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409 Cards in this Set

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Myocardial action potential
During phase 0 of the myocardial action potential, -------- ------- ------ channels open.
voltage-gated Na+
Initial repolarization, or phase 1, is when voltage-gated ---- channels begin to open and when voltage-gated Na+ channels ---- (close OR inactivate?).
K+ begin to open. Na+ channels inactivate.
Phase 2 is the plateau, when ------- influx balances ------ efflux.
Ca++ influx balances K+ efflux.
Ca++ influx triggers another Ca++ release from the ------- --------, which leads to myocyte ------.
sarcoplasmic reticulum. contraction
During what phase do the voltage-gated Ca++ channels close?
phase 3
During phase 3, the rapid repolarization phase, there is massive -------- efflux.
During resting potential, the myocyte membrane is highly permeable to what ion?
Where does the pacemaker action potential normally occur?
SA and AV nodes.
The phase 0 stroke of the pacemaker AP differs from that of the ventricular AP in that the pacemaker cells lack fast ------ ------- ------- channels.
voltage-gated Na+
By using Ca++ current for phase 0 upstroke, the conduction velocity is slowed compared to the fast Na+ upstroke of the ventricular AP. What purpose does this slowed conduction serve?
The AV node then prolongs trasmission from the atria to ventricles, allowing for sufficient filling time.
Which phase of the ventricular AP is absent in the pacemaker AP?
phase 2, during which there is Ca++ influx in the ventricular AP.
What ion is responsible for the slow depolarization current in the pacemaker AP? This current accounts for the automaticity of the SA and AV nodes.
Na+ (this is the If, or the funny current)
ACh and catecholemines alter the slope of phase 4, which determines the ------- ------.
heart rate
Phase 4 depolarization occurs during which phase of the cardiac cycle?
During exercise, cardiac output (CO) increases as a result of an increase in -----.
Stroke volume
After prolonged exercise, CO increases as a result of an increase in ------.
heart rate
the product of ----- and ----- equals cardiac output.
stroke volume X heart rate
Fick principle for cardiac output :
CO = (rate of O2 consumption) / (arterial O2 content-venous O2 content)
Formula for mean arterial pressure
What is pulse pressure?
systolic - diastolic
Pulse pressure correlates to what other measure?
stroke volume
What three entities affect stroke volume? (Mnemonic: SV CAP)
contractility, afterload, preload
If afterload is decreased, what happens to stroke volume?
What happens to stroke volume in pregnancy?
What does hypoxia/hypercapnea do to contractility?
What does a decrease in extracellular Na+ do to contractility?
Digitalis increases intracellular ---- ion.
What does acidosis do to contractility?
Ventricular end diastolic volume is -----.
What is afterload?
diastolic arterial pressure (proportional to peripheral resistance)
What class of drugs decreases preload?
venous dilators (nitroglycerine)
Drugs like hydralazine decrease ------.
afterload (they are vasodilators)
Force of contraction is proportional to -------.
initial length of cardiac muscle fiber (preload)
Sympathetic stimulation will shift the curve on a graph of CO vs. preload up and toward the ---- (right / left).
Ejection fraction is stroke volume divided by -----.
end diastolic volume
EF is an index of ventricular -------.
What is normal EF?
greater than 55%
Viscosity of blood depends mostly on ------
name three conditions in which viscosity increases.
(1) polycythemia (2) hyperproteinemic state (e.g. multiple myeloma) (3) hereditary spherocytosis
Resistance is proportional to viscosisty and inversely proportional to ---------.
radius to fourth power.
Decreasing the volume of blood shifts the venous pressure curve to the ------. (on a graph of venous return vs. RA pressure)
On a graph of CO vs. EDV, digitalis (positive inotrope) will shift the curve ------.
Isovolumetric contraction is the period between ---- valve closure and ----- valve opening.
mitral / aortic
During which period is O2 consumption by the heart the highest?
isovolumetric contraction
For each heart sound, give the significance
mitral and tricuspid valve closure
aortic and pulmonic valve closure
at end of rapid ventricular filling
high atrial pressure/ stiff ventricle
For each situation, give the corresponding heart sound.
high atrial pressure/ stiff ventricle
aortic and pulmonic valve closure
mitral and tricuspid valve closure
at end of rapid ventricular filling
Dilated CHF is associated with which extra heart sound?
S4 is associated with what condition?
hypertrophic ventricle
For each wave of the jugular venous pulse, give the corresponding physiologic event.
a wave
atrial contraction
c wave
RV contraction (tricuspid valve bulging into atrium)
v wave
increase in atrial pressure due to filling against closed tricuspid valve.
