ADRENALS
Terms
undefined, object
copy deck
- What are the 3 zones of the outer adrenal glands?
-
1. Glomerulosa
2. Fasciculata
3. Reticularis - What does each Adrenal zone produce?
-
1. Glomerulosa - Mineral corticoids; ALDOSTERONE.
2. Fasciculata - glucocorticoids; CORTISOL.
3. Reticularis - Adrenal Androgens; SEX hormones. - What does the outer adrenal gland compose, what type of gland is it?
-
cortex: 80-90% of the adrenals.
Gland that produces STEROIDS. -
What is the inner adrenal gland?
How much of the adrenal gland?
What does it produce? -
Adrenal Medulla; 10-20% of the whole gland.
Produces CATECHOLAMINES: Norepinephrine & Epinephrine. - What is special about the adrenal medulla?
- It is a modified sympathetic ganglion.
- What is the name of the cells in the adrenal medulla that synthesize and secrete hormone?
-
Chromaffin cells - synthesize Norepi and Epi and package in vesicles.
(have high affinity for chromaffin stain) - What causes chromaffin cells to release their vesicle contents into the blood stream?
- Input from preganglionic sympathetic neurons; they release AcH which causes synapse.
- What are the ratios of epi and norepi output by the adrenal medulla?
-
80-90% Epinephrine
10-20% Norepi - what are other names for epi and norepi?
- Adrenaline, noradrenaline
- What type of hormone are epi and norepi again?
- Catecholamines
- What is the major role of the hormones produced by the adrenal medulla (epi and norepi)?
- to protect the body against hypoglycemia.
- What stimulates and regulates epinephrine/norepi secretion?
-
1. Low blood glucose
2. Exercise
3. Cold
4. Pain
5. Anger/stress - What is the function of the catecholamines?
-
The FIGHT OR FLIGHT response
-increase blood glu
-incr. cardiac output, FFA, blood flow to muscles.
-Decreased GI activity. - Why do we have an adrenal medulla?
- To provide a response to acute and short term stress - by storing epi in vesicles, you don't have to wait for its synthesis.
- Why are epi and norepi especially valuable hormones?
- because they act on nervous system in places where nerves can't go, b/c they are transported by the bloodstream.
-
How does Epi affect blood vessels?
What caues this? -
It dilates vessels in skeletal muscle;
-caused by B2 adrenergic receptor stimulation. - What has a better effect when released; epinephrine or nor?
-
Epi - 10x better.
Because norepi does not act on Beta-2 adrenergic receptors. - What are the 2 effects of Epi and Norepi on the pancreas?
-
1. Increased glucagon release
2. Decreased Insulin release - What are the 2 effects of Epi and Norepi on the liver?
-
1. Increased Gluconeogenesis
2. Increased glycogenolysis
-Breaks down glycogen to increase blood glucose. - What is the effect of Epi and Norepi on skeletal muscle?
- Increased glycogenolysis - breaks it down to use the glucose right in the muscle.
- What is the effect of Epi and Norepi on adipose tissue?
- Increased lipolysis to break down Triglycerides into glycerol and free fatty acids for gluconeogenesis.
-
how specifically do Epi/norepi cause increased lipolysis?
Glycogenolysis? -
By increasing Hormone sensitive lipase.
Glycogen phosphorylase - What are two differences between hormones of the adrenal cortex and medullar?
-
1. Cortical hormones are lipophilic - not H2O soluble.
2. Cortical hormones are not stored; only synth and released as needed. - What induces release of Cortisol and glucocorticoids?
- Stress - physical or emotional.
- What pattern governs how corticoids are released?
-
Circadian rythms.
Increased release in AM
Decreased at night. - How does ACTH affect the adrenal cortex?
-
1.Simulates synthesis and release of cortisol
2. Upregulates steroidogenic enzymes
3.Increases cell size of synthesizing cells in the cortex. - What region of the cortex produces cortisol and glucocorticoids?
-
the zona fasciculata
(glomerulosa acts on the renal glomerulus, mineralcorticoids) - what is the prohormone for ACTH?
- Pro-opiomelanocortin
- What happens to the adrenals if ACTH stimulation is decreased?
- They atrophy and become smaller.
- What is the whole pathway for cortisol release stimulation and inhibition?
-
1. Hypothalamus produces CRH in response to stress.
2. Anterior pituitary produces ACTH
3. ACTH travels to pituitary and causes cortisol release.
4. Cortisol decreases insulin - How does ACTH cause cortisol synthesis/secretion, in contrast to how EPI/norepi are?
- It upregulates enzymes for gene expression; in general turns on Cortisol synthesis - takes TIME for the response.
- Why do we need to know that POMC is the prohormone for ACTH?
- Because the 1st 13 amino acids on its protein are alpha-MSH; high ACTH concentrations cause melanocyte stim, pigmentation.
- How does glucocorticoid synthesis/release fluctuate?
- Circadially - lowest at midnight, highest mid-morning.
- why is there a rythm to glucocorticoid release?
