anatomy endocrine - adrenal, thyroid, ADH mod 5 Flashcards
hypothalamic-pituitary endocrine system
The pituitary gland is located beneath the hypothalamus at the base of the skull
The pituitary gland has 2 lobes:
Anterior
Posterior (our focus for this lecture)
Synthesis and secretion of pituitary hormones are controlled by the hypothalamus
function of pituitary gland
The anterior lobe secretes 6 different hormones, including:
Thyroid stimulating hormone
Adrenocorticotropic hormone (ACTH)**
The posterior gland secretes 2 important hormones: Antidiuretic hormone (aka Vasopressin)** Oxytocin
what is ACTH - anterior pituitary lobe
Corticotropin (adrenocorticotropic hormone [ACTH]) is a polypeptide hormone produced by the anterior pituitary. This hormone acts on the adrenal cortex to stimulate production and release of adrenocortical hormones (eg, cortisol, aldosterone). The principal use of corticotropin is diagnosis of adrenocortical dysfunction. A synthetic analog of corticotropin, called cosyntropin, is available.
ADH function - posterior pituitary lobe
Released in response to high serum osmolality and/or hypotension
Function: Causes water retention via action in the kidneys
Way to remember the function of ADH:“ADH- this hormone stops the pee pee”
function adrenal glands
Adrenal glands sit on top of the kidneys
Each gland is composed of an inner medulla and an outer cortex
The adrenal medulla secretes:
Epinephrine** and norepinephrine**
In response to ACTH (from the anterior pituitary), the adrenal cortex secretes:
Glucocorticoids (Cortisol)**
Mineralcorticoids (Aldosterone)**
Sex steroids (Androgens)
adrenal medulla hormones - Think “fight or flight”
The adrenal medulla secretes 2 catecholamines in response to sympathetic nervous system stimulation
epinephrine and norepinephrine - prolong and enhance the effects of the sympathetic nervous system
adrenal cortex - steroid hormones
- cortisol, aldosterone, androgen
“three S’s”: sugar, salt, and sex
The 3 steroid hormones secreted by the adrenal cortex are essential for life
They regulate the body’s response to normal and abnormal levels of stress
They are made on demand and not stored in cells
The activities of the Steroid hormones can be remembered as the “three S’s”: sugar, salt, and sex
glucocorticoid - cortisol
The principal hormone is cortisol
These hormones are named for their primary effect on glucose metabolism, but they effect every tissue in the body
Functions include:
Raising blood sugar (opposing insulin)
Protect against physiologic effects of stress
Suppress inflammatory and immune processes
Release muscle stores of proteins
Increase blood cholesterol
mineralocorticoid - aldosterone
BP
The principal hormone is aldosterone
Regulated by the renin-angiotensin system in the kidneys
Function is to maintain salt and water balance
Promotes secretion of potassium
When triggered by angiotensin II, aldosterone promotes sodium retention and thus water retention
function of the thyroid
Butterfly-shaped gland found in the neck
Secretes triiodothyronine (T3) and thyroxine (T4)
T3 is the active form
- Converted from T4
T4 is in two forms:
1 attaches to proteins when not needed
Free T4 enters tissues when needed
T3 is T4 that has been converted mostly in the liver to a more useful form. T3 looses 1 iodine atom during the process
T4 has 4 iodine atoms and T3 has 3
thyroid hormones continued
Produces 80-90% more T4 than T3
T4 is converted to T3 when it reaches organs and tissues to aid in metabolism
Iodine is a necessary component in synthesis of thyroid hormone
Euthyroid - normally functioning thyroid gland
parathyroid gland function
**PTH in response to hypocalcemia
**stim vitamin D production
The parathyroid glands are four pea-sized glands nestled within the thyroid tissue of the neck.
The glands produce and secrete parathyroid hormone (PTH) in response to hypocalcemia and break down bone to re-establish normal calcium in the blood.
***Promotes vitamin D production
stimulation for activation of steroid hormones in adrenal cortex
hypothalamus - anterior pituitary (ACTH) - adrenal cortex on kidney (cortisol, aldosterone, androgen)
more aldosterone secretion = ?
more water and sodium retention = increase BP
what stimulates aldosterone?
angiotensin II
