Lesson 2: Divisions of the Nervous System

Question 1

Enumerate the 2 main subdivisions of the Nervous System

Answer 1

Central Nervous System - CNS
Peripheral Nervous System - PNS

Question 2

It includes mainly the brain (contains about 85 billion neurons) and spinal cord (contains about 100 million neurons). The spinal cord is connected to the brain through the foramen magnum of the occipital bone and is encircled by the bones of the vertebral column.

Answer 2

Central Nervous System - CNS

Question 3

The CNS it is the seat of complex functions like:

Answer 3

MILE
Memory
Intelligence
Learning
Emotion

Question 4

It consists of all nervous tissue outside the CNS. It is composed of Cranial Nerves (the brain’s 12 pairs of nerves) & Spinal Nerves (31 pairs of nerves associated with the spinal cord) which serve as communication lines that carry impulses from the sensory receptors located on the different parts of the body to the CNS.

Answer 4

Peripheral Nervous System - PNS

Question 5

The PNS is further subdivided
into three (3):

Answer 5

SEA
Somatic NS
Enteric NS
Autonomic NS

Question 6

Subdivision of PNS:
- (soma = body) consists of Sensory Neurons and Motor Neurons.

Answer 6

Somatic Nervous System

Question 7

carry information from somatic receptors in the head, body wall and limbs and from receptors from the special
senses of vision, hearing, taste and smell

Answer 7

SNS Sensory Neurons

Question 8

conduct impulses from the CNS to skeletal muscles. They are voluntary because these motor responses can be
consciously controlled.

Answer 8

SNS Motor Neurons

Question 9

also called the “Brain of the GUT”. Its operation is involuntary and consists of neurons (100 million) in Enteric Plexuses that spread over the entire span of the GIT.

Answer 9

Enteric Nervous System

Question 10

Activities of the ENS:
- monitor chemical changes within the GIT & the
stretching of its walls

Answer 10

Enteric sensory neurons

Question 11

Activities of the ENS:
- govern contraction of the smooth muscles of the GIT, secretions of the GIT, such as acid from the stomach, and activities of GI tract endocrine cells, which secrete hormones.

Answer 11

Enteric Motor Neurons

Question 12

Subdivision of PNS:
- auto- = self; -nomic =law) consists of sensory neurons and motor neurons

Answer 12

Autonomic Nervous System

Question 13

convey information from the autonomic sensory receptors located primarily in visceral organs (such as the stomach and lungs) to the CNS

Answer 13

ANS Sensory neurons

Question 14

conduct commands from the CNS to smooth muscles, cardiac muscles and glands. They are involuntary
because motor responses are not normally under conscious control.

Answer 14

ANS Motor neurons

Question 15

2 branches of the motor part of ANS:

Answer 15

Sympathetic Nervous System
Parasympathetic Nervous System

Question 16

dominates and controls the body during non-stressful situations

Answer 16

Parasympathetic division

Question 17

dominates and controls the body during stressful situations.

Answer 17

Sympathetic division

Question 18

sometimes called the “FIGHT or FLIGHT” system, primarily increases ALERTNESS and prepares the body for QUICK response to certain situations

Answer 18

Sympathetic Nervous System
Ex. - Increase in Heart Rate

Question 19

the “REST AND REPOSE” system / “REST-AND-DIGEST”. It primarily ACTS to CONSERVE ENERGY.

Answer 19

Parasympathetic Nervous System
Ex. Slow Down Heart Rate