Endocrinology - Lecture 3 Flashcards
What are the two divisions of the adrenal gland?
Medulla
Cortex
Adrenal Medulla
Inner portion of the gland
Part of the sympathetic nervous system…it’s a modified sympathetic ganglion
Autonomic nervous system that controls fight or flight
Derived from neural crest cells
Adrenal Cortex
Outer portion of the gland
Responds to hormones
Derived from mesothelial cells of the intermediate mesoderm
What types of hormones are secreted by the adrenal medulla?
Catecholamines: epinephrine and norepinephrine
T/F - The adrenal medulla is a gland in the sympathetic ganglion with no postsynaptic neurons with axons
True
Why does the adrenal medulla secrete more epinephrine than norepinephrine?
It contains significant amounts of the enzyme phenyl-N-methyltransferase, which converts NE to E
What are the divisions of the adrenal cortex?
Zona glomerulosa
Zona fasciculata
Zona reticularis
Zona glomerulosa
Outermost layer of the adrenal cortex
Cells are arranged in clumps
Secretes Aldosterone
Zona fasciculata
Middle layer of the adrenal cortex Cells are arranged in long, parallel lines Secretes glucocorticoids (cortisol and corticosterone)
Zona reticularis
Innermost layer of the adrenal cortex
Cells are arranged in a net-like or web orientation
Secretes sex steroids (DHEA, androstendione)
Aldosterone
Mineralcorticoid produced by cells in the zona glomerulosa
Aldosterone action
Stimulate Na and H2O retention in order to maintain blood volume and blood pressure
What is the largest target tissue of aldosterone
Kidneys
What regulates the secretion of aldosterone?
- The kidney secretes a hormone (renin) when blood pressure or Na blood levels are too low
- Stimulated by an increase in plasma K
- Stimulated by a decrease in plasma pH or an increase in plasma H+
- Stimulated by a drop in systemic blood pressure
- Inhibited by an increase in Na intake
Glucocorticoids
Cortisol and corticosterone
Secreted by the cells of the zona fasciculata
What is the major function of glucocorticoids
Increase metabolic fuel availability and use in tissues
What effect does cortisol have on the body?
Increase gluconeogenesis in the liver
Increase proteolysis in muscles
Increase lipolysis
Decrease glucose uptake in muscle and fat
Decrease immune and inflammatory responses
Decrease growth and reproductive energy
Regulate blood pressure
Androgens
Sex steroids secreted by the zona reticularis
Dehydroepiandrosterone (DHEA) and Androstenedione
Dehydroepiandrosterone (DHEA)
A precursor of other sex steroids - so it can serve as a circulating reservoir in peripheral tissues containing steroidogenic enzymes
Relatively weak androgenic action
Androstenediione
Synthesized by enzymatic conversion of DHEA
Stronger than DHEA
Provides a non-gonadal source of testosterone and estradiol - an important source of reproductive steroids prior to puberty and in postmenopausal women
What do adrenal sex steroids do?
Regulate mood, libido, hair growth, erythropoiesis, and acne
Why is the stress response important?
It is critical for maintenance of homeostasis and essential for survival
It allows the body to respond to things that are deviations from the “norm”
What happens if a stress response persists after the stress is gone?
Adverse effects that can become damaging
What adverse conditions can occur to chronic stress responses?
Cortisol will catabolize tissue, which can be rebuilt when stress is over. But if stress prolongs, it won’t rebuild and the body can be damaged
Cortisol has high anti-inflammatory and anti-immune effects. This conserves energy in the long term, but we want these things to work at some point.
Mobilization of metabolic fuels increases lipids in the blood, and along with increased blood pressure can lead to atherosclerosis, hypertension, and blood clots
What evidence is there for an interaction between immune function and activation of the stress response?
- HSV + psychiatric illness –> increased recurrences and duration of outbreak
- Influenze + family dysfunction –> increased frequency and severity of illness
- Hep B + exams –> delayed antibody response to vaccine
What is the CNS connection to the stress response?
A stress response is 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 causes of a primary insufficiency leading to Addison’s Disease
Disease
A congenital disorder
Autoimmune disorder
What are the causes of a secondary insufficiency leading to Addinson’s Disease?
Pituitary problem
Glucocorticoid therapy - can use exogenous corticosteroids, which has feedback effects on CRH and ACTH which can impair a normal stress response
What are symptoms of adrenal insufficiency (Addison’s disease)
Low cortisol
High ACTH
Weakness, lethargy, and decreased appetite
Low blood pressure
Low glucose when fasting
Hyperpigmentation due to lack of negative feedback control of POMC
How do you treat adrenal insufficiency? (Addison’s disease)
Exogenous glucocorticoids and/or dietary controls
What causes Hypercortisolinemia (Cushing’s disease)
Typically due to a pituitary tumor or administering too much exogenous glucocorticoid
How do you treat Hypercortisolinemia?
Remove the tumor that’s causing it
What are symptoms of Hypercortisolinemia?
Excessive tissue catabolism (especially bone, skin, and muscle)
Type II Diabetes-like symptoms (increased appetite and circulating glucose)
Impaired immune functions
Threat of hypertension
What is the primary concern for dentists seeing patients with Hypercortisolinemia?
Impaired immune function after a procedure
Hypertension
Osteoperosis
Increased bleeding
