Parafollicular/Parathyroid/Adrenal Flashcards
cells reside outside of the follicular cells but still within the thyroid
Parafollicular Cells
Synthesizes and secretes ____
calcitonin
Parafollicular Cells
High levels of serum Ca2+ and HPO42 ___ secretion
Parafollicular cells
stimulate
Low levels of serum Ca2+ and HPO42 ___ secretion
Parafollicular cells…
inhibit
Calcitone it down
The process of using/losing a substance
Resorption
Example: The breakdown of bone by osteoclasts in order to increase plasma Ca2+
The process of gaining something (whether for the first time or again)
Absorption/Reabsorption
Example: Osteoblasts absorbing/reabsorbing the Ca2+ from blood to build bone matrix
Calcitonin inhibits?
osteoclasts
Calcitonin increases?
osteoblasts
Calcitonin decreases calcium ___ in the intestines
absorption
Calcitonin ___ calcium loss in urine
increases
Four small glands attached to the posterior surface of the thyroid gland
Parathyroid Glands
“stuck” to it, not part of it
Principal cells (AKA __ cells) are the functional component
parathyroid glands
Chief
These secrete parathyroid hormone (PTH)
Principal cells (AKA Chief cells)
High levels of serum Ca2+ ___ secretion
parathyroid hormone (PTH)
inhibit
Low levels of serum Ca2+ ___ secretion
parathyroid hormone (PTH)
stimulate
Increases osteoclasts
Parathyroid Hormone (PTH)
Inhibits osteoblasts
Parathyroid Hormone (PTH)
Increases calcium absorption in the intestines
Parathyroid Hormone (PTH)
Decreases calcium loss in the urine
Parathyroid Hormone (PTH)
Pair of flattened, pyramidal-shaped glands located superior and adjacent to the kidneys (retroperitoneal)
adrenal gland
Adrenal cortex-
large and peripherally located
smaller and centrally located
Adrenal medulla-
Covered by a connective tissue capsule
Highly vascularized
Adrenal gland
Order of adrenal layers?
152
Hypothalamus releases ___ which targets the anterior pituitary
corticotropin-releasing hormone (CRH)
Anterior pituitary produces and releases ___ in response, which has the following actions on the adrenal cortex
adrenocorticotropic hormone (ACTH)
mineralcorticoids are produced and secreted
Zona Glomerulus
glucocorticoids are produced and secreted
Zona Fasciculata
certain androgens are produced and secreted
Zona reticularis
Secretes mineralocorticoids
Affects mineral homeostasis in the body
Zona Glomerulosa
Promotes the reabsorption of sodium in the kidneys
Promotes the loss of (secretion, excretion) of
Potassium (K+) into the urine
Hydrogen (H+) into the urine
Mineralocorticoids of zona Glomerulosa (aldosterone)
Aldosterone secretion is stimulated by both:
Elevated serum potassium and hydrogen levels
Low blood pressure
(Via the renin-angiotensin-aldosterone system (RAAS))
Aldosterone inhibited by both
Low serum levels of potassium and hydrogen
High blood pressure
Kidneys secrete renin in response to this
Blood pressure is low
Circulating renin causes the conversion of angiotensinogen (normal constituent of blood) into _____
angiotensin-I
Angiotensinogen is made by the liver and dumped into circulation regularly
Angiotensin-I circulates into the ___ vasculature where it encounters angiotensin converting enzyme (ACE)
lung
ACE splits angiotensin-I now making angiotensin-II
Angiotensin-II then circulates causing numerous things to occur
Stimulates the production of aldosterone
Causes increase in sympathetic activity
Causes arteriolar vasoconstriction
Causes release of antidiuretic hormone (ADH)
How angiotensin-II increases BP
Cortisol (95%)
Corticosterone
Cortisone
Zona Fasciculata – middle zone
Glucocorticoids help the body regain homeostasis after a “stress” event
Very effective if stressor is removed
Over-reaction occurs if stressor not removed
Glucocorticoids affects
Glucose levels
Helps to regulate metabolism
Inflammatory response
Immune system
Blood pressure
Nervous system
Sleeping
Stimulates protein catabolism
Stimulates gluconeogenesis
Stimulates lipolysis
Suppression of immune response
Acts as an anti-inflammatory
Inhibition of bone formation
Function of glucocorticoids
Suppression of immune response includes
Marked decrease in number of eosinophils (type of WBC) as well as atrophy of lymphatic tissue
Leads to a decreased number of lymphocytes and plasma cells
(lesser ability to fight infection)
Acts as an anti-inflammatory effects?
