Overview of the nervous system Flashcards
what is the function of the NS
controls and coordinates functions throughout the body, and responds to internal and external stimuli.
What is the NS responsible for?
It can detect changes within and round the brain
Respond to external changes
Receive and interpret sensory information.
what is the NS derived from?
from the ectoderm
What is neurlation?
formation of of the neural plate (ectoderm) , closure of the neural tube and early development of the NS
what is the CNS ccomposed off?
Brain
Spinal Cord
What is the PNS composed off? (peripheral NS)
Afferent info (input)
Efferent input (output)
What are the 4 cells of the CNS
Neurons
Gila= atrocyte
oligodendrocytes
Ependymal cells
where does the cell bodies of neurons live
grey metter
where can we find myleinated axons
white matter
where are gilal cells found
grey and white matter
what are the 5 componets of a neuron?
soma
dendrites
Axon
axon hillock
axon terminal
what happens in the soma
contains nucleus and most of the organelles
what happens in the dendrites
reception of incoming info
what happens in the axon
transmits eletrical impulses called AP
what happens in the axon hillock
where axon orginates and AP iniated
what happens in the axon temrinal
releases neurotransmitter
what is a snyapse
Site of communication between two neurons
what is an afferent neuron?
orininagte in the periphery with sensory or visceral receptors
efferent neurons?
originate in the CNS where the cell body and dendrites recieve synpatic communication from other neurons
interneurons
within the cns and can communicate with afferent neurons, efferent neruons and other interneruons
what are glial cells
90% of all cells in the nervous system
Do not function as signal cells
Provide structure and integrity to the nervous system
examples of gilal cells
Astrocytes
Microglia
Schwann Cells
what are astrocytes involved in
Development of neural connections
Development of blood-brain barrier
Protect neurons against toxic substances & oxidative stress
what is microglia
Protect CNS from foreign matter through phagocytosis
Protect CNS from oxidative stress
what are the 2 mylein forming cells>
schawn cells-
oligodendorcytes
what is the differnece between schwann cells and oloigendrndorcytes?
O cells cover CNS where as schwan cells cover PNS
O cells have many myekin sheath whereas schwan have one mylein sheath
Describe meylin?
Insulating wrap around the axons
Enables neurons to transmit action potentials more efficiently
Reduce leakage of ions across the cell membrane
describe myelination?
Schwann cells myelinate peripheral nerves
The myelin sheath surrounding nerve fibres in the spinal cord is from where?
oligodendroglial cells
what is cerbrospinalfluid?
clear watery extracelluar fluid bathing the CNS
the CSF summarised
Recycled 3 times/day
Secreted by ependymal cells of the choroid plexus
Circulates through ventricles to subarachnoid space
Reabsorbed by arachnoid villi
Total volume of CSF = 125 – 150 mL
what are the functions of the CSF?
cushions the brain and mantains a stable interstilala fluid envionment
how does CSF provide interstidals envrionment
provides neruons nd gilal cells with essentail nuterins and removes waste products
blood supply to the CNS
High metabolic rate
Brain uses 20% of oxygen consumed by body at rest
Brain uses 50% of glucose consumed by body at rest
blood brain barrier?
Special anatomy consisting of CNS capillaries that limit exchange
describe the capillaries in the blood brain barrier
Sites of exchange between blood & interstitial fluid
Thin: single layer of endothelial cells
Diffusion
