Endocrine system

Role of the endocrine system

regulates growth, metabolism, nutrients, immunity, reproduction

hormones are released into bloodstream to target specific cells

mechanism of hormones

lipid soluble and water soluble

lipid soluble

require carrier proteins to enter membrane

long half life

enter cell to change gene expression

water soluble

circulate freely

short half life

trigger signaling cascade

lipid soluble bind to

intracellular receptors

water soluble bind to

extracellular receptors

increased hormone presence…

stronger response

up regulation

increase number of receptors when hormone levels are low

down regulation

decrease number of receptors when hormone levels are high

permissive

dependent on eachother

synergistic

amplify effect

antagonistic

activate opposite processes or downregulate

hypothalamus

connects nervous to endocrine and control pituitary gland

pituitary gland

master gland

neurohypophysis

posterior pituitary gland

adenohypophysis

anterior pituitary gland; make own hormones

activity of hormones is affected by…

rate of secretion

rate of inactivation

removal of body

GHRH

growth hormone- releasing hormone

TRH

thyrotropin- releasing hormone

CRH

corticotropin-releasing hormone

PRH

prolactin releasing hormone

GNRH

gonadotropin releasing hormone

GHIH

growth hormone- inhibiting hormone

PIH

prolactin inhibiting hormone

oxytocin

labor/lactation; paraventricular nuclei; regulated by positive feedback loops

ADH (anti-diuretic hormone)

retain water and keep blood pressure steady; supraoptic nuclei, regulation of negative feedback loops

too little ADH

diabetes insipidus

too much ADH

SIADH

role of pancreas in blood sugar

islets of Langerhans secrete hormones to regulate blood glucose

insulin

beta cells, released when blood sugar is high

increases glucose uptake, glycogen synthesis, amnio/fatty acid uptake

glucagon

alpha cells, released when blood sugar is low

increases glycogenesis, glycogen/triglyceride breakdown

somatostatin (GHIH)

decreases insulin/glycogen release

pineal gland

pinealocytes produce melatonin

outer cortex is made up of

zones g, f, r

zona glomerulosa

maintain water balance and increase blood pressure (aldosterone secreted)

zona fasciculata

responds to stress and regulate blood glucose (cortisol released)

zona reticularis

produces estrogen/testosterone (androstenedione released)

inner medulla

secretes epinephrine/norepinephrine

parathyroid gland

secretes parathyroid hormone when blood calcium levels are low; targets osteoclasts and kidney

type 1 diabetes (diabetes mellitus)

beta cells are destroyed in the pancreas

type 2 diabetes (diabetes mellitus)

cells are resistant to insulin and don’t take glucose

steroid hormones

made from cholestorol

calcitonin

lower blood calcium levels

signaling cascade

1. hormone binds to receptor and activates

2. g protein activates

3. cAMP (2nd messenger) activated

4. adenylyl cyclase activated

thyroid gland

anterior to trachea and inferior to larynx

parathyroid glands imbedded

t3, t4, calcitonin

thyroid hormones controlled by

thyroid stimulating hormone in anterior pituitary

hyperparathyroidism can result in

bone fractures, weak bones

adrenal glands are located on top of which organ

kidneys

what types of cell secrete epinephrine/norepinephrine

chromaffin cells

Cushing’s disease

high levels of cortisol

role of insulin

facilitates movement of intracellular glucose transporters to the cell membrane

end result of RAAS

increase blood pressure

gigantism/acromegaly

too much growth hormone

dwarfism and impaired functions

too little growth hormone

graves disease

too much thyroid hormone

cretinism/myxedema

too little thyroid hormones

addison’s disease

too little cortisol

polycystic ovary syndrome

too much gonadotropin

hypogonadism

too little gonadotropin

hyperprolactinemia

too much prolactin hormone