Endocrine system physiology pt 1

what method of communication does the endocrine system use?

ductless w/ chemical signaling through hormone secretion into extracellular fluid by bloodstream transportation & binding to receptors on target cells

why does endocrine signalling take more time than neural signaling?

the precise amt of time varies w/ diff hormones in order to induce a characteristic response

how is endocrine signaling less specific than neural signaling?

the same hormone may play a role in a variety of diff physiological processes depending on the target cells involved

what is autocrine signaling?

a chemical that elicits a response in the same cell that secreted it \[takes place w/in the same cell\]

what is paracrine?

a chemical that induces a response in neighboring cell, but their concentration is generally too low to elicit a response from distant tissues

what is an example of a paracrine chemical?

histamine which is released by immune cells in brochial tree & causes the smooth muscle brochi cells to contrict & narrow the airways

what is the role of thyroid-stimulating hormone?

stimulates thyroid hormone \[thyrotropin\] release

what is the role of testosterone?

stimulates development of male sex characteristics \[deeper voice, increased muscle mass, development of body hair, sperm production\]

what is the role of progesterone?

stimulates development of female sex characteristics; adipose & breast tissue development, menstrural cycle, & prepare for the body for childbirth

what hormone chemical classes are derived from amino acids & which from lipids?

amino acids \[amines, peptides, proteins\] & lipids \[steroids\]

what does a chemical group of a hormone determine?

hormone distribution, type of receptors it binds to, & other aspects of its function

what are the characteristics of amine hormones?

synthesized from an amino acid, either tryptophan \[melatonin\] or tyrosine \[catecholamines/metabolism-regulating hormones {epinephrine, norepinephrine, dopamine}\]

what is the role of dopamine?

secreted by hypothalamus & inhibits release of certain anterior pituitary hormones

what are the characteristics of peptide & protein hormones?

synthesized by multiple amino acids making a chain \[short amino acid peptide chains, long protein polypeptide chains\]

what is the role of the antidiuretic hormone in the heart?

atrial-natriuretic peptide is produced by the heart to help decrease blood pressure/volume & sodium ion concentration

what are the characteristics of the steroid hormones?

derived from cholesterol & hydrophobic, so they must travel to their target cell bound to a transport protein

what is the role of hormone receptors?

located in or w/in cell membrane & processes message by initiating other signaling events or cellular mechanisms that result in target cell’s response

what is the 1st step of lipid-soluble hormone binding?

lipid-soluble hormone \[steroid\] diffuses through the plasma membrane

what is the 2nd step of lipid-soluble hormone binding?

hormone binds to its receptor in the cytosol/cytoplasm & forms a receptor-hormone complex

what is the 3rd step of lipid-soluble hormone binding?

the receptor-hormone complex enters the nucleus & triggers gene transcription by binding to the target gene on the DNA

what is the 4th step of lipid-soluble hormone binding?

transcription of the gene creates a messenger RNA that is translated into the desired proteins w/in the cytoplasmto alter cell activity

what is the 1st step of water-soluble hormone binding w/ cAMP?

water-soluble hormone \[insulin\] binds to a membrane receptor & activates the G protein which activates adenylyl/adenylate cyclase

what is the 2nd step of water-soluble hormone binding?

adenylyl/adenylate cyclase catalyzes the conversion of ATP to the secondary messenger \[cAMP\]

what is the 3rd step of water-soluble hormone binding?

cAMP activates the enyzme protein kinases which phosphorylate proteins in the cytoplasm

what is the 4th step of water-soluble hormone binding?

activated protein kinases initiate a phosphorylation cascade which activates proteins in the cell that carry out the changes specified by the hormone

what are the factors that vary the effect of water-soluble hormone binding?

type of target cell, G proteins & kinases involved, & phosphrylation of proteins

what are the factors that make sure the duration of a hormone signal is short?

phosphodiesterase \[PDE\] in the cytosol & growth inhibiting hormone \[somatosatin\] deactivates cAMP

what is the 1st step of water-soluble hormone binding w/ calcium ions?

water-soluble hormone binds to a membrane receptor & activates the G protein which activates the enzyme phospholipase

what is the 2nd step of water-soluble hormone binding w/ calcium ions?

phospholipase cleaves a membrane-bound phospholipid into diacylglycerol \[DAG\] & inositol triphosphate \[IP3\]

what is the 3rd step of water-soluble hormone binding w/ calcium ions?

diacylglycerol activates protein kinases to initiate a phosphorylation cascade & inositol triphosphate releases calcium ions from storage sites w/in the cytosol to act as second messengers

what is the 4th step of water-soluble hormone binding w/ calcium ions?

calcium binds w/ the protein calmodulin which modulates protein kinases w/in the cell

how do calcium ions act as second messengers?

influence enzymatic & other cellular activities directly or they bind to calcium-binding proteins \[calmodulin\]

what are hormones that uses calcium ions as second messengers?

angiotensin ii \[regulates blood pressure through vasoconstriction\] & growth hormone-releasing hormone \[ causes pituitary gland to release hormones

what is downregulation?

significant lvl of a hormones circulating the bloodstream causes its target cells to decrease their number of receptors for that hormone & cells become less reactive to excessive hormone lvls

what is upregulation?

lvl of hormone is chronically reduced & target cells increase their number of receptors which allow cells to be more sensitive to the hormones present

what is the permissive effect?

presence of 1 hormone enables another hormone to act as seen w/ the relationship between thyroid hormone \[iodine\] w/ reproductive hormone/system devleopment & functioning

what is the synergistic effect?

