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

1 Answer

Answer :

all above

Related questions

Description : Dantrolene sodium reduces skeletal muscle tone by: A. Reducing acetylcholine release from motor nerve endings B. Suppressing spinal polysynaptic reflexes C. Inhibiting the generation of muscle action potential D. Reducing Ca2+ release from sarcoplasmic reticulum in the muscle fibre

Last Answer : D. Reducing Ca2+ release from sarcoplasmic reticulum in the muscle fibre

Description : Calcium is important in skeletal muscle contraction because it (a) binds to troponin to remove the masking of active sites on actin for myosin (b) activates the myosin ATPase by binding to it ... filament (d) prevents the formation of bonds between the myosin cross bridges and the actin filament.

Last Answer : (a) binds to troponin to remove the masking of active sites on actin for myosin

Description : Calcium is important in skeletal muscle contraction because it :- (1) binds to troponin to remove the masking of active sites on actin for myosin. (2) activates the myosin ATPase by binding to ... filament. (4) prevents the formation of bonds between the myosin cross bridges and the actin filament.

Last Answer : (1) binds to troponin to remove the masking of active sites on actin for myosin.

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 : The biochemical mechanism of action of digitalis is associated with (a) A decrease in calcium uptake by the sarcoplasmic reticulum (b) An increase in ATP synthesis (c) A modification of the actin molecule (d) An increase in systolic intracellular calcium levels (e) A block of sodium/calcium exchange

Last Answer : Ans: D

Description : Why can cardiac muscle fibres contract for longer periods than skeletal fibres? (a) Cardiac muscle is self-excitatory (b) Extracellular calcium partially controls the strength (and length) ... tubules are more developed in cardiac muscle (d) Cardiac muscle is uninucleate rather than multinucleate

Last Answer : Ans:(a)

Description : The felderstrukter fibres of the extraocular musclea. form the bulk of the orbital part of the muscle b. have poorly developed sarcoplasmic reticulum c. are singly innervated d. are more richly supplied by blood than the fibrillenstrukter fibres

Last Answer : have poorly developed sarcoplasmic reticulum

Description : Match the column - I with column - II. Column-I Column-II (A) P-wave (i) Depolarisation of ventricles (B) QRS complex (ii) Repolarisation of ventricles (C) T-wave (iii) Coronary ischaemia (D) Reduction in the size of T- wave (iv) ... ) (i) (ii) (iii) (c) (iv) (i) (ii) (v) (d) (ii) (i) (v) (iii)

Last Answer : (b) (iv) (i) (ii) (iii)

Description : Stimulation of a muscle fibre by a motor neuron occurs at (a) the neuro-muscular junction (b) the transverse tubules (c) the myofibril (d) the sacroplasmic reticulum.

Last Answer : (a) the neuro-muscular junction

Description : In the skeletal muscle: a. myosin is found in the thick filament b. the thin filament contains actin and troponin c. during stimulus excitation calcium ions are derived from the serum d. tropomyosin masks the myosin-combining sites on the actin

Last Answer : tropomyosin masks the myosin-combining sites on the actin

Description : The phase of contraction of a muscle occurs when: a) tropomyosin binds and releases actin b) myosin binds and releases actin c) actin binds and releases myosin d) none of the above

Last Answer : ANSWER: B -- MYOSIN BINDS AND RELEASES ACTIN

Description : Match the source gland with its respective hormone and function and select the correct option. Source Hormone Function gland (a) Anterior Oxytocin Contraction of uterus pituitary muscles during ... (c) Corpus Estrogen Supports pregnancy luteum (d) Thyroid Thyroxine Regulates blood calcium level

Last Answer : (b) Posterior Vasopressin Stimulates pituitary reabsorption of water in the distal tubules in the nephron

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 : The QRS complex in a standard ECG represents (a) repolarisation of auricles (b) depolarisation of auricles (c) depolarisation of ventricles (d) repolarisation of ventricles.

Last Answer : (c) depolarisation of ventricles

Description : Assertion : `Ca^(2+)` plays important role in the musclc contraction. Reason : `Ca^(2+)` Combines with troponin chain, displacing tropomyosin allowing

Last Answer : Assertion : `Ca^(2+)` plays important role in the musclc contraction. Reason : `Ca^(2+)` ... false . D. If both Assertion and Reason are false.

