Cells of the Nervous System Flashcards
The central nervous system (CNS) consists of…
two cerebral hemispheres, the brainstem, the cerebellum and the spinal cord
The peripheral nervous system (PNS) consists of…
the nerve fibres originating from the CNS.
Frontal lobe function
Responsible for executive functions such as personality
voluntary movement, expressive language and for managing higher level executive functions.
Executive functions refer to a collection of cognitive skills including the capacity to plan, organise, initiate, self-monitor and control one’s responses in order to achieve a goal
Parietal
Contains the somatic sensory cortex responsible for processing tactile information
One involves sensation and perception and the other is concerned with integrating sensory input, primarily with the visual system.
Temporal
Contains important structures such as the hippocampus (short term memory), the amygdala (behaviour) and Wernicke’s area (auditory perception & speech)
Occipital
Processing of visual information
The brainstem consists of
the midbrain, pons and the medulla
what order
descending order
midbrain highest
medulla lowest
cerebellum function
motor coordination, balance and posture.
Unipolar cells
1 axonal projection
0—-0
Psuedo-unipolar
Single axonal projection that divides into two
0
0—-1—-0
Bipolar
2 projections from cell body
0—–0—–0
1 axon
1 dendron
Multipolar
Numerous projections from cell body
how many axons and dendrite
only 1 is axon rest is dendrite
types of multipolar
Pyramidal cells
Purkinje cells
Golgi cells
what is the cell body known as and what does it contain
Soma, perikaryon
nuclues and ribosomes
Neurofilaments
what are Neurofilaments
structure & transport
what is an axon
single projection from cell body/originates from soma at axon hillock
Can branch off into ‘collaterals’
what are they covered in
Usually covered in myelin
structure in dendrites
Highly branched cell body
are they covered in myelin
NO
function
Receive signals from other neurons
most abundant cell in mammilian brain
Astrocytes
function
structural cells and are known to play an important role in cell repair, synapse formation, neuronal maturation and plasticity.
what are oligodendrocytes
are the myelin producing cells of the CNS,
Schwann cells
same function in the PNS.
differences
oligodendrocyte is capable of myelinating a number of axons a Schwann cell only myelinates a single axonal segment.
Microglia function
and similarty to what other cell
microglial cells are specialised cells that are similar to macrophages and they perform immune functions in the CNS
Ependyma function and what sort of cell
epithelial cells that line the fluid filled ventricles regulating the production and movement of cerebrospinal fluid.
what are the major physiological ions in cns
potassium
sodium
chloride
calcium
are the cell membranes permeable to those
- impermeable to these ions transportation regulated by channels & pumps
what conc is highest outside the cell
Na+ & Cl-
highest inside
K+
where is calcium greatest
extracellular
what is the resting potential inside the cell
-50 to -90
= -70mv
which channels are closed closed
Voltage-gated Na+ channels (VGSCs
voltage-gated K+ channels (VGKCs
Membrane depolarisation change
- opening of VGSC Na+ influx further depolarisation
membrane repolarisation
VGKCs opens at a slower rate and causes efflux of K+ from cell
why is sodium open faster
it is faster to open
last dip in graph
hyperpolarisation
how is it restored back
sodium potassium pump
what sort of movement
active, na pumped out
k enters
next
na k pump back to resting state- na enters
k leaves
what is Saltatory conduction
ap can jump across areas of no myelin
faster
what does mylein do
prevents AP spreading because it has - high resistance & low capacitance
Nodes of Ranvier
- Small gaps of myelin intermittently along axon:
The synapse position
is a junction consisting of a pre-synaptic nerve terminal
separated from the postsynaptic cell
by an extracellular space known as the synaptic cleft
nuerotrasnmition at a synapse
Propagation of the action potential (AP)
AP is propagated by VGSCs opening
Na+ influx membrane depolarisation AP ‘moves along’ neurone
VGKC opening K+ efflux repolarisation
next part
AP opens voltage-gated Ca2+ channels at presynaptic terminal
Ca2+ influx vesicle exocytosis
and then
NT dissociates from receptor and can be:
Metabolised by enzymes in synaptic cleft
Recycled by transporter proteins
lastly
NT binds to receptors on post-synaptic membrane
Receptors modulate post-synaptic activity
what happens to teh nt
broken down by enzymes and enters back into pre synaptic terminal c
enzyme not always needed, it can enter back into the pre synamitic terminal directly
