Introduction to the Nervous System

Question 1

Briefly describe the Central nervous system

Answer 1

It is found in the encephalon and spinal cord, covered with a system of membranes (meninges) and it is suspended in cerebrospinal fluid

Question 2

Anatomically, briefly describe the Peripheral nervous system

Answer 2

It is composed of the cranial and spinal nerves and their ganglia

Question 3

In more depth, anatomically describe the central nervous system

Answer 3

It is composed of the;

1. Spinal cord
2. Brain Stem (medulla, pons and midbrain)
3. Cerebellum
4. Cerebrum (Telencephalon and Diencephalon)

Question 4

Name and describe the Glial cells of the peripheral nervous system

Answer 4

Satellite cells (supports neurons) and Schwann cells (myelination cells)

Question 5

Name and describe the Glial cells of the central nervous system

Answer 5

Oligodendrocytes (myelination, they are able to myelinate many neurons at a time), Astrocytes (important in the blood brain barrier), Ependymal cells (produce CSF) and microglial (remove dead or damaged cells)

Question 6

Describe some of the features of myelin

Answer 6

It is an insultation material that is rich in lipids and proteins and makes conduction faster, therefore requiring less energy.

Question 7

Describe the basics of neural communication

Answer 7

Neurons release vesicles full of neurotransmitters. The receptors for these are on the surface of another neuron. The release and binding of neurotransmitters occurs in a synapse. This communication can occur between axons and dendrites.

Question 8

What is a ganglion?

Answer 8

It is a collection of nerve cell bodies outside of the central nervous system. The axons that enter these ganglia are called preganglionic fibres and axons that exit are called postganglionic fibres

Question 9

Name the two gross appearances the nervous system has

Answer 9

White and grey matter

Question 10

Describe grey matter

Answer 10

Predominately cell bodies of neruons, neuroglia (glial cells) and unmyelinated neurites (axons or dendrites)
Where ganglions are found in the PNS/ Nucleus in the CNS.

Question 11

Describe the location of Grey and white matter in the brain and spinal cord.

Answer 11

Brain - Grey matter on the surface, white matter in the centre
Spinal Cord - White matter on the surface and grey matter in the centre
White - Usually myelinated axons

Question 12

Describe the features of Afferent (sensory) and Efferent (motor) divisions

Answer 12

Afferent - transmits signals from the PNS to the CNS, comprised of sensory neurons.
Efferent - Transmits signals CNS to the PNS to cause a reaction, comprised of motor neurons

Question 13

What does the somatic nervous system involve?

Answer 13

Innervation of the skeletal muscle which is voluntary.

Question 14

What does the autonomic/visceral nervous system involve?

Answer 14

Innervation of the cardiac. smooth muscle and glands. Important for homeostasis and is involuntary.

Question 15

What is the autonomic/visceral nervous system divided into?

Answer 15

The sympathetic and parasympathetic

Question 16

Describe some of the features of the sympathetic nervous system

Answer 16

Activates the body under conditions of emergency - therefore causing pupils to dilate, increase the heart and respiratory rate and blood glucose levels, it causes vasoconstriction but dilates bronchial smooth muscle and induces sweating. The preganglionic sympathetic neurons are loacted in the T1-L2 spinal cord segments. It has short pre-synaptic fibres and long post-synaptic fibres.

Question 17

Describe some of the features of the parasympathetic nervous system

Answer 17

It conserves body energy and maintains body activities at basal levels. Its preganglionic parasympathetic neurons arise from the brain stem and S2-S4. It has long pre-synaptic fibres and short post-synaptic fibres

Question 18

What is an example of a neurotransmitter in the somatic nervous system and its effector organs

Answer 18

Acetylcholine which stimulates skeletal muscle

Question 19

Name an example of a sympathetic NS neurotransmitter and its effector organ

Answer 19

Acetylcholine which stimulates the release of noradrenaline which causes an effect on smooth muscle, cardiac muscle and glands

Question 20

Name an example of a parasympathetic NS neurotransmitter and its effector organ

Answer 20

Acetylecholine which stimulates the release of more acetylcholine which causes an effect on smooth muscle, cardiac muscle and glands

Question 21

What is the encephalon and spinal chord protected by?

Answer 21

Bone, meninges and cerebro-spinal fluid (CSF)

Question 22

Describe the features of Dura matter (outermost layer of the meninges)

Answer 22

It is the most superficial and touch,
Composed of two layers;
Inner meningeal and periosteal. These two layers are adherent except when they create the dural venous sinus.