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 : All the following statements regarding calcium are correct except (A) It diffuses as a divalent cation (B) It freely diffuses across the endoplasmic reticulum of muscle cells (C) It can exist in the blood as ionic form and also protein bound (D) It is found in high concentration in bones

Last Answer : Answer : B

Description : In a standard ECG which one of the following alphabets is the correct representation of the respective activity of the human heart? (a) S - start of systole (b) T - end of diastole (c) P - depolarisation of the atria (d) R - repolarisation of ventricles

Last Answer : (c) P - depolarisation of the atria

Description : Which one of the following pairs of chemical substances, is correctly categorised? (a) Calcitonin and thymosin - Thyroid hormones (b) Pepsin and prolactin - Two digestive enzymes secreted in ... and myosin - Complex proteins in striated muscles (d) Secretin and rhodopsin - Polypeptide hormones

Last Answer : (c) Troponin and myosin - Complex proteins in striated muscles

Description : Myosin bridges can be prevented from combining actin by two regulator proteins in resting muscle by (a) troponin (b) myofibril (c) troponin and tropomyosin (d) natural inhibiting proteins

Last Answer : Ans:(c)

Description : The contractile proteins in a muscle are (1) Actin and Myosin (2) Actin and Tropomyosin (3) Myosin and Troponin (4)Troponin and Tropomyosin

Last Answer : (1) Actin and Myosin Explanation: Muscle fibers or myofibrils are formed of three types of proteins which are (1) contractile, (2) regulatory, and (3) structural. Contractile proteins are the force ... are Actin which is part of thin filament and Myosin, which is part of the thick filament.

Description : With reference to the skeletal muscle myofilaments a. actin is the major constituent of thin filaments b. myosin and tropomyosin combine to form the thick filaments c. troponin is a constituents of thin filaments d. tropomyosin prevents the interaction of actin and myosin in the resting state

Last Answer : actin is the major constituent of thin filaments

Description : The contractile protein of skeletal muscle involving ATPase activity is (a) troponin (b) tropomyosin (c) myosin (d) α-actinin.

Last Answer : (c) myosin

Description : The contractile proteins in a muscle are (1) Actin and Myosin (2) Actin and Tropomyosin (3) Myosin and Troponin (4) Troponin and Tropomyosin

Last Answer : Actin and Myosin 

Description : What disease is described by: "the toxin acts at the neuromuscular junction, preventing the release of neurotransmitters needed to inhibit muscle contraction." a. Botulism b. Tetanus c. The Plague d. A-C Are Correct

Last Answer : b. Tetanus

Description : The action of Vitamin K in formation of clotting factor is through (A) Post transcription (B) Post translation (C) Golgi complex (D) Endoplasmic reticulum

Last Answer : Answer : B

Description : What is needed besides calcium for muscle contraction?

Last Answer : Need answer

Description : Name the ion responsible for unmasking of active sites for myosin for cross-bridge activity during muscle contraction. (a) Calcium (b) Magnesium (c) Sodium (d) Potassium

Last Answer : (a) Calcium

Description : Which is an example of negative feedback? A) Nursing action stimulates the hypothalamus to release oxytocin that triggers mammary gland milk production. B) When the blood becomes dilute, ADH ... produce sperm or eggs. E) TRH stimulates the anterior pituitary to release thyroid-stimulating hormone.

Last Answer : B) When the blood becomes dilute, ADH is no longer released from the hypothalamus

Description : The following kinin action is mediated primarily by the kinin B1 receptor: A. Intestinal contraction B. Bronchoconstriction C. EDRF release and vasodilatation D. Production of Interleukin, TNFα and other inflammatory mediators

Last Answer : . Production of Interleukin, TNFα and other inflammatory mediators

Description : Given below is the ECG of a normal human. Which one of its components is correctly interpreted below? (a) Complex QRS - one complete pulse (b) Peak T - initiation of total cardiac ... R together - systolic and diastolic blood pressures (d) Peak P- initiation of left atrial contraction only

Last Answer : (a) Complex QRS - one complete pulse

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 : 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 : 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 : When the potential difference across a membrane of a neuron equals the threshold, what results? a) movement of the membrane b) action potential c) relaxation d) contraction

Last Answer : ANSWER: B -- ACTION POTENTIAL 

Description : Release of sperms from seminiferous tubules is called

Last Answer : Release of sperms from seminiferous tubules is called A. Spermiogenesis B. Spermiation C. Spermatogenesis D. Fertilization.