- To respond to stress fluctuations normal to every person.
- why are glucocorticoids vital for life?
- Without them you can't deal with stress, or prolonged fasting.
- What are the 3 main things glucocorticoids effect?
-
1. Metabolism
2. Stress
3. Inflammation - How do glucocorticoids affect metabolism?
- Cortisol has an anti-insulin effect; result is to increase plasma glucose, amino acid, and calcium levels.
- How does cortisol affect bones?
- Increases break-down, can be a cause of osteoporosis.
- Why are glucocorticoids important for dealing w/ stress?
-
-necessary for coping (idiopath)
-necessary for vascular smooth muscle to constrict
-affects norepi/epi release by blood flow from cortex-medulla - What affect does cortisol have on immunity?
- suppresses immune response - an anti-inflammatory.
- Why are mineralcorticoids important?
- because they regulate Na/K levels, thus blood pressure, salt and water balance.
- What two things stimulate Aldosterone?
-
-Decreased blood pressure/Na levels (detected by juxtamed apparatus)
-Increased sympathetic activity - By what pathway/system is aldosterone regulated?
-
The renin-angiotensin system:
Angiotensinogen is activated by Renin; angiotens 1 activates to Angiotens II, and increases aldosterone. - what is the main stimlulator of aldosterone, and what is the affect?
- Angiotensin II, produced by the lungs; causes general vasoconstriction.
- What is the function of mineralcorticoids in a nutshell?
-
Regulate Salt/Water balance by:
-Increasing Na reabsorption
-Increasing K/H excretion - finish this!
- ok
- What 3 effects can Cortisol incur on the body at HIGH concentrations?
-
1. Psychotic effects on mood
2. Osteoporosis (bone bkdown)
3. Immunosuppressant - What are the NORMAL effects Cortisol has on the body?
-
Increased GLUCONEOGENEIS by
1. Skeletal muscle breakdown of glucose -> free amino acids
2. Liver glycogen breakdown -> free glucose
3. BLOCKING insulin to prevent glycogenesis. - What is the response to increased plasma glucose from cortisol's stimulation?
- it actually feedsback to incrase insulin levels in response to high blood glucose.
- How do blood glucose levels change as the body transfers from fed to fasting states?
-
1. Blood glucose rises initially, in response to Cortisol.
2. Then gluconeogenesis stops when glycogen is exhausted; fatty acids + ketone bodies then take over. -
OK keren, HOW DOES ALDOSTERONE CONTROL WATER AND SALT BALANCE?
(3 things) -
1. Stimulates Na+ reabsorption
2. Stimulates K+ excretion
3. Stimulates H+ excretion. - 3 things that stimulate RENIN secretion:
-
1. Decreased Na levels
2. Decreased blood pressure
3. Increased sympathetic NS activity - What happens when Renin is stimulated?
- The angiotensin system, which ultimately results in increased aldosterone synthesis.
- What are the 2 Adrenal Androgens?
-
1. DHEA - dehydroepiandrosterone
2. Androstenedione - How does DHEA work, and what does the body do with it?
-
1. Mimics testosterone and binds its receptors WEAKLY.
2. Body converts DHEA to testosterone in tissues. -
What is the role of DHEA in
-Men?
-Women?
-Both? -
Men - has no role!
Women - probly causes hair growth, libido.
Both - probly involved in development before puberty. - What is the one disorder that occurs in the adrenal medulla?
- Pheochromocytoma
- What in the world is Pheochromocytoma?
- A tumor of the chromaffin cells - therefore more Epi and Norepi are produced - makes you have high blood pressure.
- What are the 3 disorders of the Adrenal Cortex?
-
1. Cushing's syndrome
2. Addison's disease
3. Congenital adrenal Hyperplasia. - What causes Cushing's syndrome?
-
1. Therapeutic glucocorticoids causing high cortisol levels.
2. Hypothalamic, pituitary, or adrenal tumor
-In general: HIGH CORTISOL - what is the result of high cortisol seen in Cushing's?
-
-Moon face/buffalo hump
-fat re-distribution
-Immune suppression
-poor wound healing
-muscle wasting
-high blood glucose. - How does Addison's disease compare to Cushing's, pathologically?
-
Cushing = cortisol overproductn
Addison = ADRENAL insufficiency - cortisol AND aldosterone. - What causes addison's disease?
- an autoimmune disorder where cortisol AND aldosterone are decreased; resulting ACTH increase causes pigmentation.
- What are the symptoms of addison's disease?
-
-from low cortisol, inability to deal with stress, weak, fatigue.
-from low aldosterone, low blood volume, hypotensive - death.
-from high ACTH, hyperpigment. - What is the underlying problem in congenital adrenal hyperplasia?
- An enzyme needed to synthesize the adrenal steroids is missing; The precursors of are shunted over to the ANDROGEN pathway.
- What is the result of congenital adrenal hyperplasia?
-
-Cortisol/aldosterone are low
-Androgens (DHEA and androstenedione are high;
-women/children are masculinized
-men have low sperm counts
-addison symptoms too