Newman Clin Med 2 Flashcards
What is the HPA axis and what does it regulate?
NE system that controls reactions to stress and regulates
- 1. Digestion
- 2. Immune system
- 3. Moods and emotions
- 4. Sexuality
- 5. Energy storage and expenditure
Why is negative feedback in the HPA axis important?
Regulate the concentration of hormones in the blood to prevent over/under correction
- Identify the “zone” of the adrenal cortex responsible for the production of
- a. Mineralocorticoids
- b. Glucocorticoids
- c. Sex steroids
- Glomerulosa => mineralcorticoids
- Fasiculata => glucocorticoids
- Reticulata => sex steroids
Describe the difference between short-term and long-term stress response in terms of the HPA axis and the adrenal cortex.
Short-term stress response: stimulation of the adrenal medulla via preganglionic sympathetic fibers => release of catecholamines (EPI and NE)
Long-term stress response: release of CRH from the hypothalamus => AP => ACTH => adrenal cortex => release of mineralcorticoids and glucorticoids.
What physiological changes do we see in the short-term response to stress?
- ↑ HR
- ↑ BP
- ↑ metabolic rate
- ↑ blood glucose: Glycogen conversion to glucose in the liver
- Dilation of bronchioles
- Changes in blood flow patterns leading to ↓ digestive system activity and ↓ urine output
What physiological changes do we see in the long-term response to stress?
-
Mineralcorticoids
- => ↑ retention of Na+/water by kidneys => ↑ BV/BP
-
Glucocortoids (cortisol)
- Proteins/fats => converted to glucose or broken down for NRG = > ↑ blood glucose
- Suppresion of immune system
The renin-angiotensin-aldosterone system is important in the regulation of what?
renal
cardiac
vascular physiology
Describe the renin-angiotensin-aldosterone system (RAAS) and how angiotensin II stimulates
aldosterone secretion from the adrenal cortex.
- Renin is secreted from the kidney dt ↓ renal perfusion and/or ↑ sympathetic activity
- Angiotensinogen is converted to angiotensin I (by renin)
- Angiotensin I becomes Angiotensin II (via ACE)
- Angiotensin II stimulates aldosterone secretion from the adrenal cortex
What is something you ALWAYS examine in a BB?
Genitalia
The most common cause of ambiguous genitalia in a genetically female infant is what?
CAH: congenital adrenal hyperplasia (causing virilization of the genitalia)
When ambigous genitalia is ID’d, what must be thought of?
CAH => LIFETHREATENING
What is the most common form of CAH?
21-hydroxylase deficiency (results in deficiency of aldosterone and cortisol, increase in testosterone)
What metabolic precursor will be elevated in 21-hydroxylase deficiency>
17- OH progesterone
Signs and sx of 21-hydroxylase deficiency
- i. Failure-to-thrive
- ii. Recurrent vomiting
- iii. Dehydration
- iv. Hypotension
- v. Hyponatremia/ Hyperkalemia
- vi. Shock
What do the effects of [low ald/cortisol and high testosterone] in 21-hydrolase deficiency depend on
severity of 21-hydroxylase abnormality
Treatment of an infant in crisis due to CAH
- Hydrocortisone (IV/IM) = MUST
- Fluids/glucose IV
- Management of hyperkalemia
- Summarize the purpose of mandatory newborn screening.
detect potentially fatal or disabling conditions in newborns as early as possible, hopefully before they develop serious illness.
Identify the three categories of adrenal gland defect responsible for primary adrenal insufficiency (Addison disease).
- a. Adrenal dysfunction
- b. Adrenal dysgenesis
- c. Impaired steroidogenesis
MCC of adrenal dynsfunction => Addisons disease
Autoimmune
Cause of adrenal dysgenesis => Addisons disease
Congenital adrenal insufficiency