Description : What is the sequence of events of a threshold potential?

Last Answer : Death.

Description : What is the sequence of events of a threshold potential?

Last Answer : Death.

Description : Fibrinolytic therapy is based on activation of plasminogen, the inactive proteolytic enzyme of plasma that binds to fibrin during the formation of thrombosis. Activation of plasminogen to plasmin results ... TPA all exceed 30 minutes d. Streptokinase is significantly cheaper than urokinase or TPA

Last Answer : Answer: a, b, d Streptokinase is a bacterial protein produced by group C b-hemolytic streptococci. It is therefore antigenic in humans and can be associated with allergic reaction in ... one agent over the other. Streptokinase however, is markedly less expensive than either urokinase or TPA

Description : Which does NOT occur in a cell stimulated by a steroid hormone? A) The steroid hormone enters the cell by crossing the plasma membrane. B) The hormone binds to a receptor molecule in the ... activates certain genes. E) DNA is transcribed, mRNA is translated, and the result is protein synthesis.

Last Answer : C) The second messenger cyclic AMP is stimulated by the hormone-receptor complex. D) The hormone-receptor complex binds the chromatin and activates certain genes.

Description : N-acetyl cysteine is beneficial in acute paracetamol poisoning because: A. It reacts with paracetamol to form a nontoxic complex B. It inhibits generation of the toxic metabolite of ... scavenger D. It replenishes hepatic glutathione which in turn binds the toxic metabolite of paracetamol

Last Answer : D. It replenishes hepatic glutathione which in turn binds the toxic metabolite of paracetamol

Description : All of the following statements about eukaryotic promoters are true except (A) They may be located upstream or down stream from the structural gene (B) They have two consensus sequences ( ... (D) Mutations in promoter region can decrease the efficiency of transcription of the structural gene

Last Answer : Answer : A

Description : Repressor binds to DNA sequence and regulate the transcription. This sequence is called (A) Attenuator (B) Terminator (C) Anti terminator (D) Operator

Last Answer : Answer : D

Description : Following statements describe the characteristics of the enzyme restriction endonuclease. Identify the incorrect statement. (a) The enzyme recognises a specific palindromic nucleotide sequence in the DNA. (b) ... (d) The enzyme cuts the sugar-phosphate backbone at specific sites on each strand.

Last Answer : (c) The enzyme binds DNA at specific sites and cuts only one of the two strands.

Description : During transcription holoenzyme RNA polymerase binds to a DNA sequence and the DNA assumes a saddle like structure at that point. What is that sequence called? (a) AAAT box (b) TATA box (c) GGTT box (d) CAAT box

Last Answer : (c) GGTT box

Description : During transcription holoenzyme RNA polymerase binds to a DNA sequence and the DNA assumes a saddle like structure at that point. What is that sequence called? (a) AAAT box (b) TATA box (c) GGTT box (d) CAAT box

Last Answer : (b) TATA box

Description : Metoclopramide blocks apomorphine induced vomiting, produces muscle dystonias and increases prolactin release indicates that it has: A. Anticholinergic action B. Antihistaminic action C. Anti 5-HT3 action D. Antidopaminergic action

Last Answer : D. Antidopaminergic action

Description : The action of histamine that is not mediated through H1 receptors is: A. Release of EDRF from vascular endothelium resulting in vasodilatation B. Direct action on vascular smooth muscle causing vasodilatation C. Bronchoconstriction D. Release of catecholamines from adrenal medulla

Last Answer : B. Direct action on vascular smooth muscle causing vasodilatation

Description : The action of histamine that is not mediated through H1 receptors is: A. Release of EDRF from vascular endothelium resulting in vasodilatation B. Direct action on vascular smooth muscle causing vasodilatation C. Bronchoconstriction D. Release of catecholamines from adrenal medulla

Last Answer : B. Direct action on vascular smooth muscle causing vasodilatation

Description : Select the correct sequence for transport of sperm cells in male reproductive system. (a) Testis → Epididymis → Vasa efferentia → Vas deferens → Ejaculatory duct → Inguinal canal → Urethra → ... → Urethral meatus (d) Seminiferous tubules → Vasa efferentia → Epididymis → Inguinal canal → Urethra

Last Answer : (c) Seminiferous tubules → Rete testis → Vasa efferentia → Epididymis → Vas deferens → Ejaculatory duct → Urethra → Urethral meatus