Endocrine I

hormones are carried via _

bloodstream

lymph

endocrine glands lack _ (structural feature)

ducts

target cells contain _ to hormones

specific receptors

the response from a target cell is the _

physiological response

examples of endocrine glands

thyroid

pituatary

pineal

adrenal

pancreas

ovary/testis

common ground between nervous system and endocrine

both systems allow for long distance communication

aspects of neural/endocrine regulation (4)

long distance communication

target cell has specific receptor

molecule + receptor must create a specific sequence of changes

must be a mechanism to turn off the action of the regulator

how do exocrine glands function

secrete into a duct and to the outside of the body surface

examples of exocrine glands

sweat

tear ducts

saliva

secretion of a hormone by one cell with transmission via intercellular fluid to a second, nearby cell

paracrine

secretion of a hormone by one cell with reception and response by the same cell

autocrine

secretion by one organism and sensation and response by a second

pheremonal

endocrine glands of pancreas

Islets of Langerhans

Hormone released by a cell interacts with appropriate receptor on physically adjacent cell without involving extracellular fluid

juxtacrine

what aspects are hormones involved with (4)

maintenance of internal environment

reproduction

energy storage, production, utilization

growth and development

chemical groupings of hormones

amines

polypeptides and proteins

glycoproteins

steroids

(polar/nonpolar)

amine hormones are derived from

tyrosine and tryptophan

examples of amine hormones

norepinephrine

epinephrine

T4

melatonin

serotonin

where are polypeptide/protein hormones derived from

gene products

how large are polypeptide proteins

less than 100 amino acids

examples of polypeptide hormone

ADH

oxytocin

insulin

glucagon

ACTH

parathyroid hormone

example of protein hormone

growth hormone

what are steroids derived from

cholesterol

polar hormones bind to receptors located _

on plasma membrane

polarity of ADH

polar hormone

where do nonpolar hormones bind

intracellularly

function of oxytocin

uterine and mammary contraction

examples of glycoprotein hormones

FSH, LH, TSH

polarity of thyroid hormones

nonpolar

term for precursor forms of active hormone as it is processed within the cell that ultimately secretes the hormone

preprohormone

prohormone

what is a preprohormone and example

larger precursor molecule to a prohormone

ex: preproinsulin

what is a prohormone

Precursor form which is converted to active form

where does the pre segment of a preprohormone direct the protein

to the appropriate organelle, where it is then cleaved

what convert prohormones to active hormones

proprotein convertases

prohormone and hormone produced by the skin (where does conversion occur)

prohormone: vitamin D3

hormone: 1,25-dihydroxyvitamin D3

location: liver and kidneys

testes - prehormone and hormone

pre: testosterone

hormone: dihydrotestosterone , estradiol

thyroid - prehormone and hormone

pre: thyroxine (T4)

hormone: T3

hormone receptor characteristics (5)

protein

specific for hormone

high affinity for binding

low capacity (saturable)

localized to responding tissues

types of cell surface receptors for polar hormones

G protein coupled receptors

tyrosine kinase receptor

immune inhibitory receptor

GPCR type of membrane protein

integral

structure of GPCR

7 transmembrane domains linked to a guanine binding protein

examples of GPCR (6)

adrenergic receptors

neurotransmitter receptors

olfactory receptors

opiod recceptors

rhodopsin

chemokine

hormones derived from tyrosine

NE

epinephrine

T4

hormones derived from tryptophan

melatonin

seratonin

how do tyrosine kinase receptors work

Ligand binds to receptor

dimerization occurs

receptor is phosphorylated -> becomes active

signal molecule becomes phosphorylated

cascade effect (signal transduction)

physiological benefit of hormones being synthesized in prehormone form

prehormone is already synthesized and can quickly be converted to active form when needed (efficiency)

how many amino acids is a preprohormone

75-200 amino acids

how many amino acids is a prohormone

70-190 amino acids

where is testosterone converted to estradiol

brain

where is testosterone converted to its active form

androgen dependent tissue

polar hormones require the activation of

second messengers

3 classes of second messenger systems

-adenylate cyclase / cAMP,cGMP / protein kinase

- phospholipase C / IP3

-tyrosine kinase

what activates protein kinase

cAMP

phospholipase C activation causes release of _

inositol triphosphate (IP3)

