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Parathyroid hormone (PTH) enhances the release of calcium from the bone into the blood. Its secretion is controlled by a negative-feedback system between the concentration of calcium in the blood and the PTH-producing cells. Therefore, which of the following is correct?
a decrease in blood calcium concentration stimulates PTH secretion, which in turn increases the blood calcium concentration.
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Taking ecstasy (MDMA) can cause excess water ingestion and increased water retention in users. Water intoxication can lead to serious side effects because:
water enters cells by osmosis leading to cell swelling
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All of the following decrease the rate of diffusion for a molecule through a membrane EXCEPT?
decreasing the distance a molecule needs to move
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Which of the following conditions would increase the glucose transport into a cell?
- d: a & b
- a: increasing the number of glucose transporters in the plasma membrane
- b: increasing the Vmax of the glucose transporters present in the plasma membrane
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With secondary active transport, the movement of:
- a: Na+ into the cell by the co-transport carrier is down its electrochemical gradient
- c: Energy is required to pump Na+ out of the cell
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Poisoning (blocking) the sodium-potassium pump would most likely result in:
- d: a and c
- a: a more positive resting membrane potential
- c: cell swelling due to sodium accumulation and water uptake
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Assume that a membrane that is permeable to Cl- but not to Na+ separates two solutions. The concentration of sodium chloride on side 1 is much higher than side 2. Which of the following ionic movements will take place?
a membrane potential, positive on side 1 will develop
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Mutation in an epithelial sodium channel that prevents its degradation, such as occurs in Liddle syndrome leads to:
increased blood sodium
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If the extracellular concentration of Na+ is 120 mM and the intracellular concentration is 12 mM, at 370C the equilibrium potential for Na+ would be ___ using the Nernst equation.
+61.5
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Which of the following about the resting membrane potential is FALSE?
membrane permeability to Na+ is higher than to K+ at rest
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Hyperpolarization can result from
K+ moving out of the cell
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Sodium channels:
- -possess alpha and beta subunits
- -have open activation and inactivation gates during the depolarization phase of the action potential
- -have closed activation gates and open inactivation gates at rest
- ALL OF THE ABOVE
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Tetrodotoxin:
blocks Na+ channel and prevents membrane depolarization
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During the repolarization phase of the action potential
- -potassium channels are open
- -sodium channels are inactivated
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Low extracellular calcium causes:
- -increased excitability of neurons
- -decreased threshold of neurons
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A drug that prolongs the action potential duration could exert its action by:
- -blocking potassium channels
- -preventing sodium channel inactivation
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Select the INCORRECT statement about the action potential
can increase in amplitude when a neuron is stimulated at high frequency (eg. Piggybacking)
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Which of the following about saltatory conduction is TRUE?
involves the impulse jumping from one node of Ranvier to the adjacent node
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Spatial summation occurs in a postsynaptic neuron
when EPSPs from several presynaptic inputs sum to reach threshold
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Which of the following statements concerning refractory periods is/are CORRECT?
- ALL OF THE ABOVE:
- -the absolute refractory period refers to the period of time during which another action potential cannot be initiated in a patch of membrane that has just undergone an action potential, no matter how strong the stimulus.
- - the absulute refractory period corresponds to the time period during which the Na+ gates are first opened and then closed and inactivated
- -during the relative refractory period, the patch of nerve fiber membrane that has just undergone an action potential can be restimulated only by a stronger stimulus that is usually necessary.
- -the absolute and relative refractory periods assure the unidirectional spread of the action potential down the nerve fiber away from the initial site of activation
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Assume a hypothetical postsynaptic neuron has three presynaptic inputs--X, Y, and Z. When presynaptic neuron X and Y are stimulated simultaneously, the postsynaptic neuron reaches threshold and undergoes an action potential, yet when presynaptic neuron Y and Z are stimulated simultaneously, there is no change in potential of the postsynaptic neuron. What can you tell about presynaptic neurons Y and Z?
presynaptic neuron Y is excitatory, and presynaptic neuron Z is inhibitory
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The skeletal muscle membrane at the motor end plate
- -contains receptor sites that are capable of binding curare
- -contains acetylcholinesterase
- -increases in permeability to cations when receptors bind to acetylcholine
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Cross-bridge cycling occurs when:
calcium binds to troponin, which exposes actin binding sites covered by tropomyosin
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During muscle contraction, the
A band remains unchanged
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Which steps in muscle contraction do NOT require ATP?
calcium release by the SR
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All of the following agents wold cause rigid paralysis EXCEPT
TTX
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Which of the following statements about malignant hyperthermia is FALSE?
