chapter 46 : general organisation of the nervous system

Question 1

define the nervous system?

Answer 1

Nervous system is the communication and control system of the body. It functions on the basis of conduction of impulses. Conduction of impulses provide information about stimuli to the center and then directions to the effectors.

Question 2

what 2 parts is the nervous system anatomically divided into?

Answer 2

a central nervous system
and
a peripheral nervous system

Question 3

briefly describe CNS

Answer 3

consists of the brain and spinal cord

Question 4

briefly describe peripheral nervous system

Answer 4

consists of nerves that arise in the cns and go to the periphery
includes cranial and spinal nerves

Question 5

how many cranial nerves.
what are they?

Answer 5

12 pairs of cranial nerves
1. Olfactory nerve
2. optic nerve
3. oculomotor nerve
4. trochlear nerve
5. trigeminal nerve
6. abducens nerve
7. facial nerve
8. vestibulocochlear nerve
9. glossopharengeal nerve
10. vagus nerve
11. accesory spinal nerve
12. hypoglossal nerve

Question 6

how many spinal nerve pairs, what are they?

Answer 6

31 total
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal

Question 7

functional division of the nervous system? what divisions?

Answer 7

somatic nervous system
autonomic nervous system

Question 8

what does somatic nervous system supply?

Answer 8

The Somatic nervous system supplies the general structures of the body, like skeletal muscle and skin

Question 9

what does autonomic nervous system supply?

Answer 9

The autonomic nervous system supplies the viscera or the body’s involuntary effectors like Cardiac muscle, Smooth muscle, and Glands,

Question 10

what types of nerve fibers are in a nerve that arises from the cns?

Answer 10

A nerve that arises from the CNS may contain both Somatic and Autonomic nerve fibers. It may also contain both motor and sensory fibers.

Question 11

what else is the autonomic nervous system known as? what does is control?

Answer 11

It is also known as vegetative or visceral nervous system. It controls:
1. Heart rate
2. Blood pressure
3. Capillary dilation and constriction
4. GIT motility
5. Temperature regulation 6. Secretion
7. Micturition
8. Sweating

Question 12

why is autonomic nervous system called autonomic nervous system?
what controls it?

Answer 12

This system was given the name “autonomic” because it was thought that it was autonomous, but it is actually not. Certain centers are present which control it. These are in:
1. Spinal cord
2. Brain stem
3. Parts of cerebral cortex 4. Parts of limbic system

Question 13

functional division of autonomic nervous system?

Answer 13

The autonomic nervous system is functionally divided into:
1. Sympathetic nervous system
2. Parasympathetic nervous system

Question 14

Organization of autonomic nervous system?

Answer 14

This system is organized on the basis of reflex arc. It has the following components: 1. Receptors
2. Afferent neurons
3. Center
4. Efferent neurons
5. Effectors/target tissue
Impulses arise from receptors in the viscera, are conducted by afferent neurons to the center (CNS) from where it travels along efferent neurons to the target tissue/effector
The afferent (sensory) part is not as well organized as is the efferent (motor) part

Question 15

types of efferent neurons in autonmic nervous system?

Answer 15

Efferent part consists of two types of neurons:
1. Pre-ganglionic neurons
2. Post-ganglionic neurons

Question 16

note on pre ganglionic neurons in autonomic nervous system?

Answer 16

Preganglionic neurons’ cell bodies are located in the CNS and their nerve fibers come out as outflows.

There are 3 types of outflows:
1. Cranial outflow
2. Thoracolumbar outflow 3. Sacral outflow
The thoracolumbar outflow is sympathetic in nature while The cranial and sacral outflows are parasympathetic in nature

Question 17

type of efferent pre ganglionic outflows in the efferent part of autonomic nervous system? detail too

Answer 17

There are 3 types of outflows:
1. Cranial outflow
2. Thoracolumbar outflow 3. Sacral outflow
The thoracolumbar outflow is sympathetic in nature while The cranial and sacral outflows are parasympathetic in nature

Question 18

note on post ganglionic neurons of efferent part on the autonomic nervous system?

Answer 18

The cell bodies of the post ganglionic neurons, on the other hand, are located outside the CNS in the form of aggregations called ganglions. Different groups of autonomic ganglia are present:
1. Para-vertebral ganglia: these are present in the form of a bilateral sympathetic chain or trunk, lying on the anterolateral aspect of the vertebral column. These ganglia are interconnected with each other.
The sympathetic chain contain 23-24 autonomic ganglia: a. 3 cervical
b. 10-12 thoracic
c. 4 lumbar
d. 4 sacral
e. 1 coccygeal
2. Pre-vertebral ganglia:
These include the celiac ganglia, superior mesenteric ganglia and inferior mesenteric ganglia.
These are located anterior the aorta, in relation with the artery of their name.
They contain sympathetic post ganglionic neurons.
3. Terminal ganglia: These are situated on or around an innervated organ.
They contain parasympathetic post ganglionic neurons.

Question 19

paravertebral ganglia note?

Answer 19

1. Para-vertebral ganglia: these are present in the form of a bilateral sympathetic chain or trunk, lying on the anterolateral aspect of the vertebral column. These ganglia are interconnected with each other.
   The sympathetic chain contain 23-24 autonomic ganglia: a. 3 cervical
   b. 10-12 thoracic
   c. 4 lumbar
   d. 4 sacral
   e. 1 coccygeal

Question 20

prevertebral ganglia note?

Answer 20

2. Pre-vertebral ganglia:
   These include the celiac ganglia, superior mesenteric ganglia and inferior mesenteric ganglia.
   These are located anterior the aorta, in relation with the artery of their name.
   They contain sympathetic post ganglionic neurons.

Question 21

terminal ganglia note?

Answer 21

3. Terminal ganglia: These are situated on or around an innervated organ.
   They contain parasympathetic post ganglionic neurons.

Question 22

detail of nerve fibers in the pre and post ganglionic neurons?

Answer 22

The nerve fibers of the pre ganglionic neurons are called pre ganglionic nerve fibers and These pre ganglionic nerve fibers are myelinated and belong to Type B nerve fibers. They synapse with the cell bodies of the post ganglionic neurons, either paravertebral, prevertebral or terminal.

From these, nerve fibers arise, which are called post ganglionic nerve fibers and are unmyelinated and belong to Type C nerve fibers.