Physio Test 5 - Endocrine 1

Front 1

juxtacrine hormone

Back 1

affects a neighboring cell but remains attached to the cell that made it. Not secreted.

Front 2

A-A derivative hormones

Back 2

made from tyrosine, tryptophan, histidine. Ex: serotonin, dopamine, thyroid hormones

Front 3

Peptide hormone synthesis, storage and release

Back 3

made from mRNA precursor, stored in secretory granules and released via Ca++-mediated fusion w/ plasma membrane

Front 4

Peptide hormone transport

Back 4

usually free in circulation; bind receptor at plasma membrane and initiate rapid response via 2nd mess

Front 5

Examples of peptide hormones

Back 5

Growth Hormone, Parathyroid hormone, insulin

Front 6

steroid hormone synthesis, storage and release

Back 6

made from cholesterol; not stored in cells; passively diffuse across membrane

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steroid hormone transport

Back 7

bound to plasma binding proteins; bind receptor in cytoplasm or nucleus; regulate gene transcription over long period of time

Front 8

what's unique about GH and IGF-1

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peptide hormones that are bound to binding proteins in bloodstream

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hormones released by anterior pituitary

Back 9

ACTH, TSH, FSH, LH, Prolactin, GH

Front 10

ACTH

Back 10

stimulates growth of adrenal cortex, stimulates production and release of cortisol

Front 11

TSH

Back 11

stimulates growth of thyroid, production and release of TH

Front 12

FSH

Back 12

stimulates follicle development in females, spermatogenesis in males

Front 13

LH

Back 13

stimulates ovulation and production of corpus luteum in females; sex hormone synthesis in males and females

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Prolactin

Back 14

milk production

Front 15

GH

Back 15

body growth, organ growth, regulation of metabolism

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Releasing hormones

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made in hypothalamus; long axons release them on capillaries at median eminence >> hypophysela portal system >> don't have to go through systemic circulation

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Stimulatory releasing hormones

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TRH, GHRH, GnRH, CRH

Front 18

inhibitory releasing hormones

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SS and Dopamine

Front 19

negative feedback - long loop

Back 19

peripheral hormone or metabolite acts on anterior pituitary or hypothalamus to regulate secretion of hormones

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short loop

Back 20

anterior pituitary acts at level of hypothal to regulate secretion of its releasing hormone

Front 21

ultra short loop

Back 21

hypothalamic releasing hormone acts at level of hypothal to regulate its own secretion (autocrine)

Front 22

Growth Hormone

Back 22

required for growth in childhood, adolescence (not fetal dev or infancy); involved in regulation of metabolism in adulthood

Front 23

Direct effects of GH

Back 23

Mostly acute, metabolic. stimulates lipolysis in adipocytes and stimulates glucose production by liver (opposes insulin - inhibits glucose use by fat and muscles)

Front 24

Indirect effects of GH

Back 24

mostly long-term, dealing w/ somatic growth. stimulates liver and other tissues to release IGF-1; which encourages chondrogenesis in skeletal muscles and cell proliferation and protein synthesis in extraskeletal tissues.

Front 25

IFG-1

Back 25

paracrine effects; important for growth and differentiation. similar to insulin, so the two can mimic each other's effects somewhat.

Front 26

GH secretion

Back 26

depends on balance between Growth Hormone Releasing Hormone and Somatostatin. Pulsatile secretion during day and night in childhood, though daytime secretion decreases w/ age

Front 27

stress, exercise and hypoglycemia and GH

Back 27

increase secretion independent of circadian pattern

Front 28

acromegaly

Back 28

excessive Gh secretion in adults, often due to benign pituitary tumor

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giantism

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excessive GH secretion in children/teens, often due to tumor.

Front 30

GH deficiency

Back 30

results in dwarfism in kids if untreated. Treat w/ injections b/c peptide hormone is broken down in gut.

Front 31

GH and short bowel syndrome

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promotes adaptation of remaining bowel

Front 32

anatomy of the thyroid

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2 lobes on either side of trachea; lobes are made up of follicles (layer of follicular cells w/ colloid in lumen). Follicular cells secrete T3 and T4

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T3 vs T4

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derivatives of tyrosine that share the same function; T3 is 4x as potent but has a shorter half-life. most T4 >> T3 in tissues.

