Wk11 - adrenal glands

Question 1

For the adrenal glands, answer the following:

a. ) Situated superior to which structure?
b. ) Embedded within what tissue?

Answer 1

a. ) Superior to kidneys.

b. ) Embedded within adipose tissue.

Question 2

What hormones does the adrenal MEDULLA secrete? What type of hormones are these?

Answer 2

The adrenal medulla secretes catecholamines, adrenaline and noradrenaline.

Question 3

The adrenal medulla is considered to be a ‘modified part’ of what larger system? Describe the composition of the adrenal medulla.

Answer 3

The adrenal medulla is a modified part of the SNS; it is composed of modified post-ganglionic sympathetic neurons. When these neurons are stimulated, they release catecholamines into the bloodstream.

Question 4

t/f: adrenaline and noradrenaline may act as NT’s (in the brain for example), but when released by the adrenal medulla into the bloodstream, they are considered to be hormones.

Answer 4

True.

Question 5

How are A/ NA stored? What is this tissue known as?

Answer 5

Adrenomedullary cells (cells of adrenal medulla) store catecholamines as

Question 6

Upon stimulation, what is the name of the process adrenomedullary cells undergo to release catecholamines?

Answer 6

Ca+2 dependant exocytosis.

Question 7

t/f: A/ NA have the same affinities toward different adrenergic receptors.

Answer 7

False, A/ NA have different affinities towards different adrenergic receptors (α or β).

Question 8

Which type of adrenergic receptor is found exclusively within the heart?

Answer 8

β1.

Question 9

Generally, which adrenergic receptors are:

a. ) Excitiatory?
b. ) Inhibitory?

Answer 9

a. ) Excitiatory - α1, α2, β1.

b. ) Inhibitory - β2.

Question 10

t/f: Catecholamines are not essential for life.

Answer 10

True.

Question 11

NA binds predominantly to which receptors?

Answer 11

α1, α2, β1.

note: NA doesn’t really bind to β2 much

Question 12

t/f: niether catecholamine is totally specific to one receptor type.
PROVIDE AN EXAMPLE to validate your answer.

Answer 12

True - they have different affinities however are not absolute in specificity.
For example:
A and NA both increase HR via binding with cardiac β1 receptors, and both induce vasoconstriction of the skin or GIT via binding to α1 adrenoreceptors.

Question 13

State the relevance of catecholamines in the body. (3)

Answer 13

1. CVS control.
2. Regulation intermediary metabolism.
3. Stress response.

Question 14

Vasodilation of the BV’s to the heart and skeletal muscles occurs due to the binding of:

a. ) Which hormone?
b. ) To which receptor?

Answer 14

Adrenaline binding to β2.

Question 15

Adrenaline functions only to the bidding of the (SNS/ PNS).

Answer 15

SNS.

Question 16

During times of fear or stress, by what factor can adrenaline secretion increase? State the general purpose of this.

Answer 16

2-300x normal secretion rate. This is in order to prepare the body for the “fight or flight” response.

Question 17

The adrenal cortex constitutes how much of the adrenal gland? How many layers does the adrenal cortex have?

Answer 17

The cortex comprises 80% of the adrenal gland, which consists of 3 layers.

Question 18

State the 3 layers of the adrenal cortex, from outermost to innermost.

Answer 18

“Zona … GFR”

1. Zona Glomerulosa (outer).
2. Zona Fasciculata (middle).
3. Zona Reticularis (inner).

Question 19

All hormones produced in the adrenal cortex are derived from what? What can we therefor infer of their structure?

Answer 19

Cholesterol, therefor they are steroid hormones (lipophillic) and must travel in the blood bound to proteins.

Question 20

State the 3 types of hormones released from the adrenal cortex.

Answer 20

1. Mineralocorticoids (aldosterone, influence electrolytes).
2. Glucocorticoids (influence metabolism).
3. Sex hormones.

(remeber: cortex –> “…corticoids”)

Question 21

State which part of the adrenal glands the following hormones are SYNTHESISED in:

a. ) Androgens and oestrogen.
b. ) Aldosterone.
c. ) Cortisol.

Answer 21

a. ) Androgens and oestrogen - zona reticularis (mostly) but also zona fasciculata.
b. ) Aldosterone - zona glomerulosa.
c. ) Cortisol - zona fasciculata.

Question 22

How do adrenocortical hormones travel within the blood; and why?

Answer 22

All adrenocortical hormones are derived from cholesterol, therefor they are steroids. This means they must be lipophillic, and have to travel through the blood bound to proteins.

Question 23

60% of aldosterone travels in the blood bound to what?

Answer 23

Non-specific albumen.

Question 24

98% of cortisol travels in the blood bound to what?

Answer 24

Specific cortisol binding protein.

Question 25

What’re the main effects of mineralocorticoids? (2)

Answer 25

1. Influence electrolyte balance.

2. BP homeostasis.

Question 26

State the main mineralocorticoid released by the adrenal cortex.