2 hormones w/ similar effects produce an amplified response as seen w/ follicle-stimulating hormone from pituitary gland & estrogen from ovaries for maturation of ova \[egg cells\]

what is the antagonistic effect?

2 hormones have opposing effects as seen w/ insulin & glucagon in blood glucose lvls

what is an example of positive feedback loop in endocrine system?

release of oxytocin during childbirth making the uterine muscles contract & stretch which induces the pituitary gland to release more oxytocin & intensify labor contractions

what is an example of a negative feedback loop in endocrine system?

the release of adrenal glucocorticoids is stimulated by the release of hypothalamus & pituitary gland hormones; signaling is inhibited when glucocorticoid lvls become elevated by causing negative signals to the pituitary gland & hypothalamus

what is the role of endocrine gland stimuli?

humoral stimuli are changes in blood lvls of non-hormone chemicals \[nutrients/ions\] that cause that release/inhibition of a hormone to maintain homeostasis

what is the result of the fight or flight response?

the dilation of blood vessels, increase in heart & respiratory rate, & suppression of the digestive & immune systems boost the body’s transport of oxygen to the brain & muscles to improve the body’s ability to fight or flee

what are the components of the hypothalamus-pituitarty complex from superior to inferior?

thalamus, hypothalamus, infundibulum, anterior & posterior pituitary lobes \[secretes diff hormones in response to signals from hypothalamus\]

what are osmoreceptors?

specialized cells w/in hypothalamus that re sensitive to the concentration of sodium ions & other solutes to monitor blood osmolarity

what is the relationship between blood osmolarity & postierior pituitary antidiuretic hormone release?

decrease in blood osmolarity results in a decrease of ADH secretion & less water reabsorbed; increase in blood osmolarity results in increase of ADH secretion & water reabsobtion

what are the regions of the anterior pituitary from most anterior to posterior?

pars distalis, pars intermedia, pars tuberalis

what are some of the processes the growth hormone takes part in?

stimulates lipolysis, diabetogenic effect, growth/protein synthesis

what is lipolysis?

glucose-sparing effect, breakdown of adipose tissue, releasing fatty acids into blood & causes less glucose to be taken up from the bloodstream.

what are the glands of the endocrine system?

pituitary, thyroid, parathyorid, pineal, adrenal cortex/medulla, pancreas, testes, ovaries

what are the organs that contain endocrine cells?

hypothalamus, thymus, heart, kidneys, stomach, small intestine, liver, skin, ovaries & testes, & adipose tissue

what are hormones?

the messengers of the endocrine system that elicit a response from target cells & plays a role in regulation of physiological processes \[reproduction, growth, development, metabolism, fluid, electrolyte balance, sleep\]

what are the 2 types of messengers of the endocrine system?

lipid soluble & water soluble

what are lipid soluble messengers?

3 hydrophobic groups of hormones \[steroid, thyroid, gas\]

what is the role of steroids of the adrenal cortex?

regulation of long-term stress response, blood pressure & volume, nutrient uptake & storage, fluid & electrolyte balance, & inflammation

what are the steroids of the kidneys?

calcitriol

what are the steroids of the testes & ovaries?

testosterone; estrogens & progesterone

what are the hormones of the thyroid gland/follicular cells?

T3\[triiodothyronine\] & T4 \[thyroxine\]

what are the gas hormones that endothelial cells line blood vessels with?

nitric oxide

what are the 3 types of water soluble messengers?

amines, peptides/proteins, eicosanoids

what are the amines \[derived from amino acid tyrosine\] in the adrenal medulla which stimulate fight or flight neural stimuli response?

epinephrine/adrenaline & norepinephrine/noradrenaline; produced by chromaffin cells

what are the amines in the mast cells in connective tissues?

histamine

what are the amines in the blood platelets?

serotonin

what is the role of peptides/proteins in the hypothalamus?

hypothalamic releasing & inhibiting hormones usually to control a variety of pituitary hormones

what are the hormones in the posterior pituitary?

oxytocin & antidiuretic hormones; does not produce hormones, but stores/releases into the blood via capillary plexus

what are the peptide/protein hormones in the anterior pituitary?

growth, thyroid-stimulating, adrenocorticotropic, follicle stimulating, luteinizing, prolactin, melanocyte-stimulating

what are the proteins in the pancreas?

