vphy 3100: chapter 11

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what two hormones does the thyroid gland produce?

T4 and T3- 90;10%

how is a steroid hormone transported through the blood and why?

carrier proteins; steroid hormones are hydrophobic so they are not soluble in water/blood plasma

epinephrine and norepinephrine are ___________ secreted by the adrenal medulla. they help the body cope with ________.

catecholamines; stress

steroid hormones are synthesized from __________ by the adrenal cortex and gonads. it is the precursor for ALL steroid hormones.

cholesterol

steroid hormones have _________ as a precursor and include...

cholesterol corticosteroids sex steroids

how do alpha and beta-adrenergic receptors help metabolic effect in hepatocytes/ liver cells?

- beta-adrenergic receptors bind w epinephrine, increase the cAMP concentration intracellularly, activate protein kinase A, glycogen converts to glucose and exits the cell - alpha-adrenergic receptors bind w epinephrine, increase the Ca2+ concentration intracellularly, Ca2+ binds w calmodulin, protein kinase C is activated, glycogen converts to glucose and exits the cell * now the blood-glucose level is much higher

what are the sympathoadrenal effects of the adrenal medulla relating to epinephrine?

- increased heart rate and increased contractility-> increased cardiac output - increased alertness and increased respiratory rate

process of oxytocin release in posterior pituitary

- suckling-> increase oxytocin release-> contraction of smooth muscle of mammary glands-> lactation - oxytocin also causes smooth muscle of uterine to contract during labor

anabolism: catabolism:

- the process of building up larger molecules from smaller ones - the process of breaking down large molecules into smaller ones

contractility: cardiac output:

- the strength and vigor of the hearts contraction during systole - the amount of blood the heart pumps through the circulatory system in a minute

why does the metabolic rate increase in the adrenal medulla?

- there in an increase in glycogenolysis in the liver which means an increase in blood glucose level; glycogenolysis is the conversion of glycogen to glucose - there is an increase of lipolysis in the adipose tissue which means an increase in blood fatty acid level

synergistic effect; 2 types; example

- two or more hormones work together to produce the same effect - additive: two hormones effect target in the same way; E and NE both increase heart rate - complementary: each hormone contributes a different piece of an overall outcome; milk production requires estrogen and prolactin to increase the production of milk and oxytocin to stimulate the ejection of milk

besides long-range signaling, what ways can cells communicate with each other?

1. direct contact 2. neurotransmission 3. local signaling (autocrine/paracrine)

insulin is the major hormone that promotes anabolism. when blood insulin increases...

1. increase in cellular uptake of glucose 2. increase in glycogenesis- increase in entry of glucose into liver and skeletal muscle cells-> increase in glycogen storage 3. increase in lipogenesis- increase triglyceride storage in adipose cells 4. increase cellular uptake of amino acids-> increases protein synthesis

activation of receptor tyrosine kinases (RTK)

1. insulin binds to receptor proteins 2. phosphophorylation of receptor-> actice tyrosine kinase 3. phosphophorylation of signal molecules-> cascade of effects-> glucose uptake of anabolic reactions

alpha cells in the islet of langerhans in the pancreas make up _______% and secrete _______.

25; glucagon

beta cells in the islet of langerhans in the pancreas make up _______% and secrete _______.

60; insulin

alpha-adrenergic receptors

G-coupled protein receptor; epinephrine binds to the alpha-adrenergic receptor increasing phospholipase C increasing Ca2+ concentration intracellularly causing many biochemical reactions

beta-adrenergic receptors

G-coupled protein receptor; epinephrine binds to the beta-adrenergic receptor increasing the cAMP concentration intracellularly causing many biochemical reactions

example of pulsatile secretion

GnRH is released in spurts every 1-2 hours; if it was administered continuously, its response at the pituitary gland would be decreased to the baseline level

what is the thyroid gland stimulated by?

TSH thyroid stimulating hormone from anterior pituitary

neuroendocrine signaling

a neuron secretes a hormone which goes directly into the blood circulation instead of through synapse; hormones are secreted from the nerve terminal of a neuron and go directly into blood to the target cells

post absorptive state

absorption of nutrients from the GI tract is complete, and energy needs must be met by fuels already in the body; there will be a drop or decrease of plasma glucose level, plasma amino acid level, and fatty acid level - increase glucagon secretion-> increase glycogenolysis-> increase blood glucose

response to adrenal cortex secreting glucocorticoids

adrenal cortex secrete glucocorticoids such as cortisol which has a catabolic effect; there is an increase in gluconeogenesis and decrease in the utilization of glucose in the tissues which increase blood glucose so brain neurons and skeletal muscle can use it - increases lipolysis which increases blood fatty acid level - immune suppresion and anti-inflammation

response to the adrenal cortex secreting mineralocorticoids

adrenal cortex secrete mineralocorticoid such as aldosterone which increases renal absorption of Na+ and H2O and K+ excretion; this increases the blood volume and pressure which balances electrolytes

hydrophobic hormones; examples

aka lipophilic hormones; interact with intracellular receptors at target tissue; steroid hormones and thyroid hormones

what are the three classifications of hormones by chemical structures?

