Question

Which of the following variables can have an effect on the speed of an action potential once it has been initiated?

	a.	myelination
	b.	diameter
	c.	type of neurotransmitter
	d.	temperature
	e.	More than one of the above.

Corneal eye surgery is now routinely performed to change the shape of the cornea and improve vision. This surgery is beneficial because ________________.

	a.	the cornea is responsible for the circulation of nutrients to the eye
	b.	the cornea regulates the sensitivity of the photoreceptors
	c.	the cornea controls the amount of light entering the eye
	d.	the cornea is involved in focusing light onto the retina

1. Neurotransmitters released from the vagus nerve cause a decrease in heart rate. To which part of the vertebrate nervous system would the vagus nerve belong?

   	a.	parasympathetic nervous system
   	b.	sympathetic nervous sstem
   	c.	somatic nervous system
   	d.	autonomic nervous system
   	e.	More than one of the above is correct

Answer 1

ANSWER :

The myelination (covering the nerve axon with myelin sheath) & diameter of nerve fibres are two major variable, which affect the transmission of action potential. Hence option (e) is the correct answer choice.

Corneal eye surgery is now routinely performed to change the shape of the cornea and improve vision. This surgery is beneficial because the cornea is involved in focusing light onto the retina of eye.

The left and right branch of vagus nerve (CN X) makes synapse with the parasympathetic division of autonomic nervous system, and release the neurotransmitter (acetylcholine) at sinoatrial & atrioventricular node of the heart to decrease in heart rate. Hence option (e) is the correct answer choice.