adrenal gland Flashcards by Richard Wu

composition of adrenal glands

2 endocrine glands

adrenal medulla

adrenal cortex

How well did you know this?

Not at all

Perfectly

what controls adrenal cortex

hormones from anterior pituitary gland

How well did you know this?

Not at all

Perfectly

describe blood flow to adrenal glands

rich blood supply

adrenal arteries arise directly from aorta

blood flows through cortex and drains into medulla

How well did you know this?

Not at all

Perfectly

histologically describe adrenal gland

3 layers of cortex

1 layer of medulla

How well did you know this?

Not at all

Perfectly

properties of adrenal medulla

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

How well did you know this?

Not at all

Perfectly

composition of adrenal medulla

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)

How well did you know this?

Not at all

Perfectly

what are chromaffin cells & what roles

specialised cells in the medulla

depolarisation releases noradrenaline and adrenaline

also secrete dopamine

How well did you know this?

Not at all

Perfectly

roles of adrenaline and noradrenaline

part of general sympathetic stimulation

short lived and rapid effects

rapidly inactivated after

fight or flight response

prepares body for acute stress

How well did you know this?

Not at all

Perfectly

cardiovascular effects of adrenaline

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

How well did you know this?

Not at all

Perfectly

metabolic effects of adrenaline

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

How well did you know this?

Not at all

Perfectly

roles of beta blockers

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

How well did you know this?

Not at all

Perfectly

draw summary of differences between adrenal medulla and adrenal cortex

How well did you know this?

Not at all

Perfectly

structure of adrenal cortex

3 morphological distinct zones:

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

GFR

How well did you know this?

Not at all

Perfectly

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

steroid hormones

receptors are inside the cells - inside the nucleus

hormones differ due to different enzyme

How well did you know this?

Not at all

Perfectly

draw flowchart of biosynthesis of the adrenal cortex hormones

cholesterol is starting point for all steroid biosynthesis

hydroxylation reactions to achieve hormones

How well did you know this?

Not at all

Perfectly

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

depends on enzymes. different enzymes in each layer

e.g.

zona glomerulosa lacks 17a-hydroxylase

zona fasciculata & zona reticularis lack 18 hydroxylase

role of andrenal androgens

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

effect of adrenal androgens in males

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

effect of adrenal androgen in female

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

effect of excessive production of adrenal androgen in women

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

Adrenal aldosterone

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)

renin-angiotensin-aldosterone system (RAAS)

angiotensin converting enzyme - produced in the lungs

cascade of events leading to production of aldosterone

roles of aldosterone

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

adrenal cortisol importance

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

roles and effects of adrenal cortisol

* 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. A**mino 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

orther actions of adrenal cortisol

* 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

control of cortisol release

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

examples of adrenal cortex hyperfunction

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

examples of adrenal function hypofunction

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

if there was autoimmune destruction of adrenal cortex, what would happen to the plasma hormone levels of : * cortisol * ACTH * CRH * aldosterone * DHEA (androgen) * Adrenaline

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