Lecture 2

cholesterol based hormones- steroids, testosterone

endocrine and exocrine- female and male reproductive systems, pancreas

endocrine system distributes through the body through the bloodstream

nervous system quickly responds, endocrine system responds slowly

stalk- infundibulum

hypothalamus> pituitary> target gland > effect

hypothalamus- usually a releasing hormone

pituitary- usually a stimulating hormone

6 anterior pituitary hormones- FSH, LH, TSH, ACTH, PRL, GH

2 posterior pituitary- ADH, oxytocin

the two hormones are produced in the hypothalamus and transported to the posterior lobe of the pituitary

oxytocin- important during lactation

oxytocin- surge of hormone released during sexual arousal and orgasm, promotes sexual and emotional satisfaction between partners, stimulates labor contractions, stimulates flow of milk flow during lactation, may promote emotional bonding between mother and infant

feedback inhibition-

negative feedback- increased target organ hormone levels inhibit release of hormones

positive feedback- stretching of uterus increases OT release, causing contractions, causing stretching

growth hormone- IGF-I prolongs the action of GH

Growth hormone- induces liver to produce growth stimulates

GH bone growth, thickening, and remodeling influenced, especially during childhood and adolescence

GH secretion high during first 2 hours of sleep

GH can peak during exercise

GH levels decline with age

Hypersecretion of GH- problems in childhood and adolescence giantism if hypersecretion

Hyposecretion of GH- pituitary dwarfism

pineal gland- attached to roof of third ventricle beneath the posterior end of the corpus callosum, the third eye

after age 7 the pineal gland undergoes shrinkage

pineal gland shrinks by 75% after puberty

the pineal gland may influence the timing of puberty in humans

pineal gland synthesizes melatonin at night

phototherapy- two to three hours of bright light exposure each day reduces the melatonin levels and symptoms

thymus- plays a role in three systems- endocrine, lymphatic, immune

thymus- goes through involution after puberty (much larger when younger)

thymus- site of maturation of T cells (immune system)

know gland + hormone it may produce

thyroid gland- the largest purely endocrine gland, secretes T3 and T4

90% of the thyroid gland is in the form of T4, Aka thyroxine

thyroid gland helps with increasing the metabolic rate, 02 consumption, heat production, appetite, growth hormone secretion, alertness, reflex speed

calcitonin tones down ca2+ in the bloodstream to store it

thyroid gland is composed of two lobes, isthmus is below the larynx

C (clear) cells - secrete calcitonin

thyroid disorders- congenital hypothyroidism- treat with oral thyroid hormone

myxedema- decreased TH- treat with oral thyroid hormone

goiter- too much thyroid release, any pathological enlargement of the thyroid gland

parathyroid hormone has the opposite effect from calcitonin

PTH increases blood ca2+ levels, decreases urinary excretion, increases bone reabsorption

parathyroid disorders: hypoparathyroidism- surgical excision, fatal tetany for 3 to 4 days

hyperparathyroidism- parathyroid tumor, bones become soft, fragile and deformed, Ca2+ and phosphate blood levels increase

adrenal glands- zona glomerulosa- secretes salt or mineralocorticoids, aldosterone

zona fasciculata- secretes sugar, cortisol, corticosterone, glucocorticoids

zona reticularis- secretes sex hormones, androgens

adrenal medulla- inner core, 10%-20% of gland

adrenal medulla- has dual nature acting as an endocrine gland and a ganglion of the sympathetic nervous system

adrenal medulla- releases catecholamines and a trace of dopamine straight into the bloodstream

parasympathetic effects- SLUDDE, salivation, lacrimation, urination, defecation, dyspnea, emesis

catecholamine effects- increase alertness and prepare for physical activity

parathyroid- rest and digest

The adrenal cortex: memory triggers: GFR, salt, sugar, sex

peptides and catecholamines bind to receptors which cause a chain reaction