L12/L13 Flashcards
ADH stimulates release of _____
ACTH
describe a sandwich ELISA
coat wells of plate with primary (capture) antibody.
antigen binds to primary antibody.
secondary (detection) antibody, which is attached to an enzyme, binds to the antigen. this forms a sandwich around the antigen.
a substrate is added which the enzyme converts into a colored compound.
the amount of product (color) is proportional to the amount of antigen present.
advantages of monoclonal and polyclonal antibodies
monoclonal - high specificity and consistency. unlimited supply after cell line is established.
polyclonal - broad antigen recognition. high sensitivity. inexpensive to produce.
explain radioimmunoassay (RIA)
Radioactive ligand and unlabeled ligand compete for same antibody. Competition is basis for quantitation.
what is immunoprecipitation?
binding of antibodies to the protein of interest and then isolating the antibody-bound complexes through selection for the antibody
advantages and disadvantages of RIA
advantages:
extremely sensitive, can process large numbers of samples, quantifiable, easily automated.
disadvantages:
can’t determine if hormone measured has biological activity, also must get rid of radioactive material.
explain direct ELISA
the unknown sample with the antigen of interest is adhered directly to the well, followed by detection with a primary antibody
explain indirect ELISA
the unknown sample with the antigen of interest is adhered directly to the well. a primary antibody binds to it. then a secondary antibody binds to the primary one for detection.
explain competitive ELISA
The sample containing the target antigen is added to the plate.
A labeled version of the antigen is also added, competing with the unlabeled antigen in the sample for binding to the antibody on the plate.
The more target analyte is present in the sample, the less of the labeled reference antigen will bind to the antibody.
An enzyme-linked secondary antibody is then added, which binds to the labeled reference antigen and allows for color detection
describe the patch clamp technique
an electrophysiological method that allows researchers to record and measure the flow of ions across biological membranes through ion channels, either at the whole-cell or single-channel level. It involves creating a high-resistance seal between a glass micropipette and a cell membrane to isolate and study the electrical activity of a small “patch” of the membrane
https://www.youtube.com/watch?v=mVbkSD5FHOw
key features of inbred mice
homozygous at all genetic loci, so genetic variation is a controlled variable. but immune systems are still different
knockout mouse
Technique that specifically removes
expression of a gene from both the
mouse germline and somatic tissues.
transgenic mice
Technique to produce mice carrying
multiple copies of a gene that will be
overexpressed in the genome
how is inducible transgenics useful?
Inducible transgenic mouse models allow for the activation of genes in specific cells and tissues at specific times by administering a drug or some other external agent
5 hormones secreted by kidneys
erythropoietin, calcitriol (active vitamin D), renin, thrombopoietin, klotho
where is erythropoietin secreted from and what is its function?
excreted from extraglomerular mesangial cells. stimulates erythrocyte production.
function of calcitriol
active form of vitamin D. increases absorption of calcium/phosphate from GI tract
where is renin secreted from and what is its function?
secreted from juxtaglomerular cells. activates the renin-angiotensin system by producing angiotensin I and ultimately aldosterone synthesis
function of thrombopoietin
stimulates megakaryocytes to produce platelets
where is klotho secreted from and what is its function?
secreted from distant tubules in kidney. calcium, phosphate, and aging.
_____ affects sodium reabsorption in the nephron.
Aldosterone
__________ promotes tubular reabsorption of calcium, phosphate excretion and the synthesis of 1,25-dihydrocholecalciferol (the active form of vitamin D).
Parathyroid hormone
_______ is made by the juxtaglomerular cells and catalyses the formation of angiotensin I and ultimately aldosterone synthesis.
Renin
V2 receptor location and function
found in principal cells of renal collecting duct. controls the reabsorption of water from the renal tubules into the bloodstream
ADH release triggered by ______ and inhibited by ________ in blood
vessels.
osmoreceptors; stretch receptors
ADH is also found in blood vessels, where it ________, which causes _____
contracts smooth muscle cells –> increase in blood pressure
oxytocin and vasopressin are released from the __________
posterior pituitary
target areas of vasopressin
kidneys, vascular smooth muscle
effects of ADH/vasopressin
water reabsorption and vasoconstriction
ADH and oxytocin are synthesized in the cell bodies of hypothalamic neurons in the _____ and _____ nuclei
supraoptic + paraventricular nuclei
oxytocin is synthesized as a pre-prohormone including neurophysin [I/II]
Neurophysin I
ADH is synthesized as a pre-prohormone including neurophysin [I/II]
Neurophysin II
true or false: oxytocin release is affected by emotional stimuli
true
during the onset of labor, the primary factor initiating oxytocin secretion is what?
