Nerves Flashcards
Cerebral Hemispheres (clockwise)
Frontal, parietal (proprioception), occipital, temporal (sound and speech recognition)
Folds in white matter
Gyri - ridges
Sulci - Valleys
Brainstem Anatomy (descending)
- midbrain
- pons
- medulla
Cerebellum
- hindbrain attached to the brainstem
- used for fine-tuning motor function and aiding balanced and posture.
Nerve Cell Types
- unipolar
- psudeounipolar
- bipolar
- multipolar (only one axon, the rest are dendrites
- Pyramidal
- Purkinje (GABA neurones found in the cerebellum)
- Golgi (GABA neurones found in the cerebellum)
Classic Structure
Soma (nucleus within), single axon (from soma at axon hillock), neurofilaments and then dendrites
Neurofilament Function
type of intermediate filament that provides structural support and transport
Astrocyte Info
- neuroglia
- outnumber neuronal cells in CNA
- not excitable
- can proliferate
- most abundant cell in mammalian brain
Astrocyte Function
- structural cells as act as ‘glue’
- repair by providing nutrients for neuronal cells
- facultative macrophages (can become one if necessary)
- Homeostasis vie clearing neurotransmitter and other substances released in CNS
Oligodendrocyte Function
Forms the myelin within the CNS. One oligodendrocyte can myelinate many axons.
Difference between Oligodendrocytes and Astrocytes
- oligodendrocytes are smaller
- oligodendrocytes have a denser cytoplasm and nucleus
- oligodendrocytes do not have intermediate filaments and glycogen in the cytoplasm
Schwann Cell Info
- produce myelin for peripheral nerves
- one schwann cell myelinates one axon
Microglial Cell Function
Immune cells of the CNS. Similar to macrophages
Ependymal Cell function
- Epithelial cells of the CNS. They line fluid filled ventricles (CSF). Regulate production/movement of CSF
Neurotransmission Major Ions
- Na+
- K+
- Ca2+
- Cl-
Normal Ion Values Intracellularly
K+ = 150mM Na+ = 10mM Ca2+ = 0.0001mM Cl- = 5mM
Normal Ion Values Extracellularly
K+ = 4mM Na+ = 140mM Ca2+ = 2mM Cl- = 120mM
Action Potential Order
1) Resting membrane potential = -90mV–40mV
2) at -40mV, VGSC open leading to Na+ influx
3) Depolarisation occurs till VGKC open and efflux of K+ occurs (therefore repolarisation)
4) membrane returns to resting potential after hyperpolarisation
5) Na-K+ pump restore resting potential
Saltatory Conduction
Myelin prevents depolarisation apart from at the Nodes of Ranvier (these have a dense conc of VGSC and VGKC). Action potential jumps
Synapse Occurences
1) AP propagated towards synapse
2) AP cause VGCC’s to open allowing Ca2+ influx and therefore vesicle exocytosis
3) the NT binds to post-synaptic receptors which modulate post-synaptic activity
4) NT dissociates from receptor and is either metabolised by enzymes in synpatic cleft or recycled by transporter proteins