What is the function of the T tubule?
allows depolarization to travel down it, leading to muscle contraction
This band in a skeltal muscle contains myosin filaments (thick filaments)
H band/zone
This band in a skeltal muscle contains only actin filaments (thin filaments)
I band
Which band in a muscle remains the same size?
A band (dark bands)
During muscle contraction, which bands shrink?
H, I, and Z bands
What is the function of the ryanodine receptor?
voltage-sensing CA+2 channel protein in the sacroplasmic reticulum
What is the function of the dihydropyridine receptor?
voltage-sensing CA+2 channel protein in the T-tubule
Where does the calcium come from that stimulates cardiac muscle contraction?
extracellular calcium enters the cell during the plateau of the action potential and stimulates release of calcium from the sarcoplasmic reticulum (calcium-induced calcium release)
Name three ways that cardiac muscle differs from skelatal muscle with regards to its electrophysiolopgy.
1. action potential has a plateau which is due to Ca++ influx. 2. Cardiac nodal cells spontaneously depolarize, resulting in automaticity. 3. Cardiac myocytes are electrically coupled to each other by gap junctions.
How does the action potential in smooth muscle lead to contraction?
The smooth muscle membrane depolarizes, voltage-gated calcium channels open, calcium rushes into the cell, calcium binds to calmodulin, calcium calmodulin complex activates myosin light chain kinase, MLCK phosphorylates myosin light chain which crosslinks with actin and causes contraction.
How is myosin light chain phosphatase involved in relaxation.
It dephosphorylates myosin light chain, making it less able to cross-bridge with actin--allowing relaxation
Muscle contraction is a result of cross-linking between which two proteins?
actin and myosin
____binds to myosin head during a skeletal muscle contraction
Identify the significance of each of the following:
P wave
atrial depolarization
PR segment
conduction delay through AV node
QRS complex
ventricular depolarization
QT interval
mechanical contraction of ventricles
T wave
ventricular repolarization
ST segment
isoelectric, ventricles depolarized
U wave
caused by hypocalemia
What is masked by the QRS complex?
atrial repolarization
Where is the pacemaker of the heart?
SA node in right atrium
Match the ECG finding with the description of the ECG trace:
1. Progressive lengthening of the PR interval until a beat is "dropped" (a pwave not followed by a QRS complex). Usually asymptomatic.
B. 2nd degree AV block, (Mobitz type I) (wenckebach)
2. A rapid succession of identical, back-to-back atrial depolarziation waves. "sawtooth appearance"
G. Atrial flutter
3. Dropped beats that are not preceded by a change in the length of the PR interval . These abrupt, nonconducted P waves result in a pathologic condition.
C. Mobitz Type II
3. PR interval is prolonged (>200 msec). Asymptomatic
A. AV block 1st degree
4. Chaotic and erratic baseline with no discrete p waves in between irregularly spaced QRS complexes
F. Atrial Fibrillation
5. The atria and ventricles beat independently of each other. Both P waves and QRS complexes are present, although the P waves bear no relation to the QRS complexes. The atrial rate is faster than the ventricular rate.
D. 3rd Degree, complete AV block
6. A completely erratic rhythm with no identifiable waves.
E. Ventricular Fibrillation
Name four compensatory mechanisms that are activated when baroreceptors detect low MAP
Heart rate increases (beta1), contractility increases (beta1), venous tone--venous return increases (alpha), TPR increases (alpha), kidneys retain sodium and H20 (renin-angiotensin-aldosterone system)
Aortic Arch baroreceptor transmits via what nerve to the medulla?
vagus (X)
Carotid Sinus baroreceptor transmits via what nerve to the medulla?
glossopharyngeal (IX)
Decreasing the stretch on the baroreceptors leads to: (increased/decreased) efferent sympathetic stimulation
Increased. Decreased stretch as a result of decreased MAP decreases the afferent signal from the baroreceptor which leads to an increase in the efferent sympathetic signal from the brain
Hypotension leads to vaso____(constriction/dilation)
What is the effect of a carotid massage?
It increases the pressure in the carotid artery, increases the stretch of the baroreceptors, and leads to a decrease in heart rate.
Which receptor transmits to the medulla, responding only to increase blood pressure
Aortic arch
Name three physiological changes that are sensed by peripheral chemoreceptors (carotid and aortic bodies).
1. decreased pO2 below 60 mmHg; 2. increased pCO2; 3. decreased pH of blood
Central chemoreceptors (in brain) respond to ____ and ____ but do not directly respond to _____.
pH; pCO2; pO2
Which organ has the largest share of systemic cardiac output?
Which organ has the highest blood flow per gram of tissue?
