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adrenal gland Flashcards

1
Q

composition of adrenal glands

A

2 endocrine glands

adrenal medulla

adrenal cortex

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2
Q

what controls adrenal cortex

A

hormones from anterior pituitary gland

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3
Q

describe blood flow to adrenal glands

A

rich blood supply

adrenal arteries arise directly from aorta

blood flows through cortex and drains into medulla

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4
Q

histologically describe adrenal gland

A

3 layers of cortex

1 layer of medulla

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5
Q

properties of adrenal medulla

A

part of sympathetic nervous system

not under hormonal control (not a true endocrine gland)

enlarged & specialised sympathetic ganglion

secretes catelcholamine hormones :

  • adrenaline
  • noradrenaline
    • Instead of noradrenaline being released into the synaptic cleft as a nuerotransmitter, it is released into the circulation as a hormone.

neutrotransmitter = acetylcholine

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6
Q

composition of adrenal medulla

A

mostly chromaffin cells

Specialised postganglionic neurons

Preganglionic = Splanchnic nerve fibres

Neurotransmitter is acetylcholine

80% of the medulla secretions is ADRENALINE (epinephrine)

20% is NORADRENALINE (norepinephrine)

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7
Q

what are chromaffin cells & what roles

A

specialised cells in the medulla

depolarisation releases noradrenaline and adrenaline

also secrete dopamine

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8
Q

roles of adrenaline and noradrenaline

A

part of general sympathetic stimulation

short lived and rapid effects

  • rapidly inactivated after

fight or flight response

prepares body for acute stress

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9
Q

cardiovascular effects of adrenaline

A
  • Increases Heart rate and stroke volume
  • Increase in blood pressure (systolic)
  • Vasodilation of coronary and skeletal muscle blood vessels
    • increase blood flow to heart and skeletal muscles
  • Vasoconstriction of blood vessels to ‘non-essential’ tissues (GIT, skin, kidneys)
  • Bronchodilation
    • to get oxygen
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10
Q

metabolic effects of adrenaline

A
  • Increases the amount of energy for immediate use
  • Liver converts glycogen to glucose
  • Metabolic rate increases
  • Blood flow changes, reducing digestive system activity and urine output
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11
Q

roles of beta blockers

A
  • for individuals with high blood pressure
  • adrenaline usually binds to beta receptors
  • beta blockers suppress action of adrenaline
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12
Q

draw summary of differences between adrenal medulla and adrenal cortex

A
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13
Q

structure of adrenal cortex

A

3 morphological distinct zones:

  • Zona Glomerulosa Mineralocorticoids
    • (Aldosterone)
    • salt
  • Zona Fasciculata Glucocorticoids
    • (Cortisol)
      • controlling blood glucose levels
    • sugar
  • Zona Reticularis Gondocorticoids
    • (Androgens)
    • sex

GFR

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14
Q

What type of hormones are produced in adrenal cortex? where are their receptors

A

steroid hormones

receptors are inside the cells - inside the nucleus

hormones differ due to different enzyme

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15
Q

draw flowchart of biosynthesis of the adrenal cortex hormones

A

cholesterol is starting point for all steroid biosynthesis

hydroxylation reactions to achieve hormones

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16
Q

how does synthesis of adrenal cortex hormones differ from one another?

A

depends on enzymes. different enzymes in each layer

e.g.

zona glomerulosa lacks 17a-hydroxylase

zona fasciculata & zona reticularis lack 18 hydroxylase

17
Q

role of andrenal androgens

A
  • produce testosterone precursors:
    • Dehyroepiandrosterone (DHEA)
    • dehydroepiandrosterone sulfate (DHEA-S),
    • androstenedione.
  • out into circulation - peripheral conversion into testosterone
  • DHEA/DHEAS not involved in feedback
  • adrenal gland controlled by anterior pituitary gland
    • by ACTH
18
Q

effect of adrenal androgens in males

A
  • no function in men
    • testosterone produced by testes in high level
  • male secondary characteristics
    • aggressive young boys
  • over-secretion or under-secretion has very little consequences in men
19
Q

effect of adrenal androgen in female

A
  • ovaries make testosterone - most is convered into oestrogen immediately
  • adrenal glands produce abundance
  • production of pubic hair & sex drive
  • kick starts puberty
20
Q

effect of excessive production of adrenal androgen in women

A
  • over production of ACTH or tumour in adrenal cortex or Cushing’s syndrome
    • masculinisation of women
  • facial hair, acne, irregular periods
  • play a role in PCOS

treatment

  • medication that blocks androgens
  • reduces symptoms
21
Q

Adrenal aldosterone

A
  • Mineralocorticoid – Zona glomerulosa
  • Essential to life
  • absence leads to circulatory failure & death within a few days if removed
  • Aldosterone secretion is regulated by the plasma levels of sodium and potassium via the renin-angiotensin system (covered in Kidney lectures)
22
Q

renin-angiotensin-aldosterone system (RAAS)