amino acid derivatives peptides and proteins steroids

insulin is a _________ hormone, while glucagon is a _________ hormone.

anabolic; catabolic

the pituitary gland is separated into... functions?

anterior pituitary gland (adrenohypophysis): hormonal regulation by the hypothalamus posterior pituitary gland (neurohypophysis): neural extension of the hypothalamus; receives action potentials from the hypothalamus to control the release of hormones from nerve endings

water soluble hormone receptors... and include

are on the plasma membrane; enzyme-linked receptors and G-coupled-protein receptors

what are the two local signaling options?

autocrine signaling: same cell; cell secretion binds to the same type of cells and exerts its biochemical reaction paracrine signaling: has effect on neighboring cell which happens through diffusion

what is the long range, endocrine signaling characteristics?

blood-borne: hormones are transported by blood; relies on diffusion to transport hormones to nearby capillaries, which carry the hormone to the systemic circulation ductless: does not need specific ducts for transport

lipophilic hormones travel to target cells attached to ________.

carrier proteins

how are steroid hormones synthesized?

cholesterol-> pregnenolone-> progesterone

What hormones does the adrenal cortex secrete?

corticosteroids 1. mineralocorticoids 2. glucocorticoids 3. sex steroids

downregulation

decrease in receptor number in response to high concentration of hormone

the hypothalamus is a part of the _____________; it is located under the ___________; it is connected to the pituitary glands by the ___________.

diencephalon; thalamus; hypothalamus/pituitary axis (HPA)

a person has a meal, starts digestion, and starts absorption 4 hours after eating. what happens generally in the absorptive state?

digested food-> monosaccharide-> amino acids-> fatty acid-> absorbed-> transported in the blood

amino acids hormones include...

epinephrine and norepinephrine thyroid hormones melatonin

the adrenal medulla secretes what two hormones directly into the blood stream, and the adrenal medulla is stimulated by what nervous system?

epinephrine mainly and some norepinephrine; sympathetic

what are the long range signaling types?

exocrine signaling endocrine signaling (blood-borne/ductless) neuroendocrine signaling

the pancreas functions in what two ways...

exocrine: secretion requires specific ducts endocrine: secretion is blood borne and ductless

what structure in the thyroid gland secretes T4 and T3?

follicle cells

how do cells communicate via direct contact?

gap junctions: signal goes from one cell to the next through gap junctions

endocrine glands

glands that secrete hormones directly into the bloodstream

referring to insulin as an anabolic hormone, insulin helps the entry of ____________ from blood circulation into the cell.

glucose, fatty acid, and amino acids

insulin effect

high blood glucose levels-> increase secretion of insulin-> insulin receptor activation at target tissues-> increase insertion of glucose transporters GLUT4 to cell membrane of insulin-sensitive cells

what are the 3 characteristics for hormone receptor interactions?

high specificity: bind to very few types of hormones high affinity: binding has to be firm low capacity/saturation: # of receptors on target tissue is limited

how does the body avoid desensitization?

hormones are released in spurts called pulsatile secretion

what is the process of hormones getting transported from the cells in the hypothalamus to the capillary network in the anterior pituitary gland?

hormones go through a portal system; hypothalamic nerve endings secrete hormones into the blood A capillary/venule system known as the hypothalamo-hypophyseal portal system; hormones will be released by the cells travel down the axons to the primary capillary network-> go through the portal vessels-> enter the secondary capillary network-> release into blood circulation

antagonistic effect; example

hormones work in opposite directions; insulin decreases the blood glucose level while glucagon increases the blood glucose level; they work antagonistically to regulate the blood-glucose level

what are the two classifications of hormones by physical properties?

hydrophilic hydrophobic

peptide and protein hormones include...

hypothalamic and pituitary hormones insulin and glucagon parathyroid hormones

neuroendocrine reflex

hypothalamic neurons are stimulated-> nerve endings in posterior pituitary release ADH and oxytocin into capillaries into blood circulation

process of ADH release in posterior pituitary

increase blood osmolality-> increase ADH secretions-> increase insertions of aquaporins in kidneys-> increase water absorption/retention

absorptive state

increase in blood glucose and amino acid levels increase in insulin secretion

upregulation

increase in receptor number in response to low concentration of hormone

what structure connects the hypothalamus to the pituitary glands?

infundibulum

hydrophilic hormones; examples

interact with cell-surface receptors at target tissues; all peptide and protein hormones, epinephrine, and norepinephrine

the pancreas has little white dots on it called the ______________ and it contains what types of cells?

islet of langerhans; alpha, beta, and delta

importance of the hypothalamus/pituitary axis (HPA)

it is the master control of the endocrine system and integrates the neuro and endocrine/hormonal systems

how does a hydrophilic hormone have an effect on its target tissue?

