Endocrine Physiology 3 Flashcards
Posterior pituitary hormones include
Vasopressin
Oxytocin
Hormones released from the post pit are synthesized as
pre prohormones in magnocellular neurons located in the supraoptic and paraventricular nuclei of the nypothalamus
Post pit hormone processign occurs as the
nuerosecretory vesicles are transported down the hypothalamic hypophysial tract
The other name for vasopressin is
Antidiuretic hormone or ADH
Argnine vasopressin (AVP) or antidiuretic hormone (ADH) - neurogenic (hypothalamic or central) diabetes insipidus
Problem in the hypothalamus or the connection btw the hypothalamus and the post pituitary
Nephrogenic diabetes inspidius is when diabetes is caused by
a problem in the kidneys themselves - can be mutation that impacts V2 receptors for ADH on collecting duct cells
Central DI - can be caused by
Tumors
Trauma
Surgery
Nephrogenic DI can be caused by
Renal diseases
ADH unresponsive kidney
Drugs (lithium)
Oxytocin is stimulated during
breast feeding and childbirth
Oxytocin is synthesized mainly in
the paraventricular nuclei (and also the supraoptic nuclei) of the hypothalamus
Oxytocin - main function
Stimulate milk let down and uterine contraction
Oxytocin will make you leak milk (not produce it)
Oxytocin - milk let down reflex
Afferent signals from the nipples of the mother’s breast when an infant suckles results in the release of oxytocin which then causes the milk let down reflex
The myoepithelial cells lining the breast ducts contract causing milk ejection
Oxytocin - by term of pregnancy, the mother’s uterus has experienced an
Upregulation in the number of oxytocin receptors
Distension of the cervix and contraction of the uterus stimulate the release of oxytocin which results in pos feedback and the release of more oxytocin which further stimulates contraction of the uterus
Physiological functions of GH - General growth effects
Promotes inc size of cells
Promotes inc number of cells through inc mitosis
Physiological functions of GH - Metabolic effects of growth hormone
1 Inc rate of protein synthesis in most body cells
2 Inc release of fatty acid from adipose tissue with inc amount of fatty acid in blood which allows inc use of fatty acid for energy
3 Dec use of glucose throughout body (insulin resistance)
Physiological functions of GH - Effect of GH on bone growth
GH strongly stimulate oseoblasts
Physiological functions of GH - If person has excessive amount of GH before the growth plates close, then there is
Continued elongation of long bones and pt suffers from gigantism
Physiological functions of GH - If excessive release of GH occurs after the long bone growth plates have closed then
The pt develops acromegaly
long bones can’t grow but other things can, like hands and jaw
Physiological functions of GH - treatment of acromegaly
Main tx is currently drugs that are somatostatin analogues which inhibit the release of GH
Now there is also a drug that is a GH receptor antagonist - this drug reduces IGF and produces clinical improvement in pt who do not respond to other treatments
Physiological functions of GH - GH might exert much of its effects through the action of
Somatomedins which are also called insulin like growth factors (IGF)
4 types of Somatomedins with Somatomedin C being the most important
Physiological functions of GH - Panhypopituitarism
Congenital
Acquired from a pituitary tumor that destroys the pituitary gland
Physiological functions of GH - Dwarfism
Many diff kinds - some have normal normal GH secretion bu hereditary inability to form somatomedin C
Pituitary adenoma
Extremely common
Found in about 1/6 autopsies - most don’t produce s/s
If they do - HA, diabetes, vision changes
Thyroid gland - function
Maintenance of energy homeostasis
Stimulate cell metabolism and activity
Important in development
What is required to make thyroid hormone
Iodine
Thyroid gland - location
On the trachea below apple
Composed of two lobes interconnected with an isthmus
Thyroid gland - hormone secretion is under control of the
hypothalamus and pituitary
Thyroid gland - Thyroid hormones
Thyroglobulin is the storage form of T3 and T4
T3 = Tri iodothyronine - more potent T4 = Thyroxine - less active (90% released from thyroid is T4)
Thyroid gland - Feedback mechanism provided by thyroid hormones T3 and T4 does what
inhibits thyrotropin releasing hormone (TRH) and thyroid stimulating hormone (TSH) secretion and prevents overstimulation
Thyroid hormone - and iodine
Most iodine is stored in they thyroid - 1% released with 75% of it in the form of thyroid hormones - helps protect people from iodine deficiency
People with diets deficient in iodine can form iodine deficiency goiter
Thyroid hormone - expression of the gene for NIS is inhibited by ___ and stimulated by ____
Inhibited by iodide
