Anatomy Ch 18 & 19

functions of the endocrine system

metabolism & tissue maturation

ion regulation

water balance

immune system regulation

hr & bp regulation; erythropoiesis

controls food intake and digestion

regulation of blood glucoses & other nutrients

controls reproductive function

• uterine contractions & milk release

endocrine gland

secrete hormones into the blood

hormones

chemical messengers that act on target tissues

ways hormone secretion is regulated

negative or positive feedback loops

neuroendocrine reflexes

diurnal rhythms

what feedback mechanisms do

maintain homeostasis by controlling secretion of most hormones

what neuroendocrine reflexes do

produce a sudden increase in hormone secretion in response to a specific stimulus

what diurnal rhythms do

daily/each day rhythms

repetitive oscillations in hormone levels

membrane bound receptor characteristics

outside effects inside

water-soluble hormone bind to it

bound to plasma membrane of target cell

faster responding

hormone-receptor complex activates response inside of cell

nuclear receptor characteristics

inside effects inside

lipid-soluble hormones bind to it

in nucleus of cell, sometimes cytoplasm

slower responding

hormone-receptor complex interacts with DNA/cellular enzymes to regulate transcriptions of genes in target tissue

how hormones are transported

through the blood

how hormones are excreted

through urine or bile

major responses when hormones bind to membrane bound receptors

• activation of G-proteins that stimulates synthesis of cAMP

• regulation of ion channels

• phosphorylate intracellular proteins

structure of pituitary gland

inferior to hypothalamus, connected through infundibulum

where the NS meets endocrine system

split into posterior and anterior

regulation of posterior pituitary secretions

axon endings in posterior pituitary store neurohormones

action potentials are conducted by hypothalamic neurons through the hypothalamohypophysial tract into posterior pituitary and cause release of neurohormones into the blood

posterior pituitary gland characteristics

an extension of the hypothalamus

has axons

stores hormones made in the hypothalamus

posterior pituitary gland

hormones released by the posterior pituitary gland

antidiuretic hormone (ADH)

oxytocin

ADH target tissue

tubules of kidneys and blood vessels

ADH response

increase water reabsorption

decrease urine volume

increases bp (constricts bv)

ADH stimulus

increase of electrolyte concentration

decrease of water concentration

decrease in blood pressure

oxytocin target tissue

uterus and mammary glands

oxytocin response

uterine contraction

milk ejection from breasts

oxytocin stimulus

stretch of uterus

stretch of cervix

mechanical stimulus of nipple

regulation of anterior pituitary secretions

neurons of hypothalamus secrete releasing and inhibiting hormones

hormones pass through hypothalamohypophysial portal system into anterior pituitary

hormones leave capillaries and stimulate or inhibit release of hormones from anterior pituitary

general action of anterior pituitary hormones

regulate body functions

regulate secretions of other endocrine gland

anterior pituitary characteristics

needs signaling hormones from hypothalamus

many tropic hormones

has blood vessels

hormones released by the anterior pituitary gland

growth hormone (GH)

thyroid-stimulating hormone (TSH)

adrenocorticotrophic hormone (ACTH)

luteinizing hormone (LH)

follicle-stimulating hormone (FSH)

prolactin

GH target tissue

muscles, bones, soft tissue

GH response

stimulates uptake of AA’s

protein synthesis

lipolysis

stimulates synthesis of glycogen

promotes bone and cartilage growth

regulates blood levels of nutrients

GH stimulus

growth hormone-releasing hormone (GHRH)

growth hormone-inhibiting hormone (GHIH)

effect of hypersecretion of GH

acromegaly and giantism

causes tissue overgrowth

effects of hyposecretion of GH

pituitary dwarfism

causes slow growth, short stature with normal body proportions, delayed puberty

TSH target tissue

thyroid

TSH response

stimulates thyroid to release T3 and T4

TSH stimulus

thyroid releasing hormone (TRH)

ACTH target tissue

adrenal cortex

ACTH response

stimulates adrenal cortex to release cortisol

ACTH stimulus

corticotropin releasing hormone (CRH)

LH target tissue

testes and ovaries

LH response

regulates length and order of menstrual cycle

produces testosterone or estrogen and progesterone

role in ovulation and implantation of egg in uterus

stimulates ovulation

LH stimulus

gonadotropin releasing hormone (GnRH)

