Introduction to Nervous System Lecture

Question 1

Summarise the general pathway of the nervous system

Answer 1

Sensory receptor → brain and spinal cord (by sensory input) → effector cells (by motor output)

Question 2

Describe the structure of a neuron

Answer 2

1. Cell body (soma) contains the nucleus
2. Dendrites - multiple, thin, short extensions.
3. Axons - single, up to 1m long, usually covered with myelin.

Question 3

What are neuroglia?

Answer 3

They are supporting structures for neurons, and far outweigh the number of neurons. They carry the ability to regenerate.

In the peripheral NS, they are schwann cells, and satellite cells.

In the central NS, they are oligodendrocytes, astrocytes, microglia, and ependymal cells.

Question 4

What is the function of myelin and how is it produced?

Answer 4

Myelin insulates axons, allows for faster conduction. It is lipid and protein rich.
Myelin is produced by schwann cells in the PNS and oligodendrocytes in the CNS.

Question 5

How do neurons communicate?

Answer 5

Through the use of neurotransmitters which diffuse across synapses.

Question 6

What is a ganglion?

Answer 6

Structures that contain nerve cell bodies outside the central nervous system.

Question 7

Describe the structure, function and location of gray matter

Answer 7

Mostly made of cell bodies, dendrites and unmyelinated axons, and glial cells.
Responsible for processing sensory input and directing motor output. Gray matter in the brain is involved in voluntary motor activity.
Also found on the surface of the cerebellum and cerebral hemispheres as well as the depths of the cerebrum.

Question 8

Describe the structure, function and location of white matter

Answer 8

Made of myelinated axons, glial cells and blood vessels.
Function is around signal transmission, coordinated, and speed of communication.
Found in the corpus callosum and surface of the spinal cord.

Question 9

Briefly summarise the structure of the Central Nervous System (CNS)

Answer 9

1. Spinal cord
2. Brain Stem - contains the Medulla, Pons, and Midbrain
3. Cerebellum
4. Cerebrum - contains the telencephalon and diencephalon

Question 10

Describe the structure of the brain

Answer 10

2 hemispheres, left and right, divided by a median longitudinal fissure.
4 main lobes.
Contains folds known as gyri, separated by spaces known as sulci.

Question 11

How have we developed our understanding of the CNS?

Answer 11

PET scans and fMRI scans - imaging techniques
Animal Studies
Studying relationships between lesions and outcomes.

Question 12

What are the functions of the lobes in the brain?

Answer 12

Frontal - Motor area/Motor cortex
Parietal - Somatosensory cortex
Occipital - Visual cortex
Temporal - Auditory cortex

Question 13

Describe lateralisation of cortical functions in the brain

Answer 13

The left hemisphere is responsible for language and maths, while the right hemisphere is responsible for visual/spatial creativity.

Each hemisphere receives information from one side and sends motor impulses to the opposite side.

Question 14

Describe the structure and function of the diencephalon

Answer 14

Made of the thalamus and hypothalamus.

Thalamus involved in sensory relay; receives and redirects to the cerebral cortex.

Hypothalamus is the body’s main control centre for homeostasis. Controls autonomic functions and endocrine system.

Question 15

Describe the structure and function of the brainstem

Answer 15

Made of the medulla, pons and midbrain.

The medulla oblongata is involved in breathing, heart rate and blood pressure.
The pins is involved in communication between the cerebrum and cerebellum, and regulation of the respiratory system.
The midbrain is responsible for the eyes and auditory/visual cortex, and coordination of voluntary motor functions.

Question 16

What is the structure and function of the cerebellum?

Answer 16

2 hemispheres, internal gray matter nuclei, and surrounding outer cortex of white matter. Responsible for muscle control, including balance and movement.

Question 17

What protects the spinal cord?

Answer 17

Vertebrae, meninges, and cerebro-spinal fluid. Travels from skull base to L1/L2 vertebrae.

Question 18

Describe the anatomy of the spinal cord.

Answer 18

Gray matter of cell bodies on the interior. Posteriorly, a dorsal horn (contains neurons), and anteriorly, a ventral horn (contain somatic motor neurons), and a lateral horn (contains autonomic neurons) in between. Surrounding white matter made of nerve cell axons. A ventral and dorsal root from either end combine to produce a spinal nerve.

Question 19

Describe the structure of the spinal cord

Answer 19

Cervical - 8 segments and nerves
Thoracic - 12 segments and nerves
Lumbar - 5 segments and nerves
Sacral - 5 segments and nerves
Coccygeal - 1-4 segments

Question 20

What is the cauda equina?

Answer 20

A bundle of spinal nerves at the distal end of the spinal cord, usually found at L1/L2 level in adults.

Question 21

Describe the structure of the meninges

Answer 21

3 layers - dura mater, arachnoid, and pia mater. Arrangement is as follows - Bone → epidural space → dura mater → subdural space → arachnoid → subarachnoid space → pia mater (highly vascular).

Question 22

What are the ventricles of the brain?

Answer 22

Connected spaces filled with CSF, and also produce CSF.

Lateral ventricles (1/2) in hemispheres.
3rd ventricle between the right and left diencephalon.
4th ventricle between the cerebellum and pons.

Question 23

What is cerebrospinal fluid (CSF)?

Answer 23

Clear, cell free fluid, produced by the choroid plexus, a specialised tissue found in the ventricles.
It circulates in the subarachnoid space, and is absorbed by arachnoid granulations into the dural venous sinuses.

Question 24

Describe the divisions of the nervous system

Answer 24

The nervous system is comprised of the central nervous system (brain and spinal cord), and the peripheral nervous system, which can then be divided into the somatic nervous system, and the autonomic nervous system, which can further be divided into the parasympathetic and sympathetic nervous system.

Question 25

What is the function of the sympathetic nervous system?

Answer 25

Emergency nervous system, activation of fight or flight. Preganglionic SNS located at the lateral horn.

Examples of fight or flight: Dilated pupils, increased heart rate, increased blood pressure, increased breathing and sweating .

Question 26

What is the function of the parasympathetic nervous system?

Answer 26

Rest and digest. Preganglionic PNS located at the brain stem and S2-S4.

Examples of rest and digest, or homeostatic control include: decreased pupil size, increased digestion and glandular secretion.

Question 27

Where are the ganglia for the parasympathetic and sympathetic nervous system?

Answer 27

SNS - close to the vertebral column.
PNS - close to organs.