Endocrine glands
Secrete hormones directly into the bloodstream
Hormone
molecule that regulates cellular activities
Endocrine glands & Hormone
Acts together with nervous system
Hormone receptors
usually proteins, Bind ONLY to their specific hormone!, Constantly synthesized & degraded
Up-regulation
makes target cells MORE SENSITIVE to a hormone
Down-regulation
makes target cells LESS SENSITIVE to a hormone
Importance of receptor specificity
Hormone-receptor interaction is VITAL to a hormone’s function! It binds to specific receptors on target cells
Lipid-soluble
bound to transport protein includes steroids hormone, thyroid hormone, gases
Water- soluble
circulate in blood plasma includes proteins & peptides, amines, Eicosanoids
Lipid-soluble hormone
bind to receptors INSIDE cells
Water- soluble hormone
bind to receptors ON CELL MEMBRANE
role of nucleus
Hormone binding to receptors in cells (happen in nucleus)
gene expression
Activated receptor-hormone complex alter gene expression and new protein are made
Mechanism of lipid-soluble
results changes in cells’ activities
interactions of G proteins
activates Adenylate cyclase
adenylate cyclase
converts ATP to cAMP (2nd messenger)
cAMP
2nd messenger
role of phosphodiesterase
inactivates (breakdown) cAMP
importance of protein phosphorylation
results in various biological reaction!
hormone
1st messenger
3 Factors that influence target cell sensitivity to a hormone
Hormone concentration in blood, # of receptors present, other hormone influences
3 ways hormone secretion is controlled
Nerve signals, Blood chemistry, Other hormones
Pituitary gland (Hypophysis)
attaches to hypothalamus by a stalk, sits in sella turcica, contains 2 main lobes: ANTERIOR & POSTERIOR *functionally separate
General role of hypothalamus
special brain region (below thalamus)
receives many sensory inputs
synthesizes many hormones
exerts much control over pituitary gland
function of releasing hormones
Hypothalamic hormone stimulate secretion of anterior pituitary hormone
function of inhibiting hormones
Hypothalamic hormone prevent secretion of anterior pituitary hormones
Role of portal system
Receives hypothalamic hormones through a PORTAL SYSTEM, These hormones reach the anterior pituitary rapidly, Anterior pituitary hormones then travel to target tissues
7 major hormones of the ANTERIOR LOBE
hGH, TSH, FSH, LH, PRL, ACTH, MSH
effects of hGH
Protein synthesis, Cell growth & repair, Lipolysis, increasing blood glucose, Target cells are in many tissues
Target tissues of: TSH
secretion of thyroid hormone by the thyroid gland
Target tissues of: FSH & LH
ovaries initiate development of oocytes & ovulation; testes initiate development of spermatozoa & testosterone production
Target tissues of: PRL
stimulate breast growth, the mammary glands
Target tissues of: ACTH
from the adrenal cortex; mineralocorticoid, glucocorticoid, & androgen hormones
2 main hormones of the POSTERIOR LOBE
oxytocin & ADH (Antidiuretic Hormone)
Target tissues of: oxytocin
smooth muscle in the uterus and Mammary glands
Target tissues of: ADH
ducts in the kidney and sweat glands to minimize water loss and directly causes arterioles to constrict which increasing blood pressure
Follicular cells
secrete T3 and T4
Parafollicular cells
secrete calcitonin (CT)
IODINE
Hormone synthesis requires_____ in Thyroid
thyroid follicles
Synthesis of Thyroid hormone occurs in _______
Effects of T3 & T4
Increases BMR (and thus, core temp.), Growth (protein synthesis), Lipolysis, Enhancement of adrenaline
What hormone stimulates thyroid hormone secretion?
TSH and Ca2+
Effect of calcitonin (CT)
Decreases blood calcium
What stimulates CT secretion?
parafollicular (C-cells) of the thyroid gland
calcitonin
An increase in blood calcium will stimulate the C-cells of the thyroid to secrete _____
Increased calcitonin
causes a decrease in blood calcium
Adrenal cortex; 3 main hormone
Mineralocorticoids ,Glucocorticoids, Androgens
*these are steroid hormone*
Functions of ALDOSTERONE
Electrolyte (NA+, K+) regulation, Blood pressure, blood volume regulation
**secretion stimulated by the “Renin – angiotensin system”
what special pathway stimulates ALDOSTERONE secretion?
angiotensin II
Aldosterone
main hormone of Mineralocorticoids
Effects of CORTISOL
Gluconeogenesis (breakdown protein & fats to form glucose), hyperglycemia, Lipolysis, protein catabolism, Anti-inflammatory J , Stress response, Immunosuppression
what stimulates CORTISOL secretion?
ACTH
Cortisol
major hormone of glucocorticoid
What stimulates secretion of ANDROGENS?
ACTH
what is the main hormone of Adrenal medulla
EPINEPHRINE
Effects of EPINEPHRINE
Intensifies “fight-or-flight” responses
“fight-or-flight” functions
Increases HR, BP & blood glucose , Decreases blood flow to GI, Pupil dilation, Broncho-dilation
What stimulates secretion of EPI/NE?
ACh
What are the common cell in the pancreas
Acini
Where is the pancreas hormone secretion?
pancreatic islets
Alpha cells
secrete GLUCAGON
Beta cells
secrete INSULIN*
F cells
secrete PANCREATIC POLYPEPTIDE
Delta cells
secrete SOMATOSTATIN
Function of GLUCAGON
increase blood glucose, (done by hepatocytes)
what stimulates GLUCAGON secretion?
Decreases blood glucose (hypoglycemia), Increases sympathetic activity (exercise)
Function of INSULIN
decrease blood glucose
what stimulates INSULIN secretion?
Increases blood glucose (hyperglycemia), Various other hormone
role of “GluT” transporters
Glucose enters cells via facilitated diffusion
Type I diabetes mellitus
beta cell destruction causes very low secretion of insulin; Requires insulin injections, Diabetic ketoacidosis can occur
Type II diabetes mellitus
glucose transporter abnormalities (often cause insulin resistance); linked to obesity, Managed by changing diet, meds, etc.
Effect of PTH
increases blood calcium (secretion influenced by blood Ca2+
what stimulates PTH secretion?
Chief cells
What happens when Ca2+ level changes in CT secretion?
Increases blood calcium
What happens when Ca2+ level changes in PTH secretion
Decreases blood calcium
Ovaries major hormones
ESTROGEN & PROGESTERONE
what stimulates Ovaries & testes hormones secretion?
FSH & LH
testes major hormones
TESTOSTERONE
Pineal gland
Endocrine gland in the brain, Secretes MELATONIN (MT)
MELATONIN (MT)secretion
increase in darkness
Functions of melatonin (MT)
Regulation of body clock, Potent antioxidant
Role of thymosins
Promotes T cells maturation (immunity)
Thymus
Secrets THYMOSINS, Behind sternum between lungs (in mediastinum)
Effects of aging
Decreases in hGH, T3 & T4, adrenal cortex hormones, estrogen & testosterone secretion; Increases PTH secretion; Atrophy (weaken) of thymus & ovaries
Stressor
anything that generates a stress response (physical, emotional, etc.)
hypothalamus
Stress response control by _____
Three stages of stress responses
“fight-or-flight”, Resistance, Exhaustion
“fight-or-flight”—physiologic effects
short-lived
resistance — anterior pituitary hormones involved
ACTH, GH, TSH
exhaustion — main characteristics
Depleted energy, Immunosuppression , GI ulcers