Description : The action potential of a neuron a. is initiated by efflux of Na+ b. is terminated by efflux of K+ c. declines in amplitude as it moves along the axon d. results in a transient reversal of the ... the cell membrane e. is not associated with any net movement of Na+ or K+ across the cell membrane
Last Answer : is terminated by efflux of K+
Description : Assertion : The contraction and relaxation of muscle fiber are controlled by nerve impulses. Reason : The threshold stimulus is the minimum stimulus r
Last Answer : Assertion : The contraction and relaxation of muscle fiber are controlled by nerve impulses. Reason : ... D. If both Assertion and Reason are false.
Description : Which one of the following describes the mode of action of tetanospasmin? a. It inhibits muscle contraction. b. It damages and lyses red blood cells. c. It disrupts cell tissues. d. It inhibits muscle relaxation.
Last Answer : d. It inhibits muscle relaxation.
Description : Consider the following statements: 1. In a resting neuron, there is difference in electrical charge on either side of surface membrane called potential difference. 2. It is due to unequal distribution of K+ ions and Na+ ions on either side if the ... ? (a) 1 only (b) 1, 2 (c) 1, 2, 3 (d) 1, 2, 3, 4
Last Answer : Ans:(b)
Description : Which of the following statements is not correct? (a) An action potential in an axon does not move backward because the segment behind is in a refractory phase. (b) Depolarisation of hair cells ... d) In the knee-jerk reflex, stimulus is the stretching of muscle and response is its contraction.
Last Answer : (c) Rods are very sensitive and contribute to daylight vision.
Description : Which cells are responsible for contraction and relaxation movements? -Biology 9th
Last Answer : answer:
Description : During contraction and relaxation of striated muscle fibre the length of A band usually :-
Last Answer : During contraction and relaxation of striated muscle fibre the length of A band usually :- A. ... . Increases C. Decreases D. Decreases too much
Description : The following are true: a. Kirschman's law: the greatest contrast in colour is seen when the luminosity differnece is small b. Emmbert's law: the perceived size of an object varies in ... image in the periphery of the retina tends to fade or disappear during steady fixation of another objec
Last Answer : Troxler's phenomenon: an image in the periphery of the retina tends to fade or disappear during steady fixation of another objec
Description : Inhibition of the Edinger-Westphal nucleus: a. causes relaxation of the iris sphincter b. causes contraction of the iris dilator c. occurs in deep sleep d. occurs with narcotics
Last Answer : causes contraction of the iris dilator
Description : The effects of topically applied anticholinesterase on the eye include: a. conjunctival hyperaemia b. raised intraocular pressure c. ciliary muscle contraction d. sphincter pupillae muscle relaxation e. retraction of the upper lids
Last Answer : ciliary muscle contraction
Description : Lack of relaxation between successive stimuli in sustained muscle contraction is known as (a) tetanus (b) tonus (c) spasm (d) fatigue.
Last Answer : (a) tetanus
Description : Which of the following DOES NOT cause depression of the mandible: A. Contraction of lateral pterygoid B. Contraction of temporalis C. Contraction of the suprahyoid muscles D. Contraction of the ... E. Relaxation of all muscles so that the only forces on the mandible are the forces of
Last Answer : B. Contraction of temporalis
Description : During inspiration, the diaphragm moves: a) down by contraction b) down by relaxation c) up by contraction d) up by relaxation
Last Answer : ANSWER: A -- DOWN BY CONTRACTION
Description : Following statement is true about lidocaine (a) Reduce the slope of Phase 4 (b) Threshold excitability is not altered (c) Action potential is not affected (d) All of the above
Last Answer : Ans: A
Description : During the propagation of a nerve impulse, the action potential results from the movement of (a) K+ ions from intracellular fluid to extracellular fluid (b) Na+ ions from extracellular ... extracellular fluid to intracellular fluid (d) Na+ ions from intracellular fluid to extracellular fluid.
