Question

21) Nerve depolarization occurs whern a) Na channels open and Na+ rushes into the neuron b) Na+ channels open and Na+ rushes out of the neuron c) K+ channels open and K+ rushes into the neuron d) K+ channels open and K+ rushes out of the neuron 22) Nerve repolarization occurs when: a) b) c) d) Na+ channels open and Na+ rushes into the neuron Na+ channels open and Na+ rushes out of the neuron K+ channels open and K+ rushes into the neuron K+ channels open and K+ rushes out of the neuron 23) During the absolute refractory period, a neurorn a) Fires continuously b) c) Can only transmit impulses if it is stimulated more than normal Can not transmit impulses during this time 24) In a reflex The impulse goes into the spinal cord and is processed by the brain before a response occurs. Sensory information enters on the dorsal side of the spinal cord and motor information exits on the ventral side. Sensory information enters on the ventral side of the spinal cord and motor information exits on a) b) c) the dorsal side. d) Sensory and motor information run in and out of the spinal cord at the same point

Answer 1

Answer=

21.Nerve depolarization occurs when

a) Na⁺ channels open and Na+ rushes into the cell.

Explanation - Nerve depolarization occurs when a stimulus reaches a resting neuron.

During the depolarization phase,the gated sodium ion channels on the neuron's membrane suddenly open and allow sodium ions (Na⁺⁾ )present on outside the membrane to rush into the neuron cell.

- Occurs when inside of cell becomes less negative.

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22.Nerve repolarization occurs when

d) K⁺ channels open and K+ rushes out of the neuron.

Explanation= repolarization typically results from the movement of positively charged K+ ions out of the cell .

- K+ ion channels are open and K+ ions are rushes out of the cell.

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23.During the absolute refractory period,a neuron

c) Can not transmit impulses during this time.

Explanation-This is the time during which another stimulus given to the neuron will not lead to a second action potential.

Thus,because Na⁺ channels are inactivated during this time,additional depolarizing stimuli do not lead to new action potentials.

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24.During a reflex

c) Sensory information enters on the ventral side of the spinal cord and motor information exits on the dorsal side.

Explanation - sensory neuron carries sensory nerve impulses from receptor organ to CNS.its cyton is located in dorsal root ganglion.

The motor neuron conducts motor impulses from the spinal cord to effector organs.

its cyton is present in the ventral horn of grey matter and axon travels through ventral root.