A

angiotensin converting enzyme - produced in the lungs

cascade of events leading to production of aldosterone

23
Q

roles of aldosterone

A
  • Control ECF volume
  • Conserve body sodium
  • Stimulates reabsorption of sodium in renal distal convoluted tubules in exchange for potassium
  • Control of release
    • Response to renin-angiotensin system (RAAS)
    • Decreased ECF volume (hypovolaemia or hypotension) and decreased renal blood flow
    • Response to high plasma potassium
24
Q

adrenal cortisol importance

A
  • Glucocorticoid: Zona Fasiculata
  • Wide range of actions; essential to life
  • Stress is a powerful stimulator of cortisol production
  • Stress = physical trauma, intense heat or cold, infection, mental or emotional trauma
25
Q

roles and effects of adrenal cortisol

A
  • Mediates the body’s response to stress in response to endocrine signals
  • Metabolic effects
  • Cortisol increases plasma glucose and FFA concentration
    • Provide energy substrates to body tissues for their response to the stressful event that stimulated cortisol production
  • Increased catabolism:
    • Cortisol increases skeletal muscle protein catabolism. Amino acids are then converted to glucose (gluconeogenesis)
    • breaks down muscle mass
    • energy source
  • Increased lipolysis:
    • Liberate free fatty acids & triglycerides from adipose tissue.
    • Used as an energy source
  • Increased intake: Stimulates appetite.
    • If the stressful event doesn’t involve physical activity = weight gain
26
Q

orther actions of adrenal cortisol

A
  • cortisol causes fat stores and excess fat to be relocated in the abdomen and face
    • lipolysis enhances obesity
  • blood sugar levels rise as gluconeogenesis - insulin increases
    • stimulates lipogenesis =
  • May contribute to emotional instability
  • Anti-inflammatory
    • blocks the processes which lead to inflammation (in high doses)
  • Immunosuppressive
    • fall in antibody production and number of circulating lymphocytes
  • Used clinically: to treat patients following transplant
27
Q

control of cortisol release

A
  • CRH – Corticotrophin Releasing Hormone
  • ACTH – Adrenocorticothrophic Hormone
  • Secretion of both the glucocorticoids and adrenal androgens are controlled by ACTH secretion
  • negative feedback
28
Q

examples of adrenal cortex hyperfunction

A

CUSHINGS SYNDROME

  • Overproduction of cortisol
    • Excess cortisol binds to aldosterone receptor
  • As a result of an adrenal tumour or pituitary tumour
  • Redistribution of body fat
  • Muscle wastage
  • Thin skin, bruising abnormal pigmentation
  • Changes in CHO and protein metabolism
  • Hyperglyceamia
  • Hypertension
  • Cortisol has weak mineralocorticoid activity
  • moonface, abdominal striae, acne, baldness
  • Treatment
    • Surgery, radiation, medication

Conns disease

  • Mineralocorticoid excess
  • Rare
  • Overproduction of Aldosterone
  • Retention of sodium, loss of potassium and alkalosis
    • high blood pressure
  • Hypertension through expansion of plasma volume

Excessive production of adrenal androgens

  • Overproduction of ACTH
  • Acne, frontal baldness and hirsutism
29
Q

examples of adrenal function hypofunction

A

Addison’s disease

  • Rare
  • Damage to adrenal glands, autoimmune disease or pituitary damage
  • Deficits in glucocorticoids and mineralocorticoids
  • Progressive weakness, lassitude and weight loss
  • Pigmentation of the skin and mucosal membranes
    • low cortisol, low aldosterone, low androgens
    • excess ACTH - acts like MSH
  • patients with addisons have high ACTH because low cortisol is detected
30
Q

if there was autoimmune destruction of adrenal cortex, what would happen to the plasma hormone levels of :

  • cortisol
  • ACTH
  • CRH
  • aldosterone
  • DHEA (androgen)
  • Adrenaline
A
  • cortisol
    • decreased
  • ACTH
    • increased
  • CRH
    • increased
  • aldosterone
    • decreased
  • DHEA (androgen)
    • decreased
  • Adrenaline
    • normal

z basic sciences (21 decks)

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