Lecture 2: Intro to neurophysiology Flashcards
what does the nervous system do?
it maintains homeostasis and control subconscious body functions
what else is the nervous system responsible for
- thoughts, feelings, memories, emotions, sleep
- creating sensations and perceptions from sensory info: vision, hearing, taste, smell, touch etc
- creating perceptions of pain
- generating and co-ordinating movements and behaviours, voluntary and “innate”
- reproductive function
organisation of CNS
consists of:
- brain
- spinal cord
composed of 2 general cell classes:
- neurons
- glia
organisation of PNS
consists of:
- peripheral nerves
- ganglia
composed of 2 general cell classes:
- neurons
- glia
neurons structure
input zone:
- dendrites and cell body
- receives chemical signals from other neurons
summation zone:
structure= axon hillock
- summation of inputs
conduction zone:
- axon may be quite long
- carry electrical signals between brain areas, to and from spinal cord, or from peripheral sensory receptors and to effector cells
output zone:
- axon terminals
- contact with input zone of other neurons or effectors
- release of neurotransmitter = chemical signal
4 morphological types of neurons
- multipolar
multiple processes emanate from the cell body - bipolar
two processes emanate from the cell body - unipolar
- one process emanates from the cell body
- then branches into dendrite and axon - anaxonic
- no distinct axon
- all processes look alike
where does neuron-neuron signalling take place
synapses
Glia: CNS
(OAME)
oligodendrocytes= form the myelin sheath
astrocytes= provide nutrients, maintain extracellular environment, and provide structural support
microglia = mount the immune response
ependymal cells = circulate and produce cerebrospinal fluid
glia: PNS
schwann cells = form the myelin sheath
satellite cells = provide nutrients and structural support to neurons
what can inputs and outputs be
excitatory or inhibitory
information processing in the nervous system
Is the throughput and balance of excitatory and inhibitory signals across networks of neurons
electrical synapse (gap junctions)
- very fast
- ions flow from cell to cell
- may be bidirectional
chemical synapse
- slower
- relies upon chemical crossing the gap
- complex series of events
- neurotransmitter packaged in vesicles
- synapse strength can be modified
- are unidirectional
how is the brain organised
into regions based on function
how is the brain organised in regards to sensation
- sensory axons retain a strict spatial relationship to one another along their projection pathways
- therefore info arrives in the somatosensory cortex with a specific map of the body
why is the sensory map distorted
because regions with high receptor density and smaller receptive field sizes occupy a disproportionately large area
what does the motor efferent info split into
somatic and autonomic
autonomic nervous system contains
sympathetic nervous system= fight, flight, fright
parasympathetic nervous system = rest, digest
what is the form of signalling within a single nerve
electrical
what is the form of signalling between nerve cells or between nerve and non nerve cells
mostly chemical
resting membrane potential
the electrical potential across the membrane of an inactive nerve cell
local potential/ action potentials
when excitable cells are active, the potential (voltage) across the membrane changes very briefly
