Physiology 1-50 Flashcards
Para-amino-hippuric acid is used as a measure of renal plasma flow because ____________.
A. It is only filtered by the renal glomerulus.
B. It is both filtered and secreted.
C. It is both filtered and reabsorbed.
D. It is both reabsorbed and secreted.
E. It is filtered, reabsorbed, and secreted
B.
Theoretically, if a substance is completely cleared from the plasma, the clearance rate of that substance is
equal to the total renal plasma flow. A substance that is completely cleared from the plasma must be both filtered and secreted and not reabsorbed. PAH is about 90% cleared from the plasma and can be used as a easure of renal plasma flow.
The threshold for drinking is reached by an increase in sodium concentration of as little as: A. 1 mEq/L B. 2 mEq/L C. 3 mEq/L D. 4 mEq/L E. 5 mE/q/L
B.
When the sodium concentration increases only about 2 mEq/L above normal, the thirst mechanism is activated, causing a desire to drink water.
Corrective lenses for near-sighted persons consist of \_\_\_\_\_\_\_\_ lenses because these lenses \_\_\_\_\_\_\_\_ light rays so that these are focused on the retina. A. Convex, converge B. Convex, diverge C. Concave, converge D. Concave, diverge E. Cylindrical lenses, converge
D.
In myopia, the image falls in front of the retina. Corrective lenses should therefore be concave so that light rays diverge and fall on the retina.
In a person eating a pure carbohydrate diet, the respiratory exchange ratio is expected to be: A. 1.0 B. 0.85 C. 0.7 D. 0.5 E. 0.25
A.
Respiratory exchange ratio is the ratio of carbon dioxide released with oxygen consumed. The normal ratio is 0.825.
However, in a pure carbohydrate diet, much more carbon dioxide is released which increases the ratio to 1.0. When
oxygen is metabolized with carbohydrates, one molecule of CO2 is formed for each molecule of O2 consumed. When oxygen reacts with fats, a large share of the oxygen combines with hydrogen atoms from the fats to form water instead of CO2.
Which part of the heart is first to repolarize? A. Base B. Septum C. Apex D. Right atria E. Right ventricle
C. The first part of the ventricles to become depolarized is the left endocardial surface of the septum. The last part of the heart to become depolarized is the outer walls of the ventricles near the base of the heart. The greatest portion of ventricular muscle mass to repolarize first is the entire outer surface of the ventricles, especially near the apex of the heart. The endocardial areas, conversely, normally repolarize last. **So confusing!**
Which glucose transporter is insulindependent? A. SGLT-1 B. SGLT-2 C. GLUT-1 D. GLUT-2 E. GLUT-3
D.
Sodium-glucose transporters are secondary active co-transport systems that depends on the sodium gradient.
GLUT-1 and GLUT-3, both present in the brain, does not depend on insulin.
When a nerve action potential reaches a muscle membrane, which of the following events take place in chronological order?
A. Opening of sodium channels ? Depolarization ? Power stroke ? Calcium release from SR
B. Depolarization ? Opening of sodium channels ? Calcium release from SR ? Power stroke
C. Opening of sodium channels ? Depolarization ? Calcium release from SR ? Power stroke
D. Depolarization ? Opening of sodium channels ? Power stroke ? Calcium release from SR
E. None of the above
C. The opening of sodium channels causes more inward positive current. This causes the depolarization of the muscle membrane.
The latch mechanism of smooth muscles serves to:
A. Increase the number of cross-bridges between actin and myosin
B. Increase the power of muscle contraction
C. Allow a prolonged relaxed state
D. Avoid muscle fatigue
E. Maintain prolonged tonic contraction
E.
Once smooth muscle has developed full contraction, the amount of continuing excitation usually can be reduced to far less than the initial level, yet the muscle maintains its full force of contraction.
Which is NOT a diabetogenic hormone? A. Growth hormone B. Epinephrine C. Cortisol D. Thyroid hormone E. Glucagon
D.
The effects of thyroid hormone on carbohydrate metabolism are both
anabolic and catabolic as thyroid hormones cause an overall increase in cellular metabolic enzymes.
Spatial summation results from action potentials that are: A. Simultaneous B. Successive C. Alternating D. Decremental E. Inadequate
A.
Temporal summation results when action potential are successive.
Sounds of high frequency stimulate basilar fibers located near the oval window because in this location, the basilar fibers are: A. Short and stiff B. Short and limber C. Long and limber D. Long and stiff E. None of the above
A.
The lengths of the basilar fibers increase progressively beginning at the oval window and going from the base of the cochlea to the apex. The diameters of the fibers, however, decrease from the oval window to the helicotrema, so that their overall stiffness decreases more than 100-fold. As a result, the stiff, short fibers near the oval window vibrate best at a very high frequency.
At the base of the lungs, there is relatively more perfusion than ventilation. This is: A. Physiologic dead space B. Physiologic shunt C. Anatomic dead space D. Anatomic shunt E. None of the above
B.
At the apex, there is relatively more ventilation than perfusion. This is physiologic dead space.
Which waste product plays a crucial role in maintaining the hyperosmolarity of the renal interstitium? A. Hydrogen ion B. Urea C. Carbon dioxide D. Glucose E. Water
B.
Urea is passively reabsorbed from the medullary collecting tubules to maintain a hyperosmolar renal interstitium. This promotes water reabsorption, thus, leading to the formation of a concentrated urine.
Cushing's syndrome is ACTH-independent if the lesion occurs in the: A. Adrenal B. Pituitary C. Hypothalamus D. Ectopic sites E. All of the above
A.
The hypercortisolism from an adrenal cause of Cushing’s syndrome is not due to an increased ACTH. These patients have, in fact, low or undetectable levels of ACTH. Hence, it is ACTHindependent
Which GI hormone receptor belongs in the CCK family of receptors? A. Gastrin B. Secretin C. Histamine D. Pepsin E. Insulin
A.
CCKB is the receptor for gastrin. CCKA is for cholecystokinin.
The Edinger-Westphal nucleus of the oculomotor nerve serves \_\_\_\_\_\_\_ functions. A. Sensory B. Motor – sympathetic C. Motor – parasympathetic D. Both sensory and motor E. Neither sensory nor motor
C.
This nucleus functions in
accommodation of the eye.
Which is a correct statement regarding acetylcholine?
A. It binds both to nicotinic and adrenergic receptors.
B. It is usually the hormone released by post-synaptic sympathetic neurons.
C. It is rapidly degraded by pseudocholinesterases.
D. Its receptors located in the muscle membrane are of the nicotinic type.
E. It functions only in the parasympathetic system.
D.
Acetylcholine functions both in the parasympathetic and sympathetic systems. It is degraded by acetylcholinesterase. Receptors for acetylcholine are of the nicotinic and muscarinic types.
In blood vessels, compliance is a function of: A. Pressure and viscosity of blood B. Pressure and volume C. Volume and length of vessel D. Pressure and length of vessel E. Volume and viscosity of blood
B.
A blood vessel is compliant if its volume increases with a corresponding increase in pressure.
Which hormone accounts for the increase in basal body temperature noted around the time of ovulation? A. FSH B. LH C. Estrogen D. Progesterone E. Prolactin
D.
This is the thermogenic effect of progesterone. The increase in temperature is about 0.5 degree Fahrenheit.
Capacitation of the spermatozoon occurs in the: A. Testes B. Epididymis C. Vas deferens D. Spongy urethra E. Female genital tract
E.
Capacitation refers to the collective changes that activate the sperm upon coming in contact with the fluids of the female genital tract. These changes make it possible for the sperm to penetrate the ovum. Maturation occurs in the epididymis
