Tissues 6 - Nerve Flashcards
What are the cerebral hemispheres 4 functional regions?
Frontal, parietal, temporal and occipital lobes.
What are the gyri and suici?
In the cerebral hemisphere, the gyri are ridges and the suici are valleys.
What 3 components does the brain stem consist of?
The midbrain, pins and medulla (in descending order)
What is the positioning of the cerebellum?
Hindbrain structure attached to the brain stem.
What is the role of the cerebellum?
Motor coordination, balance and posture.
Where does the spinal chord extend from?
The medulla
What are the two basic functions of the spinal cord?
Conduit for neural transmission, co-ordinates some reflex actions.
List the 4 main types of neurones.
Unipolar, psueudo-unipolar, bipolar, multipolar
Describe the structure of unipolar neurones.
There is 1 axonal projection from the cell body.
Describe the structure of the pseudo-unipolar neurones.
There is a single axonal projection that branches to divide into two sections.
Describe the structure of the bipolar neurones
There are two projections from the cell body, an axon and a dendron
Describe the structure of multipolar neurones
There are numerous projections from the cell body
How else may the cell body be referred to?
Soma or peikaryon
What is the structure of the cell body?
The cell body contains nucleus and ribosomes, as well as neurofilaments (structure and transport).
What is the structure of the axon?
Origionates from the soma at the axon hillock, and may branch into colaterals. Often covered in myelin.
Describe the structure of dendrites
Dendeites are highly branched cell bodies, which are not covered in myelin.
What are astrocytes?
Astrocytes are star shaped cells, the most abundent type in the CNS, which can proliferate.
What is the function of astrocytes?
Astrocytes are faculative macrophages (involved in immunity). They are structural cells, involved in cell repair and neurotransmitter release and reuptake.
What are ogliodendrocytes?
Ogliodendrocytes are the cells that myelinate the cells of the CNS. They have numerous projections, so can myelinate many neurones at once.
What are Schwann cells?
Cells that myelinate neurones in the PNS. One cell myelinates one axon.
What are microglial cells?
Specialised cells that act as macrophages in the CNS.
What are ependymal cells?
Epithelial cells that line fluid filled ventricles, which regulate the production and movement of cerebrospinal fluid.
What are neuroglial cells?
Cells in the nervous system that are not neurones
What is the distribution of ions in the resting cell¬ and what is the resulting membrane potential?
Inside vs Outside: Na+ < & K+ > & Ca2+ < & Cl-
Describe briefly how an action potential is generated.
- VGSC open
- Na+ in (depolarisation) VGKC open
- K+ out (repolarisation)
- Na+K+ATPase restores ion gradients
- 3Na+ + ATP out (resting configuration)
- 2K+ enters (active configuration)
- Pump returns to resting configuration.
Describe briefly saltatory conduction.
- Myelin prevents the action potential spreading as it has a high resitance and low capacitance.
- Action potential jumps between the nodes of ranvier
Describe what happens to a neurone at the axon terminal.
Action potential opens Ca2+ channels. Calcium ions flood in, and this causes vesicle exocytosis.
What happens to neurotransmitters in the synapse?
Neurotransmitters activate receptors, are recycled by transporter proteins, or are metabolised by enzymes in the synaptic cleft.
