endocrine system (top hat)

what are the characteristics of an endocrine cell?

secretes hormones into the blood

can be a neuron

is found as a part of organs like the heart

is found within endocrine organs

what are the properties if a hormone?

variety in chemical structure

regulation of a wide range of physiological processes

binding to receptors on target cells

release in response to changes in homeostasis

what is an autocrine effect?

a cell may release a chemical messenger onto itself

what is an paracrine effect?

a cell may release into the interstitial fluid onto neighbors

what is an example of a cel that can act as a neurotransmitter and hormone

Norepinephrine

what are amine hormones and examples?

produced from single amino acids such as tryptophan or tyrosine

what are peptide hormones?

chains up to 40 amino acids

ex- adrenocorticotropic hormone

what are protein hormones?

chains greater that 40 amino acids

ex- insulin

what are steroid hormones?

derivatives of cholesterol

ex- cortisol

what is a down-regulation cell

when a target cell remove receptors from its plasma membrane

what is up-regulation?

receptor expression for a hormone is increased, makes the cell more sensitive to that hormone

what is permissiveness?

process of hormones regulating the expression of receptors for other hormones

what are hormone target cells?

found throughout the body

express a receptors for that hormone

convert info carried in the hormone structure into cellular signal

play key roles in the regulation of physiological process

what is hormone release regulated by and what is neurotransmitter release regulated by?

amplitude : frequency

how is insulin synthesized?

gene transcrpt

what is ACTH synthesized?

gene transcript

what is epinephrine synthesized by?

enzymatic synthesis

what is steroids synthesized by?

enzymatic synthesis

hormone are released in response to?

other hormones

changes in physiological systems

blood levels of key components

nervous system regulation

what are examples of water soluble hormones?

proteins and peptides

where are water soluble hormones usually transported?

in the plasma

what are examples of lipid soluble hormones?

steroids and thyroxine

where are lipid soluble hormones usually transported?

blood complex with transport proteins

complex to carrier proteins

which hormone pool is capable of interacting with target cells?

free hormone pool

what does an at home pregnancy test measure?

amount of human chorionic gonadotropin hormone (hCG) in the urine

what are hormones can be considered bound and free?

lipid soluble hormones ( 1% free and 99% bound)

what is half life altered by?

synthesis, secretion , metabolism, and excretion of the hormone

the t 1/2 of a lipid soluble hormone would be increased by?

decreased metabolism

peptide and protein hormones can be degraded by?

proteases from the liver and the kidney

what two chemical groups make steroid hormones much more soluble?

sulfation or glucuronidation

how can steroids be rendered inactive?

by addition or removal of chemical groups

what are common features of receptors

proteins found in cell membrane, cytoplasm or nucleus

change shape when bound to nucleus

interact with other proteins inside the cell, and by changing shape ca activate signal cascades that alter cell function

what are the 3 main types of hormone receptors?

seven- transmitter spanning G protein coupled receptors (GPCRs)

One transmembrane spanning receptors (1-TMS)

Cytosolic or nuclear receptors (NR)

where are the 3 main hormone receptors found?

NR- inside cell

1-TMS/ GPCRs- located on plasma membrane

what happens when drugs mimic hormones are used clinically?

have side affects that are not physiological and are known as pharmacologic effects.

what is an agonist?

compound that can bind to a hormone receptor and produce the same effects as the hormone

what is an antagonist?

compound that binds the receptors and block signal transduction

what does the intracellular portion of GPCR interact with?

GTP- binding proteins

what do G- proteins consist of?

a-, b- ,and y- subunits

what is Ga(s)

activates adenylate cyclase (AC) which converts into ATP into 3’ and 5’ cAMP

what is Ga(i)

inhibits adenylate cyclase and block production of cAMP

what is Ga(q)

activate PLC which breakdown phosphatidylinositol

what does cAMP act as to activate?

protein kinase A (PKA, left) within the cell

degraded by phosphodiesterase (PDE)

what doe kinases activate?

activate or inhibit other proteins by transferring a phosphate from ATP to a serine or threonine residue on a target protein

why is PDE important?

responsible for “turning off” signaling cascades

(most active when Ga(s) coupled receptors are not being stimulated or when adenyl cyclase is inhibited flowing activation of Ga(i) receptor

what does IP(3) bind to and cause?

binds to endoplasmic reticulum causing Ca2+ to be released

what activated Protein kinase c (PKC)

breakdown of IP(2), DAG, which phosphorylates proteins

what can cAMP do through protein kinase A

produce short term effects on channel functions, regulate gene expression

in liver cells it regulates enzymatic activities for gluclose metabolism

what is insulins transduction pathway?

1-TMS

what is steroids transduction pathway?

nuclear or cytosolic receptor

what is epinephrine transduction pathway?

GPCR

what is the growth hormone transduction pathway?