it must bind to receptors on the cell membrane instead of in the cytosol

the adrenal gland is located on top of the _________, and it contains two components.....

kidneys; adrenal medulla and adrenal cortex

in order for a target cell to respond to a hormone, a hormone needs to be secreted above a certain _______.

level

the target tissues for pancreatic hormones is...

liver cells, skeletal muscle cells, and adipose cells

humans are ________ organisms, and their cells need to communicate with eachother.

multi-cellular

the release of hormones in the posterior pituitary is controlled by _______.

neuroendocrine reflexes

example of neuroendocrine signaling

neuron-> nerve terminal-> diffuse hormones-> blood circulation-> pituitary gland aka target cell

thyroid gland location; size; contain; secrete

on the trachea close to pharynx largest endocrine gland in the body follicles-> follicle cells-> colloid-> mucoprotein thyroid hormones

permissive effect; example

one hormone makes target cell more responsive to a second hormone; exposure to estrogen makes the uterus more responsive to progesterone

before hormones become bioactive hormones, they begin as __________ aka __________-> __________-> ____________.

prehormones preprohormones prohormones bioactive hormones

lipophilic hormone receptors are... and include

present in the cytoplasm or nucleus; intracellular receptors

hydrophobic hormones- pros/ cons

pros: - easily penetrates the hydrophobic lipid bilayer of the cell membrane of the target tissue; easy to reach the receptors in the cytosol/nucleus cons: - it is difficult to be transported through the blood plasma because the blood plasma is hydrophilic because it is water; it has to have special carrier proteins to be transported through the blood circulation

hydrophilic hormone- pros/cons

pros: - easy for them to be transported through the blood circulation because they are soluble in blood plasma which is water cons: - difficult for them to have an effect on the target tissue because of the cell membranes hydrophobic lipid bilayer

referring to glucagon as a catabolic hormone, glucagon converts...

proteins back to amino acids neutral fats back to fatty acids/monoglycerides glycogen back to glucose

what is the receptor for insulin called?

receptor tyrosine kinases (RTK); the most prevalent enzyme-linked cell surface receptor

in order for hormones to have an effect, target cells must contain specific __________.

receptors

general function of pancreatic hormones

regulate blood-glucose levels and influence cellular metabolism

general functions of the endocrine system

regulate body metabolism, growth, and reproduction

function of thyroid gland

regulates metabolism rate, growth, and development

the hypothalamus produces what two types of hormones?

releasing and inhibiting

endocrine tissue

secrete hormones into the bloodstream

if blood glucose level is low, what will alpha cells do?

secrete more glucagon

if blood glucose level is high, what will beta cells do?

secrete more insulin

a target cell is usually responsive to ______ ________ hormones and therefore contains different types of _______ _________.

several different; hormonal receptors

what are the insulin sensitive cells?

skeletal muscle cells, adipocytes, and cardiac cells

delta cells in the islet of langerhans in the pancreas secrete __________.

somatostatin

what is the genomic mechanism in steroid hormones?

steroid hormone is carried through blood by carrier proteins, goes through the lipid bilayer since it is lipophilic, binds to ligand-binding domain, moves into nucleus, DNA binds to DNA-binding domain, receptor dimerizes, steroid hormone binds to hormone response element on the DNA, then transcription occurs

what are the two nuclei in the hypothalamus that are related to the posterior pituitary gland and what hormones do they release?

supraoptic nuceli; paraventricular nuclei; antidiuretic (ADH); oxytocin

how do cells communicate via neurotransmission?

synapse or neuromuscular junction; presynaptic neurons send signal to postsynaptic/target cell which can be a muscle or neuron; if the target cell is a muscle cell, the synapse will be via neuromuscular junction

what are the 3 types of effects hormones can have on target cells?

synergistic effects (additive/complementary) permissive effects antagonistic effects

desensitization

target cells become less sensitive to the stimulation of a hormone

sensitization

target cells become more sensitive to the stimulation of a hormone

what is the long range signaling via endocrine signaling?

the chemical being secreted is HORMONES

catabolic effect

the destructive metabolism (breakdown) of muscle tissue and other compounds in the body

lipogenesis: glycogenolysis

the metabolic formation of fat breakdown of glycogen to glucose

what happens if hormone levels are high for a prolonged period of time? what does it ultimately lead to?

the number of receptors decrease which decreases the responsiveness in the target tissue; desensitization or downregulation

what happens if hormone levels are low? what does it ultimately lead to?

the number of receptors increase which increases the responsiveness in the target tissue; sensitization or upregulation

endocrinology

the study of endocrine glands/ tissues, the hormones they release, and their effects on target tissue

what is the long range signaling via exocrine signaling?

there must be a duct to transport signals or chemicals

how does ADH and oxytocin hormones produced in the supraoptic and paraventricular nuclei get transported to the posterior pituitary gland?

they are transported down the hypothalamo-hypophyseal tract

sex steroids secreted by the adrenal cortex are considered....

weak androgens (male sex hormones)


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