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Cell Biology > The Adrenal Glands > Flashcards

The Adrenal Glands Flashcards

1
Q

Where are the adrenal glands located

A

Above the Kidneys

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2
Q

Name the 2 types of tissue which makes up adrenal glands

A

1- medulla (inner)

2 - cortex (outer)

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3
Q

What is the layer on the outside of adrenal glands called and the function

A

The capsule

It’s a fibrous protective layer

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4
Q

Which cells are located in the adrenal medulla and what 2 hormones do they produce

A

Chromaffin cells

Produce epinephrine and norepinephrine

(Adrenaline and noradrenaline)

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5
Q

Chromaffin cells in the medulla have the potential to become post synaptic neurones - why don’t they differentiate

A

Due to cortisol presence in the cortex stops them differentiating

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6
Q

What type of hormones are epinephrine and norepinephrine

A

Amino acid hormones (like thyroxin)

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7
Q

What 3 steroid hormones (derived from cholesterol) are produced in the adrenal cortex

A

1- cortisol
2- aldosterone
3- adrenal androgens eg testosterone oestrogen

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8
Q

Name the 3 layers of the cortex

A

1- zona glomerulosa (most outer)

2- zona fasciculata (outer)

2- zona reticularis (inner)

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9
Q

What type of steroid hormone is produced at the zona glomerulosa

A

Aldosterone

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10
Q

Why can’t zona glomerulosa produce androgens or cortisol

A

No 17alpha hydroxylase enzyme present

= can’t modify cholesterol into them

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11
Q

What type of hormone is aldosterone and give its function

A

It’s a mineralo corticoid

Important for water and mineral reuptake at the Kinsey ,colon and salivary glands

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12
Q

What type of protein binds to aldosterone because it is a steroid hormone and hydrophobic

A

Albumin

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13
Q

Explain how aldosterone does it’s mineralocorticoid job

A

Binds to mineralocorticoid receptors on areas such as collecting duct on the kidney

This allows for upregulation of the NA/K pump, and the sodium channel ENAC

Causes Na reabsorption into blood as well as water

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14
Q

Explain how renin is used to control aldosterone when blood pressure drops

A

Blood pressure drops is sensed by kidney

Renin is released

Acts on angiotensinogen in the liver

Peptides are cleaved from angiotensinogen by renin

Angiotensin 1 then is converted to angiotensin 2 by ACE enzyme

This angiotensin 2 acts on the zona glomerulosa and this releases aldosterone = more Na uptake into blood = increased BP

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15
Q

What protein does renin activate in the liver

A

Angiotensinogen

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16
Q

Which enzyme cleaved antigeotensin 1 into angiotensin 2

A

ACE enzyme

17
Q

Which hormones are produced by zona fasciculata and zona reticularis

A

Cortisol and adrenal androgens

18
Q

Why can’t zona fasciculata and reticularis produce aldosterone

A

Cells don’t have genes for the enzyme P450 aldo enzyme

19
Q

Why is cortisol released

A

When hypothalamus detects stress

20
Q

What happens when hypothalamus recieves stress signals

A

The parvocellular neurones release corticotropin releasing hormone into the anterior pituitary

This causes release of adrenocorticotropin from corticotroph cells

This adrenocorticotropin binds to adrenocorticotropin receptors (ACTH) on fasciculata and reticularis

= cortisol production and release

21
Q

What type of hormone is cortisol

A

A gluco corticoid

22
Q

What type of receptor does adrenocorticotropin bind to on fasciculata and reticularis

A

G protein coupled cell surface receptor (because it’s a peptide hormone)

23
Q

What happens when adrenocorticotropin binds to acth receptor on the fasciculata and reticularis layers at the adrenal cortex

A

G protein when activated activated adenylate cyclase

Produces cAMP from ATP

Camp then activated PKA

24
Q

What 3 effects does pKa activation have when adrenocorticotropin binds

A

1- increased transcription of enzymes for steroid hormone synthesis

2- activate cholesterol ester hydrolase enzyme

3- activate star protein

25
Q

What does cholesterol esterase enzyme do when activated by PKA

A

Turns cholesterol esters into a free cholesterol ready to produce steroid hormones

26
Q

What does star protein do

A

Allows cholesterol to get across the mitochondrial membrane

27
Q

What happens when cholesterol is moved into the mitochondria membrane by star protein

A

Cytochrome P450 enzymes such as SCC act on it

Cleave or modify cholesterol to produce cortisol

28
Q

Why is the enzyme cleaving cholesterol into cortisol called SCC

A

Because it side cleaved cholesterol

29
Q

Why is cortisol called a gluco corticoid

A

Because it effects glucose homeostasis

30
Q

Name the MANY effects cortisol has

A

Stimulates gluconeogenesis

Inhibits glucose uptake in muscle and adepose tissue

Causes muscle catabolism / breakdown

Inhibits bone formation

Increases sensitivity to epinephrine and norepinephrine in the flight or fight response

Allows modulation of behaviour

Inhibits gonad androgens like testosterone and oestrogen

31
Q

How does cortisol cause immunosuppression

A

Prevents cytokines release = not cell proliferation

32
Q

Explain which enzyme cortisol lowers to prevent inflammatory responses

A

Phospholipase A

33
Q

How does lower levels of phospholipase AZ due to cortisol cause no inflammatory response

A

Lowers production of phospholipids into arachidonic acid

Can’t produce prostaglandins and leukotienes (inflammatory agents)

34
Q

How does cortisol prevent production of inflammatory agent prostaglandin

A

Lowers levels of enzyme cyclooxygenase

35
Q

What are the 2 inflammatory agents stopped by cortisol called

A

Prostaglandins and leukoteines

36
Q

Why can cortisol and aldosterone act on the same receptors (mineralocorticoid receptors and gluco corticoid)

A

Because they are similar in shape

37
Q

What enzyme stops cortisol binding to mineralocorticoid receptors too often

A

11 beta hydroxysteroid dehydrogenase

Inactivates cortisol in aldosterone cells (in the glomerulosa)

38
Q

How does epinephrine when (released by sympathetic nervous system )with the help of thyroxine increase HR

A

Binds to adrenergic receptors g coupled and allows cAMP production

Increases HR

39
Q

Which 2 cell types do adrenaline / epinephrine bind to on cell surface to adronegic receptors

A

Heart - to increase heart rate

Muscle - allows glycogen breakdown for glucose release

Cell Biology (21 decks)

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