PTKase

what is the mechanism of action for insulin like growth factor (IGF-I) involve ?

phosphorylation of a tyrosine residue

where are nuclear receptors found and regulate ?

inside the cell that acts as transcription factors , regulate gene transcription

what do neuron receptors bind to?

steroids, thyroxine, and other liglands, and regulate gene expression

hormones that bind to trans membrane spanning receptors signal the cell inferior through effects on?

adenylate cyclase

what is the anatomy of the hypothalamus

inferior to thalamus

forms ventral portion of diencephalon

contain infundibulum which connects hypothalamus to anterior and posterior pituitary

what is the anatomy of the pituitary?

superior portion is the median eminence

hypophyseal portal system is blood vessels that connects hypothalamus to anterior pituitary

which capillary bed provide blood to the pituitary?

primary capillary plexus- provides blood to median eminence

primary capillary bed- through hypophyseal portal veins into secondary capillary bed (in anterior pituitary)

secondary capillary bed-drains into veins that carry blood into rest of the body

what are the hypothalamic hormones?

thyrotropin releasing hormone (TRH)

corticotropin releasing hormone (CRH)

growth hormone releasing hormone (GHRH)

gonadotrophin releasing hormone (GnRH0

prolactin inhibitory hormone (PIH/ dopamine)

growth hormone inhibitory hormone (GIRH, somatostatin)

what is the pituitary composed of?

anterior, intermediate, and posterior lobes

what is the anatomy if the anterior pituitary?

arises embryonically from an outpocketing of the roof of the embryonic oral cavity (Rathke’s pouch)

contains somatropes that secrete GH, thyrotropes that secrete TSH, corticotropes that secrete ACTH and ß-endorphin lactropes that secrete prolactin and gonadotropes that secrete FSH and LH

what is the anatomy of the posterior pituitary?

arises embryonically from the hypothalamus and secretes ADH and oxytocin

how does the growth hormone from the anterior pituitary is released

under regulation of the hypothalamic GHRH and GHIH

a genetic mutation leading to the loss of phosholipase C activity would affect signaling by which of the hormone

TRH

loss of GHRH would have which of the following effects?

decreased blood glucose (hypoglycemia)

what is TRH?

a tripeptide hormone that binds to a Gq coupled GPCR in anterior pituitary cells, stimulating TSH release

what is TSH secretion inhibited by?

increased thyroxine blood levels through a negative feedback loop

TSH release is stimulated by

TRH

the thyroid produces?

thyroxine and calcitonin

where is the thyroid gland found and its anatomy?

lateral to upper trachea and lateral to the larynx

and made up of two lobes of narrow band tissue called isthmus

what is the lumen of each folicule in the thyroid filled with?

a large protein called thyroglobulin

what does the thyroglobulin peptide chain contain?

many tyrosine amino acids that act as a substrate for the synthesis of thyroxine

what are parafollicular cells?

secrete hormone calcitonin and are scattered between follicles

thyroxine is synthesized as part of ….. and contains…….

thyroglobulin and iodine

what some of the effects of thyroxine

cell differentiation, growth and metabolism

tachycardia( increased heart rate)

increased respiration

increased Na+ and / K+ -ATP activity

calcitonin acts to?

decrease blood calcium

what is the anatomy of the parathyroid gland?

contain fours parathyroid gland, 2 in each thyroid gland

mainly secretes parathyroid hormone PTH

densely- packed with chief cells and oxyphil cells

what are some effects of parathyroid hormone throughout the body?

high concentraion of bone

increased calcitriol in kidney

increased calcium reabsorption in intestine

what are chief cells?

located in parathyroid gland which secrte PTH

PTH hormone is released in response to?

hypocalcemia

what is the anatomy of adrenal glands?

embedded in adipose tissue in the superior regions of the kidney

composed of endocrine and nervous tissue

organized into zones which are structurally and functionally distinct

steroids are produced by ?

enzymatic conversion of cholesterol?

what are 3 zones of the adrenal gland

zona glomerulosa

zona fasciculata

zona reticularis

what is the hormone and features of the zona reticularis?

androgen precursors

convered to androgen, effects testis and ovaries

what are the hormones and the features of zona fasciculata?

glucocorticoids

hyperglycemia, immunisuppression

increase lipolysis and decreased gluclose uptake in skeletal muscle

what are the hormones and features of the zona glomerulosa?

mineralocorticoids

aldosterone: increased Na+ resorption, and increased renal K+ excretion

what is the steroid that matches with aldosterone?

Na+ retention

what is the steroid that matches with cortisol?

hyperglycemia

what is the steroid that matches with the estrogen?

sex steroid

what is the steroid that matches with the androgen precursor?

sex steroid

what is the effect of cortisol?

hyperglycemia

immune suppression

glucose sparing

lipolysis

what does the zona reticularis produce?

androstenediol and dehydroepiandosterone (DHEA)

where is the adipose tissue located and what is it made up of?

found under skin, around organs, in bone marrow, and in muscle and breast tissue

composed predominantly of adipocytes along with fibroblast, macrophages and endothelial cells

what hormones does the pituitary tissue produce?

leptin, adiponectin, and resistin

what are the main hormone functions of the adipose tissue?

regulating body metabolism, weight , reproductive function and inflammation

where does the pancreas lay?

beneath greater curvative of the stomach and small intestine

clusters of endocrine cells are scattered through out

what hormones does the pancreas produce?

insulin and glucagon

insulins effects in target cells are

to increase lipolysis

the primary physiological effect of insulin secretion is?

to decrease blood glucose content