CRH), stimulating the anterior pituitary to release adrenocorticotropic hormone (ACTH), which then stimulates the adrenal glands to release cortisol. Plasma cortisol feeds back to the hypothalamus and anterior pituitary, reducing CRH and ACTH release, maintaining cortisol concentrations around the set point.

Question 15

What is the diurnal secretion pattern of cortisol?

Answer 15

Cortisol has a diurnal secretion pattern, with the highest levels occurring in the morning and the lowest levels at night. This pattern is intrinsic to the hypothalamus and anterior pituitary control systems.

Question 16

How can mental and physical stress influence cortisol secretion?

Answer 16

Mental and physical stress can override normal cortisol secretion patterns. Stress leads to a significant increase in CRH release from the hypothalamus.

Question 17

What stimulates the secretion of sex hormones from the adrenal cortex, and what is the most important adrenal cortex sex hormone?

Answer 17

Sex hormones from the adrenal cortex, including dehydroepiandrosterone (DHEA), are stimulated by adrenocorticotropic hormone (ACTH). DHEA is considered the most important adrenal cortex sex hormone.

Question 18

What are some physiological effects of dehydroepiandrosterone (DHEA) in females?

Answer 18

In females, DHEA is important for the growth of pubic and armpit hair, enhancement of the growth spurt at puberty, and maintenance of the female sex drive.

Question 19

What are catecholamines, and how are they synthesized and released in the adrenal medulla?

Answer 19

Catecholamines, such as epinephrine and norepinephrine, are synthesized by adrenomedullary secretory cells. Once synthesized, they are stored in chromaffin granules and released into the bloodstream through exocytosis upon appropriate stimulation.

Question 20

What is the functional significance of epinephrine in the adrenal medulla?

Answer 20

While both epinephrine and norepinephrine are secreted, functionally we primarily consider the actions of epinephrine, which constitutes 80% of the secreted catecholamines.

Question 21

Which of the following receptors are inhibitory/excitatory in their general actions?

a1
a2
b1
b2

Answer 21

a1 - excitatory
a2 - inhibitory
b1 - excitatory
b2 - inhibitory

Question 22

What are the main adrenergic receptors that norepinephrine and epinephrine bind to?

Answer 22

Norepinephrine predominantly binds with α and β1 receptors near postganglionic sympathetic nerve terminals. Epinephrine, released from the adrenal medulla, can activate all α and β1 receptors, while β2 receptors are exclusively activated by epinephrine.

Question 23

How does the activation of β2 receptors by circulating epinephrine impact skeletal muscle vasculature?

Answer 23

Circulating epinephrine activates β2 receptors in skeletal muscle vasculature, leading to vasodilation. This results in increased oxygen and nutrient supply to the skeletal muscles.

Question 24

In a generalized sympathetic response, what is the effect on vasculature in areas such as the gastrointestinal (GI) tract and urinary bladder?

Answer 24

A generalized sympathetic response leads to vasoconstriction in areas such as the GI tract and urinary bladder.

Question 25

What are the effects of epinephrine on organ systems during an emergency or stressful situation?

Answer 25

In an emergency or stressful situation, epinephrine mobilizes the adrenomedullary system, leading to increased heart rate and strength of contraction, generalized vasoconstriction, vasodilation in skeletal muscle blood vessels, dilation of respiratory airways, and decreased digestive activities.

Question 26

How does epinephrine affect metabolism?

Answer 26

Epinephrine increases blood glucose through enhanced liver gluconeogenesis, glycogenolysis in the liver and skeletal muscles, and promotes lipolysis, releasing circulating free fatty acids for use as an energy source by the heart and skeletal muscles.

Question 27

What are the roles of the sympathetic nervous system and epinephrine in the integrated stress response?

Answer 27

The sympathetic nervous system, in conjunction with the endocrine system by releasing epinephrine from the adrenal medulla, contributes to the integrated stress response by
increasing muscle strength, mental activity, blood pressure, cellular metabolism, and blood flow to essential organs while decreasing blood flow to non-essential organs.

Question 28

How does the renin-angiotensin-aldosterone system contribute to the integrated stress response?

Answer 28

During stress, the renin-angiotensin-aldosterone system increases vasopressin and angiotensin II, both vasoconstrictors that help to elevate blood pressure in an emergency.

Question 29

What role do insulin and glucagon play in the integrated stress response?

Answer 29

Insulin and glucagon, in the context of stress, work to increase blood glucose levels. Increased glucagon secretion breaks down glycogen stores to produce glucose, while decreased insulin secretion reduces the rate at which glucose is removed from circulation.

Question 30

What is the main system involved in the integrated stress response, and how does it work?

Answer 30

The CRH-ACTH-Cortisol system is the main system in the integrated stress response. Cortisol increases blood levels of glucose, free fatty acids, and amino acids, providing energy substrate for the brain and facilitating tissue repair.

ACTH may also play a role by producing β-endorphin, a natural morphine-like substance, which acts as analgesia in the case of physical injury during stress.

Question 31

Describe the role of the hypothalamus in integrating responses during stress.

