vphy 3100: chapter 11
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)