Endocrine System Pt 1

nervous system

integrates tissue functions via a physical network of neurons throughout the body, producing rapid responses

neurotransmitters

communicator of the nervous system that is broken down very fast and required for that type of intracellular communciation

endocrine system

integrates via chemical messengers secreted by endocrine cells which circulate in the blood to target tissues

endocrine system

system best for regulating metabolic processe

endocrine glands

ductless glands that release hormones directly into the bloodstream or surrounding tissue fluid to travel to targets

exocrine glands

glands that have ducts and secrete non-hormonal substances to body surfaces or into cavities (epithelial surfaces)

classical endocrine glands

anterior pituitary, thyroid, parathyroid, adrenal, and pineal glands

hormone

chemical messengers secreted by cells into extracellular fluids (blood)

target cells

tissues/cells which have a receptor specifically able to bind a particular hormone, can be in differing locations

classical endocrine signalling

endocrine cells secretes hormone via exocytosis, diffuses into the blood, circulates, and can effect distant target cells

paracrine signalling

paracrine cell secretes a chemical signal (called a paracrine) into extracellular fluid and diffuses to nearby target cell

autocrine signalling

chemical messeger secreted by a cell binds to a receptor on the same cell to regulate some function

types of signalling

endocrine, paracrine, and autocrine

hormone types

amino acid based and steriod hormones

amino acid based hormones

hormones that are water soluble and cannot pass through the plasma protein, built upon amino acids

steriod hormones

synthesized from cholesterol, all lipid soluble and can cross the plasma membrane, usually attached to a protein

cholesterol

material that steriod hormones are made from

tyrosine

amino acid derivation of catecholamines and thyroid hormone

lipid soluble hormones

the type of hormone that acts on receptors inside the cell to directly activate genes

steroid hormone types

gonadal hormones, glucocorticoids, mineralocorticoids

extracellular

amino acid based hormones have receptors located…

g protein

process that is used in signal transduction for all 2nd messenger systems

alpha subunit

where the gdp binds on the g protein in the inactive state

hormone

what associates with the g protein to change it into the active state

gamma and beta subunits

the subunits of the g protein that fall off due to the conformational change of gtp binding

hormone binds

1t step in g protein activation

receptor activates protein

2nd step in g protein acivation

gdp falls off

3rd step in g protein activation

beta and gamma subunits attach

4th step in g protein activation

gtp to gdp conversion

last step in g protein activation

cyclic AMP

the 2nd messenger in the cytoplasm, causes an inactivated protein kinase A to become active by ATP breakdown

phosphodiesterase

enzyme that degrade cAMP

1st step in cAMP messenger system

hormone binds to a receptor, acting as the 1st messenger

2nd step in cAMP messenger system

receptor activates g protein mechanism, and GDP is displaced by GTP

3rd step in cAMP messenger system

g protein activates adenylate cyclase by binding to it, which can inhibit or stimulate, which eventually becomes inactive again

4th step in cAMP messenger system

adenylase cyclase converts ATP to cAMP

5th step in cAMP messenger system

cAMP activates protein kinases by triggering a series of chemical reactions that may have different end effects

protein kinase

enzymes that phosphorylate proteins

2nd messenger

cAMP is what order of messenger?

2nd messenger

signal molecules that can amplify a signal by causing a cascade of reactions

amplification

2nd messengers have this effect on their signals, allowing 1st messengers to have effects at very low concentrations since they cause a cascade of reactions

PIP2-calcium signal mechanism

another g protein 2nd messenger system that uses phospholipase C and involves the release of 3rd messenger calcium ions

1st step in PIP2 calcium signal mechanism

hormone-receptor binding of 1st messenger and g protein activation of phospholipase C

2nd step in PIP2 calcium signal mechanism

activated phospholipase C splits membrane protein PIP2 into 2 secondary messengers, DAG and IP3

