The Adrenal gland 9/3/15 Flashcards
Where are the adrenal glands located?
One on top of each kidney
What are the 2 portions of the adrenal gland?
Adrenal medulla = inner portion (part of sympathetic autonomic nervous system that controls fight for flight.
Adrenal cortex = outer portion, not part of nervous system. It secretes hormones in response to hormone stimulation.
What does the adrenal medulla secrete?
Epinephrine and norepinephrine hormones
What does the adrenal cortex secrete?
Steroid hormones
What is the Adrenal Medulla derived from?
Neural crest cells
What is the Adrenal cortex derived from?
Mesotheial cells
____ is a modified sympathetic ganglion
Adrenal medulla
*No postsynaptic neurons with axons in it, instead the postganglionic cells release epinephrine (80%) and norepinephrine (20%) into the blood
_____ converts norepinephrine (NE) to epinephrine (E).
Enzyme pheynl-N-methyltransferase
Beta receptors have greater affinity for _____ and alpha receptors have greater affinity for _____>
Beta = E
Alpha = NE
*This means neural response to E and NE can vary.
What is the response to E and NE in tissues not directly innervated by postganglionic neurons (liver, skeletal muscles and fat)?
E = acts to increase availability of metabolic fuel by stimulating lipolysis, glycogenolysis and gluconeogenesis.
In short what does the adrenal medulla do?
Enhances the sympathetic response by releasing hormones that can reach additional target without neural circuits.
Because the endocrine (hormone) signal is blood borne, the response is ________.
longer
What are the zones of the Adrenal cortex?
Zona Glomerulosa = outermost Zona Faciculata = middle Zona Reticularis = innermost, adjacent to the medulla *Each zone produces a different class of steroid.
What are the 5 steroids secreted by the Adrenal cortex zones?
- Cortisol
- Corticosterone
- Aldosterone
- Anderostenedione
- Dehydroepiandrosterone (DHEA)
In the adrenal cortex, steroid synthesis and secretion is stimulated by_______.
ACTH, Except for aldosterone which is regulated by other signals.
Aldosterone is a ______ produced by cells in the _______.
Mineralocorticoid produced in Zona glomerulosa.
What is the principal action of Aldosterone?
stimulate Na+ and H2O retention in the kidney in order to maintain blood volume and pressure.
The mechanism by which aldosterone helps reabsorb Na+ and H2O in the kidney results in ________.
an increase of K+ and H+ in urine (Important!)
How does aldosterone do its job?
The aldosterone-receptor complex binds to DNA and stimulates the synthesis of proteins that act to increase Na+ and H2O reabsorption from the tubular fluid back into the blood.
What factors regulate the Secretion go aldosterone? (4)
- Stimulated by increase in plasma K+
- Stimulated by a decrease in plasma pH or Increase in Plasma H+
- Stimulated by a drop in systemic blood pressure
- Inhibited by increased Na+ intake
Glucocorticoids _____ and ______ are secreted by the cells of the zone fasciculata.
Cortisol and corticosterone *Cortisol is the important one in humans.
What are the major effects of Glucocorticoids (cortisol)?
To increase the availability of glucose: antagonizes the action of insulin.
- increase gluconeogenesis in liver
- Increase proteolysis in muscle
- Increase lipolysis
- decrease glucose uptake in muscle and fat
- decrease immune and inflammatory responses
- decrease growth and reproductive function
- Permissive action on Beta receptors in vascular smooth muscle to regulate blood pressure.
Synthesis and secretion of glucocorticoids is stimulated by _______.
ACTH
Cortisol has a negative feed back action on ____ and ______.
CRH and ACTH
__________ are secreted by the Zona Reticularis.
Sex hormones (androgens) DHEA and androstenedione.
_____ Is the precursor of other sex steroids.
DHEA, so it can serve as a circulating reservoir for conservation in peripheral tissues containing steroidogenic enzymes
Androstenedione is synthesized by ___________.
enzymatic conversion of DHEA.
Which is a stronger androgen, DHEA or Androstenedione?
Androstenedione
______ provides a nongonadal source of Testosterone and estradiol.
Androstenedione
______ is important source so steroids prior to puberty and in postmenopausal women.
Androstenedione
What are adrenal sex steroid important for?
Regulating:
- mood
- libido
- hair growth
- erythropoiesis
- acne
Synthesis and secretion of adrenal androgens is stimulated by _______.
ACTH
What is the Stress response?
A response of the stress axis (Hypothalamus- ant. pituitary- adrenal cortex) to a stressor that stimulates hypothalamic CRH neurons and inputs to the SNS.
What are the 3 primary goals of the stress response?
- maintain blood pressure
- mobilize and increase availability of metabolic fuel
- inhibit non-essential functions
What shuts off the stress response?
Removal of stressor and negative feedback actions of cortisol on CRH and ACTH.
What happens when cortisol is elevated for long periods and combined with chronic activation of SNS? 3 things..
- Highly catabolic use of substrates to produce glucose. These tissues can be rebuilt after stress is over, but if it continues to long it can cause problems.
- Cortisol inhibits inflammation, cytokines and phagocytosis, this conserves energy in the short term, but is damaging with chronic stress.
- Mobilization of metabolic fuels increases lipids in the blood which can increase blood pressure ann cause hypertension
What is Addison’s disease?
Adrenal insufficiency caused by: PRIMARY insufficiency: - disease - Congenital disorder - Autoimmune disorder SECONDARY insufficiency: - pituitary problem - Glucocorticoid therapy * This is important for dentist because patients may have complications with maintaining blood pressure during anesthesia.
What are the Symptoms of Adrenal insufficiency?
- low cortisol and high ACTH
- weakness, lethargy and decreased appetite
- low blood pressure
- low glucose when fasting
- hyper pigmentation due to lack of feedback control of POMC production
How do you treat Adrenal insufficiency?
You don’t, you’re a dentist not a real doctor……….ha ha ha j/k you are supposed to treat with glucocorticoids and/or dietary control.
What is Hypercortisolinemia/Cushing’s disease?
Typically caused by a pituitary tumor = excess cortisol.
What are the symptoms of Cushing’s disease?
- excessive tissue catabolism
- diabetes like symptoms
- impaired immune function
- threat of hypertension
- In dental patients the primary concern is impairment of immune function after a procedure, but hypertension, osteoporosis and increased bleeding are also a problem.