Last Answer : (b) Na+ ions from extracellular fluid to intracellular fluid
Description : What are the functions of potassium? (A) In muscle contraction (B) Cell membrane function (C) Enzyme action (D) All of these
Last Answer : Answer : D
Description : The potential difference across the membrane of a relaxed muscle fiber is called resting potential. It amounts to about
Last Answer : The potential difference across the membrane of a relaxed muscle fiber is called resting potential. It amounts to ... C. `100m V` D. `50- 100mV`
Description : The effect of noradrenaline on the heart include: a. tachycardiac b. increased duration of the cardiac action potential c. decreased potassium conductance of the membranes of pacemaker cells d. increased strength of cardiac contraction
Last Answer : increased strength of cardiac contraction
Description : The sequence of events in muscle contraction a. action potential depolarise the T-tubules b. depolarisation of T-tubules release calcium from sarcoplasmic reticulum c. calcium binds to the troponin-tropomycin complex d. all above
Last Answer : all above
Description : The sodium/potassium pump is primarily responsible for the: a) resting potential b) action potential c) excretion of salts d) contraction of muscle fibers
Last Answer : ANSWER: A -- RESTING POTENTIAL
Description : Cell regulation can be thought of as the effector side of cell communication. Most commonly cell regulation occurs by means of extracellular chemical messengers. Which of the following statement(s ... d. Most hormones, local mediators, and neurotransmitters readily cross the cell plasma membrane
Last Answer : Answer: b, c Depending on how the extracellular messenger arrives, cell regulation can be classified as paracrine, endocrine, or neurocrine. In paracrine regulation, a chemical messenger ... , local mediators, and neurotransmitters are water-soluble and cannot readily cross the plasma membrane
Description : When a neuron is in resting state i.e., not conducting any impulse, the axonal membrane is (a) comparatively more permeable to Na+ ions and nearly impermeable to K+ ions (b) equally permeable to both ... + and K+ ions (d) comparatively more permeable to K+ ions and nearly impermeable to Na+ ions.
Last Answer : (d) comparatively more permeable to K+ ions and nearly impermeable to Na+ ions.
Description : What is the movement of material across a membrane called?
Last Answer : Need answer
Description : Which of the following statement(s) is/are true concerning water movement across cell membranes? a. Water moves only actively through cell membrane transport proteins b. For most cells of ... cells such as the glomerulus of the kidney actively transport water to maintain hydrostatic pressure
Last Answer : Answer: b, c The energetics of water transport across cell membranes is simplified by the fact that water moves only passively due to gradients of hydrostatic pressure or water ... water is distributed at equilibrium. Water distribution is determined entirely by solute to solute distribution
Description : Osmosis is a. movement of solvent across a semipermeable membrane from an area where the hydrostatic pressure is high to an area where the hydrostatic pressure is low b. movement of solute across a ... area in which it is in high concentration to an area in which it is in low concentration
Last Answer : movement of solvent across a semipermeable membrane from an area in which it is in high concentration to an area in which it is in low concentration
Description : Type of synapse in which transmission of impulse across neuron is similar to conduction along a single axon
Last Answer : Type of synapse in which transmission of impulse across neuron is similar to conduction along a single axon
Description : Cromolyn has as its major action (a) Block of calcium channels in lymphocytes (b) Block of mediator release from mast cells (c) Block of phosphodiesterase in mast cells and basophils (d) Smooth muscle relaxation in the bronchi (e) Stimulation of cortisol release by the adrenals
Last Answer : Ans: B
Description : In the intact animal H2 receptor antagonists potentiate the following action of histamine: A. Cardiac stimulation B. Fall in blood pressure C. Uterine relaxation D. Bronchospasm
Last Answer : D. Bronchospasm
Description : The anaesthetic action of thiopentone sodium is characterised by: A. Good muscle relaxation B. Poor analgesia C. Sensitization of heart to adrenaline D. No postoperative residual CNS depression
Last Answer : B. Poor analgesia
