Endocrine 3

pineal gland

small gland hanging from roof of third ventricle

pinealocytes

secrete melatonin, derived from serotonin

melatonin may affect

timing of sexual maturation and puberty, day/night cycles (most important), physiological processes that show rhythmic variations (body temp, sleep, appetite), production of antioxidant and detoxification molecules in cells

pancreas

triangular gland located partially behind the stomach, has both endocrine and exocrine glands

pancreatic islets (islets of langerhans)

contains endocrine cells, alpha cells (glucagon) and beta cells (insulin)

endocrine cells of the pancreas

onable

located in the pancreatic isles (islets of langerhans) and synthesize and secrete hormones insulin and glucagon and somatostatin to systemic circulation, only 1-2% of pancreas

most significant disorders of the endocrine pancreas

diabetes mellitus and neoplasms (diabetes and cancer)

glucagon

extremely potent hyperglycemic agent, triggered by decreased blood glucose levels/rising amino acid levels/sympathetic nervous system, raises blood glucose by targeting liver to break down glycogen into glucose (glycogenolysis), synthesize glucose from lactic acid and other noncarbohydrates (gluconeogenesis), release glucose into blood

insulin

secreted when blood glucose levels increase, synthesized as proinsulin that is then modified, insulin lowers blood glucose levels by enhancing membrane transport of glucose into fat and muscle cells/inhibit breakdown of glycogen to glucose/inhibit conversion of amino acids or fats to glucose

insulin triggers cells to

catalyze oxidation of glucose for ATP production (glycolysis, first priority), polymerize glucose to form glycogen, convert glucose to fat (particularly in adipose tissue)

factors that influence insulin release

elevated blood glucose levels (primary stimulus), rising blood levels of amino acids and fatty acids, release of acetylcholine by parasympathetic nerve fibers

diabetes mellitus (DM) types

type 1 (hyposecretion of insulin), type 2 (hypoactivity of insulin)

cardinal signs of diabetes mellitus (DM)

polyuria (huge urine output), polydipsia (excessive thirst), polyphagia (excessive hunger and food consumption)

ketones (ketone bodies)

formed by fatty acid metabolism (fatty acid beta oxidation)

ketoacidosis

build up of acidic ketones in blood, similarly ketonuria (ketones in urine), causes disrupted heart activity/severe depression of the nervous system

hyperinsulinism

excessive insulin secretion, causes hypoglycemia (low blood glucose levels), anxiety/nervousness/disorientation/unconsciousness

Type 1 diabetes statistics

5-10% of people with diabetes have type 1, 1/300 people, 1/4 of type 1 are diagnosed in adulthood, most common youth diabetes

type 2 diabetes statistics

1 in 10 Americans have diabetes (34.2 million), 1 in 3 American adults have prediabetes (88 million)

type 2 diabetes

insulin deficiency and tolerance that is progressive and takes several years to progress

ovaries (female gonads)

produce estrogen and progesterone, estrogen with progesterone causes breast development and cyclic changes in uterine mucosa (menstrual cycle)

testes (male gonads)

produce testosterone, maintains reproductive organs in functional state

placenta

secretes estrogens, progesterone, and human chorionic gonadotropin (hCG)

human chorionic gonadotropin (hCG)

pregnancy tests will test for this hormone because pregnancy is one of the few reasons a person will have this hormone in their system

adipose tissue hormone secretion

secrete leptin, resistin, adiponectin

leptin

appetite control, stimulates increased energy expenditure

resistin

insulin antagonist

adiponectin

enhances sensitivity to insulin, decreased in obesity (ex. type 2 diabetes)

environmental pollutant effect

can negatively affect endocrine system (ex. BPA)

endocrine function throughout life

GH levels decline with age (muscle atrophy), TH declines with age (lower basal metabolic rate), PTH levels remain constant with a lack of estrogen in older women (more vulnerable to bone-demineralizing effects of PTH), glucose tolerance deteriorates with age