Physiology

PHYSIOLOGY Pre-Boards 2006-2007 Muscle/Vision Neurotransmitter involved in skeletal muscle contraction a. Acetylcholine c. Epinephrine b. Norepinephrine d. GABA Calcium in the cell of smooth muscle binds with a. Troponin C c. Early relaxation b. Late relaxation ADP1 P1 head of muscle --- bending At the onset of muscle contraction, the initial source of conformation --- ATP for creatinine phosphate Cross bridge linkage between actin and myosin is not possible when skeletal muscle is at rest due to --- interference by tropomyosin molecule In excitation contraction coupling, what immediately follows depolarization of transverse tubule --- diffusion of Ca ion from sarcoplasmic reticulum to myofilaments During skeletal muscle, the a. H zone becomes shorter b. A band decrease in width

c. I band remains unchanged d. both a and c

Tropomyosin a. prevents binding of actin & myosin when muscle is at rest b. is a protein of thin myofibril

c. does not bind to Ca d. all of the above

Work performance is never seen when the muscle is doing a. concentric c. isometric contraction b. eccentric d. a and b Tetanus is observe in skeletal muscle if exposed to --- increase stimulation intensity Quantal summation --- also known as graded multiple motor unit summation due to recruitment of motor unit True of sympathetic nervous system except a. longer postganglionic b. arise from thoracic to lumbar nerves

c. catabolic in nature d. discrete and localized effect

Centers for regulation of cardiovascular activity and for respiration are located in the a. spinal coard c. cerebral cortex b. medulla oblongata d. limbic system All of the following have nicotinic receptors except a. radial muscle of the iris c. skeletal muscle b. sweat glands d. smooth muscle Both parasympathetic and sympathetic preganglionic fibers release a. Acetylcholine c. Norepinephrine b. Epinephrine d. L-dopamine Which of the following is/are not cholinergic a. preganglionic sympathetic fiber b. all postganglionic parasympathetic fiber

c. preganglionic parasympathetic fiber d. most preganglionic sympathetic fiber

Atropine blocks the muscarinic receptor with a. somatic neuromuscular junction b. cholinergic sympathetic neuroeffector junction

c. parasympathetic neuroeffector d. both b and c

Which of the following statements regarding acetylcholine effect is incorrect a. decrease frequency of SA node discharge c. decrease papillary diameter b. decrease intestinal motility d. increase salivary secretion The largest component of the parasympathetic division is what CN? a. vagus c. facial b. occulomotor d. glossopharyngeal The parasympathetic nerve a. give rise to a more localized b. are derived from the thoracolumbar division of the spinal cord c. has the adrenal medulla as its ganglia d. has a short preganglionic fiber The excitatory effects of the sympathetic division are seen in all of the following except a. dilator pupillae c. gastrointestinal tract b. cardiac muscle d. cutaneous blood vessels

All visceral effector cells are dually innervated except a. sweat glands c. salivary glands b. pilomotor muscle d. a and b Not a sympathetic ganglion a. terminal ganglion b. mesenteric ganglion

c. adrenal medulla d. both a and c

DMG potentiates adrenergic effects a. those prevent reuptake and NE by the postganglionic fibers b. those that inhibit MAO c. those not interact with beta receptor d. all of the above Drugs that interact the muscarinic receptors initiating Ach a. potentiates cholinergic effect c. blocks adrenergic effect b. blocks cholinergic effect d. potentiates sympathetic effect CN6 innervates the eye muscle that will move the eye a. inward c. down and out b. outward d. up and out Parasympathetic effect of the eye include the following except --- contraction of the radial muscle Refracting media of the eye include the following except a. cornea c. pupil b. lens d. aqueous humor These neurons connect the eye photoreceptors with one another and provide the lateral inhibit mechanism in visual neural circuitry a. bipolar c. amacrine cells b. horizontal cells d. ganglion cells Optic chiasm made up of a. temporal fiber for both eyes b. nasal fiber for both eyes

c. nasal fiber for the R eye and temporal fiber for the L eye d. nasal fiber for the L eye and temporal fiber for the R eye

Visual circuitry present in a. rods and cones b. bipolar cells

c. horizontal cells d. all of the above

Mostly present in cones --- color vision Highest velocity transmitting cells a. W b. X

c. Y d. all of the above

Magnocellular pathway --- movement Right optic radiation --- right nasal left temporal Point in the lens where light rays pass without refraction --- nodal point The refractive power of the lens --- increase with an increasing in the curvature of the lens Accommodation for near vision involves --- contraction of the ciliary muscle and decrease tension in the lens ligament Which is not an optical defect of an emmetropic eye --- astigmatism In hyperopia --- retina is reached by the light rays before they come into focus In presbyopia --- decrease in amplitude of accommodation Not a characteristic of rods --- they have higher threshold for light Portion of structure of the photoreceptors contains the light sensitive photochemical substance --- outer segment In dark adaptation, true is --- resynthesis constriction Color blindness upon wavelength of light --- hue Blindness to red, decrease perception to green, normal to blue --- protanopia Lesion to optic tract --- right homonymous hemianopsia Lesion to optic chiasm --- bilateral hemianopsia Stabilize resting membrane potential of Na --- increase extracellular Ca+ concentration

