The endocrine system

Produce + secrete hormones. Major glands - pituitary, adrenal + reproductive organs. Each gland produces diff hormones, regulate activity of organs + tissues.

Endocrine system regulated by: signal sent from hypothalamus to pituitary gland, causes it to secrete stimulating hormone in bloodstream. Hormone signals target gland to secrete its hormone. As level of hormone rises in bloodstream, hypothalamus shuts down secretion of releasing hormone + PG shuts down secretion of stimulating hormone. Slows down secretion of target gland's hormone, -> stable concentrations of hormones in bloodstream.

Given hormone usually affects limited cells - target cells. TC respond to hormone b/c have receptors for it.

When enough receptor sites stimulated by hormones, -> reaction in target cells. Too much/too little at wrong time -> dysfunction of bodily systems.

Produces hormones whose main function is to influence release of hormones from other glands - regulate functions of body.

Controlled by hypothalamus, which receives info about basic functions of body, uses it to help regulate functions - controls pituitary.

'Master gland', produces hormones that travel in bloodstream to target cells - hormones cause changes in physiological processes or stimulate other glands to produce hormones. High levels hormones in other endocrine glands can stop hypo + pituitary releasing more of hormones - negative feedback.

Anterior:
 - ACTH - stress response. Stimulates adrenal glands to produce cortisol.
 - LG + FSH - stimulate ovaries to produce oestrogen + progesterone, + testes - testosterone.

Posterior:
 - releases oxytocin, stimulates contraction of uterus during childbirth, important for mother-infant bonding.

2 adrenal glands, on top of kidney. 2 distinct parts. Outer part - adrenal cortex, inner region - adrenal medula.

Main distinction b/ween them - hormones released by adrenal cortex necessary for life.

Adrenal cortex:
 - cortisol - regulates bodily functions eg cardiovascular funcitons. Increased in response to stress. If C level low, has low blood pressure, poor immune function + inability to deal w/ stress.
 - aldosterone - maintains blood volume + blood pressure.

Adrenal medula:
 - adrenaline + noradrenaline - prepare for fight/flight. Adrenaline - increases heart rate + blood flow, helps conversion of glycogen to glucose for energy. Noradrenaline - constricts blood vessels, causes blood pressure to increase.