Question

(iv) Which of these are the first and last elements in a spinal reflex?
(A) axon and dendrite
(B) sense organ and muscle effector
(C) ventral horn and dorsal horn
(D) motor neuron and sensory neuron​

Answer 1

Answer:

iv) Motor neuron and sensory neuron.

A) Axon – The long, thin structure in which action potentials are generated; the transmitting part of the neuron. After initiation, action potentials travel down axons to cause release of neurotransmitter. Dendrite – The receiving part of the neuron.

C) The ventral horns contains the cell bodies of motor neurons that send axons via the ventral roots of the spinal nerves to terminate on striated muscles.

The dorsal horn (also known as the posterior horn) contains neurons that receive somatosensory information from the body, which is then transmitted via the ascending pathways, to the brain.

D) Motor neurones are cells in the brain and spinal cord that allow us to move, speak, swallow and breathe by sending commands from the brain to the muscles that carry out these functions. Their nerve fibers are the longest in the body, a single axon can stretch from the base of the spinal cord all the way to the toes.

Sensory neurons are the nerve cells that are activated by sensory input from the environment - for example, when you touch a hot surface with your fingertips, the sensory neurons will be the ones firing and sending off signals to the rest of the nervous system about the information they have received.