stretching of the cervix
estrogen _______ expression of
OTR in the uterus
increases
during labor, oxytocin stimulates the placenta to make _______ which then ______
prostaglandins which stimulate more contractions
after birth, _____ causes oxytocin
release from posterior pituitary
suckling
oxytocin stimulates ______________________ to start the milk let-down response
myoepithelial elements surrounding
mammary alveoli
describe oxytocin receptor binding pathway
oxytocin binds to GPCR –> phospholipase C –> PIP2, DAG, Ca2+ –> contraction of uterine smooth muscle and mammary myoepithelial cells
What does Prolactin do (3)
- Initiate milk production by alveolar cells (lactogenic)
- Maintain milk production once it has been established (galactopoietic) 3. Proliferation of alveolar and duct cells (mammogenic)
Prolactin has primarily lactogenic and galactopoietic effects.
hormonal control of blood pressure (5)
increases BP:
angiotensin I, aldosterone, ADH, epinephrine/norepinephrine
decreases BP:
atrial natriuretic peptide
what happens when you consume a salty food (like potato chips)?
more sodium reabsorption by proximal convoluted tubule (PCT) and renin-angiotensin-aldosterone (RAA) system.
atrial natriuretic peptide (ANP) increases glomerular filtration rate and decreases sodium absorption
aldosterone [increases/decreases] sodium levels
increases
Atrial Natriuretic Peptide [increases/decreases] sodium levels
decreases
PTH increases ____ levels
calcium
A 2% decrease in total body water will increase ________, which will cause plasma ADH to ______
increase plasma osmolality; plasma ADH will rise
explain baroregulation of ADH
Baroreceptors located in left atrium, aortic arch & carotid sinus detect
changes in pressure.
Hypotension (decreased blood pressure) causes increase in ADH secretion. ADH acts to correct hypovolemia.
What is hypertension?
Arterial/blood pressure is too high
systolic pressure
pressure at the peak of ventricular contraction
diastolic pressure
pressure when ventricles relax
true or false: pressure in blood vessels decreases as the distance away from the heart increases
true
what are 2 short-term mechanisms for regulating blood pressure?
neural control and blood borne chemicals –> altering peripheral resistance
Vasomotor center
a cluster of sympathetic neurons in the medulla that oversees changes in
blood vessel diameter.
Cardiovascular center
vasomotor center plus the cardiac centers that integrate blood pressure control by altering cardiac output and blood vessel diameter
how does sympathetic activity affect BP?
– Vasoconstriction and a rise in blood pressure if increased
– Blood pressure to decline to basal levels if decreased
3 main factors influencing blood
pressure
Cardiac output (CO), Peripheral resistance (PR), Blood volume
true or false: parasympathetic nerves innervate the whole heart.
false; this is sympathetic. Parasympathetic nerves do not innervate most of the ventricular myocardium
Inotropic definition
pertaining to the force or energy of muscular contractions, particularly those of the
heart. An inotropic agent increases myocardial contractility
Baroreceptor Neural Response to Elevated Blood Pressure
baroreceptors in the arterial walls sense the increased stretch, triggering a reflex that inhibits sympathetic outflow (decrease in norepinephrine) and activates parasympathetic outflow (release of Ach), leading to decreased heart rate and vasodilation to lower blood pressure
The baroreceptor response to orthostatic hypotension
decreased mean arterial blood pressure upon standing –> firing of baroreceptors –> increased sympathetic output and decreased parasympathetic output –> increased heart rate, contractility, and vasoconstriction (increased peripheral resistance) to restore blood pressure
Two types of cardiac muscle cells
conducting cells and contractile cells
contraction of a cardiac muscle cell is produced by an increase in ______ around myofibrils
calcium ion concentration
20% of calcium required for a contraction come from ______. The other 80% comes from ________.
20 - extracellular calcium entering through slow channels.