Which organ has a large arteriovenous O2 difference
Match the normal pressures with a heart chamber or major vessel: A. Right atrium/vena cava, B. Right Ventricle, C. Pulmonary Artery, D. Left Atrium, E. Left Ventricle, F. aorta
F. aorta
What does the PWCP approximate?
Pulmonary capillary wedge pressure approximates left atrial pressure.
How is PWCP measured?
Swan-Ganz catheter
What factors regulate blood flow to the following tissues?
local metabolites: O2, adenosine, NO
local metabolites: CO2 (pH)
myogenic and tubuloglomerular feedback
hypoxia causes vasoconstriction (only organ in which hypoxia leads to vasoconstriction)
Skeletal muscle
local metabolites: lactate, adenosine, K+
sympathetic stimulation in response to changes in body temperature
Plasma-clotting factors = what?
Blood is ___% of body weight
Blood is ___% plasma.
55% The rest is formed elements (hematocrit)
Plasma is ____% proteins.
Plasma proteins are ___% albumin.
Plasma proteins are ___% globulins
Leukocytes are normally ____% PMNs, ___% lymphocytes, ___% monocytes, ___% eosinophils, ___basophils.
40-70% PMNs, 20-40% lymphos, 2-10% monos, 1-6% eos, <1% basophils
What is MAP in terms of systolic and diastolic pressures
1/3 systolic +2/3 diastolic
What happens to CO if HR is too high
diastolic filling decreases and CO decreases
What is an example of this
ventricular tachycardia
What is SV in terms of EDV and ESV
Name 4 things that increase myocardial 02 demand
Increased: Afterload, contractility, heart rate, and heart size
What is Wolff-Parkinson-White syndrome
accessory conduction pathway from atria to ventricle (bundle of kent), bypassing AV node
What is the characteristic wave in WPW syndrome
delta wave
What can WPW lead to
reentry current and supraventricular tachycardia
Forces that move fluid out of capillary?
Capillary pressure (Pc) and Interstitial fluid colloid osmostic pressure
Forces that move fluid into capillary?
Interstitial fluid pressure (Pi) and Plasma colloid osmotic pressure
Equation for net filtration pressure?
P net = [(Pc - Pi)] - (colloidc - collidi)]
Conditions that cause edema by increased capillary pressure?
heart failure
Conditions that cause edema by increased capillary permeability?
toxins, infections, burns
Conditions that cause edema by decreased plasma proteins?
nephrotic syndrome, liver failure
Conditions that cause edema by increased fluid colloid osmotic pressure?
lymphatic blockage
What are the physiological responses to high altitude: 1-, 2-, 3-, 4-, 5-, 6-, 7-
1- acute increase in ventilation, 2- chronic increase in ventilation, 3- increase in EPO leading to an increase in hematocrit and hemaglobin (chronic hypoxia), 4- increase in 2,3-DPG, 5- Cellular changes (increase in mitochondria), 6- increase in excretion of bicarbonates to compensate for respiratory alkalosis, 7- chronic hypoxic pulmonary vasoconstriction results in RVH
What is the action of 2,3-DPG?
binds to hemaglobin so that hemoglobin releases more O2
What does acetazolamide doe?
it increases the renal excretion of bicarbonates.
What are 5 important lung products?
Surfactant, prostaglandins, histamine, ACE, Kallikrein
What does surfactant do? What is Surfactant? What makes Surfactant?
It decreases alveolar surface tension which increases complaince, it is made of dipalmitoyl phosphatidylcholine (lecithin), it is produced by type II pneumocytes
What pathologic process has a deficiency of Surfactant?
Neonatal RDS
What are the funcitons of ACE
converst angiotensin I to Angiotensin II, inactivates bradyykinin (ACE inhibitors yield increase bradykinin and cause cough, angioedema)
What is the colapsing pressure
What does Kallikrein do?
It activates bradykinin
What is the Residual volume (RV)?
air in lung at max expiration
What is the expiratory reserve volume (ERV)?
air that can still be breathed out after nl expiration
What is the tidal volume (TV)?
air that moves into lung with each quiet inspiration (nl = 500ml)
What is the inspiratory reserve volume (IRV)?
Air in excess of tidal volume that moves into lung on max inspiration
What is the vital capacity (VC)?
What is the functional reserve capacity (FRC)?
RV + ERV (volume in lungs after normal espiration)
What is the inspiratory Capacity (IC)?
What is the total lung capacity (TLC)?