3rd step in PIP2 calcium signal mechanism

calcium ions act as another messenger in the signal cascade

2nd messengers of PIP2 calcium signal mechanism

DAG and IP3

diacyglycerol (DAG)

activates protein kinases, and stays in the membrane during PIP2 calcium signal mechanism

inositol triphosphate (IP3)

causes Ca2+ release from the ER and mitochondria, diffuses into the cytoplasm during PIP2 calcium signal mechanism

calcium ions

work as a third messenger during the PIP2 calcium signal mechanism

autophosphoylation

insulin and certain growth factors do this when their signal hormone binds

receptor tyrosine kinase

signal transduction via autophosphorylation triggered by the receptor

alpha and beta subunits

subunit parts of the receptor tyrosine kinase

alpha subunit

subunit of the receptor tyrosine kinase that is completely extracellular and has a ligand binding region for insulin

beta subunit

subunit part of receptor tyrosine kinase that is partially extracellular but has an intracellular region where RTK activity occurs

disulfide bridge

the mechanism that connects the RTK alpha and beta subunits

1st step in signal transduction by RTK

insulin binding intiates dimerization of the RTK

2nd step in signal transduction by RTK

dimerization activates tyrosine kinase activity in each monomer

3rd step in signal transduction by RTK

autophosphorylation occurs to the bound tyrosine proteins in the beta subunit, each serving as a docking station for other proteins

4th step in signal transduction by RTK

effector proteins are activated by docking with phosphotyrosine residues

5th step in signal transduction by RTK

glut-4 transporters are expressed and inserted into the plasma membrane for glucose transport so blood glucose can go down

steriod and thyroid hormones

hormone types that affect target cells intracellularly

intracellular binding

when steriods or TH go through this type of binding, the receptor-hormone complex goes to the nuclear chromatin and binds to a region of DNA

transcription of mRNA

when the receptor-hormone complex activates a section of DNA, this step is initiated

protein synthesis

this occurs once transcription of mRNA occurs from intracellular binding

ion channels, structural proteins, hormones

types of materials that can come from protein synthesis from intracellular activation

types of stimuli regulating endocrine secretion

humoral, neural, and hormonal stimuli

humoral stimuli

secretes hormones in response to changing blood levels of certain ions of nutrients, the simplest type

parathyroid hormone

hormone that uses humoral stimuli by monitoring Ca2+ blood levels

neural stimuli

nerves stimulate hormone release

epinephrine release

example of neural stimuli use by sympathetic NS

hormonal stimuli

release hormones in response to hormones from other endocrine organs

inhibitory and stimulator hypothalamus hormones

example of hormonal stimuli use which occurs in the anterior pituitary to stimulate other organs

insulin secretion and blood sugar regulation

negative feedback mechanism where when blood sugar rises, pancreas releases insulin to help body cells to abosrb glucose via glut-4 and reduce the levels, and if blood glucose is low insulin secretion decreases

lipid-soluble hormones

this type of hormone is permeable to the membrane but not water soluble

protein carrier

lipid soluble hormones are attached to this so that they can be more water soluble

rate of release and speed of removal

the factors that are reflected by the concentration of a circulating hormone

hypothalamus

part of the brain that regulates the autonomic NS, controlling BP, HR, the digestive tract, and pupil size

limbic system

one of the hypothalamus’ designations that controls strong emotions like fear

central relay system

refers to the hypothalamus’ role as the middle point between the body, sense organs, and brain input

anterior pituitary

the larger, pinker, more glandular lobe

ectoderm

during embryolical development, the anterior pituitary originates from this as it pushes down from the roof of the mouth towards the brain the form Rathke’s pouch where the sphenoid bone encircles it

sphenoid bone

the part of the skull that encircles the pituitary gland, begininng in embryological development

specialized glandular epithelial cells

the cells that make up the anterior pituitary gland

posterior pituitary

lobe composed of white, myelin covered neural tissue

3rd ventricle

during embryological development, the posterior pituitary forms from the hypothalamus pushing down and through this part of the brain but never fully separate

pituicytes

the specialized neural cells that make up the posterior pituitary

axon terminals

the part of hypothalamic nuclei that pituicytes tend to surround

portal system

2 capillary beds between veins and arteries

hypothalamic portal system

consists of the primary capillary plexus, hypophyseal portal veins, and the secondary capillary plexus

primary capillary plexus

1st part of the hypophyseal portal system, located in the hypothalamus, where the hypothalamic hormones are released

hypophyseal portal veins

2nd part of the hypophyseal portal system that transports hormones from the primary capillary plexus to the anterior pituitary

secondary capillary plexus

3rd part of the hypophyseal portal system in the anterior pituitary where hormones take effect

anterior pituitary

the hypophyseal portal system allows hypothalamic inhibitory/stimulatory hormones to reach this gland quickly and concentrated

hypothalamic-hypophyseal tract

neural connection in the posterior pituitary that originates in the paraventricular and supraoptic nuclei

neurohormones

messengers released by hypothalamic neurons in the hythalamic-hypophyseal tract into capillary beds