Nervous system pt. I

Question 1

What are the components of CNS and PNS?

Answer 1

CNS: 
- Brain and spinal cord
PNS:
- Cranial nerves from brain
- Spinal nerves from spinal cord
- Receptors (nerve endings or specialised cells in sense organs)

Question 2

What are the respective purposes of the afferent component and the efferent component in the PNS?

Answer 2

Afferent:
- Sensing of stimulus by sensory neurons
Efferent:
- Effect response by motor neurons

Question 3

What are the names of the voluntary and involuntary systems?

Answer 3

Somatic nervous system is voluntary, autonomic nervous system is involuntary

Question 4

What are the branches of the autonomic nervous system and their functions?

Answer 4

Parasympathetic: prepares the body for fight or flight response
Sympathetic: inhibits the body from overworking

Question 5

Give 3 differences between the nervous system and the endocrine system.

Answer 5

Nature of formation:
Nervous system transmits messages through electrical impulses, while endocrine system transmits messages through hormones.

Transport medium:
Electrical impulses are transported along nerve fibers and across the synapse in the nervous system while hormones are transported in blood in the endocrine system.

Response:
Nervous system’s response is rapid and immediate while that of the endocrine system is much slower.
Nervous system’s response is short-lived while that of the endocrine system can be short-lived, long-lasting or permanent.
Nervous system’s response is localised and precise while endocrine system’s response is wide-spread and may affect more than one target organ.

Magnitude of stimuli:
The magnitude of stimuli in nervous system is reflected by the frequency of action potential and amount of neurotransmitter.
The magnitude of stimuli in endocrine system is reflected by the amount of hormones.

Control:
Signaling in the nervous system may be voluntary or involuntary, while signaling in the endocrine system is always involuntary.

Question 6

Outline the nervous system communication pathway.

Answer 6

Detection of stimuli -> Brain / Spinal cord -> Perception + Response

Question 7

Define a neuron.

Answer 7

A neuron is a specialised cell for carrying information in the form of electrical impulses from receptors to CNS, and from CNS to effectors.

Question 8

State the functions of the different parts of a neuron.

Answer 8

Dendrites conduct impulses from other cells to the cell body.
Axon generally transmits impulses away from cell body.
Schwann cells are non-neuronal supporting cells that wrap around axons / dendrons to form an insulating myelin sheath.
Myelin sheaths increase the rate of conduction of nervous impulse along an axon.
Node of Ranvier is the gap between successive Schwann cells on an axon that is unsheathed.
Synapse is the fluid-filled gap between the axon terminal of the transmitting neuron and the dendrites or cell body of another neuron

Question 9

How do neurons communicate with one another?

Answer 9

Neurons communicate chemically with the help with neurotransmitters at synapses.

Question 10

Distinguish between nerve fibre and a nerve.

Answer 10

A nerve fibre is a threadlike extension of a nerve cell consisting of an axon and myelin sheath, while a bundle of nerve fibers make up a nerve.