FSH target tissue

testes and ovaries

FSH response

help regulate menstrual cycle

stimulates follicles in ovaries to grow and prep eggs for ovulation

produces testosterone or estrogen and progesterone

stimulates sperm production

FSH stimulus

gonadotropin releasing hormone (GnRH)

prolactin target tissue

mammary glands

prolactin response

milk synthesis

prolactin stimulus

prolactin releasing hormone (PRH) and prolactin inhibiting hormone (PIH)

thyroid gland characteristics

one of largest endocrine glands

superficial to trachea, inferior to larynx

butterfly shaped

highly vascular

makes up thyroid gland

follicles

parafollicular cells

follicular cells in thyroid

small spheres that are surrounded by a single layer of cuboidal epithelial cells

secrete thyroglobulin into lumen of follicle

creates and store T3 and T4

parafollicular cells in thyroid

the remaining cells outside/between the follicles

secrete calcitonin

hormones produced by the thyroid

triiodothyronine (T3), tetraiodothyronine (T4), and calcitonin

T3 and T4 target tissues

most cells

T3 and T4 response

responsible for normal growth and development

increased BMR

• which increases body temp and metabolic rate

increases Na/K pump activity

increases activation of the # of and activity of mitochondria

T3 and T4 stimulus

thyroid stimulating hormone

calcitonin target tissue

bone

calcitonin response

decreases blood calcium levels

decrease osteoclast activity

increases osteoblast activity and lifespan

calcitonin stimulus

high blood calcium levels

parathyroid gland characteristics

embedded in thyroid

4 glands

posterior side of thyroid

hormones produced by parathyroid gland

parathyroid hormone (PTH)

PTH target tissue

bone, kidneys, small intestine

PTH response

increases blood calcium

increase osteoclast activity and vitamin D synthesis

promotes Ca2+ reabsorption by kidneys,

PTH stimulus

low blood calcium levels

adrenal gland characteristics

2 glands

superior poles of kidneys

divided into adrenal cortex (outer) and adrenal medulla (inner)

zones of the adrenal cortex

zona glomerulosa

zona fasciculate

zona reticularis

zona glomerulosa

superficial layer of adrenal cortex

secretes minerocorticoids

zona fasciculate

middle layer of adrenal cortex

secretes glucocorticoids

zona reticularis

deep layer of adrenal cortex

secretes adrenal androgens

hormones secreted by the adrenal cortex

aldosterone - minerocorticoid

cortisol - glucocorticoid

aldosterone target tissue

kidneys

aldosterone response

promotes sodium reabsorption at kidneys, which causes bp to increase

causes potassium and hydrogen to move into urine

regulates ion balances in blood

aldosterone stimulus

low bp

low sodium concentrations

high levels of potassium or hydrogen

cortisol target tissue

most tissues

cortisol response

discourages tissue building, encourages tissue breakdown

increases blood glucose, glucose synthesis

decreases inflammatory response

cortisol stimulus

ACTH and CRH

chromaffin cells

‘post-ganglionic’ cells in the adrenal medulla

no dendrites or axons

releases a mix of epinephrine, norepinephrine, and domaine into blood stream

hormones secreted by the adrenal medulla

epinephrine and norepinephrine

epinephrine and norepinephrine target tissue

anything with sympatheticc receptors

epinephrine and norepinephrine response

reinforce the sympathetic NS and preps body for fight or flight

increase BGL, glycogen breakdown, fat breakdown in adipose tissue, hr and force of contraction

dilates BV in cardiac and skeletal muscle

vasoconstriction in peripheral areas

inhibits non-essential functions

epinephrine and norepinephrine stimulus

sympathetic pre-ganglionic nerve fibers

pancreas characteristics

just behind stomach and around small intestine

exocrine and endocrine gland

regulates blood sugar by releasing insulin and glucagon

what are pancreatic islets

endocrine glands of the pancreas

what makes up each pancreatic islet

alpha cells

beta cells

delta cells

alpha cells of the islets secrete

glucagon

beta cells of the islets secrete

insulin

delta cells of the islets secrete

somatostatin

insulin target tissue

liver, skeletal muscle, adipose tissue, and satiety center of hypothalamus

insulin response

facilitates glucose transport into cells

stimulates glycogenesis

inhibits glycogenolysis and glyconeogenisis

lowers blood sugar

increases insulin secretion

hyperglycemia, presence of certain AA’s, parasympathetic stimulation, GI hormones

decreases insulin secretion

hypoglycemia/fasting, sympathetic stimulation, somatostatin

glucagon target tissue

liver, skeletal muscle, adipose tissue, satiety center of hypothalamus

glucagon response

signals glycogen to be broken down

promotes release of glucose from intracellular stores

raises blood sugar

increases glucagon secretion

hypoglycemia/fasting, presence of certain AA’s, exercises

decreases glucagon secretion

hyperglycemia, insulin, somatostatin

type one diabetes mellitus

the body doesn’t any insulin or very little insulin

an autoimmune disorder

type two diabetes mellitus

body produces insulin but the cells don’t respond to it

insulin resistence

biggest risk factor is obesity

can be ‘cured’ by weight loss

reproductive organs in endocrine system

males: testes

females: ovaries

hormones produced by testes

testosterone

testosterone target tissues

most cells

testosterone response

stimulates fetal and adolescent male reproductive development

spermatogenesis

promotes secondary sex characteristics