Cells and Tissues of the Nervous System

Question 1

Describe the divisions of the nervous system

Answer 1

CNS - brain and spinal cord and PNS - cranial and spinal nerves
PNS - sensory and motor division
Motor - somatic motor and autonomic (sympathetic and parasympathetic)

Question 2

What are the 2 types of cells in nervous system?

Answer 2

Neurons and Glial cells

Question 3

Describe neuron cells

Answer 3

Structural and functional unit
Excitable cells
Impulses carried as action potentials
High metabolic rate (a lot of glucose used, long living and amitotic

Question 4

Describe glial cells

Answer 4

Non-excitable supporting cells
Much smaller than neurons

Question 5

What is a typical neuron structure?

Answer 5

Multiple dendrites and one axon
Impulses transmit by action potential travel in one direction from cell body to synaptic terminal

Question 6

Describe structures in neurons

Answer 6

Nucleus is loose chromatin and prominent
Mitochondria, rER (nissl bodies) and diffuse golgi apparatus
Cytoplasm in the cell body is perikaryon and axon is axoplasm

Question 7

What are the 3 types of neurons?

Answer 7

Multipolar, bipolar and psuedounipolar

Question 8

What neurons are multipolar?

Answer 8

Interneurons
Motor neurons

Question 9

What neurons are bipolar?

Answer 9

Olfactory mucosa
Retinal nerve fibres

Question 10

What neurons are pseudounipolar?

Answer 10

Sensory neurons

Question 11

Where does cell body of multipolar neurons lie?

Answer 11

Within brain and spinal cord

Question 12

What is the function of a myelin sheath?

Answer 12

Increase conduction speed in axons by saltatory conduction
Is formed by schwann cells in PNS and oligodendrocytes in CNS

Question 13

What happens to myelin sheath in multiple sclerosis?

Answer 13

Patchy loss/scarring of myelin sheath (demyelination) which causes abnormal nerve conduction on affected axons

Question 14

What is the difference between grey and white matter?

Answer 14

White - myelinated axons
Grey - neuronal cell bodies

Question 15

What are ascending and descending tracts?

Answer 15

Ascending - tracts are sensory and go up to spinal cord
Descending - spinal cord to periphery
Tracts are bindles of axons carrying specific info into specific part of brain or periphery

Question 16

What is the difference between dorsal and ventral root?

Answer 16

Dorsal - sensory
Ventral - motor

Question 17

What is a nucleus in the hemisphere?

Answer 17

Collection of grey matter inside cerebral hemisphere

Question 18

What is a collection of neuronal cell bodies in the CNS called?

Answer 18

Ganglion

Question 19

What are some different types of glial cells?

Answer 19

In CNS - astrocytes, oligodendrocytes, phagocytes and ependymal cells
In PNS - Schwann cells and satellite cells

Question 20

What are astrocytes?

Answer 20

Have end feet which surround synapses and capillaries
Help in K+ buffering

Question 21

What are phagocytes function?

Answer 21

Phagocytosis and scar tissue formation

Question 22

What is the function of ependymal cells?

Answer 22

Line ventricles and central canal of spinal cord

Question 23

What is the function of satellite cells?

Answer 23

Surround neural cell bodies

Question 24

Describe the blood brain barrier

Answer 24

Protective mechanism that helps maintain a stable environment for brain and prevents harmful amino acids and ion present in bloodstream and blood cells entering the brain

Question 25

What are the layers of the blood brain barrier?

Answer 25

Endothelium with tight junctions
Thick basal lamina
Foot processes of astrocytes

Question 26

What is allowed in and out of blood brain barrier?

Answer 26

Lipid soluble molecules, O2 and H2O can diffuse
Water soluble molecules (glucose and aa) are pump mediated

Question 27

Where is the BBB not present?

Answer 27

Centriventricular organs
Parts of hypothalamus, posterior pituitary

Question 28

Describe the basic topography of the brain

Answer 28

Cerebrum, Cerebellum, Brainstem and diencephalon
Brainstem - midbrain, pons and medulla. Has vital centres and pathway of fibre tracts

Question 29

What can be seen on dura mater covering brain?

Answer 29

Emissary vein in superior sagittal sinus
Branches of middle meningeal vasculature

Question 30

What are the folds of dura mater?

Answer 30

Falx cerebri - separates hemisphere
Tentorium cerebelli - separates cerebellum hemispheres

Question 31

What are the ventricles of the brain?

Answer 31

Lateral ventricle - C shaped and lie in cerebral hemispheres
3rd ventricle - connected by interventricular foramen, in cavity within diencephalon
Cerebral aqueduct in midbrain
4th ventricle in hindbrain

Question 32

Where is the 4th ventricle?

Answer 32

Between pons and medulla (in front) and cerebellum at back

Question 33

Describe the meninges of the CNS

Answer 33

Dura, arachnoid and pia mater
Pia mater is vascularised and dips into folds
Subarachnoid space contains CSF
Subdural space is potential space which is traversed by blood vessels penetrating into CNS

Question 34

Describe the CSF

Answer 34

Fluid inside cavity of brain (the ventricles) and central canal of spinal cord
Responsible for maintenance of intracranial pressure
Between pia and arachnoid mater

Question 35

Where is CSF present?

Answer 35

Inside ventricles
Between pia and arachnoid space

Question 36

Where is CSF formed?

Answer 36

By choroid plexus in each ventricle

Question 37

Where is CSF absorbed?

Answer 37

By arachnoid villi into sagittal sinus (venous channel in brain)

Question 38

How does CSF circulate?

Answer 38

Leaves ventricular system through 3 holes at roof of 4th ventricle
Circulates through subarachnoid space
Reabsorbed into superior sagittal sinus through arachnoid villi