Answer 26

Aldosterone.

Question 27

State the main target tissue, and effect of aldosterone. What is the consequence of this?

Answer 27

Aldosterone exerts it’s primary effect on the distal tubules of the nephron, and CD. It stimulates Na+ reabsorption and K+ secretion, and, as a consequence, increases ECF (thus blood) volume and MAP.

Question 28

t/f: aldosterone exerts a colonic effect.

Answer 28

True.

Question 29

t/f: aldosterone is essential for life.

State reasoning for your answer.

Answer 29

True; without mineralocorticoids an individual will die of circulatory shock.

Question 30

Aldosterone secretion is largely (dependant/ independent) of anterior pituitary control, as ACTH has a (weak/ strong) effect.

Answer 30

Independant; weak.

Question 31

What’re the 2 factors which control aldosterone release?

Answer 31

1. Plasma [K+] at Zona Glomerulosa.

2. RAA system and renin release.

Question 32

What’re the main effects of glucocorticoids? (2)

Answer 32

1. Influence intermediary metabolism.

2. Play important role in adaptation of body to stress.

Question 33

What is the main glucocorticoid released by the adrenal cortex?

Answer 33

Cortisol.

Question 34

State result, and cost (or “expense”) of cortisol secretion.

Answer 34

Cortisol release –> increased [glucose], at the expense of protein and fat stores (gluconeogenesis).

Question 35

Primarily, how is cortisol secretion regulated?

Answer 35

Long-loop negative feedback from the anterior pituitary and release of ACTH.

Question 36

What control’s ACTH release?

Answer 36

The hypothalamus controls ACTH release by variable level of corticoid releasing hormone (CRH) released.

Question 37

Cortisol secretion is primarily controlled by levels of ACTH released by the anterior pituitary. What 2 additional factors also effect cortisol secretion; and how?

Answer 37

1. Diurnal rhythm - highest in AM, lowest at night.
2. Stress - increased stress causes increased cortisol secretion, in order to provide the body with a deeper ‘pool of metabolites’ for those fight or flight situations.

Question 38

Cortisol levels are influenced by diurnal rhythms.

a. ) Which hormone related to cortisol spikes in release, a couple hours before waking?
b. ) When is ACTH levels lowest?

Answer 38

a. ) CRH.

b. ) A couple hours before falling asleep.

Question 39

How does the majority (~75%) of cortisol travel in the blood?

Answer 39

~75% of cortisol is bound to protein transcortin.

Question 40

How does the minority (~25%) of cortisol travel in the blood?

Answer 40

15% is bound to albumen, 10% is unbound or “free”.

Question 41

Where is transcortin produced?

Answer 41

The liver.

Question 42

Where are most steroids (including cortisol for example) metabolised (broken down)?

Answer 42

The liver.

Question 43

State the half life of cortisol.

Answer 43

60-90 minutes.

Question 44

Not all cortisol is metabolised in the liver; what happens to this left over cortisol?

Answer 44

It is converted into cortisone; another active glucocorticoid.

Question 45

Explain what is meant by the following term(s):

Cortisone.

Answer 45

The descendent of cortisol, cortisone is an active glucocorticoid (like cortisol) which is produced in the liver (unlike cortisol, which is produced by the adrenal gland).

Question 46

What is transcortin also known as?

Answer 46

Corticosteroid binding globulin (CBG).

Question 47

State the actions of cortisol.

Answer 47

1. Stimulates hepatic gluconeogenesis (mainly from AA), replenishing hepatic glycogen stores.
2. Inhibits glucose uptake from blood (sparing it for brain).
3. Stimulates protein breakdown, increasing blood [AA] for gluconeogenesis or cellular repairs.
4. Facilitates lipolysis, increasing [FFA] which can then be used as alternative fuel for other tissues (as they can’t uptake glucose).

Question 48

t/f: cortisol is not essential for life.

Answer 48

FALSE - cortisol is essential for life.

Question 49

Cortisol, as well as other glucocorticoids, exert (anabolic/ catabolic) effects on the liver, and (anabolic/ catabolic) effects on most other tissues. The end result is an (increase/ decrease) in blood [glucose].

Answer 49

Anabolic; catabolic; increase.
(note: this means that liver glucose output increases, and tissues (such as adipose, muscle etc.) uptake of glucose decreases).

Question 50

In addition to it’s effects on blood sugar, cortisol is important in ensuring what?

Answer 50

Cortisol aids the body’s ability to deal with stress; ensuring other hormones perform effectively.

Question 51

When cortisol is administered therapeutically, what effects (other then on blood sugar) are seen?

Answer 51

1. Anti-inflammatory effects.

2. Immuno-suppressive effects.

Question 52

Provide an example of how cortisol could be used in a clinical setting.

Answer 52

Cortisol can be used to treat rheumatoid arthritis, due to it’s anti-inflammatory effects.