glucocorticoids
Inhibits synthesis of precursor to prostaglandins and leukotrienes
Inhibits production of interleukin-2 and proliferation of T-lymphocytes
Inhibits release of histamine and serotonin from mast cells and platelets
Inhibition of bone formation effects?
glucocorticoids
Decreases Type I collagen (major component of bone matrix)
Decreases osteoblast activity
Decreases intestinal absorptions of calcium
Secretes small amounts of weak androgens
Converted in testes to testosterone for males
Portion converted to estrogen in women (various tissues)
Zona Reticularis - inner zone
androgens
Dehydroepiandrosterone (DHEA)
Androstenedione
Dihydrotestosterone (DHT)
Weak androgenic effect on its own
Precursor to numerous hormones:
Androstenedione, testosterone, dihydrotestosterone (DHT), estrogen
DHEA
Dehydroepiandrosterone
Weak androgenic effect on its own
Can be converted to:
Testosterone or estrone (precursor to estradiol)
Androstenedione
More potent androgen than testosterone
Made from conversion of testosterone
Is active in tissues where testosterone is not
DHT
Dihydrotestosterone
Kidney secrete renin in response to
low BP
Renin, in circulation, cause the angiotensinogen (normal constituent of blood) into
angiotensin 1
Angiotensinogen is made by the ___ and dumped into circulation ____
liver
regularly
Angiotensin 1 circulates into the lung vasculature where it encounters ____ and spit angiotensin 1 into _____
ACE
angiotensin 2
Angiotensin 2 increases BP by:
stimulates production of aldosterone
causes increase in sympathetic activity
causes vasoconstriction
causes release of ADH
Stimulates protein catabolism
Essentially from all cells except the liver
These liberated amino acids travel to liver where they participate in gluconeogenesis
Glucocorticoids
Zona Fasciculata
Stimulates gluconeogenesis
Liver converts amino acids to glucose
Glucocorticoids
Zona Fasciculata
Stimulates lipolysis
Stimulates shift from carbohydrate catabolism to lipid catabolism
Liberates fatty acids also used in gluconeogenesis in the liver
Glucocorticoids
Zona Fasciculata
Suppression of immune response
Marked decrease in number of eosinophils (type of WBC) as well as atrophy of lymphatic tissue
Leads to a decreased number of lymphocytes and plasma cells
These cells produce numerous anti-bodies
With a reduced level of these cells, the body’s ability to fight infections is greatly reduced
Glucocorticoids
Zona Fasciculata
Acts as an anti-inflammatory
Inhibits synthesis of precursor to prostaglandins and leukotrienes
Inhibits production of interleukin-2 and proliferation of T-lymphocytes
Inhibits release of histamine and serotonin from mast cells and platelets
Glucocorticoids (Zona Fasciculata)
Inhibition of bone formation
Decreases Type I collagen (major component of bone matrix)
Decreases osteoblast activity
Decreases intestinal absorptions of calcium
Glucocorticoids (Zona Fasciculata)
Middle region of the adrenal gland
Adrenal Medulla
functional unit of the adrenal medulla
Chromaffin Cells
Synthesizes and secretes catecholamines
Epinephrine (more potent, more abundant)
Norepinephrine (precursor to epinephrine)
Chromaffin Cells
Adrenal Medulla
These cells are considered modified sympathetic ganglion of the autonomic nervous system (ANS)
Chromaffin Cells
Adrenal Medulla
Direct nervous system input, ie, fast
Stimulation of sympathetic nervous system sends signal down through splanchnic nerves.
These nerves synapse at the ____.
Signals epi/norepi to be released
Chromaffin Cells
Adrenal Medulla
Catecholamines intensify ____ responses throughout the body
sympathetic
Increase heart rate, force of contraction, cardiac output, blood pressure
Increases blood flow to heart, liver, skeletal muscles
Dilates airways to lung tissue
Causes liver and skeletal muscle to convert glycogen into glucose
Vasodilation (lungs, brain, heart, skeletal muscle)
Vasoconstriction (GI, kidneys, skin)
Catecholamines
from Chromaffin Cells
Adrenal Medulla
Usually caused by a benign tumor of the chromaffin cells
Causes a prolonged “fight or flight” response in the body
Pheochromocytoma
These tumors increase production and secretion of epinephrine and norepinephrine
Pheochromocytoma
