CH. 16 Pineal Gland, pancreas, gonads. (misc. adipose, GI, heart, kidneys)

pineal gland

small gland hanging from roof of third ventricle

pinealcytes

secrete melatonin derived from serotonin

melatonin may affect

• timing of sexual maturation and puberty

• day/night cycles

• physiological processes that slow rhytmic variations (body temp, sleep appetite)

• production of antioxidant and detoxification molecules in cells

pancreas

triangular gland located partially behind stomach

• has both exocrine and endocrine cells

• has acinar cells, and pancreatic islets (contain endocrine cells like alpha and beta cells)

acinar cells

located in pancreas

• exocrine function

• produce enzyme-rich juice for digestion

pancreatic islets

contain endocrine cells

• alpha cells

• beta cells

alpha cells

produce glucagon

• hyperglycemic hormone

beta cells

produce insulin

• hypoglycemic hormone

glucagon

triggered by decreased BG levels, or SNS. Raises BG by targeting liver to:

• break down glycogen into glucose (glycogenolysis)

• synthesize glucose from lactic acid and other noncarbohydrates (gluconeogenesis- turn fatty and amino acids into glucose)

• release glucose into blood

insulin

secreted when BG levels increase. insulins lowers BG levels in 3 ways:

1. enhances membrane transport of glucose into fat and muscle cells

2. inhibits breakdown of glycogen to glucose (glycogenolysis)

3. inhibits conversion of amino acids or fats to glucose (gluconeogenesis)

• also converts glucose to fat as storage

what does insulin bind to

tyrosine kinase enzyme receptor, triggering cell to increase glucose uptake (not cAMP)

what stimulus triggers insulin release

• elevated BG

• rising blood levels of amino and fatty acids

• release of aCh by PSNS nerve fibers (glucose is stored in cells rather than blood when relaxed)

what inhibits insulin release

• homrones, glucagon, epinephrine, GH, thyroxine, glucocorticoids, and SNS

gonads produce

same steroid sex hormones as those of adrenal cortex, just lesser amounts

ovaries

produce estrogens and progesterone

estrogen

• maturation of reproductive organs

• causes breast development and cyclic changes in uterine mucosa

testes produce

testosterone

• inititates maturation on male reproductive organs

• necessary for normal sperm production

• maintains reproductive organs in functional state

adipose tissue

adipose cells release leptin

leptin

secreted by adipose cells in adipose tissue

• control appetite

• stimulates increased energy expenditure

GI tract

has enteroendocrine cells that secrete hormones:

• gastrin

• ghrelin

• secretin

• cholecystokinin (CCK)

gastrin

stimulates release of HCI when food hits the stomach

ghrelin

from stomach, stimulates food intake

secretin

stimulates liver and pancreas

cholecystokinin (CCK)

activates pancreas, gallbladder, and hepatopancreatic sphincter

what does heart secrete

atrial natriuretic peptide (ANP)

• decreases blood Na+ concentration, therefore blood pressure and blood volume

what do kidneys secrete

erythropoietin and renin

erythripoietin

secreted from kidneys

• signals production of red blood cells

renin

secreted by kidneys

• inititates the renin-angiotensin-aldosterone mechanism (RAAS)

type 1 diabetes

An autoimmune condition where the body attacks and destroys the insulin-making cells in the pancreas. The body makes little to no insulin.

type 2 diabetes

A metabolic condition where the body still makes insulin, but the cells do not respond to it properly. This is called insulin resistance. Over time, the pancreas cannot keep up with the demand.