The Endocrine System Outline Part 2

Pancreatic Islets alpha cells secrete what? What does it do?

GLUCAGON

• released between meals when blood glucose concentration is falling

• in liver, stimulates gluconeogenesis, glycogenolysis to release of glucose into circulation- raise blood glucose level

pancreatic islets beta cells secrete what? What does it do?

INSULIN

• secreted during/ after meal when glucose and amino acid blood levels are rising

• stimulates cells to absorb these nutrient and store or metabolize them; lowers blood glucose levels

• promotes synthesis of glycogen, fat, and protein

• suppresses use of already-stored fuels

• insufficiency/ inaction= diabetes mellitus

pancreatic islets delta cells secrete what? What does it do?

SOMATOSTATIN

• partially suppresses secretion of glucagon & insulin

• prolongs absorption of nutrients

pancreatic polypeptide secreted by PP cells does what?

• act on brain to reduce pancreatic secretions

Gastrin secreted by G cells does what?

stimulates stomach acid secretion, motility, and emptying

Hyperglycemic hormones … blood glucose concentration

RAISE

• glucagon, growth hormone, epinephrine, norepinephrine, cortisol and corticosterone

Hypoglycemic hormones … blood glucose concentration

LOWER

• insulin

Ovaries and testes are both…

endocrine and exocrine

• exocrine product: whole cells- eggs and sperm

• endocrine product: gonadal hormones— mostly steroids

steroids- from, secretion, examples

• from cholesterol

• secreted by gonads and adrenal glands

• estrogens, progesterone, testosterone, cortisol, corticosterone, aldosterone, calcitriol

peptides and glycoproteins- from, secretion, examples

• from chains of amino acids

• secreted by pituitary & HT

• oxytocin, ADH, insulin, anterior pituitary hormones

monoamines- from, secretion, examples

• from amino acids

• secreted by adrenal, pineal, and thyroid glands

• epinephrine, norepinephrine, melatonin, and thyroid hormone

most monoamines & peptides=

hydrophilic

• mix easily with blood

steroids and thyroid hormone=

hydrophobic

• bind to transport proteins (globulins) (to prevent filtration and degradation)

• bound hormones have longer half life

• only unbound hormone leaves capillaries to reach target cell

Thyroid hormone binds to 3 transport proteins in plasma

• albumin, thyretin, thyroxine-binding globulin (TBG)

specific receptor for each hormone. Saturated when…

all receptor molecules occupied by hormone molecules

receptors are

protein/ glycoprotein molecules

act like switches, turn on metabolic pathways when hormone binds

Hydrophilic hormones mode of action

• peptide hormone

• need membrane receptor

• changes physiology via second messenger

• quick

• does NOT enter cell

Hydrophobic hormones

• steroid hormone

• goes INTO cell

• act directly on genes to change target cell physiology

• take several hours to days to show effect

Thyroid hormone mode of action

thyroid hormone enters target cell by diffusion, mostly as T4 (little metabolic effect)

within target cell, T4 converted to more potent T3

T3 enters target cells, binds to receptors in chromatin

activates genes makes

• myosin, strengthens heartbeat

(Don’t worry too much about this) Peptides and Catecholamines mode of action

most common: activates G protein—activates adenylate cyclase—produces cAMP

enzyme amplification

one hormone molecule—synthesis of many enzyme molecules

small stimulus—large effect

circulating concentrations very low

Up vs Down regulation to adjust response to hormones

UP= increase receptor density and stronger response

DOWN=reduce receptor density and diminished response

synergist effects def and example!!!

Multiple hormones act together for greater effect

• ex- FSH & testosterone on sperm production

permissive effects def and example!!!

one hormone enhances target organ’s response to second later hormone

• ex: estrogen preps uterus for progesterone

Antagonistic effects def and example!!!

one hormone opposes action of another

• ex: insulin lowers blood glucose; glucagon raises it

hormone clearance def

turning off hormone signals when they have served purpose

Metabolic clearance rate (MCR)

rate of hormone removal from blood

• half-life: time required to clear 50% of hormone from blood

General adaptation syndrome (GAS)

• consistent way body reacts to stress; involves elevated levels of epinephrine & glucocorticoids (especially cortisol)

cortisol & corticosterone type of anti-inflammatory drugs and what it does

steroidal anit-inflammatory drugs (SAIDs)

blocks release of arachidonic acid & inhibits eicosanoid synthesis

• disadvantage- cushing syndrome symptoms (excess cortisol)

Aspirin, ibuprofen, and naproxen (Aleve) type of anti-inflammatory drugs and what it does

nonsteroidal anti-inflammatory drugs (NSAIDs)

• COX (enzyme converts arachidonic acid to thrombox, etc.) inhibitors: block cyclooxygenase

• treats fever & thrombosis

• Ibuprofen blocks the production of prostaglandins which reduces aches and fever

Hyposecretion def and example

inadequate hormone release

• gland destroyed or lost ability to receive signals

• ex: pituitary’s inability to secrete ADH (retain water)— Diabetes insipidus: chronic polyuria from lack of ADH (causes you to pee more— dehydration)

Addison’s disease

deficiency of glucocorticoids and mineralocorticoids

Hypersecretion def

excessive hormone release

• tumors or autoimmune disorder

Toxic goiter (Graves disease)

autoantibodies mimic effect of TSH on thyroid, causing thyroid hypersecretion

Pheochromocytoma

tumor of adrenal medulla secretes excessive epinephrine and norepinephrine

Cushing syndrome

excess of cortisol

Diabetes mellitus

most prevalent metabolic disease

• disruption of metabolism due to hyposecretion or inaction of insulin

• symptoms: polyuria, polydipsia (extreme thirst), polyphagia

Transport maximum: limit to how fast glucose transporters can reabsorb

• excess glucose enters urine and water follows it— dehydration

Type 1 (IDDM) problem

insulin INSUFFICIENCY (something wrong with beta cells)

Insulin used to treat

• monitoring blood glucose levels and controlling diet

auto-antibodies attack and destroy pancreatic beta cells

Type 2 (NIDDM) problem 90-95% of diabetics

insulin RESISTANCE

• failed response of target cells to insulin

risk factors: heredity, age, obesity, etc.

treated with weight loss program and exercise

Ozempic how does it work?— Increase insulin production and reduce cravings

Pathogenesis

cells cannot absorb glucose; rely on fat and proteins for energy, thus weight loss and weakness

• fat catabolism increase fatty acids and ketones in blood

ketonuria promotes

osmotic diuresis, loss of sodium and potassium, irregular heartbeat, and neurological issues

Ketoacidosis

ketones decrease blood pH

• diabetic coma

Diabetic neuropathy

nerve damage from poor blood flow can lead to erectile dysfunction, incontinence, poor wound healing, loss of sensation