3nervous physiology week 3 LSB258

Question Answer
what is an action potential the rate of speed of an electrochemical event, which starts at the cell body and travels down the axon terminal
what is an electrochemical event its the communication in the nervous system
what are the 2 main control centre software the human bidy nervous system and endocrine system
what are the electrical signals used by the nervous system Action potentials
what does synaptic transmission/electrical communication allow the nervous system to provide rapid and specific communication between neurones,
what variable is used to express the speed of electrical communication conduction velocity, m/s-1
what is the typical range of conduction velocity 0.5-130 m/s-1
what does the nervous system allow us to do 2 things: simple and complex, SIMPLE: sensory functions and motor functions. COMPLEX: higher functions such as memory, communication, personality, creativity, conciousness
what are the two major cell types that make up nervous tissue neurones and neuroglia
what is the function and general features of neuroglia (glia cells) to support, assist and insulate neurones. smaller than neurones and are able to proliferate
what are the 4 types of neuroglia cells astrocytes, microglia cells, oligodendrocytes (CNS)/schwann cells (PNS), ependymal cells
function of astrocytes and shape provide physical support for neurones, regulate ionic environment. Star shaped body
function of microglia cells and shape the cells are usually stationary however respond to injury by phagocytosing debris at the site of damage. oval body
oligodendrocytes (CNS)/schwann cells (PNS) function and shape wrap around axons to create a militated sheath this is to provide isolation, prevent short signalling of electrical signals and increase speed of action potentials. round cell body
function of ependymal cells and shape line the ventricles of the CNS to act as a barrier between CNS tissue and fluid. the cilla moves fluid inside the ventricles. single layer of cuboidal or columnar cells with cilia.
function of neurons they are electrically excitable cells which are responsible for all nervous system functions. do not proliferate, vary in shape in size
what is the structure of a neurone cell body, dendrites(extensions of the body), axon(long process radiating from body) and axon terminals(bulbous endings on the end of each branch off the axon)
what is the function of the neurones cell body to control all the metabolic processes of the nervous sytem
what is the function of the dendrites to collect information in the environment or from other neurones. increases surface area of the cell body
what is the function of the axon to connect the cell body to other parts of the NS to enable communication
what is the function of the axon terminals to create a synapse which enables communication between neurones
what are the two types of neurones myelinated and unmyelinated axons
what are the features of unmyelinated neurones smaller in diameter, no myelinated sheath rather axons sit in pockets made of oligodendrocytes which provides insulation. slower rate of action potential (0.5-2.5m/s-1)
what is a membrane potential the potential difference across the membrane
what is the potential difference the difference in charge between two points
what is membrane potential measured in millivolts mV – by a voltmeter
what is the resting membrane potential of a cell -80mV
what is the membrane potential referred to at rest the membrane potential is polarised, which means the inside charge is different from the outside
a membrane can be referred to by 3 different types depolarisation, depolarisation, hyperpolarisation
what is depolarisation when the membrane potential decreases in magnitude from the resting membrane potential. membrane becomes less polarised
what is depolarisation where the membrane potential increases in magnitude towards the resting membrane potential. membrane is restoring in polarisation
what is hyperpolarisation where the membrane potential increases in magnitude from the resting membrane potential
what is graded potential when a small, transient, graded, local change in the membrane potential is produced by a stimulus. the size of a graded potential depends on the size of the stimulus. e.g. small stimulus = small graded potential. changes in the membrane potential are only seen adjacent to where the stimulus is applied.
what are the two types of graded potentials depolarising graded potential or hyper polarising graded potential
what is a depolarising graded potential the graded potential is produced by an excitatory stimulus to cause a small transient depolarisation of the membrane potential
what is a hyperpolaring graded potential the graded potential is produced by an inhibitory stimulus that causes a small transient hyperpolarisation of the membrane potential
describe an action potential consistant in shape and duration, has a complete 3 phase change, stimulus effects the whole cell, large and fast change. a change will only be seen is stimulus exceeds the threshold of -65mV
what are the 3 phases of an action potential the action potential will start with a depolarising phase,where the membrane potential will increase, followed by a repolarising phase where it will decrease back to RMP and with a final undershoot phase of hyperpolarsing, increasing from bellow the RMP.
how do action potentials encode information through the principle of frequenting encoding. this is measured in HZ and is the frequency of number of action potentials per second not the size of the action potential (as all AP are consistent in size) eg. heavy weight is picked up = high frequency of action potentials. light weight = low frequency of action potentials
In synaptic transmission what is the structure presynaptic neurone, presynaptic membrane, synaptic cleft, postsynaptic membrane, postsynaptic neurone
what is the mechanism of synaptic transmission to change the excitability of the postsynaptic neurone. this is achieved by a neurotransmitter released by the presynaptic neurone, which diffuses across the synaptic cleft and binds to the receptors on the post synaptic neurone.
what is an excitatory synapse The neurotransmitter binds to the receptor resulting in a depolarising graded potential – taking the membrane potential closer to threshold (cell is becoming more excited)
what is an inhibitory synapses Neurotransmitter binds to the receptor resulting in a Hyperpolarising graded potential – takes the membrane potential away from threshold (Cell becomes inhibited or less excited)
What is synaptic integration the way we use excitatory and inhibitory synapses. we use them the decision making process. A neurone will receive multiple synaptic inputs both excitatory and inhibitory, the neurone will determine whether the threshold is reached or not. if it is reached we will get an action potential (which means we do something) if it isn't we do not.
what are the features of myelinated neurones larger in diameter. contained myelinated sheath which provides insulation. rapid action potential conduction (15-130 m/s-1)

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