Home
Class 12
BIOLOGY
Assertion:When an impules arrives at the...

Assertion:When an impules arrives at the end plate of an axon, the vesicals releases acetylcholine into the myoneural junction
Reason:Acetylcholine diffuses across the nerve-muscle gap ,binds to receptors on the sarcolemma which gets depolarized and results in cantraction of the muscle fibre.

A

if both assertion and reason are true and the reason is correct explanton of Assertion

B

IF both assertion and reason are true but reason is not a correct explanation of assertion

C

IF assertion is true and reason is wrong

D

if both assertion and reason are wrong

Text Solution

AI Generated Solution

The correct Answer is:
### Step-by-Step Solution: 1. **Understanding the Assertion**: - The assertion states that when an impulse arrives at the end plate of an axon, vesicles release acetylcholine into the myoneural junction. - This is true because the arrival of an action potential at the axon terminal triggers the release of neurotransmitters from synaptic vesicles. 2. **Understanding the Reason**: - The reason explains that acetylcholine diffuses across the nerve-muscle gap, binds to receptors on the sarcolemma, which leads to depolarization and results in muscle fiber contraction. - This is also true as the binding of acetylcholine to its receptors on the sarcolemma initiates a series of events that lead to muscle contraction. 3. **Analyzing the Relationship**: - The reason provided explains the mechanism by which the assertion occurs. The release of acetylcholine (assertion) leads to its binding to receptors and subsequent muscle contraction (reason). - Therefore, the reason is a correct explanation of the assertion. 4. **Conclusion**: - Since both the assertion and reason are true, and the reason correctly explains the assertion, the correct answer is: - **1. Both assertion and reason are true and reason is the correct explanation of assertion.**
Promotional Banner

Similar Questions

Explore conceptually related problems

Assertion: Calcium required for skeletal muscle contraction Reason: Calcium influx releases acetylcholine at neuromuscular junction.

[A] : Acetylchoiine allows a nerve cell to com- municate chemically with a muscle cell at neuromuscular junction. [R]: Acetyicholine diffuses across the junc- tion and binds to some receptors on mem- brane of muscle cell.

Which option is correct for conduction of nerve impulse along chemical synapse? i. At synapse, the membranes of the pre and postsynaptic neurons are separated by a fluid-filled space called synaptic cleft ii. Chemicals called neurotransmitters are incolved in the transmission of impulses at these synapses iii. The axom terminals contain vesicles filled with these neurotransmitters iv. When an impulse arrives at the axon terminal, synaptic vesicles release their neurotransmitters in the synaptic cleft. v. The release neurotransmitters bind to their specific receptors, present on the pre-synaptic membrane. vi. Opens ion channels allowing the entry of ions which can generate a new potential in the postsynaptic neuron vii. The new potential developed is only excitatory

Which of the following statements given below are true with reference to muscle contraction. I. Neurotransmitter acetycholine is released as nerve impulse reaches the end of axon and binds to receptor sites of motor end plate. II. Action potential passes from motor end plate over sarcoplasmic and then into the T-tubules and sarcoplasmic reticulum. III. Calcium ion are released into the sarcoplasm bind to troponin, causing a change in its shape and position. IV. Myosin cross bridges are able to bind to exposed active sites of actin. Choose the correct option.

Which statements about muscle contractions are true (i) Acetylcholine is released when neural signal reaches motor end plate (ii) Muscle contraction is initiated by a signal sent by CNS via a sensory neuron (iii) During muscle contraction , isotropic band gets elongated (iv) Repeated activation of the muscle can lead to lactic acid accumulation .

Which of the following statements about the mechanism of muscle contraction are correct ? (i) Acetylcholine is released when the neural signal reaches the motor end plate. Muscle contraction is initiated by a signal sent by CNS via sensory neuron. (iii) During muscle contraction, isotropic band gets elongated (iv) Repeated activation of the muscles can lead to lactic acid accumulation.

Read the following statements and select the correct option : I. In the skeletal muscles fibre, large number of myofilaments are arranged in the sarcoplasmic . II. The central part of an anisotropic band where the only thick , filament is present and thin filament is absent is called 'A' band. III. In the resting state , a tropomyosin protein masks the active b binding sites for myosin on the active filaments . IV. The junction between a motor neuron and the sarcolemma of the muscle fibres is called motor-end plate.

Following is given a randomly arranged list of events that occur at neuromuscluar junction to trigger mucle contraction. (i) Receptor sites on sarcolemma Nerve impulse (iii) Release of Ca^(+2) from sarcoplasmic reticulum (iv) The neurotransmitter acetylcholine is released (v) Sarcomere shorten (vi) Synaptic cleft (vii) Spread of impulses over sarcolemmna on T-tubules Which of the following gives the correct sequence of these steps?

Which of the statements about the mechanism of muscle contraction are corrcet (I) Acetylcholine is released when the neural signal raches the motor end plate (II) Muscle contration is initiated by a singnal sent by CNS via a sensory neuron (III) During muscle contration, isotropic band gets elongated (IV) Repeated activation of the muscles can be lead to lactic acid eccumulation