Troponin cannot bind to calcium in the presence of anesthetic agents
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Compared to a long distance runner, an Olympic weight lifter would
have muscles with greater glycolytic activity
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Which of the following statements about smooth muscles is INCORRECT?
it uses more energy than skeletal or cardiac muscle
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Cross-bridge activation in smooth muscle depends on all of the following EXCEPT:
ATP phosphorylation of actin
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When comparing skeletal and cardiac muscle, which of the following is INCORRECT?
nervous stimulation is required for both skeletal and cardiac muscle
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Which of the following are characteristic(s) of sensory neurons?
Nociceptors adapt slowly or not at all to noxious stimulation
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In the case of Isidro Meija, he lost his ability to communicate in English following his accident. The area of the brain that was most likely damaged and affected his speech was the
Broca's area
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Which of the following is CORRECT?
stimulation of the golgi tendon organ results in reflex relaxation of the attached muscle
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In the withdraw/crossed-extensor reflex:
- -There is an IPSP to the hip flexor motor neuron on the contralateral side
- -There is an IPSP to the hip extensor on the ipsilateral side
- -Both of the above
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All of the following statements about pain are true EXCEPT:
endorphins stimulate the release of substance P
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The brain
- -has 4 ventricles which produce cerebral spinal fluid via the choroid plexus
- -is protected by the 3 layers of the meninges
- -possesses a blood brain barrier except in the emetic center and posterior pituitary
- -ALL OF THE ABOVE
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The parasympathetic nervous system:
- -Both A and B
- -A: has long, myelinated preganglionic and short, unmyelinated postganglionic neurons
- -B: has cholinergic preganglionic and postganglionic fibers
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Which statement characterizes sympathetic activity?
the secretion of the sweat glands is stimulated
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Atropine is a ______ and ______ which acts to _____ heart rate.
muscarinic antagonist, sympathomimetic, increase
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_____ blood enters the ______ from the _____.
deoxygenated, right atrium, vena cava
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The wall of the left ventricle is thicker than the wall of the right ventricle because the
left ventricle must pump the same amount of blood into the high-resistance, high-pressure systemic system as does the right ventricle into the low-resistance, low-pressure pulmonary system.
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The AV valves are closed and the semilunar valves are open during
ventricular ejection
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When aortic pressure>atrial pressure>ventricular pressure
The semilunar valves are closed
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Which of the following factors will INCREASE cardiac output?
Acetylcholine _____ heart rate by increasing ____ permeability of SA nodal cells, causing _____ of the SA node.
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The neurotransmitter norepinephrine
- A and B
- A: increases the heart rate
- B: increases the contractile strength of the heart muscle
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Which is the normal sequence of the cardiac cycle?
1. QRS complex
2. P wave
3. atrial contraction
4. ventricular ejection
5. First heart sound
6. Second heart sound
2-3-1-5-4-6
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_____ are the major resistance vessels, _____ are the exchange vessels, _____ are capacitance vessels, and _____ return filtered fluid to the circulation.
arterioles, capillaries, veins, lymphatics
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Which of the following factors would DECREASE blood flow?
- A and B
- A: decrease the radius of the blood vessel
- B: decrease the pressure gradient within the blood vessel
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Each of the following factors produces the contraction of arteriolar smooth muscle EXCEPT:
nitric oxide
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A sudden decrease in pressure within the carotid sinus will result in
- A and B
- A: decreased firing rate of barorecptors
- B: reflex increased sympathetic nerve activity and decreased parasympathetic nerve activity
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Each of the following will cause an increase in blood pressure EXCEPT
increased levels of atrial natriuretic factor
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In the online case study, Dee had a genetic test performed to determine her genotype for the angiotensinogen gene. Because she had the ____ genotype, her preferred treatment would be _____.
TT, ACE inhibitors
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Which of the cardiac biomarkers rises earliest following a heart attack?
