What are the two types of potentials
Localised
- passive and operate over short distances
- graded (info encoded by amplitude)
- typically sensory receptors endings and PS membranes
Action potentials
- all or nothing
- regenerative
- info encoded by frequency and timing
- directional
What are the 4 glial cells
- Astrocytes
- Oligodendrocytes
- Ependymal
- Microglia
General characteristics of Glial cells
Large negative resting membrane potential- 90mV; due to K+ distribution
Electrically coupled at gap junctions
Can divide and multiply
5 properties of astrocytes
- Scaffold for neurones and blood vessels
- Regulate external environment
- Maintain integrity of BBB
- Regulate synaptic transmission
- NS repair - become phagocytic, replace damaged cells with glial scar tissue
Role of oligodendrocytes
- Large number in white matter
2. Resemble Schwann cells of PNS; can form myelin for 3-50 nerve fibres
Role of Ependymal cells
- Line cavities and ventricles
2. CSF production and movement (cilliated cells)
Role of microglia
- White and grey matter
- Macrophages of CNS
- Mediates immune response in CNS
- Act as APCs to interact with T-helper cells
What are the 3 germ layers
- Ectoderm
- Mesoderm
- Endoderm
What does the Ectoderm become
Epidermis and CNS
What does Mesoderm become
Muscles Bones Kidneys Circulatory system Gonands
What does endoderm become
Inner mucosal lining- GI and respiratory
Describe the development of CNS and PNS
- Neural tube forms CNS
2. Neural crest forms PNS
Describe cortical layer development
- 3 processes: proliferation, migration, differentiation
- Neurones migrate along radial glial cells
- Inside out cortical development
Describe neuralation
Formation of neural tube from flat sheet of ectoderm, induced my signalling from notochord
What does the neural tube differentiate into
- Spinal cord
2. 3 primary brain vesicles
How do dendrites ‘scale up’ synaptic input to achieve a democratic weighting
- thinner dendrites
- higher resistance
- higher voltage required (Ohm’s law)
What is the order of embryo development
Day 0: fertilisation Day 1: blastomere Day 3: Morula Day 6: Blastocyte Gasturlaton leads to 3 germ layers
What are the 3 primary vesicles
Prosencephalon: forebrain
Mesencephalon: midbrain
Rhombencephalon: hindbrain
What does the prosencephalon differentiate into
- Telencephalon: cerebral cortex
- Diencephalon: thalamus, hypothalamus and epithalmus
- Optic vesicles
- lateral and 3rd ventricles
What does the Mesencephalon differentiate into
- tectum and tegmentum
- cerebral aqueduct
What does the Rhombencephalon differentiate into
- metencephalon (cerebellum and pons)
- myelenceohalon (medulla)
- 4th ventricle