Answer 31

When the hypothalamus receives input about physical and emotional stressors, it activates the sympathetic nervous system, secretes CRH to stimulate ACTH and cortisol release, triggers the release of vasopressin, and influences pancreatic secretion of insulin and glucagon. Additionally, vasoconstriction from catecholamine release reduces blood flow through the kidneys, initiating the renin-angiotensin-aldosterone system. Through these mechanisms, the hypothalamus integrates responses of the sympathetic and endocrine systems during stress.

Question 32

What is hyperadrenalism, and how is it related to the adrenal glands?

Answer 32

Hyperadrenalism refers to conditions in which the adrenal glands secrete excessive amounts of hormones. There are three main patterns of symptoms caused by hyperadrenalism, each related to the specific hormones produced by the adrenal glands.

Question 33

What are the three main patterns of symptoms caused by hyperadrenalism?

Answer 33

The three main patterns of symptoms caused by hyperadrenalism are:

1. Cortisol Hypersecretion
2. Adrenal Androgen Hypersecretion
3. Hyperaldosteronism

Question 34

What is cortisol hypersecretion also known as, and what are some causes of it?

Answer 34

Cortisol hypersecretion is also known as Cushing’s Syndrome. It can occur due to overstimulation of the adrenal cortex by CRH and/or ACTH, adrenal tumors hypersecreting cortisol independent of ACTH, and ACTH-secreting tumors located somewhere other than the pituitary.

Question 35

What are some characteristic physical features of Cushing’s Syndrome?

Answer 35

Characteristic physical features of Cushing’s Syndrome include a buffalo hump (redistribution of fat causes increased depositions on the back between the shoulder blades) and moon face (cortisol causes excessive edema in the cheeks).

Question 36

What is oedema?

Answer 36

Oedema is a condition characterized by an excess of watery fluid collecting in the cavities or tissues of the body.

Question 37

What are the symptoms of adrenal androgen hypersecretion in adult females?

Answer 37

Adult females with adrenal androgen hypersecretion may develop masculine-like body hair (hirsutism), experience an increase in male secondary sex characteristics (such as deepening of the voice and increased muscle mass), and may see a decrease in breast size with the possibility of cessation of menstruation.

Question 38

What are the effects of adrenal androgen hypersecretion in adult males?

Answer 38

In adult males, there are usually little to no effects as the actions of DHEA (dehydroepiandrosterone) are minor compared to that of testosterone.

Question 39

What symptoms are observed in newborn females with adrenal androgen hypersecretion?

Answer 39

Newborn females with adrenal androgen hypersecretion generally exhibit male-type external genitalia. During development, the clitoris enlarges and takes on a penile-type appearance.

Question 40

What occurs in prepubertal males with adrenal androgen hypersecretion?

Answer 40

Prepubertal males with adrenal androgen hypersecretion may experience early development of male secondary sex characteristics, a condition known as precocious pseudo-puberty.

Question 41

What are the two main causes of excessive mineralocorticoid secretion leading to hyperaldosteronism?

Answer 41

Excessive mineralocorticoid secretion causing hyperaldosteronism can be due to either an aldosterone-secreting tumor (primary hyperaldosteronism) or abnormally high activity of the renin-angiotensin-aldosterone system (secondary hyperaldosteronism).

Question 42

What symptoms are associated with hyperaldosteronism based on the activity of aldosterone?

Answer 42

Symptoms of hyperaldosteronism include excessive sodium retention (hypernatremia), potassium depletion (hypokalemia), and high blood pressure.

Question 43

What is the difference between primary and secondary adrenocortical insufficiency?

Answer 43

Primary adrenocortical insufficiency (Addison’s disease) occurs when all layers of the adrenal cortex are undersecreting, typically caused by autoimmune destruction of the cortex, leading to deficiencies in both aldosterone and cortisol. Secondary adrenocortical insufficiency results from a problem in the hypothalamus or anterior pituitary, leading to reduced ACTH and cortisol deficiency, while aldosterone levels remain unaffected.

Question 44

What are the symptoms of primary adrenocortical insufficiency (Addison’s disease), and why can it be fatal?

Answer 44

Symptoms of primary adrenocortical insufficiency include hyperkalemia, hyponatremia, poor response to stress, low blood glucose (hypoglycemia), and hyperpigmentation of the skin due to excessive ACTH. It can be fatal due to the impact on cardiac rhythms (from hyperkalemia) and reduced extracellular fluid (ECF) and circulating blood volumes (from hyponatremia), leading to hypotension.

Question 45

What are the symptoms of secondary adrenocortical insufficiency?

Answer 45

Symptoms of secondary adrenocortical insufficiency include severe fatigue, loss of appetite, weight loss, nausea, vomiting, diarrhea, muscle weakness, irritability, and depression. Unlike primary insufficiency, low blood pressure and muscle spasms are less likely, as aldosterone levels remain unaffected.

Question 46

Match each of the following terms:

Hyperaldosteronism
Cushing’s Syndrome
Addison’s Disease
Adrenal Androgen Hypersecretion

with
- Hirsutism
- High blood pressure
- Buffalo hump and moon face
- Hypotension and hyperpigmentation of face

Answer 46

Hyperaldosteronism - high blood pressure

Cushing’s Syndrome - buffalo hump and moon face

Addison’s Disease - hypotension and hyperpigmentation of skin

Adrenal Androgen Hypersecretion - hirsutism