Pituitary, Pineal, Islets of Langerhans

Question 1

characteristics of endovrine organs

Answer 1

• ductless glands
• usually secrete hormones into bloodstream via fenestrated caps
• generally have systemic effects

Question 2

protein hormones

Answer 2

• prolactin, growth hormone

- bind surface receptors

Question 3

peptide hormones

Answer 3

• ADH, oxytocin

- bind to cell surface receptors and activate 2nd messangers

Question 4

cholesterol derived hormones

Answer 4

• steroid hormones, estrogen, glucocorticoids

- diffuse into cell and directly effect transcription

Question 5

eicosinoid derived

Answer 5

• prostaglanidins

- diffuse into the cell and directly effect transcripition

Question 6

monoamine hormones

Answer 6

-derived from single amino acids such as phe, tyr, tryp

Question 7

posterior lobe of the pit components

Answer 7

• aka neurophysis
• pars nervosa
• infindibulum

Question 8

anterior lobe components

Answer 8

• aka adenohypophysis
• pars distalis
• pars intermedia
• pars tuberalis

Question 9

pituitary development

Answer 9

• anterior pituitary is derived from the oropharynx ectoderm and originally has a Rathke’s pouch which later partially closes
• posterior pit is derived from neuroectoderm (from floor of 3rd ventricle)
• eventually the pit will be surrounded by the sphenoid bone

Question 10

cells of the pars distalis

Answer 10

• chromophobes
• basophils
• fenestrated caps
• acidophils
• endothelium

Question 11

acidophiles

Answer 11

• somatotropes: growth hormone

- lactotropes/mammotropes: prolactin

Question 12

growth hormone

Answer 12

• growth of muscle
• cartilage
• bone
• liver
• pancreas
• immune system devel

Question 13

prolactin

Answer 13

• mammary gland development
• milk production
• modulates spermatogenesis
• surfactant synthesis in fetal lung

Question 14

basophils

Answer 14

• corticotropes: ACTH
• thyrotropes: TSH
• gonadotropes: FSH and LH

Question 15

tropic hormones

Answer 15

-act on other endocrine organs to realease their product

Question 16

chromophobes

Answer 16

• not quite sure what these do
• degranulated acidophils/basophils
• folliculostellate cells

Question 17

folliculostellate cells

Answer 17

• devoid of granules, occupry 10% of the ant pit
• form cell clusters (follicles)
• dendritic morphology
• possess gap junctions that extend to other follicular cells and acidophils/basophils/chromophobes
• functions: paracrine regulation, neuro/immune regulation of inflammation, stem cells maybe

Question 18

pars intermedia

Answer 18

• part of the anterior lobe
• consists mostly of basophils (corticotrophs)
• synthesizes proopiomelanocortin which is cleaved to form: MSH, beta-endorphin, and ACTH
• contains colloid filled cysts

Question 19

pituitary portal system

Answer 19

• hypothalamic-hypophyseal portal system
• TRH-thyrotropin releasing hormone
• CRH: corticotropin releasing hormone
• GnRH: gonadotropin releasing hormone
• GHRH: growth hormone releasing hormone
• there is a negative feedback loop once the final hormone is released from the target organ which inhibits both the pit and hypothalamus

Question 20

posterior lobe

Answer 20

• contains pars nervosa and infundibulum
• neurosecretory organ
• storage and release of ADH and oxytocin
• contains unmyelinated axons, pituicytes (glia)

Question 21

neurosecretion of the posterior pit

Answer 21

• hormones are stored in herring bodies
• axons terminate near blood vessels
• hormones are coupled to neurophysin (N) 1 and 2
• calcium release stimulates exocytosis

Question 22

oxytocin

Answer 22

• smooth muscle contraction of the uterus
• myoepithelial cell contraction in the mammary glands
• emotional trust and calmness

Question 23

ADH (vasopressin)

Answer 23

• increase collecting duct permeability

- vasoconstriction (minor role)

Question 24

pineal gland

Answer 24

• neuroendocrine gland
• the retina is stimulated by light, nerve impulses are sent to the hypothalamus, norepinephrine is then sent to inhibit the pineal gland
• divided into lobule
• contains pinealocytes and interstitial cells (glial)
• contains calcifications

Question 25

pnealocyte

• what does is make and when
• what does this product do?

Answer 25

• tryptophan is used to make melatonin
• this pathway is active in darkness
• melatonin participates in circadian rhythms, puberty, and is a powerful antioxidant

Question 26

two types of calcifications in pineal glands

Answer 26

• corpora arenacea: large, mulberry-like concentrations; hydroxyapetite, protein, glycoprotein; increases with age
• myeloconia: small crystals, calcite, glycoprotein; similar to otoliths of inner ear

Question 27

composition of islets

Answer 27

-surrounded by exocrine acini

then first inside is the alpha cells then beta cellls are throughout the inside of the organ

Question 28

beta cells

Answer 28

-produce insulin

Question 29

delta cells

Answer 29

-somatostatin

Question 30

gamma cells

Answer 30

pancreatic polypeptide

Question 31

epsillon cells

Answer 31

-ghrelin

Question 32

insulin

Answer 32

• synthesized by beta cells in the islets
• released in reasponse to elevated blood glucose
• promotes glucose absorption in muscle and adipose tissue

Question 33

glucagon

Answer 33

• synthesized by alpha cells in islets
• released in response to low blood sugar
• promotes glycogen conversion to glucose, gluconeogensis

Question 34

somatostatin

Answer 34

• synthesized by the gama cells in islets

- inhibitory actions: pituitary, GI hormones, endocrine and exocrine pancreas