1 Rank the components of a reflex arc in the correct order f

1. Rank the components of a reflex arc in the correct order from stimulus to response.

A.control center

B. effector organ

C. motor neuron

D. receptor

E. sensory neuron

2. When eliciting the withdraw and crossed-extensor reflexes, flexion withdrawal occurs in the __________ (contralateral/ipsilateral) limb, whereas extension occurs in the _________(contralateral/ipsilateral) limb.

Solution

1. Reflex arc is the nerve pathway involved in a reflex action, including at its simplest a sensory nerve, motor nerve with a synapse between. The 5 essential components of a reflex arc are as follows:

a. Receptor: Site of stimulus action

b. Sensory neuron: It transmits efferent impulses to the CNS.

c. Integration center (Control center): In simple reflex arcs, there may be single synapse between the sensory and the motor neurons while in more complex reflex arcs, multiple synapses may occur. The integration center is always within the CNS.

d. Motor neurons: Conducts efferent impulses from the integration center to the effernt organs.

e. Effector: Muscle fibre or gland cell that responds to the efferent impulses.

2. a. Ipsilateral

b. Contralateral

The crossed-extensor reflex is a withdrawl reflex.