insulin & glucagon

what are the peptide hormones in the parathyroid glands?

parathyroid hormone

what is the amine & peptide hormone in the thyroid gland?

follicular cells - thyroxine \[T4\] & triiodothyronine \[T3\]; parafollicular cells - calcitonin

what are the peptides/proteins in the gastrointenstinal tract?

gastrin, secretin, cholecystokinin, glucose-dependent insulinotropic peptide, glucagon-like peptide

what are the peptides/proteins in the kidneys?

erythropoietin, renin, calcitriol

what are the peptides/proteins in the adipose tissue?

leptin & adiponectin

what are the eicosanoids in all cells \[but rbc\]?

prostaglandins & leukotrienes

what is the action pathway of lipid-soluble hormones?

steroid hormone, plasma membrane, cytosol, nucleus, nuclear receptors, hormone-receptor complex, positive or negative to mRNA, cytosol, protein

what is the transcriptional activation in lipid-soluble hormone action?

the hormone receptor complex binds turns on or off RNA synthesis

what is the action pathway of water-soluble hormones?

non-steroid hormone, cell-surface receptor on plasma membrane, adenylate cyclase \[ATP\], cAMP, activates kinases that phosphorylate proteins

what is a characteristic in water-soluble hormone binding that is different from lipid-soluble?

hydrophilic & cannot diffuse through the lipid bilayer of the cell membrane, so it passes the message through a receptor on the membrane surface

what is the secondary messenger in water-soluble hormone action?

cyclic adenosine monophosphate \[cAMP\] &/or calcium ions

what are the major endocrine organs in the head & neck?

pineal glands, hypothalamus, pituitary gland, thyroid gland, parathyroid gland

what are the major endocrine organs in the trunk?

thymus \[between the lungs\], adrenal glands \[on top of kidneys\], pancreas \[posterior to bottom half of the stomach\]

what are the major endocrine organs in the bottom?

ovaries & testes

what are some of the effects of hormones?

growth, development, metabolism, energy, glucose/calcium/sodium balance, coping w/ stress, reproduction

what are the 3 regulations of hormonal secretion?

hormonal, humoral, neural

what is the hypothalamus-pituitary complex \[command center hormonal regulation\]?

hypothalamus delivers neurotransmitters to anterior pituitary to make thyroid, adrenal, & gonad hormones \[hormones that directly produce responses in target cells, regulate synthesis & secretion of hormones in other glands, coordinates messages between endocrine & nervous systems\]

what is humoral regulation?

control by levels of ions & nutrients in blood where low calcium in the blood stimulates parathyroid glands to secrete parathyroid hormone

what is neural regulation?

the nervous system’s control of the secretion of epinephrine & norepinephrine by the adrenal glands

what is negative feedback in the endocrine system?

glucagon \[glucose/blood sugar\] & insulin in blood glucose levels

what occurs to the blood glucose level after a meal?

causes high levels resulting in the activation of beta cells of the pancreatic \[langerhans\] islets to secrete insulin into the blood stream so that cells can uptake glucose

what occurs to the blood glucose levels after starvation?

causes low levels resulting in the activation of alpha cells \[glucagon\] of the pancreatic islets to secrete glucagon into the bloodstream so the liver can break down glycogen into glucose

what are the glycoprotein hormones of the pituitary glands?

growth hormone \[reg protein\], thyroid-stimulating hormone, follicle-stimulating hormone

what is the role of the master endocrine gland \[anterior pituitary\]?

manufacture & release of hormones from the hypothalamus \[that turn on/off functions of other endocrine glands\] & are secreted through the hypophyseal portal system circulation

what is the role of the growth hormone \[somatotropin\]?

anabolic; promotes growth of the body tissues in bones/muscles through release of growth hormone-releasing hormone & inhibition of growth hormone

what is the role of prolactin?

promotes milk production in the mammary glands

what is the role of the follicle-stimulating & luteinizing hormone?

gonadotropin glycoprotein hormones of the testes & ovaries that stimulates gamete \[egg & sperm\] production & stimulates androgen production by gonads

what are the steroid hormones of the adrenal cortex?

cortex \[aldosterone, cortisol, corticosterone, cortisone\] & medulla \[epinephrine & norepinephrine\]

what is the hormone of the thyroid?

thyrotropic hormone

what is the hormone of the liver?

somatotropin

what are the hormones produced by the hypothalamus?

somatotropin, thyrotropin, follicle-stimulating hormone, luteinizing hormone, prolactin, corticotropin, melanocyte-stimulating hormone

what is the diabetogenic effect?

growth hormone stimulates liver to break down glucogen to glucose & is deposited into blood & causes blood glucose lvls to rise

what is the role of thyrotropin?

stimulates synthesis & secretion of thyroid hormones

what is the role of follicle-stimulating hormone in females?

stimulates development of oocytes & induces ovarian secretion of estrogens