Cells and Tissues of the Nervous System Flashcards
What are the division of the nervous system?

What direction do motor and sensory nerves run?
motor - form CNS to periphery
sensory - from periphery to CNS
What cells make up the nervous system?
Neurons
Glial cells
What are neurons?
structural and functional units of the nervous sytem
excitable cells
impulses are carried as action potentials
What are glial cells?
non-excitable cells
supporitng cells
much smaller than neurons but higher in numbers
How many dendrites and axons do neurons have?
multiple dendrites
one axon
How does an impulse travel through a typical neuron?
in only one direction from cell body to synaptic terminal
What are the 2 main types of neuron? and what are they for?

What is a sensory neuron called?
pseudounipolar
What is a motor neuron called?
multipolar
What are the features of a neuron?
Nucleus - loose chromatin, prominent nucleolus
Cell organelles - Mitochondria, rER( Nissl bodies), diffuse Golgi apparatus
High metabolic rate
Cytoplasm in the cell body is perikaryon, and in the axon is axoplasm
Long living and amitotic - dont regenerate when damaged
What is the process of an impulse and the events along a neuron?

What is the function of the myelin sheath?
Increase conduction speed in axons by ‘saltatory conduction (jumping from one node of Ranvier to the next node)
Depending on presence or absence of myelin sheath, neurons may be….
myelinated or non-myelinated
What is the myelin sheath formed by?
Schwann cells in PNS
Oligodendrocytes in CNS
The clinical importance of the myelin sheath is that it can related to Multiple Sclerosis (MS), how does it?
Patchy loss/scarring of myelin sheath (demyelination) - nerve conduction across affected axons abnormal
Cause unknown (? Viral, ?autoimmune)
How owuld demyelination show on an MRI?
whitish plaques of demyelination
What is the prognosis of MS
varies
What makes up white and grey matter in the spinal cord?
White matter: myelinated axons
Grey matter: neuronal cell bodies
What is a tract?
Things carried to and form the brain and carried in tracts
Different modalities clustered together for various speeds
All these different receptors (touch, pain, vibrations, temperature, pressure) are connected to different sensory neurons and their axons pass through spinal cord on the way to the brain and cluster in different bundles

What are nuclei?
a nucleus (plural form: nuclei) is a cluster of neurons in the central nervous system, located deep within the cerebral hemispheres and brainstem
Collections of grey mater in the brain are called nuclei and are just collection of neuronal cell bodies
What is 1?

sensory so a pseudounipolar
What is 2?

dorsal root ganglion
what is 3?

tract and white matter
What is 4 called?

nucleus
Do glial cells carry action potentials?
no they are non-excitable
How many types of glial cells are there and where are they located?
4 in CNS and 2 in PNS
a

satellite cell
b

schwann cell
c

astrocytes
d

oligodendrocytes
e

microglia
f

ependymal cell
What is the function of satellite cells?
surrounds neuronal cell bodies
What is the function of schwann cells?
myelination
What is the funciton of astrocytes?
have endfeet - surround synapses and capillaries - help in the blood brain barrier
help in K+ buffering
What is the function of oligodendrocytes?
myelination
What is the function of microglia?
phagocytosis
scar tissue formation
What is the function of ependymal cells?
line ventricles
What is the bloodbrain barrier?
Is a protective mechanism that helps maintain a stable environment for the brain and prevents harmful amino acids & ions present in the bloodstream and blood cells from entering the brain
Barrier created between capillaries and brain tissue and prevents a lot of stuff leaking out of the capillaries
What 3 things make up the blood brain barrier?

A?

cerebrum
B?

cerebellum
C?

Diencephalon
D?

Brainstem
What is the function of the cerebrum?
seat of consciousness
e.g. interpreting touch, vision and hearing, as well as speech, reasoning, emotions, learning, and fine control of movement
What is the function of the cerebellum?
balance and coordination
What makes up the diencephalon
Thalamus
Hypothalamus
What makes up the brain stem?
the midbrain, the pons and medulla (oblongata)
What is the function of the brain stem?
Vital centres eg: cardiorespiratory,
Pathway for fibre tracts
The brain stem controls the flow of messages between the brain and the rest of the body,controls basic body functions such as breathing, swallowing, heart rate, blood pressure, consciousness, and whether one is awake or sleepy
What is A?

midbrain
What is B?

PONS
What is C?

Medulla
What are ventricles?
cavities in the brain filled with CSF

What are the first 2 ventricles called?
The lateral ventricles are C-shaped cavities which lie in the cerebral hemispheres
What is the 3rd ventricle?
The interventricular foramen connects the lateral ventricles with the 3rd ventricle - the cavity within the diencephalon
What part of the ventrical system lies in the midbrain?
The cerebral aqueduct lies in the midbrain
What is the 4th ventricle?
The diamond-shaped 4th ventricle lies in the hindbrain
Overall what is all of the ventricular system made up of?
The ventricular system is composed of:
2 lateral ventricles
the third ventricle
the cerebral aqueduct
the fourth ventricle
What is A?

lateral ventricles
What is B?

interventricular foramen
What is C?

third ventricle
What is D?

cerebral aqueduct
What is E?

Fouth ventricle
study this picture of the ventricular system

What part of the ventricular system do you have in the cerebrum?
Within cerebral hemispheres (x2) = lateral ventricle (x2)
What part of the ventricular system do you have in the diencephalon?
3rd ventricle
What part of the ventricular system do you have in the midbrain?
cerebral aqueduct
What part of the ventricular system do you have between the Pons + medulla (infront) and cerebellum (at back)?
4th ventricle
What are the meninges?
3 coverings of the CNS
What is A?

dura mater
What is B?

arachnoid mater
What is C?

pia mater
What is the dura mater?
outer layer
The dura mater is tough, fibrous and has dural folds
What is the arachnoid mater?
spider web like
middle layer
dont normally see in wet specimens
What is the pia mater?
The pia mater is vascularised and dips into the folds of the brain
The inner layer
What is the subdural space?
Between the dura and arachnoid mater
The subdural space is a potential space which is traversed by blood vessels penetrating into the CNS
What is present in the subarachnoid space?
The subarachnoid space contains cerebrospinal fluid
What is cerebrospinal fluid (CSF)?
fluid in teh cavity of the brain (i.e. the ventricles) and central canal of the spinal cord
it is to some extent responsible for maintenance of intracranial pressure
also present surrounding the brain and the spinal cord in between the layers of the meninges which are coverings of the brain (between pi and arachnoid mater)
Where is CSF present?
Inside ventricles
Between pia & arachnoid mater
Where is CSF formed?
By choroid plexus in each ventricle

Where is CSF absorbed?
By Arachnoid villi (small protrusion of the arachnoid mater) into saggital sinus (venous channel in brain)
What is the prcoess of CSF?
CSF secreted by choroid plexus, enters subarachnoid space, absorbed by arachnoid villa
What does the blood brain barrier maintain?
Blood Brain Barrier maintains homeostasis in brain parenchyma