GP-BB
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In the capillaries, fluid will move from the tissue into the blood when there is
increased tissue hydrostatic pressure
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Of the formed elements in the blood _____ are the smallest cells, _____ are the most numerous cells, and _____ are nucleated cells.
platelets, erythrocytes, leukocytes
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Which of the following cells is the precursor to the different types of blood cells?
hemocytoblast
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Neutrophills are _____ and function to _____.
granulocytes, phagocytize microbes
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Which of the following WILL NOT lead to anemia?
living at high altitude
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Hemoglobin:
- Both A and C
- A: binds O2 on the heme group, CO2 on the globin protein
- C: can turn green in color when combined with sulfur
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Which of the following is part of the hemostasis response?
platelets release ADP as a chemoattractant for plug formation
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The last 3 steps of common pathway of blood coagulation are in order:
factor X in converted to Xa, prothrombin is converted to thrombin, fibrinogen is converted to fibrin
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Which of the following agents act to prevent platelet aggregation?
ADP receptor blockers
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An individual with type O blood possesses _____ antigens on their RBCs and _____ antibodies in their plasma.
neither A nor B antigens, both A and B antibodies
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When the diaphragm relaxes
the intra-alveolar pressure increases
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At sea level, the arterial blood PO2 is approximately ___ and PCO2 is approximately ___.
100 mmHg, 40 mmHg
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When airflow is very low compared to the blood flow to the alveoli, what mechanism(s) are responsible for balancing the ventilation with the perfusion?
- A and B
- A: Increased CO2 causes relaxation of the airway smooth muscle
- B: Decreased O2 causes vasoconstriction
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Which of the following will shift the PO2 versus % hemoglobin saturation curve to the right?
a decrease in pH
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In the spirogram show above, how would you determine expiratory capacity?
B+C
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Which of the following statements concerning pulmonary surfactant is FALSE?
pulmonary surfactant is secreted by Type I alveolar cells
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Which of the following correctly describes CO2 transport?
Most CO2 is converted to carbonic acid in red blood cells, which dissociates to H+ ion and bicarbonate ion.
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The primary regulator of the magnitude of ventilation in normal circumstances is the
H+ concentration of the brain extracellular fluid monitored by central chemoreceptors
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Select the correct statement(s) about the neuronal mechanisms of respiratory control.
The dorsal respiratory group neurons establish the pattern of breathing at rest.
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Which of the following is not a function of the kidneys?
secreting aldosterone to regulate sodium
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The majority of tubular reabsorption occurs in the
proximal convoluted tubule
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Afferent arteriolar vasoconstriction ______ blood flow into the glomerulus, which causes the glomerular-capillary blood pressure to ______, leading to a(n) ______ in the net filtration pressure and a resultant ______ in the GFR.
decreases, decrease, decrease, decrease
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Decreased fluid flow to the macula densa leads to
- B and C
- B: Increased release of renin
- C: Decreased Na+ concentration in the fluid reaching the macula densa
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Hypersecretion of aldosterone would lead to
Hypokalemia
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The ascending limb of the loop of Henle is where
NaCl is actively transported into the interstitial fluid, leaving water behind because the tubular cells are not permeable to water.
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Dehydration leads to _____ blood osmolality, _____ release of ADh, and _____ reabsorption of water by the renal tubules.
increased, increased, increased
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When the bladder wall is distended as a result of urine accumulation, the stretch receptors are stimulated and send afferent impulses to the spinal cord that
- Both A and B
- A: stimulate parasympathetic nerves, which return to the bladder and cause it to contract.
- B: inhibit the motor neurons that normally keep the external urethral sphincter closed
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What compensatory mechanism(s) restore(s) normal pH during alkalosis?
- -hypoventilation
- -increased absorption of H+
- -increased secretion of HCO3-
- ALL OF THE ABOVE
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An elderly woman is in a coma after suffering a stroke. She is in the intensive care unit and has been placed on a ventilator. Arterial blood measurements from the patient reveal the following:
pH = 7.30, pCO2 = 60 mmHg, [HCO3] = 24 meq/liter
What is your diagnosis of these results?
uncompensated respiratory acidosis
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A 28-year-old man has been sick with the flu for the past week, vomiting several times every day. He is having a difficult time keeping solids and liquids down, and has become severely dehydrated. After fainting at work, he was taken to a walk-in clinic, where an IV was placed to help rehydrate him. Arterial blood was drawn first, revealing the following:
pH = 7.5, pCO2 = 50 mmHg, [HCO3] = 32 meq/ liter
What is your diagnosis based on these results?
compensated metabolic alkalosis
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