12

Question 1

distinguish between the adrenal medulla and the adrenal cortex

Answer 1

adrenal medulla = modified sympathetic ganglia
adrenal cortex = steroid factory

Question 2

where is the adrenal gland broadly located?

Answer 2

on top of the kidney

Question 3

what regulates catecholamine release from the adrenal medulla?

Answer 3

1. stimulus begins at the spinal cord due to activation of the sympathetic nervous system (fight or flight response)
2. Preganglionic sympathetic neurons release acetylcholine (ACh) onto nicotinic receptors of the adrenal medulla’s chromaffin cells.
3. catecholamines (epinephrine, norepinephrine, and dopamine) are released into the blood to target tissues

Question 4

what is the chromaffin cell?

Answer 4

a modified postganglionic sympathetic neuron

Question 5

what is the main hormone released in response to the fight or flight response and why?

Answer 5

epinephrine, because it is secreted in sufficient quantity to exert effects

Question 6

what is the role of epinephrine

Answer 6

mediate the rapid stress response

liver: glucose release (via enhanced glycogenolysis)
fat: fatty acid release
heart: increases force of contraction
intestine: muscle relaxation
intestine, skin, kidney: arteriole constriction
muscle: arteriole contraction (alpha receptors), arteriole relaxation (beta-2 receptors)
brain: increases altertness
resp: bronchodilator

Question 7

anaphylactic shock

Answer 7

severe allergic reaction:
- bronchospasm (or constriction of the airways), potentially leading to respiratory failure
- dangerous decrease in blood pressure

Question 8

clinical use of epinephrine

Answer 8

Epi-Pen: counteracts the symptoms of anaphylactic shock by promoting:
- bronchodilation
- vasoconstriction (intestine, skin, kidneys)
- vasodilation (skeletal and cardiac muscles)

Question 9

state the regions of the adrenal cortex and what they secrete

Answer 9

zona glomerulosa: aldosterone
zona fasciculata: glucocorticoids
zona reticularis: sex hormones

Question 10

draw a flow chart of the formation of hormones by the adrenal cortex from cholesterol

Question 11

weak androgens

Answer 11

have less than 20% activity of testosterone but are converted to more potent androgens and oestrogen’s in peripheral tissues

Question 12

what is the effect of ACTH on androgen production?

Answer 12

ACTH increases androgen production

Question 13

physiological roles of androgens

Answer 13

children: male prenatal development, also contribute to andrenarche - pubic hair, body odour, skin oiliness and acne at onset of puberty for both males and females

adult men: no physiological role

adult women: maintain pubic and axillary hair, source of oestrogen’s after menopause

Question 14

cortisol is the main ——–

Answer 14

glucocorticoid

Question 15

what is the control pathway and nature of cortisol secretion?

Answer 15

• the hypothalamic-pituitary-adrenal pathway
• continuous secretion, diurnal rhythm

Question 16

what are the main roles of cortisol?

Answer 16

• mediation of short and long term stress
• protective effect against hypoglycaemia through permissive effect

Question 17

cortisol - short-term stress pathway

Answer 17

1. stress generates nerve impulses
2. these travel to the spinal cord
3. the signal travels through the preganglionic sympathetic fibres to the adrenal medulla
4. this results in secretion amino acid-based hormones (catecholamines - epinephrine and norepinephrine)

Question 18

cortisol - short-term stress pathway response

Answer 18

• heart rate increases
• blood pressure increases
• bronchioles dilate
• liver converts glycogen to glucose and releases glucose to blood
• blood flow changes, reducing digestive system activity and urine output
• metabolic rate increases

Question 19

cortisol - prolonged stress pathway

Answer 19

1. stress is sensed by the hypothalamus
2. this causes CRH (corticotropin-releasing hormone) to be released
3. CRH causes the corticotropin cells of the anterior pituitary to release ACTH (adrenocorticotropic hormone)
4. ACTH travels to the adrenal cortex, which secretes steroid hormones

Question 20

cortisol - prolonged stress response

Answer 20

• kidneys retain sodium and water
• blood volume and blood pressure rise
• proteins and fats converted to glucose or broken down for energy
• blood glucose increases
• immune system suppressed

Question 21

regulation of cortisol through negative feedback loop

Answer 21

when cortisol levels increase, both ACTH and CRH production will be decreased

Question 22

what is the use of cortisol analogs?

Answer 22

used as drugs to suppress the immune system
- inhibit inflammatory responses
- poison ivy, allergies, asthma

Question 23

long-term use of cortisol analogs can result in

Answer 23

inhibition of ACTH secretion and atrophy (inactivation) of cortisol-secreting cells

Question 24

Addison's disease

Answer 24

- also known as adrenal insufficiency - hyposecretion of adrenal steroid hormones - causes: destruction of the adrenal cortex by autoimmunity, sometimes infection - symptoms: hypotension, hypoglycaemia

Question 25

how can Addison's disease be treated?

Answer 25

by giving cortisol

Question 26

Crushing's syndrome

Answer 26

- cortisol excess - causes: tumours, excess cortisol therapy - synptoms: hyperglycaemia, muscle protein breakdown, lipolysis but build up of fat on trunk and face, increased appetite, mood elevation followed by depression, difficulty with learning and memory

Question 27

4 main metabolic effects of cortisol

Answer 27

primarily catabolic: 1. promotes gluconeogenesis 2. causes breakdown of skeletal muscle proteins 3. enhances lipolysis 4. suppresses immune system