Decreased affinity of hemoglobin for O2 = shift ___
A right shift is caused by an increase or decrase in each of the following factors: P50, metabolic needs, PCO2, temperature, H+, pH, altitude, and 2,3-DPG
Increase in all but pH
Fetal Hb curve is shifted ___
Left (increased affinity for O2)
T/F: Pulmonary circulation is normally a low-resistance, low-compliance system
F - Low-resistance, high-compliance
Cor pulmonale and subsequent RV failure are a consequence of pulmonary ______
Hypoxic vasoconstriction that shifts blood away from poorly ventilated regions is caused by ______
Decrease in PaO2
In normal health, O2 is perfusion or diffusion limited?
Perfusion limited - gas equilibrates along the length of the capillary
Which of the following is diffusion limited: CO2, N2O, or CO?
CO - gas does not equilibrate by the time the blood reaches the end of the capillary
When is O2 diffusion limited?
What is the equation for Vd?
Exercise, emphysema, fibrosis
(Vt) x (PaCO2 -PeCO2)/PaCO2; Pa = arterial & Pe = expired air
What is the ideal V/Q ratio?
V/Q = 1 (permits adequate oxygenation)
At the base of the lung, there is greater ventilation, perfusion, or both?
Both are greater
What is V/Q at the apex of the lung?
V/Q = 3 (wasted ventilation)
What is V/Q at the base of the lung?
V/Q = 0.6 (wasted perfusion)
V/Q = 0 implies _____
Airway obstruction (shunt)
V/Q = infinity implies ______
Blood flow obstruction (physiological dead space)
Organisms such as TB that thrive in high O2 flourish in the apex or base of the lung?
During exercise (increased cardiac output), the vessels in the apex of the lung ___-------_______
Vasodilate such that V/Q approaches 1 (versus normal apex V/Q of 3)
CO2 is transported from tissue to lungs in these 3 forms: ______
(1) Bicarbonate (2) Bound to hemoglobin (3) Dissolved CO2
What percentage of CO2 is transported in the form of bicarbonate?
What is the intracellular enzyme that converts CO2 into H2CO3?
Carbonic anhydrase
H2CO3 is broken down into H+ and HCO3. What happens to the H+?
H+ combines with Hb to form HHb (deoxyhemoglobin)
H2CO3 is broken down into H+ and HCO3. What happens to the HCO3?
HCO3 is pumped out of the red blood cell in exchange for Cl-
What is the Haldane effect?
Oxygenation of hemoglobin promotes the dissociation of CO2 from hemoglobin
What does kallikrein do
Activates bradykinin
What affect to ACE inhibitors have on bradykinin
Increase bradykinin, which lead to cough and angioedema
Equation for clearance?
Cx = UxV/Px; Cx = clearance of X; Ux = urine concentration of X; Px = plasma concentration of X; V = urine flow rate
Significance of Cx < GFR?
net tubular reabsorption of X
Significance of Cx > GFR?
net tubular secretion of X
Significance of Cx = GFR?
no net secretion or absorption of X
The two determinants of filtration across the glomerular filtration barrier are - and -.
size and charge
Components of filtration barrier?
Fenestrated capillary endothelium, fused basement membrane with heparin sulfate, epithelial layer
What comprises epithelial layer?
podocyte foot processes
The charge on the fused basement membrane is -.
The charge barrier is lost in - , characterized by what four findings?
nephrotic syndrome, albuminuria, hypoproteinemia, generalized edema, hyperlipidemia
What substance is freely filtered and is neither reabsorbed nor secreted?
Clinically, - clearance is a good measure of GFR.
Equation for GFR
GFR = U(in) X V/P(in) = C(in)
Where in nephron is PAH secreted?
proximal tubule
By what mechanism is it secreted?
2˚ active transport. Mediated by a carrier system for organic acids
What drug competively inhibits PAH's secretion?
What substance entering the nephron is filtered AND secreted?
Equation for effective renal plasma flow?
ERPF = U(pah) X V/P(pah) = C(pah)
Equation for renal blood flow?
RBF = RPF/1-Hct
Equation for filtration fraction?
Class of substances responsible for dilating afferent arteriole?
Class of drug that inhibits production of above substances?
Substance responsible for constricting efferent arteriole?
angiotensin II
Class of drugs that inhibits production of angiotensin II?
ACE inhibitors
What factors do you need to know to calculate free water clearance?
urine flow rate, urine osmolarity, plasma osmolarity
Equation for free water clearance?
C(H2O) = v - C (osm)
Where is glucose absorbed in the nephron?
proximal tubule
At what plasma glucose level does glucosuria begin?
200 mg/dL
At what plasma glucose level is the glucose threshold mechanism (Tm) saturated?
350 mg/dL
How many carrier systems involved in amino acid reabsorption?
