Endocrine Glands

Two general types of glands

1. endocrine

2. exocine

exocrine system

• use ducts to release secretions to direct places / no receptors

• don’t spread throughout bloodstream

endocrine system

• ductless

• secretion flows throughout blood stream and delivered throughout the body

• has hormones

hormones

substances manufactured by secretory cells; can only trigger a reaction in specific cell (target cell with right receptors)

secretory cells

make and release secretions

gland

• any structure that makes and secretes a hormone

anterior / inferior to the thalamus

location of hypothalamus

function of hypothalamus

Controls pituitary gland

1. sends hormones (ADH and Oxytocin) directly to posterior pituitary

2. communicates through hypophyseal portal system to anterior pituitary

infundibulum

connects the hypothalamus to the thalamus

hypophyseal portal system

indirectly communicates with the anterior pituitary and how hormones reach the pituitary from system

hypothalamus nuclei

• SON

• PVN

• VM nuclei

SON

produces oxytocin

PVN

produces ADH

VM nuclei

produces other 6 hormones in anterior pituitary; extend axon to bottom of hypothalamus and produces releasing and inhibiting growth hormones

GnRH, TRH, PRH, GHRH, CRH, GHIH

hypothalamus hormones

pituitary gland

consists of two lobes that arise from distinct parts of embryonic tissue

sella turcica in sphenoid bone

location of pituitary

two pituitary lobes

1. posterior

2. anterior

neurohypophysis

(neural tissue); another name for posterior pituitary

adenohypophysis

(glandular tissue); another name for anterior pituitary

anterior pituitary cells

1. acidophils

2. basophils

acidophils

produce GH and prolactin (PRL)

non tropic hormones

hormones that act directly on cell

• GH and Prolactin (PRL)

basophils

produce FSH, LH, TSH, ACTH and other tropic hormones

tropic hormones

hormones that control activity of other glands

• TSH, FSH, LH, ACTH, etc

ADH and Oxytocin

posterior pituitary hormones

FSH, LH, TSH, ACTH, GH, PRL

anterior pituitary hormones

FSH, LH, TSH, ACTH, GH, PRL, ADH, and Oxytocin

hormones of the pituitary gland

ADH

helps control water balance; inhibits or prevents urine production

oxytocin

helps with childbirth and bonding / milk ejection

FSH

helps testes create sperm; stimulates gamate production

LH

helps with increase of testosterone; promotes production of gonadal hormones

PRL

helps produce milk

TSH (thyroid stimulating hormone)

tells thyroid to release its hormones

TSH

tells thyroid to release hormones

ACTH

stimulates adrenal gland

GH

helps with growth; stimulates most cells in the body to grow and divide

secretion

process where substances are released and discharged from gland

synthesize

to make

anterior to the trachea and inferior to the larynx

location of thyroid

thyroid cells

1. follicular cells

2. c-cells

follicular cells

single layer surrounds central cavity

• synthesizes thyroglobulin protein that gets iodinized

T3 and T4, Calcitonin

hormones of thyroid gland

T3 and T4

after iodine gets added to thyroglobulin protein in the colloid (central cavity), this hormone is created

thyroglobulin

protein needed to create T3 and T4

stimulation of thyroid gland

falling levels trigger anterior pituitary releases TSH, which stimulates T3 and T4 to go back to the follicular and then the bloodstream

function of T3 and T4

1. control how much energy body uses

2. increase use of oxygen to produce ATP

3. cause increase of nutrient breakdown

function of c-cells

produce calcitonin in response to elevated Ca2+ in blood (calcium homeostasis)

• dont need TSH from ant. pit

embedded in posterior surface of the thyroid gland

location of parathyroid gland

parathyroid cell

1. chief cells (epithelial cells)

2. oxphil cells

PTH

parathyroid hormone

PTH function

involved in regulation of blood calcium levels; reabsorb calcium from filtrate in kidney and increase vitamin D which increases calcium absorption in intestines

posterior to the bottom of the stomach

location of pancreas

pancreas cells

1. islets of langerhans

2. alpha cells

3. beta cells

4. delta cells

5. polypeptide cells

insulin, glucagon, somatostatin, polypeptide

pancreas hormones

insulin

• released by beta cells

• lowers blood sugar by increasing rate which cells store sugar

glucagon

• released by alpha cells

• increases blood sugar by decreasing the rate which cells store sugar

somatostain

released by delta cells

polypeptide

released by polypeptide cell (pp)

pancreas function

regulates your blood sugar

adrenal gland

has

1. cortex

2. medulla

dorsal surface of each kidney

location of adrenal gland

adrenal cortex

secretes steroid hormones that are important for longterm stress response, blood pressure etc

stimulation of cortex

hypothalamus stimulates ant. pit. to release ACTH hormone which stimulates production / secretion of corticosteroid

CRH - ACTH - cortisol

3 regions of cortex

1. zona gomerulosa

2. zona fasciculata

3. zona reticlaris

zona gomerulosa

superficial layer

aldosterone (mineralocorticoids)

zona glomerulosa produces

aldosterone function

increases blood volume and blood pressures; stimulates reabsorption of sodium in kidney

aldosterone stimulation

CRH (hypothalamus) stimulates ACTH (anterior pituitary) stimulates increase in aldosterone

zona fasciculata

intermediate layer

cortisol (glucocorticoids)

zona fasciculata produces

cortisol function

breaks down nutrients, glycogen, triglycerides, proteins for body fuel uses

cortisol stimulation

CRH (hypothalamus) stimulates ATCH (anterior pituitary) stimulates cortisol

zona reticularis

deepest region

androgens (gonadocorticoids)

zona reticularis produces these steroid sex hormones

• produced in gonads

• produces sex hormones, plays a role in puberty

androgen function

helps with puberty and sexual development

adrenal medulla

• comprised of postganglionic sympathetic neurons

• activated in response to sympathetic nervous system activation

NE and Epinephrine

adrenal medulla releases

chromaffin cells

adrenal medulla cells

• produces NE and Epininpherne

leydig cell

cells of the testes

testosterone

testes hormone

testosterone function

muscle development, bone growth, sex drive etc

testosterone stimulation

GnRH (hypothalamus) stimulates LH and FSH (anterior pituitary) stiulates increase of testosterone and sperm

granulosa and theca

ovary cells

granulosa

promote follicle growth and maturation

theca

produce androgens and precursors for estrogen

estrogen and progesterone

ovary hormone

ovary hormone function

hormone production, oogenesis

oogenesis

development of female gametes

GnRH (gonadotropin releasing hormone)

• hypothalamus hormone

• controls FSH and LH (gonadotropins))

GHRH (growth hormone)

• hypothalamus hormone

• growth releasing hormone

GHIH (growth hormone)

• hypothalamus hormone

• inhibiting hormone

TRH (thyroid releasing hormone)

• hypothalamus hormone

• conditions where there is increased energy requirements cause TRH release from hypothalamus

CRH

• hypothalamus hormone

• rising glucocorticoids inhibits CRH secretion

PRH

• hypothalamus hormone

• stimulates prolactin

PIH

• hypothalamus hormone

• production of this inhibits PRL

• prevents milk production

calcitonin

lowers blood calcium levels

• calcium acts as a humoral signal for calcitonin release

• inhibits calcium release from bones by osteoclast activity