Hypothalamic, Adrenal, Pituitary, Thyroid, Adrenal, Hypothalamus, Pituitary Flashcards
What is the overall function of the endocrine system? How would you define the endocrine system?
Function: processes involved in maintaining physiological equilibrium (homeostasis)
-tissues or glands that secrete hormones into blood –> bind to specific receptors that allows the hormone to exert effect
–> only affect tissues with appropriate receptor
-negative feedback system regulates most hormone secretion
How is the endocrine system diff than the NS?
–> NS: neurotransmitters, neurohormone
–> endocrine: hormones
- What is meant by the lock & key relationship? How does that “relationship” influence hormone delivery and action throughout the body?
-tissues or glands that secrete hormones into blood –> bind to specific receptors that allows the hormone to exert effect
–> only affect tissues with appropriate receptor
What is set point?
In endocrinology, a set point is the physiological value around which a normal range fluctuates. For example, body weight and body temperature are set points that the endocrine system contributes to regulating. A set point is also the level at which a physiological state tends to stabilize, such as body temperature or weight.
What is a negative feedback loop?
-way the system maintains homeostasis
-secretion of specific hormones are turned on or off by specific physiological changes
EX: plasma glucose levels and insulin/glucagon response
Difference between steroid and non-steroid hormones and delivery to target tissues/organs/mech of action
A steroid hormone will actually enter the target cell and act directly on the DNA of the cell. A non-steroid hormone will land on a receptor on the cell surface, but not enter the cell. In this case a second messenger will carry out the work, but the hormone stays outside the cell.
How does the hypothalamus influence the Ant Pituitary?
Hypothalamus: major link between nervous and endocrine systems
-pituitary gland attached to hypothalamus by infundibulum
FUNCTIONS OF HYPOTHALAMUS:
-synthesizes and secretes regulatory hormones: releasing hormones (stimulate anterior pituitary hormone release) and release inhibitory hormones (inhibit release of anterior pit. hormones)
-directs pituitary gland (hypophysis)
-regulatory hormones need to travel through hypophyseal portal system to reach ant. pit.
GnRH–> FSH, And, LH
GHRH–> growth hormone
Somatostatin (GHIH)–> inhibits GH release
TRH–> TSH and prolactin
Dopamine–> inhibits prolactin release
CRH–> ACTH
PRH–> prolactin
Hypothalamus and posterior pituitary:
-synthesizes two hormones stored in post. pit.
–> oxytocin and vasopressin (ADH)
VASOPRESSION;
-regulates blood volume and salt concentration (plasma osmolality)
-the cells of the supraoptic and paraventricular nuclei are osmoreceptors
-released by post pit in response to low blood volume (baroreceptors sense low BP)
-increased plasma osmotic pressure (osmoreceptors in hypothalamus sense increased solute in blood)
-alcohol is a diuretic–> less ADH is produced–> less water retention
Pituitary disorders:
IN GENERAL:
-too much or too little hormone release
-hyperpituitarism
–>acromegaly/gigantism (inc. GH)
–> Cushing’s disease (inc. cortisol)
-hypopituitarism
–> Diabetes insipidus (decreased ADH)
COMMON SYMPTOMS:
-headache
-visual changes
-lethargy/fatigue
-nausea and vomiting
-nasal drainage
-behavior changes
-changes in sense of smell
TUMORS:
-pituitary tumors account for 10-15% of intra-cranial tumors
-majority are adenomas: benign
Gigantism vs Acromegaly
From anterior pituitary
GIGANTISM
- excessive
secretion of GH in
children
-epiphyseal plate not yet closed
ACROMEGALY
-GH secretion excessive in adults
-most often in 4th decade
-slow but continuous progression
Cortisol release and functions
-normally controlled by hypothalamus
–> CRH
-CRH triggers ant pit ot secrete ACTH into vascular system–> ACTH is carried in the blood to the adrenal cortex, stimulating the synthesis of cortisol
FUNCTIONS:
-counter regulatory to insulin: promotes hyperglycemia
-decreases bone formation (decrease osteoblast function) and decreases intestinal Ca++ absorption
-acts as a diuretic
-influences immune function (inhibits production/release of inflammatory mediators)
Cushing’s disease etiology
-associated with the adrenal and pituitary glands
-hypersecretion of cortisol
CAUSES:
(Pituitary cushing’s)
-pituitary adenoma- secretees ACTH
-ACTH dependent = disease
(Adrenal cushing’s)
-adrenal adenoma- secretes cortisol
–> exogenous corticosteroids (iatrogenic cushing’s syndrome)
-ACTH-indepedent- Syndrome
Cushing’s disease S/S
INCREASED CORTISOL
-central obesity
–> rapid weight gain with sparing of limbs
–> moon face and buffalo hump fat distribution
-skin
–> thinning and capillary fragility
–> bruising
–> striae
–> poor wound healing
-muscle wasting and weakness
-tachycardia; hypertension
-osteoporosis
–> impaired GI ca++ absorption (antagonizes vit D)
-hyperglycemia/DM (stress response)
-immunosuppression–> increased infection risk
Cushing’s disease similarities with DM
-hyperglycemia
-immunosuppression
-poor wound healing
-hypertension
Cushing’s disease medical treatment (steroids)
–>DISEASE: pituitary tumor excision via trans-sphenoidal surgery
–> SYNDROME: adrenal tumor excision- adrenalectomy
-Iatrogenic: decrease corticosteroids dosing
