L1 Flashcards
how many pairs of cranial nerves are there
12
how many spinal nerves are there
31 pairs
what are the cranial nerves responsible for
they connect directly to the brain and they are responsible for….
smell vision eye movement trigeminal (facial sensation, mastication) facial expression hearing and balance oral sensation, taste and salivation vagus (heart, lungs, digestion) shoulder elevation and head turning tongue movement
what is a sensory dermatome
it is the map of the body where particular nerves are receiving information from
where is information leaving and and entering the spinal cord form
it enters from the dorsal region through unipolar sensory neurons
it efferent information leaves through the ventral region through multipolar motor neurons
what are the 3 divisions of the human brain
the forebrain, midbrain and the hindbrain
what are the divisions of the forebrain
the telencephalon and the diencephalon
what is the telencephalon
it is the cerebral cortex.
what is the diencephalon
it contains the thalamus, hypothalamus and the pineal gland
what causes there to be an ion greaident
ion pumps
what is a concentration gradient
different concentrations of an ion on either side of the membrane
what is an electrical gradient
unlike charges attract therefore ions are going to try and balance out the charges on either side of the membrane
how is information transmitted within a cell
through transient alterations in the membrane potential produced when ions are allowed to cross the membrane
what is the difference between a graded and an action potential
graded is a pulse in the dendrites and an action potential is actively propagated in the axon
action potential is over a long distance and graded is short
action potentials are all or none
graded potentials degrade over time, action potentials do not
how can channels on the membrane be opened or closed
by receptor activation, signaling molecules or an environmental change (eg light, sound, touch)
when the cell is at RMP what state is it in
at -70mV the cell is in its polarized state
what is depolerisation
it is when Na enters the cell through voltage gated Na channels. the more Na that comes into the cell the more voltage gated Na channels that open
what is the hodgkin huxley cycle
it starts with a synaptic or receptor potential that causes the depolerisation of the membrane
that then causes the opening of voltage gated Na channels which causes the flow of Na ions into the cell
that flow of ions courses further depolerisation of the membrane and you enter almost like a positive feedback loop
this is why Na into the cell causes the activation of more voltage gated Na channels
this is what causes the large and rapid response of the neuron
describe the voltage trace of an action potential
you start at -70mV, if you reach threshold (-60mV) then the voltage gated Na channels open. this is the start of the rising phase.
at about -50mV the K+ channels open
at about +35mV the Na channels close and repolarisation starts
when the cell gets back down to RMP the K+ channels close and hyperpolarisation happens
what is the range of conduction velocity of an action potential
0.5 - 2 m/s
why are we able to have fast reaction times
because of myelination
what are the nodes and internodes
the internodes are myelinated
the nodes work as boosters as they have a high conc of ion channels so that you are able to refire the action potential. this is what allows us to increase our conduction velocity to 100m/s
what disease is a result of demyelination
multiple sclerosis
state some symptoms of multiple sclerosis
- numbness/weakness in one or more limbs
- partial or complete loss of central vision (usually in one eye)
- double or blurry vision
- tingling or pain
- electric shock sensations that occur with certain head movements
- tremor/lack of coordination
- slurred speech
- fatigue
- dizziness
why does multiple sclerosis have a wide range of symptoms
because you are losing the insulating layer of your neurons therefore action potentials are unable to be transduced as quickly
how is usain bolt able to run so fast
because he runs reflexively
this means that he is running in an open loop system as he is acting without deciding what he is going to do (open loop is a spinal reflex). this is why you often see sprinters trip over nothing
what is a closed loop system
when information is coming in and you plan a response
