Lecture 17 & 18: The Nervous System Flashcards
features of a neuronal cell
- soma: cell body
- dendrites
- axon / nerve fibre
- axon terminal
- axon hillock
label a neuron
check
features of a unipolar neuron
- one axon only
- pseudounipolar neurons have soma halfway up the axon
- primary sensory neuron is pseudounipolar
- cell bodies sit in ganglia, eg dorsal root ganglia found close to intervertebral foramen
features of a bipolar neuron
- one axon and one dendrite
- found in retina and olfactory epithelia
- associated with specialised sensory neurons
- not very many in humans
features of a multipolar neuron
- one axon, multiple dendrites
- majority of nerves in the brain are multipolar
- sit within autonomic ganglia
what is saltatory conduction
in myelinated axons, where action potential passes from node of Rhanvier to node of Rhanvier, skipping myelinated internodes
speeds of myelinated conduction vs unmyelinated
- myelinated: 120 m/s
- unmyelinated <1.5 m/s
what are afferent axons
carry information towards central nervous system, eg primary sensory neron
what are efferent axons
carry information away from central nervous system, eg motor neuron
what are the neuroglia of the central nervous system
- astrocytes
- oligodendrocytes
- microglia
what are the neuroglia of the peripheral nervous system
Schwann cells
what do astrocytes do
- form scaffold for neurons during development
- supply nutrients like glucose and lactate
- remove K+ to maintain the ionic environment
- uptake neurotransmitters
- form glial scars to repair damage
- form barriers around blood vessels
what do oligodendrocytes do
produce myelin, one oligodendrocyte myelinates multiple axons
what do microglia do
immune cells that can:
- secrete cytokines
- be phagocytic
- be cytotoxic and release H2O2
- promote repair by clearing debris
what do Schwann cells do
- myelinate axons, but one Schwann cell myelinates one axon
- can secrete cytokines and be phagocytic
- provide substrate (a tube) for a damaged axon to grow
what is the forebrain made up of
- cerebral hemispheres
- thalamus
- hypothalamus
what is the function of the cerebral hemispheres
process motor and sensory information, mostly cognition
what are the lobes of the cerebral hemispheres and what are their functions
- frontal: primary motor cortex
- parietal: primary somatosensory cortex so processes pain, touch and temperature
- temporal: primary auditory cortex and primary olfactory cortex
- occipital: primary visual cortex
structure and function of thalamus
- paired structure
- relay centre of the brain
- except for olfactory, sensory information passes through the thalamus before reaching the cortex
function of the hypothalamus
- important in homeostasis
- controls autonomic nervous system and endocrine system
- controls pituitary gland
structure and function of the brainstem
- formed by midbrain and hindbrain
- connects cortex to spinal cord
- medulla within the brainstem controls respiration and cardiovascular systems
- damage would most likely be fatal
function of cerebellum
- co-ordinates muscular activity
- damage causes ataxia, lack of co-ordination
what does the spinal cord extend to
from atlas to L1, first lumbar vertebra
what does the spinal cord sit within
vertebral canal