80 - calcium ion reserves from sarcoplasmic reticulum
how do beta-adrenergic blockers work?
preventing epinephrine and norepinephrine from bonding to beta receptors in the body. Reduces cardiac output (CO) by diminishing sympathetic nervous system response.
how do calcium channel blockers work?
preventing calcium ions from entering the cells of the heart and blood vessel walls, causing vasodilation, leading to lower blood pressure and improved heart function
name the parts of the nephron
glomerulus, bowman’s capsule, proximal convoluted tubules, loop of henle, distal convoluted tubules, collecting duct
ADH-dependent water reabsorption is called __________
facultative water reabsorption
______ is the signal to produce concentrated urine
ADH
juxtaglomerular cells
- enlarged smooth muscle cells in kidney arteriole walls
- have secretory granules with renin
- act as mechanoreceptors
macula densa
- tall, closely packed distal tubule cells
- adjacent to JG cells
- chemoreceptors/osmoreceptors
where in the nephron does ADH act to reabsorb water?
throughout but more so in the collecting ducts
explain the receptor pathway of V2
ADH binds –> activates GPCR –> adenylate cyclase –> cAMP –> PKA –> insertion of water channels into the apical membrane of the cell and luminal migration of AQP2
where are V1 receptors found?
vascular smooth muscle
4 stimuli for thirst
Hypertonicity: Cellular dehydration acts via an osmoreceptor mechanism in the hypothalamus
Hypovolaemia: Low volume is sensed via the low pressure baroreceptors in the great veins and right atrium
Hypotension: The high pressure baroreceptors in carotid sinus & aorta provide the sensors for this input
Angiotensin II: This is produced consequent to the release of renin by the kidney (eg in response to renal hypotension).
_________ is thirst associated with low volume of body fluids
Hypovolemic thirst
explain osmolality pathway of thirst
water lack –> increased osmolality –> osmoreceptors –> SON and PVN release ADH and lateral pre-optic area enhances thirst –> more absorption of water from collecting duct and more water intake –> normal plasma osmolality
contrast the 3 vasopressin receptors V1a, V1b, and V2
V1a –> PLC –> IP3 and Ca2+ –> contraction of vascular/GI smooth muscle
V1b –> PLC –> IP3 and Ca2+ –> ACTH secretion
V2 –> adenylate cyclase –> cAMP –> insertion of aquaporin into luminal membrane of renal medullary collecting ducts
how does ADH concentrate urine?
Increases permeability of collecting ducts to H2O by inserting H2O channels (Aquaporins). Helps you make small amount of
concentrated urine.
Primary polydipsia
compulsive water-drinkers, causing frequent urination (polyuria) and hyponatremia
diabetes insipidus
characterized by polydipsia and polyuria. Inability to produce concentrated urine. happens when the body does not secrete enough ADH or cannot respond to it in the kidney
compare the two types of diabetes insipidus (DI)
central - Caused by a deficiency in ADH production in the hypothalamus or pituitary gland
nephrogenic - mutation of ADH receptor or aquaporins, renal disease, lithium
what is SIADH
syndrome of inappropriate ADH secretion.
Hypersecretion of ADH –> Person retains water –> Blood volume & pressure increase
summary of RAAS
beautiful video: https://www.youtube.com/watch?v=ibjodC7Ft7U
3 stimulants of renin release
- Sympathetic nervous system stimulation. Renal sympathetic nerves directly innervate the juxtaglomerular cells –> renin production
- Decreased filtrate osmolality at macula densa
- Decreased stretch (due to decreased blood pressure). Juxtaglomerular cells are sensitive to pressure in the afferent arterioles and function as intra-renal baroreceptors
how does macula densa impact renin secretion?
Macula densa senses sodium and chloride concentration in tubular fluid, decreased salt concentration –> release prostaglandins –> granular juxtaglomerular cells lining the afferent arterioles release renin into the bloodstream
effects of angiotensin II
- general vasoconstriction
- constriction of the efferent arteriole next to the kidney, which causes more filtration to occur at the glomerulus.