Where does 2˚ active transport occur?
proximal tubule
Substances reabsorbed in the early proximal tubule?
all glucose and amino acids; most bicarbonate, sodium, and water
- is secreted in the early proximal tubule, which acts as a buffer for -.
ammonia, H+
Section of the nephron that is impermeable to sodium?
thin descending loop of Henle
Substances actively reabsorbed in the thick ascending loop of Henle?
Na+, K+, Cl-
- and - are indirectly reabsorbed in the thick ascending loop of Henle.
Ca+2 and Mg+2
Substances actively reabsorbed in the early distal convoluted tubule?
Na+ and Cl-
Reabsorption of - is under the control of - (hormone) in the early distal convoluted tubule,
Ca+2, PTH
Substances regulated by aldosterone in collecting tubules?
Na+, K+
Reabsorption of water is regulated by - in the collecting tubules?
Osmolarity of the medulla can reach a concentration of -.
1200 mOsm
Relative concentration equation for comparing concentrations of substances in renal tubule to plasma?
[tubular fluid]/[plasma]; TF/P
Substance with highest TF/P?
Why does this substance have the highest TF/P?
Its both filtered and secreted
Substances with lowest TF/P?
glucose and amino acids
Why do these substances have the lowest TF/P's?
They are reabsorbed almost completely in the early proximal tubule
What substance has a TF/P = 1?
Where does renin come from in the kidney?
Cells in the juxta-glomerular apparatus
Mechanism stimulating renin release?
Decrease in blood pressure in kidneys
What does renin do?
Cleaves angiotensinogen to angiotensin I
Angiotensin I is then cleaved by -, primarily in the -, to make -?
angiotensin converting enzyme, lung capillaries, angiotensin II
4 actions of angiotensin II?
1) Potent vasoconstriction, 2) Release of aldosterone from adrenal cortex, 3) release of ADH from the posterior pituitary, 4) Stimulates hypothalmus to increase thirst.
Overall actions of angiotensin II?
Increase intravascular volume and blood pressure
- (hormone) released from the - may act as a "check" on the renin-angiotensin system in such cases as heart failure.
ANP, atria
Endothelial cells of peritubular capillaries secrete - in response to hypoxia.
What is the enzyme responsible for converting 25-OH vitamin D to I,25-(OH)2?
What hormone activates this enzyme?
What is the function of secreted prostaglandins in the kidney?
Vasodilation of the afferent arterioles to increase GFR
Class of drugs that can cause renal failure in high vasoconstrictive states due to inhibition of prostaglandin production?
NSAIDS. Prostaglandins are keeping the afferent arterioles vasodilated to maintain GFR. Inhibition of prostaglandin production leads to acute renal failure.
Name two stimuli for ADH secretion?
Increased plasma osmolarity; decreased blood volume
Two actions of ADH other than increasing water permeability in the collecting duct
Increase urea absorption in the collecting duct; Increase Na/K/2Cl activity in thick ascending limb
Hormones stimulated to be released by a decrease in blood volume?
ADH, aldosterone, angiotensin II (via renin)
Hormones that increase Na+ reabsorption?
Aldosterone (distal tubule); angiotensin II (proximal tubule
Three effects of PTH on the kidney?
1) Increase Ca+2 reabsorption, 2) Decrease phosphate reabsorption, 3) Increase vitamin D production
Hormone that decreases sodium reabsorption?
What is the primary disturbance in Metabolic acidosis?
a decrease in bicarbonate
What is the compensation?
A drop in CO2 by hyperventilation
What are common causes?
diabetic ketoacidosis (production of ketone acids), diarrhea (loss of GI bicarb), salisylate overdose, acetazoleamide (diuretic) OD, lactic acidosis, renal failure (can't excrete organic acids), ethylene glycol ingestion
What is the primary disturbance in respiratory acidosis?
A build-up in CO2
What is the compensation?
Increased bicarb reabosrobtion from the kidney
What are some common causes?
COPD, airway obstruction, opiates and sedatives, guillan-barr or ALS,
What is the primary disturbance in metabolic alkalosis?
increased bicarbonate
What is the compensation?
Increased CO2 by decreased respiration
What are some common causes?
hyperventilation, high altitude, pneumonia and pulmonary embolus (hypoxemia causes hyperventilation_
What is the Henderson Haselbach equation?
pH = pKa + Log (HCO3-)/(.03*pCO2)
Acid Base Nomogram
Low pH, low pCO2 (low HCO3-)
metabolic acidosis
Low pH, high pCO2 (high HCO3-)
chronic respiratory acidosis
High pH, low pC02 (low HC03-)
acute respiratory alkalosis
High pH, high pCO2 (high HCO3-)
metabolic alkalosis
Anion gap acidosis
How do you calculate it
Na - Cl - HCO3
What is normal?
