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Flashcards in Adrenal gland Deck (31):
1

Characteristics of adrenal gland

Weighs between 8-10 g

Sits above the kidneys

2

What is the function of the adrenal glands?

To help our bodies respond well to environmental changes

Can control many fight or flight responses in response to stress

3

What are the two areas of the adrenal gland?

Medulla

Cortex

4

What is the function of the medulla in the fight or flight response?

Dilation of airways

Improved gas exchange

Increase cardiac output

5

What is the funciton of the cortex in the fight or flight response?

Prevent losing extracellular fluid

Mental preparation -> if not able to mentally prepare = not able to cope

Suppress pain and inflammation

6

What do both the medulla and the cortex do in response to stress?

Keep blood glucose high

7

Characteristics of the arenal medulla

Made of chromaffin cells

Produces catecholamines

Extension of the sympathetic nervous system - nerves synapse with neuroendocrine cells in the medulla

8

What are chromaffin cells?

Neuroendocrine cells in the medulla

Synthesise and store epinephrine and norepinephrine

9

What are catecholamines?

Any structure with a catechol ring and an amine

10

What is a catechol ring?

Phenol ring with 2 OH

11

Process of catecholamine synthesis

1. Main precursor = tyrosine

2. Addition of -OH makes DOPA => catalysed by tyrosine hydroxylase

3. DOPA -> dopamine by removing carboxyl group => catalysed by DOPA decarboxylase

4. Dopamine -> norepinephrine by adding -OH => catalysed by dopamine oxidase

5. Norephinephrine -> epinephrine by adding CH3

12

What is the main hormone in the adrenal medulla?

Epinephrine

13

What 3 layers make up the cortex?

Zona reticularis - inner
Zona fasciculata
Zona glomerulosa - outer

14

What are the differences between the layers that make up the adrenal medulla?

Their shape and the hormones they produce

15

What hormones does the zona glomerulosa produce?

Mineralocorticoids -> aldosterone

16

What hormones does the zona fasciculata produce?

Glucocorticoids -> cortisol

17

What hormones does the zona glomerulosa produce?

DHEA

18

What is DHEA?

Sex hormone precursor of estrogen/ progesterone

19

What does DHEA stand for?

Dehydropiandrosterone

20

What is common between all the hormones produced in the adrenal cortex?

They are all cholesterol derivatives

21

When is cortisol released?

In response to stress

Can ve either internal or external stress

Information is sent to the CNS

CNS signals to the hypothalamus

22

What is the process by which cortisol is released?

1. Hypothalamus releases cortisol releasing hormone

2. This activates the pituitary gland which in turn releases ACTH

3. ACTH stimulates the adrenal gland

4. Activates the zona fasciculata to make glucocorticoids

23

What mechanism ensures the level of cortisol in the body is optimal?

Negative feedback mechanism

Cortisol suppresses:

Pituitary from releasing ACTH
Hypothalamus from releasing CTH

24

What are the functions of cortisol?

Has two functions:

1. Metabolic effect - affects glucose metabolism. Increases plasma glucose by increasing lipolysis, gluconeogenesis and increases mobilization of amino acids.

2. Stress response - anti-inflammatory action: inhibits immune-mediated tissue damage. Creates a feeling or state of excitement

25

How is cortisol found in the body?

Normally found bound to proteins

Only 5% is found freely in plasma

26

What form of the cortisol is active?

The 5% of cortisol found freely in plasma is active

27

What is an example of a mineralocorticoid?

Aldosterone

28

What is the role of aldosterone?

Maintenance of extracellular fluid

29

What stimulates the release of aldosterone?

Low extracellular volume - after bleeding

High extracellular potassium levels - can induce arrhythmia

30

How does low extracellular volume stimulate aldosterone release?

Activates renin-angiotensin system

Activates the release of aldosterone

Increases renal absorption of salt and water

31

How does high extracellular potassium levels stimulate aldosterone release?

Activates the adrenal cortex

Releases aldosterone

Increases renal secretion of potassium