week 3 communications in the brain Flashcards
what 2 systems are part of the peripheral nervous system
somatic and autonomic nervous system
what is part of the central nervous system
spinal cord and brain
what are 3 types of glia cells
astrocytes, oligodendrocyte and schwann
what are astrocytes
serve as the matrix that hold neurons in place and insulates them from others
they surround and isolate synapses, limiting dispersion of neurotransmitters released by terminal buttons
what are oligodendrocytes
provides support for neurons and forms myelin sheaths around axons in CNS
What is a Schwann cell
formation of myelin sheath in PNS
what is the blood brain barrier
a semipermeable barrier between the blood and the brain produced by the cells in the walls of brains capillaries
what does the selective permeability of the blood brain barrier mean
some substances eg water can pass through capillary passively, but other molecules require AT
sensory neuron (unipolar)
detects changes in external or internal environment and sends info to CNS
motor neuron (multipolar)
located in CNS and controls contraction of muscle/ secretion of gland
interneuron or relay (bipolar)
located entirely through CNS and connects motor to sensory neuron
why is reflex arc fast
doesn’t need input from the brain
what do microtubules do
transport neurotransmitters and proteins from soma to terminal buttons (anterograde axoplasmic transport) and move materials from terminal buttons to soma eg recycled neurotransmitters (retrograde)
how is a resting potential of -70mV established in an axon
- active transport of 3 Na+ ions out of neuron and 2k+ in
- since more + charged are moved out, this creates more - charge inside
- now, k+ ion diffuse out of the neuron down their concentration gradient, making the inside more -, but electrostatic pressure allows for k+ to re-enter, so k+ level is balanced
- the membrane has more k+ channels than Na+, but evenso some Na+ ions diffuse back in
describe the process of an action potential
- after stimulation, p.d reaches threshold and action potential generated. Na+ channels open, Na+ ions enter the cell
- k+ channels open and k+ leaves the cell (depolarization)
- Na+ channels become refractory - no more Na+ enters
- k+ continues to leave the cell, causing membrane potential to return to resting level (repolarisation)
- k+ channels close, Na+ channels reset
- extra k+ outside diffuses away - hyperpolarisation (-90mV)
what 2 things can cause an AP
activation by a previous neuron
activation by previous AP
why does saltatory conduction speed up velocity at which an axon can conduct an AP
because it doesn’t have to depolarize along the whole length of the axon
what’s the max velocity of conduction in human motor neurons
60 meters per second
what’s the all or nothing principle
the membrane potential must reach the threshold (-50mV) for an action potential to fire
what is the rate law
variations in the intensity of a stimulus are represented by variations in the rate at which the axon fires
what’s the 4 steps in the lifecycle of a neurotransmitter
- synthesis
- release
- binding
- inactivation
what are the 2 types of receptors
ionotropic receptors, metabotropic receptors
what do ionotopric receptors do
control ion channels
you can have excitatory/inhibitory responses
what channels open for an excitatory response
Na+