- synthesis/release of aldosterone from adrenal cortex which increases sodium retention in nephron —> more sodium in blood means more water in blood so blood volume/pressure go up
- also causes release of ADH from posterior pituitary which causes aquaporins to reabsorb more water in collecting ducts.
how does aldosterone increase sodium retention?
stimulates transcription of sodium channels and Na+/K+ pumps –> increased Na+ absorption and K+ secretion
impact of estrogens on sodium balance
– Enhance NaCl reabsorption by renal tubules
– May cause water retention during menstrual cycles (bloating)
– Are responsible for edema during pregnancy
impact of progesterone on sodium balance
– Decreases sodium reabsorption
– Acts as a diuretic, promoting sodium and water loss
impact of glucocorticoids on sodium balance
enhance reabsorption of sodium and promote edema (bloating)
where and why is atrial natriuretic factor (ANF/ANP) released?
Is released in the heart atria as a response to stretch (elevated blood pressure)
ANF acts on the tubules to ______ sodium reabsorption
inhibit
effects of ANP
- inhibits aldosterone release and renin production
- increases glomerular filtration rate by dilating afferent arterioles
– Vasoconstriction of efferent
arterioles
– Reduces ADH release
how is cortisol relevant in the RAAS pathway?
cortisol can mimic the effect of aldosterone when levels are high (so stress –> increased BP)
cortisol is converted to cortisone by an enzyme 11-ß-HSD2. _______ inhibits this enzyme, preventing cortisol from binding to mineralocorticoid receptors.
Glycyrrhizic acid (found in licorice)
molecules that cause vasoconstriction (4)
Angiotensin II, catecholamines, ADH, endothelin
molecules that cause vasodilation (5)
prostoglandins, adenosine, bradykinin, ANF, NO
how do ACE inhibitors link the RAAS and bradykinin pathways?
ACE inhibitors prevent the conversion of angiotensin I to angiotensin II within the reninangiotensin system, and prevent the conversion of bradykinin to inactive peptides in the
kallikrein-kinin system
so its like double vasodilation which raises your BP prob too much
Erythropoietin (EPO) release by the
kidneys is triggered by:
- Hypoxia due to decreased RBCs
- Decreased oxygen availability
- Increased tissue demand for oxygen
erythropoietin mechanism of action
- Binds specifically to Erythropoietin Receptor (cytokine receptor)
- dimerization of receptor, tyrosine kinase activity
- Multiple cytoplasmic & nuclear proteins phosphorylated
- Nuclear signal sent to activate production of proteins leading to proliferation and differentiation
explain blood doping
explain the vitamin D pathway
Vitamin D synthesis begins in the skin when ultraviolet (UV) light from sunlight interacts with 7-dehydrocholesterol, a precursor molecule, producing previtamin D3, which then transforms into vitamin D3 (also known as cholecalciferol). Vitamin D3, a fat-soluble vitamin, is transported in the blood by vitamin D binding protein (DBP) to the liver, where it undergoes its first hydroxylation (addition of an -OH group) at the 25th position, converting it to 25-hydroxyvitamin D (25(OH)D), also known as calcidiol. 25(OH)D circulates in the blood and is further hydroxylated, this time at the 1α position in the kidneys, by the enzyme 1α-hydroxylase (CYP27B1), forming the active, hormonal form of vitamin D, 1,25-dihydroxyvitamin D (1,25(OH)2D), also known as calcitriol. Calcitriol, the active form of vitamin D, plays a crucial role in maintaining calcium and phosphorus homeostasis, promoting calcium absorption in the intestines, and regulating bone mineralization.
ET-1 is a strong [vasoconstrictor/vasodilator]
vasoconstrictor
effects of bradykinin
– Increased vascular permeability
– Arteriolar dilatation
– Smooth muscle contraction
vitamin D path through body organs
skin –> blood –> liver –> kidneys
how does PTH come into the vitamin D pathway?
PTH is activated by low calcium levels and then goes and activates 1-alpha-hydroxylase in the PCT of kidneys which turns calcifediol into calcitriol, the active form of vitamin D
3 functions of PTH
- increases calcium reabsorption at the kidneys
- blocks phosphate reabsorption from the tubules.
- acts on the kidneys to stimulate the formation of vitamin D
where is klotho produced?
distal convoluted tubules
_______ exerts major effects on several biological processes relevant to aging and disease
Klotho
3 main functions of klotho
1) FGF23-dependent phosphate, calcium and vitamin D regulation.
7) Anti-apoptotic and anti-senescence functions; stem cell preservation.
8) Protection against neurodegenerative disease (Alzheimer’s and other).