tyrosine kinase receptor structure

one transmembrane domain

exists as a dimer

example of a tyrosine kinase receptor

insulin receptor

how does phosphorylation of tyrosine kinase occur

one unit phosphorylates the other (autophosphorylation)

adenylate cyclase - cAMP pathway steps

hormone binds to receptor

intracellular G proteins are activated

alpha subunit dissociates

alpha subunit activates adenylate cyclase

adenylate cyclase cleaves ATP to cAMP and PPi

cAMP binds to inhibitory subunit of protein kinase -> activates protein kinase

protein kinase phosphorylates proteins (either activates or inactivates enzymes)

G proteins subunits involved with GPCR

alpha

beta

gamma

what is the effect of insulin binding

insertion of GLUT4 proteins

stimulate glycogen synthesis

phospholipase C pathway steps

hormone binds receptor

G protein subunit activates phospholipase C

phospholipase C releases IP3

IP3 enters endoplasmic reticulum

Ca++ gets released from ER

second messengers involved with phospholipase C pathway

IP3

Calcium

name of receptors for lipophilic hormones

nuclear hormone receptors

how to lipophilic hormones travel to target cells

attached to plasma carrier proteins

where are nuclear hormone receptors found

cytosol or nucleus

what happens once hormone binds nuclear hormone receptor

translocation into the nucleus

hormone + nuclear receptor protein bind to _

specific DNA sequences

T4 passes into _ and is converted to _

cytoplasm; T3

where are T4 receptor proteins located

in the nucleus

T3 works alongside _ to create a hormone response

9-cis retinoic acid

what binds RXR

vitamin A derivative (9 cis retinoic)

how does T3 pathway work

T3 binds TR

RXR binds to vitamin A derivative

dimerization occurs

bind to DNA

hormone response element is activated

gene transcription is stimulated

what can cause hormone deficiency

-genetic disease: absence/malformation of endocrine gland or enzymes involved

-acquired diseases: gland becomes destroyed or damaged

3 types of diseases to the endocrine system

hormone deficiency

hormone excess

resistance to hormone action

how can excess hormone action occur (3)

activating mutation in receptors

ectopic production of hormone

autonomous production of target hormone by alternate signal

how can resistance to hormone action occur

inactivation of hormone receptors (mutation/acquired)

primary endocrine disease

disease occurs in the target endocrine gland

secondary endocrine disease

disease state occurs by aberrant action of the master glands that produce the hormone

which are the polar hormones

amines

polypeptides

glycoproteins

which are the nonpolar hormones

steroids

vitamin D

thyroid hormone

tyrosine kinase receptors eventually cause the production of a _

phosphorylation cascade

where is the pituatary gland located

below hypothalamus at the base of the forebrain

what connects the hypothalamus and pituatary gland

via the infundibulum

how is the pituatary gland divided

anterior lobe

posterior lobe (neural tissue)

nerve fibers extend through _ in the pituitary gland

infundibulum

what is the anterior pituatary derived from

a pouch of epithelial tissue that migrates upward from the embryonic mouth

what is the posterior pituatary derived from

brain

the hormones released by the anterior pituatary are classified as _

tropic hormones

high hormone concentration causes target organ to _

hypertrophy

low hormone concentration causes target organ to _

atrophy

hormones relesed by anterior pit

TSH

ACTH

FSH and LH

Growth Hormone

prolaxctin

where does growth hormone act

adipose tissue

bone

muscle

5 cell types of the anterior pituatary

somatotropes

lactotropes

corticotropes

thyrotropes

gonadotropes

relationship between ant pituitary and a particular target gland is called _

axis

ACTH target tissue, principal action, regulation of secretion

adrenal cortex

stimulates secertion of glucocorticoids

stimulated by CRH, inhibited by glucocorticoids

hormones released by posterior pituatary

vasopressin/ADH

oxytocin

oxytocin function

stimulates uterine contraction

stimulates mammary gland contraction

where are posterior pituitary hormones produced

hypothalamus

regulatory hormones produced by hypothalamus neurons

releasing and inhibiting hormones

where are regulatory hormones from the hypothalamus transported to

axon endings in basal portion of hypothalamus (median eminence)