T3 Adrenal Hormones Flashcards
What does the medulla secrete?
epinephrine and norepinephrine
The medulla is functionally related to the _______ nervous system.
sympathetic
What does the cortex secrete?
corticosteroids
What are corticosteroids synthesized from?
cholesterol
The synthesis of corticosteroids synthesized from cholesterol is provided mainly by _______ in the plasma, mostly attached to coated pits
LDLs
_______ increases the number of LDL receptors.
ACTH
Where is cholesterol converted to pregnenolone?
mitochondria
Conversion of cholesterol to pregnenolone is catalyzed by what? What is significant about this step?
cholesterol desmolase; rate limiting step
Both ACTH and _______ increase the conversion of cholesterol to pregnenolone.
angiotensin II
Progesterone can be converted to what?
deoxycorticosterone, which is then converted to aldosterone. Also can be converted to cortisol
What is the major mineralocorticoid? What’s its half-life?
aldosterone; 20 minutes
Hyperkalemia has what effects?
aldosterone secretion
What substance increases sodium reabsorption by kidney tubules?
mineralocorticoids
Aldosterone increase ___________ secretion by kidneys, by acting on __________ in _________.
potassium; principle cells; late distal tubules
Aldosterone increase ___________ secretion by kidneys, by acting on __________ in _________.
hydrogen ion; intercalated cells; late distal tubules
What is secretion of mineralocorticoids controlled by?
angiotensin II and K+
What are mineralocorticoids secreted by?
zona glomerulosa
What is the major glucocorticoid?
cortisol
What is essential in the stress response?
cortisol
What is cortisol secretion controlled by?
ACTH from anterior pituitary
What are glucocorticoids secreted from?
zona fasciclutata
Cortisol has a ______ feedback response to both CRH and ACTH.
negative
Cortisol oscillates with circadian rhythm. When is it highest? when is it lowest?
highest = before wakeing lowest = in evening
What are the precursors to estrogens?
DHEA and androstenedione
Where is DHEA converted to testosterone?
in the testes
What is the outcome of a lack of aldosterone?
- total loss causes death in days
- total ECF and blood volume reduced
- diminished CO and progresses to shock-like state
- hyperkalemia and serious cardiac toxicity follow
What is the outcome of a excess of aldosterone?
- increase ECF and arterial pressure
- hypokalemia and muscle weakness
- causes alkalosis
- Small effect on plasma sodium concentration because sodium reabsorption in renal tubules is accompanied by equivalent amount of water reabsorption
What is the overall effect of aldosterone?
increases renal tubular reabsorption of sodium and increases potassium in the urine
What are the functions of glucocorticoids
Stimulate gluconeogenesis by: -increase protein catabolism -mobilizes aa -enhances transport of aa into hepatic cells -increase enz req to convert aa to glucose -decrease glucose utilization by cells -increase lipolysis May lead to adrenal diabetes Resists stress Resists inflammation Causes resolution of inflammation Inhibits immune response Maintains vascular response to catecholamines
What are catecholamines?
norepi and epi
What is primary Addison’s disease caused by?
injury to adrenal cortex
What is secondary Addison’s disease caused by?
impaired function of pituitary gland
What are some disturbances of hypoadrenalism/addisons?
Due to mineralocorticoid deficiency, due to glucocorticoid deficiency, and melanin pigmentation
What are symptoms of mineralocorticoid deficiency?
- decreased EC volume
- hyponatremia
- hyperkalemia
- mild acidosis
- rise in RBC concentration
- decrease in CO and BP
- metabolic acidosis
- death from shock
What are symptoms of glucocorticoid deficiency?
- hypoglycemia
- weight loss, nausea, vomiting
- muscle weakness
- highly susceptible to stress
- reduction in both proteins and fats leading to depression of other bodily functions
What are symptoms of melanin pigmentation?
- may be caused by loss of negative feedback to pituitary, allowing increased amounts of MSH
- results in uneven distribution of pigmentation, esp in thin skin areas
What are the causes of Cushings/hyperadrenalism
- administration of glucocorticoids
- adenomas of ant pituitary
- abnormal function of hypothalamus
- ectopoc secretion of ACTH by tumor
- adenomas of adrenal cortex
- excess ACTH secretion is cause of Cushing’s
What are the characteristics of Cushing’s?
- increase in cortisol and androgen levels
- “buffalo torso”
- moon face
- acne and hirsutism
- hypertension
- increased blood glucose
- increase in protein catabolism and muscle wasting