8-12 mEq/L
What is the mnemonic
Paraldehyde or Phenformin
Iron tablets or INH
Lactic Acidosis
Ethanol, Ethylene Glycol
Acid Base Compensations
Metabolic acidosis
pCO2 = 1.5(HCO3) + 8 +/- 2
Metabolic alkalosis
pCO2 increases 0.7 mm Hg per 1 mEq/L HCO3 increase
Respiratory acidosis (acute)
HCO3 increases by 1 mEq/L for every 10 mmHg increase of pCO2
Respiratory acidosis (chronic)
HCO3 increases by 3.5 mEq/L for every 10 mmHg increase of pCO2
Respiratory alkalosis (acute)
HCO3 decreases by 2 mEq/L for every 10 mmHg decrease of pCO2
Respiratory alkalosis (chronic)
HCO3 decreases by 5 mEq/L for every 10 mmHg decrease of pCO2
Factor initiating intrinsic pathway?
Factor(s) initiating extrinsic pathway?
VII and tissue factor
Function of factor XIII?
Forms cross-linked fibrin
Factors examined with prothrombin time (PT)?
VII, X, V, prothrombin, fibrinogen (Hoffbrand. Haematology. 247)
Factors examined with partial thromboplastin time (PTT)?
VIII, IX, XI, XII, X, V, prothrombin, fibrinogen (Hoffbrand. Haematology. 247)
Vitamin K dependent factors?
II, VII, IX, X, protein C, protein S (243)
Factors requiring phospholipid surface for activation?
IX and X
Factor I also known as?
Factor II also know as?
Two substrates of Factor XIIa?
Factor XI and Prekallikrein
Components involved in the activation of factor XII?
Collagen, basement membrane, activated platelets, HMWK (cofactor [high molecular weight kallikrein])
Two substrates of kallikrein?
HMWK and Plasminogen
Complement protein on which plasminogen acts?
Three functions of bradykinin?
Increase vasodilation, increase permeability, increase pain
What converts HMWK to bradykinin?
What does plasmin's action on fibrin produce?
fibrin split products
Hormones released from the posterior pituitary?
ADH and oxytocin
Where are they made?
Hormones released from the anterior pituitary?
FLAT PiG: FSH, LH, ACTH, TSH, prolactin, GH
Embryological origin of anterior and posterior pituitary, respectively.
oral ectoderm (anterior), neuroectoderm (posterior)
Hormones derived from proopiomelanocortin?
hormones with common alpha subunit?
Subunit determining hormone specificity?
beta subunit
Cells in the parathyroid that secrete PTH.
Chief cells
Organs/tissue on which PTH acts.
Bone, small intestine (via 1, 25 dihydroxy vitamin D), kidney
Cells stimulated in bone by PTH.
osteoblasts (directly) AND osteoclasts (indirectly)
How does PTH affect phosphate levels?
Decreases them; it’s the Phosphate Trashing Hormone
What is the function of PTH on bone?
Increase bone resorption of calcium and phosphate
What stimulates PTH release?
Low free serum Ca+2
Three action of PTH on the kidney.
1) Increase vitamin D production, 2) Phosphate secretion, 3) Calcium reabsorption (distal convoluted tubule)
What are two sources of Vitamin D?
Plants, and sun exposire on skin
What are they converted to in the kidney?
1,25-OH-vitamin D (biologically active form)
What are three fucntions of Vitamin D?
Increases calcium and phosphate absorbtion from the gut, increases bone resobtion of Calcium and phosphate.
If calcium or potasium in the blood drop, what effect does that have on vitamin D procudtion?
They both act to increase it. Makes sens, if you think about its actions.
What effect does PTH have on vitamin D?
increases its formation - again, PTH wants to increase blood calcium levels, so an increase in vitamin D would help that.
What effect do vitamin D levels have on vitamin D production?
negative feedback loop
If you lack vitamin D as a child you get:
If you lack vitamin D as a adult you get :
What are som common cuases of Hypercalcemia?
Malignancy, Intoxication with Vit. D, Sacroidosis, Hyperparathyroidism, Alkalie syndrome, and Pagets (bone). Remember: MISHAP
What is alkaline phsphtase a measurement of?
It is an enzyme found in bone and liver. The bone specific enzyme indicates attemtped growth in the bone.
In Hyperparathyroidism, what are the Ca levels?
Increased, remember, PTH acts to increase CA in the serum.
In Hyperparathyroidism, what are the Phosphate levels?
Decreased. TPH increases its secretion in the kidney to keep serum Ca high
In Hyperparathyroidism, what are the Alk Phos levels?
Elevated, because PTH actiavrse osetoblasts as well as osteoclasts
In Paget's (bone) what are the Ca levels?
