Endo Phys - Ninja Nerd

What are the two main types of endocrine hormones? How are they different?

Peptide (water soluble) - need contact with cell surface receptors -> messenger to function

Steroid (lipid soluble) - can just penetrate through cell membranes to reach interior receptors

Examples of peptide hormones?

insulin, prolactin, glucagon, FSH, PTH, LH, oxytocin

Examples of steroid hormones?

cortisol, aldosterone, estrogen, progesterone, testosterone

what structure produces ADH?

posterior pituitary gland (supraoptic nucleus)

what triggers ADH release?

pituitary gland sensing low BP, high plasma osmolality

(opposite of ^ and EtOH inhibit ADH)

Where is oxytocin released?

posterior pituitary hormone (paraventricular nucleus)

What triggers oxytocin release?

Labor (uterus stretching), breast feeding, ejaculation, emotional interaction

What is CRH and what does it do?

Corticotropin-releasing hormone; stimulates ACTH release

Where is CRH released?

hypothalamus -> anterior pituitary gland (ACTH stimulation)

Where is TRH released?

hypothalamus -> anterior pituitary gland (TSH stimulation)

What does TRH do?

Stimulates the production and release of TSH

Where is GH released from?

anterior pituitary

What function does dopamine have in the anterior pituitary gland?

Inhibits release of prolactin

What is released from the gonatotrope in the anterior pituitary gland?

follicle-stimulating hormone (FSH) and Luteinizing hormone (LH)

What stimulates the release of ACTH?

fever, hypoglycemia, stress

What stimulates the release of prolactin?

Estrogen, birth control, breast feeding

What stimulates the release of GH?

Exercise, health stress, low BG, low serum fatty acids, high serum amino acids

What effect does oxytocin have on the uterus? On the breast?

Stimulates...

Uterus contraction (during labor)

Milk ejection/let down reflex during breast feeding

Love/compassion emotions

What is a oxytocin mimicking drug?

ptosin

What two major regions of the brain communicate together in releasing central hormones?

Hypothalamus (sensory) & pituitary gland (release)

How does ADH function in the nephron?

Stimulates the production of aquaporin II resulting in water reabsorption in the collecting duct

= less urine/higher BP/lower osmolality

How does ADH function on blood vessels?

Increases vasoconstriction -> peripheral resistance -> higher BP

Hormone imbalance in diabetes insipidus?

low ADH -> polyuria

Hormone imbalance in SIADH?

high ADH -> hyponatremia/normovolemia

What is the role of growth hormone (GH)?

Stimulates muscle growth/function, bone turnover (endochondral ossification), gluconeogenisis, cartilage growth

Which hormone stimulates prolactin?

TRH (thyrotropin releasing hormone) from anterior pituitary

Estrogen (which promotes & inhibits dopamine release)

What does prolactin do?

produces breast milk and breast tissue stimultion

What hormones originate in the anterior pituitary?

Growth Hormone, Prolactin, ACTH, TSH, LH, FSH

What hormones originate in the posterior pituitary?

Arginine Vasopressin (ADH,AVP), Oxytocin

How does T4 turn to T3 in peripheral cells?

Enzyme pulls iodine off of T3

How does T3 increase basal metabolic rate?

inc NA+/K+ ATPase activity--->inc O2 consumption, RR, body temp, incr #/size of mitochondria

What does thyroid hormone (T4+T3) do in the liver?

Glycogenolysis

(chops up glycogen into glucose -> blood glucose)

&

Gluconeogensis

(Adding glycol +Aa.A. +lactate -> blood glucose)

&

Incr LDL receptors (decr serum LDL)

What does thyroid hormone (T4+T3) do in the heart?

Stimulates Epi/NE --> incr CO, HR, BP

What does thyroid hormone (T4+T3) do in the bones?

Balances osteoclasts and osteoblasts, stimulates interstitial growth (@ epiphyseal plates), bone remodeling, endochondral ossification

What does thyroid hormone (T4+T3) do in fat?

Breaks down fat ---> fatty acid chains + glycerol

What does thyroid hormone (T4+T3) do in muscle?

Balancing muscle anabolism & catabolism

**in hyperthyroid, thyroid switches mostly to catabolism (atrophy)

What does thyroid hormone (T4+T3) do in the skin?

Sweating & makes nails brittle

What does thyroid hormone (T4+T3) do in the GI?

Enhances motility/secretions

Which cells in the parathyroid gland makes PTH?

Chief cells

What triggers parathyroid hormone release?

Low blood Ca++ levels

What triggers calcitonin hormone release?

High blood Ca++ levels

What mechanism does PTH to increase blood calcium by?

Stimulates osteoclasts, DCT renal reabsorption, activate Vitamin D in kidney (inc GI Ca++ absorption)

What are the main endogenous substances stimulating aldosterone production?

Angiotensin II, ACTH, low Na+, high K+

What is the main endogenous substance inhibiting aldosterone production?

Atrial naturetic peptide (ANP)

What does aldosterone do in the kidneys?

retain sodium, reabsorbs water and increases blood pressure

Which hormone released from the anterior pituitary stimulates cortisol release?

ACTH

How does cortisol (hydrophobic) travel in blood?

Bound to proteins (ex: albumin)

What function does cortisol have in the body?

- Protein breakdown in muscles/bone, release of glycerol from adipose tissue

--> amino acids/glycerol go to liver --> GLYCOGENESIS

- Inc vasoconstriction (inc BP)

- Inc blood glucose (by binding to adrenergic receptors on liver)

- Immunosuppression

What factors increase cortisol release?

Long term stress, hypoglycemia,

Why is chronic stress bad?

Inc cortisol release --> immunosuppression, inc BP, inc muscle catabolism

"stressed, sick, and skinny"

Which pituitary hormone stimulates gonadocorticoid release? Where are gonadocorticoids released?

ACTH acting on adrenal glands

What do gonadocorticoids do?

Promote the secretion of the sex hormones (testosterone/estrogen)

Which pancreas cells stimulate insulin? Which secrete glucagon?

Alpha cells - glucagon

Beta cells - insulin

(both part of Islets of Langerhan)

What does insulin do to serum potassium?

Pushes potassium into cells

How does K+ levels affect glucagon?

Low K+ in cell leads to more glucagon secretion into blood

How does glucagon increase blood glucose levels?

-stimulating conversion of glycogen to glucose in the liver (glycogenolysis)

-stimulating breakdown of fat and protein into glucose

What occurs in beta cells when blood glucose is high?

in rushes Ca++ allowing insulin, amylin, and C-peptide (lab metric) to be excreted

What does insulin do in the liver?

- stimulates:

* glycogen synthesis

- inhibits:

* gluconeogenesis (production of glucose)

* ketogenesis (production of ketones)

What does insulin do in the muscle?

-inc uptake, storage and use of glucose

-inc uptake of amino acids and protein synthesis

What does insulin do in adipose tissue?

inc glucose uptake--> inc lipogenesis/dec lipolysis