Inwards septae of dura (dural partitions) secure the brain to skull, dampen movement of the brain in cranial cavity and divide cranial cavity into freely communicating compartments.

Question 23

Describe the features of the arachnoid matter

Answer 23

Adhere closely to dura and are web-like in appearance

Question 24

Describe the features of the pia matter

Answer 24

This is the deepest layer and is in direct contact with tissue of the CNS, it is highly vasuclar and enters every sulci

Question 25

Name the spaces between the meninges layers

Answer 25

Epidural (extra dura) space - between dura and bone Subdural - between dura and arachnoid Subarachnoid - between arachnoid and pia (contains CSF and cerebral arteries)

Question 26

What are the cerebral ventrical and where are they located?

Answer 26

They are interconnected spaces filed with CSF. This is where CSf is produced by ependmyal cells in the choroid plexus. There is a lateral ventrical found in the cerebral hemisphere, 3rd ventrical in the diencephalon, 4th ventrical in the brain stem and central canal in the spinal cord

Question 27

Describe some of the features of cerebro spinal fluid

Answer 27

It is a clear cell-free fluid, produced by the choroid plexus found in the lateral and 3rd ventricle. CFS passes from the ventricles to the subarachnoid space. It is then absorbed by arachnoid granulations into dural venous sinuses.

Question 28

What are the bumps and dips called in the brain?

Answer 28

The bumps are called gyri (gyrus for singular) | Dips are called sulci (sulcus for singular)

Question 29

Describe the features of the cerebrum

Answer 29

It is two hemispheres divided by a medial longitudinal fissure. Each hemisphere consists of a cerebral cortex, cerebral white matter and nuclei

Question 30

Name the different lobes of the cerebrum

Answer 30

``` Frontal lobe, Parietal lobe, Occipital lobe, Temporal lobe Limbic lobe Insula ```

Question 31

Describe the functions of the cerebrum

Answer 31

Motor - primary motor and premotor areas in the frontal lobe Sensory - Primary somatosensory and somatosensory association areas in parietal lobe Vision - primary visual and visual association areas found in the occipital lobe Auditory - primary auditory and auditory association areas in temporal lobe

Question 32

What do the two hemispheres of the cerebrum

Answer 32

Left hemisphere is specialized for language and math skills. | Right hemisphere is specialized for visual-spatial skills and creativity.

Question 33

Describe the function of the thalamus

Answer 33

Major relay station for: Sensory impulses ascending to sensory cortex , inputs from subcortical motor nuclei and cerebellum travelling, encolses the 3rd ventricle

Question 34

Describe the function of the hypothalamus

Answer 34

It is autonomic control, endocrine control, It regulates thirst (fluid electrolyte balance) Eating (energy balance) Sexual Reproduction behavior Body temperature

Question 35

Describe some of the functions of the midbrain

Answer 35

It has superior and inferior colliculi which are centres for visual and auditory reflexes Red nucleus which is the centre for subcortical motor control Substantia nigra which is involved in reward-seeking and motor learning The midbrain also surrounds the cerebral aqueduct

Question 36

Describe some of the functions of the Pons

Answer 36

It is a conduction areas, providing connections between the forebrain and the cerebellum. The nuclei found in the pons contribute to the regulation of respiration as well as hearing and balance.

Question 37

Describe some of the functions of the medulla

Answer 37

It contains vital centres for regulating respiratory rhythm, heart rate and blood pressure. It also contains no vital centres that regulate coughing, sneezing, swallowing and vomiting.

Question 38

Describe some of the functions of the cerebellum

Answer 38

Composed of two hemispheres in cerebellar fossa. With internal grey matter, surrounded by white matter with an outer cortex of grey matter It is connected to the brain stem by cerebellar peduncles It processes and interprets impulses from motor cortex and sensory pathways and coordinates motor activity for movement (important in balance)

Question 39

Describe some of the features of a section of cross sectioned spinal chord

Answer 39

It contains grey matter in an H-shape which contains neural cell bodies with different horns. This grey matter is surrounded by white matter, this contains columns with a number of ascending and descending tracts. (Ventrical/anterior column, lateral columns and dorsal/posterior column)

Question 40

Of the spinal cord name the different horns and their function

Answer 40

Dorsal/posterior horns - contains interneurons Lateral horns - visceral/autonomic motor neurons Ventrical/anterior horns - somatic motor neurons

Question 41

How many cranial nerves are there?

Answer 41

12