Description : The following action of adrenaline is mediated by both α and β receptors producing the same directional effect: A. Cardiac stimulation B. Intestinal relaxation C. Dilatation of pupil D. Bronchodilatation
Last Answer : B. Intestinal relaxation
Description : . A shortest time span in the life cycle of a crop when weeding results in highest eco nomic returns a). Economic threshold b). Critical period c). Competitive threshold d). None of these
Last Answer : b). Critical period
Description : When a stimulus is applied on axonal membrane then generation of action potential is due to
Last Answer : When a stimulus is applied on axonal membrane then generation of action potential is due to
Description : Consider the following statements: 1. When a nerve fibre is stimulated, a profound change is produced in the electrical properties of surface membrane and in steady potential. 2. Upon excitation, the resting potentialis suddenly changed. 3. It is due ... 1, 2, 3 (b) 2, 3 (c) 1, 2, 3, 4 (d) 1, 2, 4
Last Answer : Ans:(d)
Description : The following are true about an action potential in a nerve fibre: a. it occurs when its membrane potential is hyperpolarized b. it is associated with a transient increase in membrane ... permeability to potassium d. it has an amplitude which varies directly to the strength of stimulus
Last Answer : there is a decreased in membrane permeability to potassium
Description : In the neurone: a. the magnitude of the action potential is dependent on the strength of the stimulus b. impulses can travel in both direction c. depolarization is accompanied by increased ... potassium ions d. during depolarization, the potential of the neurone changes from -70mV to +40mV
Last Answer : during depolarization, the potential of the neurone changes from -70mV to +40mV
Description : The following processes depend on changes in membrane conductance to Na and K. a. Action potential b. depolarization c. repolarization d. all of them
Last Answer : all of them
Description : The most significant feature of the antiarrhythmic action of lignocaine is: A. Suppression of phase-4 depolarization in ventricular ectopic foci B. Prolongation of action potential duration C. Prolongation of effective refractory period D. Depression of membrane responsiveness
Last Answer : A. Suppression of phase-4 depolarization in ventricular ectopic foci
Description : The electrophysiological effects of digitalis on Purkinje fibres include the following except: A. Enhancement of resting membrane potential B. Decrease in the slope of phase-0 depolarization C. Increase in the rate of phase-4 depolarization D. Abbreviation of action potential duration
Last Answer : A. Enhancement of resting membrane potential
Description : What parts of a neuron is capable of generating a graded potential?
Last Answer : The dendrites portion of a neuron will generate a potential.
Description : The resting potential of a neuron is dependent on what two ions? a) lead and calcium ions b) calcium and phosphate ions c) sodium and potassium ions d) potassium and phosphate ions
Last Answer : ANSWER: C -- sodium and potassium ions
Description : What is the sequence of events of a threshold potential?
Last Answer : Death.
Description : The excess energy of reactants in a chemical reaction required to dissociate into products is termed as the __________ energy. (A) Activation (B) Potential (C) Binding (D) Threshold
Last Answer : (A) Activation
Description : Which of the following terms indicates the amount of blood pumped out of the ventricle with each contraction of the heart? a) Stroke volume Stroke volume is the amount of blood pumped out ( ... d) Preload Preload is the pressure created by a volume of blood within a ventricle before contraction.
Last Answer : a) Stroke volume Stroke volume is the amount of blood pumped out (ejected) with each contraction of the heart (heart beat). Stroke volume times heart rate equals cardiac output.
Description : The true power indicated by the pointer movement of a wattmeter depends on the current flow through the load, the magnitude of the potential across the load, and the ____________. A. power factor of the ... B. angle of coil displacement C. inertia of the movable coil D. high resistance from the load
Last Answer : Answer: A
Description : Microtubule is involved in the (a) muscle contraction (b) membrane architecture (c) cell division (d) DNA recognition
Last Answer : (c) cell division
Description : In human relations the irritation threshold is the A. action that causes an annoyance. B. frequency of the annoying behavior. C. point at which a person notices something and becomes annoyed. D. lengt?