Physiology of Adrenal Gland Flashcards Preview

SF3-EXAM 4 (CAMELITA) > Physiology of Adrenal Gland > Flashcards

Flashcards in Physiology of Adrenal Gland Deck (34)
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1
Q

Which hormone is required to stimulate norepinephrine to epinephrine?

A

Cortisol

2
Q

Which amino acid is norepinephrine stimulated from?

A

Tyrosine-> Dopamine-> Norepinephrine

3
Q

Which substances are assessed in urine to clinically assess the level of catecholamine production in a patient?

A

Vanillylmandelic acid (VMA) and metanephrine

4
Q

Adrenal catecholamines are methylated by _______ in nonneuronal tissues such as the liver and kidney.

A

Catechol-O-methyltransferase (COMT)

5
Q

Pheochromocytoma

A

Benign tumor of the adrenal gland

6
Q

What factors can stimulate release of epinephrine?

A

Anxiety

Pain

Trauma

Hypovolemia

Hypoglycemia

Hypothermia

7
Q

Catecholamines require ________ and _______ to exert their full effects.

A

Thyroid hormone; cortisol

8
Q

Epinephrine and norepinerphrine ____________ (increase/decrease) blood flow to muscles.

A

Increase

9
Q

Epinephrine promotes _____________ (glycogenesis/glycogenolysis) in muscle.

A

Glycogenolysis

10
Q

Epinephrine and norepinephrine stimulate glucogon secretion and inhibit insulin secretion. Which receptor is used carry out each action, respectively?

A

B2: Stimulate glucagon secretion

A2: Inhit insulin secretion

11
Q

Catecholamines cause ___________ (relaxation/constriction) of bronchiolar smooth muscle.

A

Relaxation

*They also act to decrease energy demand by visceral smooth muscle

12
Q

Pro-opiomelanocortin (POMC) is a precursor for which hormones? What is the function of each?

A

α-MSH

  • regulation of appetite
  • production of melanin.

ACTH

  • regulates the secretion of glucocorticoids from the adrenal cortex.

β-Endorphin and Met enkephalin

  • endogenous opioid peptides with widespread actions in the brain.
13
Q

What are the major effects of cortisol at normal levels?

A
  • Stimulates:
    • Gluconeogenesis
      • Induces synthesis enzymes involved in hepatic gluconeogenesis
    • Protein catabolism
      • To provide substrate for glucogenesis​
    • Lipolysis
      • In adipise
    • Inhibition of insulin-stimulated glucose uptake by muscle and adipose tissue

REMEMEBER: Cortisol is considered a diabetogenic hormone

14
Q

Physiological actions of glucocorticoids

A
15
Q

Cortisol inhibits ______ that is activated in response to injury.

A

Prospholipase A2

16
Q

Cortisol decreases ______ migration to the site of injury.

A

Leukocyte

REMEMBER: Cortisol has immunosuprressive activity

17
Q

What are the different types of causes of Cushing’s syndrome?

A

ACTH-dependent

  • Cushing’s disease (pituatary dependent)
  • Ectopic ACTH syndrome
  • Ectopic CRH syndrome

ACTH-independent

  • Adrenal adenoma and carcinoma
  • Iatrogenic

Pseudo-cushing’s syndrome

  • Alcoholism
  • Depression
  • Obesity
18
Q

What are the major signs and symptoms of Cushing’s syndrome?

A

Central obesity

Increased body weight

Fatigabilty and weakness

Hypertension

Hirtuitism

Amennorhea

Cutaneous striae

Personality changes

Ecchymoses (bruises)

Proximal myopathy

Edema

19
Q

What are the symptoms that are more specific to Cushing’s syndrome?

A

Central obersity

Hirsuitism

Amenorrhea

Cutaneous striae

Ecchymoses

Proximal myopathy

20
Q

Dexamethasone suppresion test

A
  • Assess the pituatary corticotroph cell response to glucocoticoid negative feedback on ACTH secretion.

NOTE: Dexamethasone is potent glucocorticoid, about 30 to 40 times more potent than cortisol

21
Q

How should the following results be interpreted?

  • Low dose dexamethasone administered
  • Decrease in cortisol levels
A

Normal

22
Q

How should the following results be interpreted?

  • Low dose dexamethasone administered
  • Cortisol is not suppressed by low doses
  • ACTH is undetectable or low
A

Cushing’s syndrome (primary hypercortisolism)

  • Cortisol is being released in high levels so even with feedback from the dexamethasone to the hypothalamus and pituatary, one small dose is not enough to lower cortisol levels.
23
Q

How should the following results be interpreted?

  • High dose dexamethasone administered
  • Cortisol is not suppressed by low doses, but is suppressed by high doses
  • ACTH is normal to elevated
A

Cushing’s disease (Secondary hypercortisolism)

  • Likely a pituatary adenoma
  • ACTH is elevated
24
Q

How should the following results be interpreted?

  • High dose dexamethasone administered
  • Cortisol is not suppressed by high or low doses
  • ACTH is elevated into hundreds
A

Ectopic ACTH syndrome

25
Q

What effect does aldosterone have on the following molecules?

Sodium, Potassium, Hydrogen Ion, Bircarbonate, Water

A
  • Sodium
    • increases reabsorption
  • Potassium
    • Increases secretion in colelcting duct
  • Hydrogen Ion
    • Increases secretion by intercalated cells of the collecting duct
  • Bircarbonate
    • Produces
  • Water
    • Reabsoption
26
Q

Which hormones stimulate Na+/K+ ATPase in reponse to the rise in plasma K+

A

Insulin, aldosterone, and epinephrine

NOTE: These hormones also stimulate Na+/K+/Cl= symporter and the Na+/Cl- symporter to increases cellular uptake. The kidneys then excrete excess K+

27
Q

How do high plasma potassium levels stimulate aldosterone secretion?

A

Increase in plasma K+ depolarizes the plasma membrane and opens voltage-gated Ca+ channels leading to steroidogenesis in the glomerulosa of the adrenal cortex

28
Q

___________ binds to receptors in the zona glomerulosa and inhibits the synthesis of aldosteron.

A

ANP

REMEMBER: ANP is released by the cardiac atrial muscle fibers in response to expansion of blood volume. It causes small increases in GFR and decreases sodium reabsorption at the collecting ducts

29
Q

Addison’s disease

A
  • The adrenal glands do not produce enough steroid hormones.
    • Low cortisol
    • Low aldosterone
30
Q

What are the causes of adrenal insuffiency?

A
  • Primary
    • Destruction of gland
    • Metabolic
      • Congenital adrenal hyperplasia
  • Secondary
    • Hypothalamic-pituatary disease
    • Suppression of HPA- exogenous steroids
31
Q

What are the signs and symptoms of adrenal insufficiency?

A

Weakness

Pigmentation of skin

Weight loss

Anorexia, nausea, and vomiting

Hypotension

Pigmentation of mucus membranes

Abdominal pain

Diarrhea

Syncope

32
Q

What is the most likely cause of polyuria?

A

Aldosterone escape

33
Q

Major cause of secondary hyperaldosteronism

A

Usually caused by over-secrection of renin secondary to a decrease in renal blood flow and/or pressure

34
Q

What are the major clinical symptoms of hyperaldosteronism?

A
  • Increased whole body sodium, fluid, and circulating blood volume
  • Increase peripheral vasoconstriction and TRP
  • Borderline to severe hypertension
  • Edema rare
  • Hypokalemia