Saltatory conduction is possible because of --- myelination of the fiber Visual accommodation involves which of the mechanism a. relaxation of ciliary muscle b. increase in the refractive power of the lens

c. the lens is held under tension d. the lens is pulled into flattened shape

The extraocular muscle moves eyeball downward lateral --- superior oblique The only retinal neural cells that generate action potential --- ganglion cells Which of the following region of the eye has the greatest concentration of cones --- foveal region The blind spot of the eye a. contain the rod only b. has greatest concentration of cones

c. it is the region with lowest visual acuity d. is insensitive to light

The part response, accommodation, convergence of visual axes and papillary contraction is called a. near point c. near response b. light reflex d. adaptation Most common of the following refractive media of the eye except a. cornea c. pupil b. lens d. aqueous humor Blind spot is --- absent in the visual field in binocular vision The layer prevents the reflection of light rays back through the retina --- pigment epithelium Neural cells that connect one ganglion with another ganglion cells --- amacrine cells Vitamin A deficiency will lead to --- night blindness Correct about color blindness --- autosomal recessive disorder Type of receptor does epinephrine stimulate in aortic veins to produce venous constriction --- alpha 1 Nerve fibers that conducts fast pain --- type A delta Application of a supramaximal stimulus after maximum stimulation will … the size of the action potential of peripheral nerves --- no effect Pacemaker cells are present in --- smooth and cardiac T-tubule system of cardiac muscle is located --- Z discs Number of myosin binding site exposed when tropomyosin is displaced --- 7 Types of muscle fiber contribute large amount of myoglobin a. type I d. a and b b. type IIA e. b and c c. type IIB Ca is pumped actively back to the sarcoplasmic reticulum through a. Na-K ATPase pump c. Na-2Na ATPase pump b. Ca-Mg ATPase pump d. 3Na-2K ATPase pump Primary source of calcium for initiation of smooth muscle contraction a. sarcoplasmic reticulum c. intracellular calcium b. mitochondria d. extracellular calcium All of the following events occur during the latent phase of a muscle twitch except --- release of Ca from troponin Applying several stimuli of increasing intensity --- quantal summation Characteristic of isotonic contraction --- there is approximation of ends of muscle Which muscle tension is maximal during resting length a. passive tension c. total tension b. active tension d. resting tension the axons of the cells converge and leave the eye as the optic nerve a. bipolar cells c. amacrine cells b. horizontal cells d. ganglion cells Is responsible for formation of a modulated neuronal discharge --- extensor and reflex extension The generation of receptor --- withdrawal reflex Substance use to deficit EPP for muscle contraction --- tubocurarine

Norepinephrine as its major secretion a. adrenal medulla c. postganglionic sympathetic neurons of radial muscle of the iris b. adrenal cortex d. postganglionic sympathetic neurons to sweat glands Hexamethonium drug that blocks action of Acetylcholine on postganglionic autonomic neuron which has resting subject a. decrease heart rate d. increase arterial pressure b. increase heart rate e. prevent skeletal muscle vasodilatation c. disappearance of intestinal resistance Patient has been receiving phenoxybenzamine (A-blocking agent) complained of dizziness and fainting while walking up flight of stairs during his exercise --- heart rate would increase Which of the following is correct a. epinephrine produce more marked increase action potential than norepinephrine b. norepinephrine produces more marked increase action potential than epinephrine c. norepinephrine has same B2 stimulator action as epinephrine d. Epinephrine produces more extensive vasoconstriction than norepinephrine Which of the following best defines contraction --- reaction that cause the muscle to pull An isotonic contraction differs from an isometric contraction is that isotonic contraction --- muscle uses more increased energy phosphate level A skeletal muscle participating in a strenuous exercise differs from a resting skeletal muscle in that the exercising musle --exhibits all characteristics Ca++ sequestered by the sarcoplasmic reticulum of skeletal muscle during twitch is directed to a. the rate of tension d. neither b. the rate of ATP hydrolysis by myosin e. the rate of relaxation c. both The difference between slow muscle fiber twitch and fast muscle fiber twitch a. …… b. small muscle fibers in each motor unit c. higher concentration of myoglobin and mitochondria d. b and c