Normal or elevated
In Paget's (bone) what are the Phosphate levels?
In Paget's (bone) what are the Alk Phos levels?
Elevated a lot, becxuase of all the bone formation going on.
In Vit. D intoxication what are the Ca levels?
High. Vit. D increase absorbtion in the gut.
In Vit. D intoxication what are the Phosphate levels?
In Vit. D intoxication what are the Alk Phos levels?
Normal or high, as the calcium is incorperated
In Osteoperosis what are the Ca levels?
In Osteoperosis what are the Phosphate levels?
In Osteoperosis what are the Alk Phos levels?
In renal insufficiency what are the Ca levels?
Low - no vit. D means less abosorbtion
In renal insufficiency what are the Phosphate levels?
High - kideny can't excrete well
In renal insufficiency what are the Alk Phos levels?
Where is calcitonin made?
Thyroid gland
What cells?
Parafolliclular cells (C cells)
What is it's function?
supresses osteoclasts
What triggers its release?
Increases serum calcium and calcium secretion
Is this important in humans?
No. It oppses PTH, but in humans it is not vital to ca+ homeostasis.
What do T3 and T4 do, basically?
Control the body's metabolic rate
What are the four Bs that describe T3's function?
Brain maturation, bone growth, beta adrenergic effects, basal metabolic rate increased
What is the mechanism by which metabolic rate is increased?
Increased Na+/K+ ATPase activity: increased O2 consumption, increased body temperature
What happens to glucose and lipid balance under T3's effect?
Increased glycogenolysis, gluconeogenesis, lipolysis
What tells the thyroid to release T3?
Hypothalamus releases TRH which stimulates TSH from the pituitary which stiumlates follicle cells
What prevents there from being too much thyroid hormone?
Negative feedback of T3 to the anterior pituitary: decreases sensitivity to TRH from hypothalamus
What also stimulates follicle cells (pathological)?
TSI - Grave's disease
Describe how T3 andd T4 are made?
Iodine enters follicle cells and is oxidized; goes into lumen as I2. Thyroglobulin (made from tyrosine) enters lumen and combines with I2 to form monoiodotyrosine and di-iodotyroside (2 of di makes T4 and one di and one mono makes T3). The T3 and T4 re-enter the follicular cell and are degraded by proteolysis, releasing the T3 and T4 into the bloodstream
How doees a steroid hormone effect its function?
Binds to a receptor in the nucleus or cytoplasm and moves to the nucleus; the receptor transforms to expose the DNA binding domain and the hormone/receptor complex binds to an enhancer-like element in DNA. Bottom line: steroids and thyroid hormone cause gene transcription and protein formation
Why are the actions of steroid and thyroid hormones delayed?
You have to wait for the gene transcription and protein synthesis to happen.
What are the steroid hormones?
I had a PET CAT who was buff because she took steroids. Progesterone, Estrogen, Testosterone, Cortisol, Aldosterone, Thyroxine
How do steroids circulate if they are lipophilic?
Bound to binding globulins: increases their solubility and allows for increased delivery to the target organ
What enzyme does ACTH work on?
Desmolase: convesion of cholesterol to pregnenolone
What does ketoconazole do?
Inhibits desmolase, see above
What happens if you have a 17 alpha hydroxylase deficiency?
You can't make sex hormones, cortisol but you can make mineralcorticoids. You get hypertension and hypokalemia because you are wasting all the K in your kidneys while retaining Na. You are phenotypically femal but have no maturation.
What happens in 21 beta hydroxylase deficiency?
This is the most common. You have decreased cortisol, increased ACTH, decreased mineralcorticoids, and increased sex hormones. You are masculinized and have female pseudohermaphroditism.
What is blood pressure and electrolytes in 21 beta hydroxylase deficiency?
Hypotension, hyponatremic, hyperkalemic, volume depleted and increased renin activity to compensate
What condition do you suspect if a newborn has hypovolemic shock?
21 beta hydroxylase deficiency
What happens if you don't have 11 beta hydroxylase?
Decreased cortisol, decreased aldosterone and corticosterone, increased sex hormones
What does angiotensin II work on?
Aldosterone synthase: creates more aldosterone from corticosterone
What does DHT come from and how?
Testosterone via 5 alpha reductase
What does estradiol come from?
Testosterone via aromatase
What does estrone come from?
Androstenedione via aromatase
What does DHEA lead to eventually?
Testosteron (and its byproducts)
What can progesterone be enzymatically transformed to?
Glucocorticoids, Androgens and estrogens eventually
What cells can take in glucose regardless of insulin levels? Via what receptoir?
Bran and RBC: GLUT-1 receptor
What does the brain use in starvation when there is no glucose?