Stimulated by TSH
Thyroid hormones - enter cells by
a carrier mediated energy temperature, and Na dependent process
Thyroid hormone action on cells has what metabolic impacts
INC BMR
Inc protein syntheis, lipolysis, gluconeogenesis, glycogenolysis, O2 consumption, Na/K ATPase, mitochondria
Thyroid hormone action on cells has what cardiac impacts
Inc CO, tissue blood flow, HR, Heart strength, RR
WIthout thyroid hormone during early infancy, what is consequence
CNS will not develop
If you start to give them thyroid hormone, bone age and height will inc, but the mental age will not (treatment started at age 4.5)
Causes of congenital hypothyroidism
Maternal iodine deficiency
Fetal thyroid dysgenesis
Inborn errors of thyroid hormone synthesis
Maternal antithyroid antibodies that cross the placenta
Fetal hypopituitary hypothyroidism
Too much thyroid hormone =
You increase adrenergic receptors on your heart (get twitchy heart)
Every time you are put under stress, you inc release of adrenergic and your heart will react
Graves disease
Hyperthyroidism
Too much thyroid hormone, but their TSH is low
They are making antibodies that bind to the TSH receptor in the thyroid though so the thyroid thinks it is responding to TSH
S/s of graves disease
Exopthalamos Goiter CV - tachy, palpitations, a fib Weight loss Heat intolerance Mm weak Fatigue OP Pretibial myxedema
Hashimoto’s thyroiditis
Hypothyroidism
Caused by autoimmune antibodies directed against thyroglobulin and thyroid peroxidase
In the world, Iodine deficiency is most common cause of hypothy
But in US is Hashimoto
S/s of hypothyroidism
Low mental energy Periorbital edema Goiter Constipation Cold dry skin Intolerance to cold Bradycardia Reflex slow to relax
If extremely low thyroid function - what can develop
Myxedema
Non pitting edema of face
Bags under eyes and swelling of the face
Adrenal gland sits where
on top of the kidney
Adrenal gland secretes what hormones
Glucocorticoid hormones - Cortisol, Corticosterone
Mineralocorticoids - aldosterone
Androgenic steroids - DHEA
Adrenal gland - cortisol is released in response to
physical, mental, and metabolic stress
Adrenal gland - cortisol does what to plasma glucose level
Increases it!
Adrenal gland - cortisol - circulating cortisol levels provide
normal feedback signal inhibiting CRH and ACTH
Addison’s disease
Hypoadrenalism (primary adrenal insufficiency)
Can be from adrenal atrophy or injury to the adrenal cortices
Addisons disease - decrease in adrenal cortex hormones secondary to impaired fucntion of pituitay - damage to pituitary can causer
Severe decrease in ACTH and atrophy of adrenals
What is controller of cortisol
ACTH (not aldosterone)
Cushings syndrome
Hyperadrenalism
Central and generalized obesity Dorsal kyphosis Moon face Hirsutism Enlarged supraclavicular fat pads
Adrenal medulla releases what
Epinephrine (80%)
Norepinephrine (20%)
Adrenal cortex vs. medulla
Cortex - making cortisol and sex hormones and aldosterone
Medulla - Epi and NE and responding as part of SNS
Islet of langerhans hormone secretion - B cells
Insulin is big one
Islet of langerhans hormone secretion - A cells
Glucagon is big one
Islet of langerhans hormone secretion - D cells
Somatostatin
Islet of langerhans hormone secretion - Gamma or PP cells
Pancreatic polypeptide
Islet of langerhans hormone secretion - Epsilon cells
Ghrelin
Insulin is considered
A fuel storage hormone
Promotes the storage of glucose and fatty acids
Actions of glucagon
Considered the fuel mobilization hormone
Glucagon is stimulated by low blood glucose
Clinically important complications of diabetes mellitus
Macrovascular complications
Microvascular complications
Neural complications
Trousseau’s sign
Tetany?
Chvostek’s sign
A sign of latent tetany associated with hypocalcemia
Contraction of mm of the eye, mouth or nose elicited by tapping over the facial nerve in front of the ear
Which endocrine gland works with Ca
Parathyroid (PTH)
Parathyroid (PTH) is synthesized by
synthesized and secreted by chief cells
If Ca levels go down, what happens with PTH
You want to release more parathyroid
The higher the free Ca, the lower the parathyroid hormone
Parthyroid and the kidney
Parathyroid makes the kidney lose phosphate
What is a way of decreasing Ca
Calcitonin
Calcitonin is stimulated by an inc in plasma Ca
Hyperparathyroidism
Most cases are from parathyroid tumors that cause hypersecretion
Elevated PTH - inc bone reabsoprtion, renal Ca reabsoprtion and active vit D
All of these can cause hypercalcemia
Hypoparathyroidism
Usually result of thyroid or parathyroid surgery
The lack of parathyroid hormone reduces formation of active vit D, dec renal Ca reabs, alters bone resorption
Hypocalcemia develops and low plasma Ca levels inc neuronal and mm cell excitiation (twitching, cramping, tetany)