Front 34

Functions of the thyroid

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autonomic NS function, BMR, metabolism of fats, protein, CHO, thermogenesis

Front 35

TH mechanism of action

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acts by altering gene expression in target cells. changes level of mRNA >> alters protein synthesis >> influences cell function by altering type and amt of proteins that are produced. Functions similarly to steroid hormone mechanism

Front 36

TH receptors

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found in nuclei of target cells, bound to DNA. Higher affinity for T3 than T4.

Front 37

hyperthyroidism

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fatigue, muscle weakness, tremors, tachycardia, irritability, anxiety, insomnia, heat intolerance, increased appetite, weight loss, amenorrhea, decreased libido

Front 38

hypothyroidism

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fatigue, slow reflexes, decreased Co, memory loss, lethargy, cold intolerance, less appetite, constipation, infertility, dry skin, less sweating and libido

Front 39

TH and GH

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TH stimulates GH expression in somatotroph cells of anterior pituitary. GH synthesis declines if TH is low.

Front 40

TH and developing nervous sytem

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TH regulates synaptogenesis; critical period: last 6 months of fetal life and 6 months after birth. If deficient, cognitive deficits result

Front 41

Cretinism

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decreased TH in newborn >> dwarfism and cognitive impairments

Front 42

Calorigenic action of TH

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regulates rate of oxidative phosphorylation in cells, sets basal rate of body heat production and oxygen consumption.

Front 43

Regulation of TH secretion

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when TH low, TRH >> TSH. When TH is high, it acts directly at pituitary to downregulate TSH. And some at level of hypothalamus, but not as much.

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TH in circulation

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most bound to thyroxine-binding globulin or othe rproteins; less than 1% is free.

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removal of TH

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deiodinated in liver and kidney

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graves' disease

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autoimmune; antibodies mimic TSH >> hyperthyroidism

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Hashimoto's thyroiditis

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autoimmune; thyroid gland degraded

Front 48

physiological roles of Calcium

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1. Ca salts in bone provide structural integrity; 2. Ca ions in intracellular and extracellular compartments regulate nerve excitability, NT secretion, etc

Front 49

Serum calcium

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50% ionized, 40% bound to protein like albumin, 10% bound to other ions. **free ionized form is readily available for physiological processes

Front 50

PTH

Back 50

protein derived from AA prohormone; made in chief cells in PT glands; acts in crease plasma Ca and decrease plasma Phosphate to avoid formation of Calcium phosphate crystals

Front 51

Control of PTH

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controlled by circulating levels of ionized calcium; when Ca is low >> PTH increases. Normally can increase up to 5-fold

Front 52

PTH @ kidney

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increases reabsorption of Ca; decreases reabsorption of Phosphate; stimulates biosynthesis of Vit D3 from its precursor

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PTH @ bone

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activates osteoclasts to resorb bone; stimulates maturation of osteoclasts; inhibits collagen synthesis to decrease formation of ECM. (Less Ca will move from plasma to bone)

Front 54

PTH-rP

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causes humor hypercalcemia of malignancy; binds PTh receptor w/ similar affinity

Front 55

Vitamin D2

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obtained from diet, mostly in veggies

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Vit D3

Back 56

made in skin from rxn involving UV light; also some dietary sources like cod liver

Front 57

Formation of active vitamin D3

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25-OH-D3 formed in liver, can be stored for long periods of time. When it passes through the kidney is converted to active 1,25-Oh2-D3 form. PTH is key for this rxn to occur efficiently.

Front 58

relationship between Ca and Vit D3

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Ca, when high in the blood, decreases PTH, which decreases formation of D3

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vit D3 in GI tract

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increases synthesis of calcium binding protein in intestinal epithelial cells. increases absorption

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D3 in kidney

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increases tubular reabsorption of Ca

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D3 in bone

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potentiates actions of PTH to promote osteoclast activity

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implications of Low vit D3

Back 62

calcium is poorly absorbed, so PTH is high, osteoclast activity is high and bone mineralization is poor