Ketone bodies
What does prolactin have to do with dopamine?
Prolactin increases dopamine synthesis and secretion from the hypothalamus, which then inhbits prolactin secretion
What do dopamine agonists do to prolactin secretion? Eg bromocriptine
Inhibit it
What does prolactin do to GnRH and what does this mean clinically?
Inhbitis synthesis and release: inhibits ovulation
What is a common sign of prolactinoma?
What causes prolactin releas?
TRH from hypothalamus works on anterior pituitary to cause prolactin release
What is the order of potency for estrone, striol, estradiol?
Most to least: estradiol >estrone>estriol
Where does estradiol come from?
Do the testes make estrogen?
Where does estriol come from?
What are the benefits of hormone replacement therapy with estrogen post-menopause?
Less hot flashes, less bone loss
What are the negative effects of unopposed estrogen?
Increased risk of endometrial cancer.
What can decrease the risks of giving estrogen?
Giving progesterone with it.
What does estrogen do to the follicle?
Makes it grow
What does estrogen do to the endometrium and the myometrium?
Growth and excitability
What does estrogen do to the genitalia?
What does estrogen do to breasts?
Stromal development
What does estrogen do to fat distribution?
Female pattern
What does estrogen do to transport proteins?
Increases hepatic synthesis
What does estrogen do to FSH?
Feedback inhibition
What does estrogen do to LH?
Causes surge: feedback switches from negative to posititve just before LH surge.
What does increased progesterone indicate?
What does progesterone come from?
Corpus luteum, placenta, adrenal cortex, testes.
What does progesterone do to the endometrial glands and spinal artery development?
Increase secretions, increase artery growth
What does progesterone do for a pregnancy?
Maintains it
What doe progesterone do to myometrial excitability?
Decreases it
What does progesterone do to sperm travel?
Creates thick cervical mucus that inhibits sperm entry into uterus
What does progesterone do to body temperature?
What does progesterone do to gonadotropins?
Inhibits (LH, FSH)
What does progesterone do to uterine smooth muscle?
Follicular grwoth is fastest when?
during the 2nd week of the proliferative phase
The grafian follicle matures when?
The proliferative phase day 0-14
What is the sequence of Hormone surges prior to Ovulation?
Estrogen surge, then LH surge along with FSH surge.
When does Progesterone surge
During the Secreoty phase days 14-21
What hormone is associated with the Maintance of the Endometrium
What is the sorce of hCG
The syncytiotrophoblasts
What is Function of hCG: 1- physiologic, 2-diagnostic, 3-diagnostic
1- maintains the corpus luteum throughout the 1st trimester (acts like LH) 2- is useful for pregancy detection. Appears in urine 8 days post fertilization, 3- hCG is elevated in wone with hydatidiform moles
What is the average age of Menopause
51 (earlier in smokers)
Wge linked decline in number of ovarian follicles is associeated with decline in what hormone
What are th hormoneal changes during menopause
decreased estrogen, increased FSH, increased LH (but no surge), increased GnRH
What are the si/sx of menopause
HAVOC: hot flashes, Atrophy of vagina, osteoprosis, coronary artery disease
What are the androgens? Where are there sources?
Testosterone , dyhydrotestosterone (DHT), androstenedione: testis, testis/adrenal, adrenal
What are the potencies of the Andrognes?
DHT > testosterone > androstenedione
What are the targets of androgens
skin prostate, seminal vescles, epididymis, liver, muscle, brain
What active molecule is testosterone converted to? What converts it? What Drug inhibits it's conversion?
Testosterone is converted to DHT bu 5 alpha reductase which is inhibited by finasteride
What are the functions of androgens: 1-, 2-, 3-, 4-, 5-
1- differentiation of wolffian duct system into internal gonadal structures, 2- secondary sex characteristics and growth spurt, 2- required for normal spermatogenesis, 4- anabolic effects (increase in muscle size, increase in RBC production, 5- libido
What is the fate of Testosterone and androstenedione in adipose tissue?
testosterone and androstene dione are converted to estrogen in andipose tissue by enzyme aromatase.
Male sperpatogeneis
What is the function of FSH?
Stimulates sertoli cells to produce ABP and inhibin, stimulates sperm production.
What is the function of LH?
stimulates testosterone release from Leydig cells.
What is the function of ABP (androgen-binding protien)?
ensures that testosterone in seminiferous tubule is high
What is the function of Inhibin?
It inhibits FSH release from the anterior pituitary
What is the function of testosterone?
differentiates male genitalia, has anabolic effects on protein metabolisim, maintains gametogenesis, maintains libido, inhibits Gn RH, fuses epiphyseal plates in bone.