4.12 Nervous System Flashcards
What is a neuron?
Functional unit of the nervous system
What are the three different types of neurons? SIM
Sensory, inter neuron and motorneuron
What is the job of the sensory nervous system?
Communicate environmental stimuli to the central nervous system
Where is sensory neurons found?
In clusters outside the spinal cord called ganglions
What are 2 examples of sensory neurons?
Photoreceptors and thermoreceptors
What is the job of interneurons?
Link neurons within the body
Interpret sensory information and connect it to motor neurons that initiate the correct response
How is information received in the nervous system?
Dendrites from sensory neurons receive information from sensory receptors located near the surface of the skin. The information is then carried to the interneurons in the CNS that coordinate the information and relay it to the appropriate motor neuron(s). motor neurons transmit information onto the appropriate effector
How do impulses enter all three types of neurons?
Impulse enters at the dendrite into the cell body
How does an impulse leave all three types of neurons?
Leaves via the axon and extension of the cytoplasm
How long or short can an axon be?
These axons can reach up to a metre in length while in other organisms it may be a little more than and micro meter
How many neurons can a neuron link to?
One neuron may link to and affect multiple other neurons while other may come together and affect a single neuron
What are glial cells known as in the nervous system?
They are the unsung hero’s of the nervous system and outnumber neurons 50:1
What are the three functions of the glial cells? PGM
They provide physical support for neurons since neuron lack sufficient extra cellular matrix
They direct the growth of neurons during repair and development
They provide metabolic support to nerve cells
How many types of glial cells are in the CNS?
4
How many types of cells are in the PNS?
2
What are the two most important cells in CNS and PNS and what are they responsible for?
Schwann and ogliodendrocytes they are responsible for the production of myelin
What are the three functions of myelin? CDS
A white fatty protein that covers most axons
Insulates the axons and slow degradation of the signal (charged ions)
Along the axon there are gaps between the stealth called nodes of ranveir where nerve impulses jump from one node to the next speeding up signal propagation
where is neurilemma found? What is the function of neurilemma?
All nerve fibres in the PNS contain an additional wrapping called the neurilemma
The membrane helps regenerate damaged neurons that cut axons can join
Grey vs white matter in the brain?
Grey matter contains mostly cell bodies while white matter contains relatively few cell bodies and is composed chiefly of myelinated white matter. The colour difference arises mainly from the whiteness of myelin
Why do you think damage to grey matter is usually permanent?
Grey matter lack neurilemma to regenerate damaged cell bodies
nerve transmission versus electricity transmission, where they travel, their strength, charges by, substances they carry
current electricity travels along a wire much like impulses travel along a nerve
electrical current is diminish along a wire but nerve impulses remind strong until the end
electrical wires rely on some type of outside energy source like a battery while nerves rely on cellular energy
nerve impulses are created by the movement of ions across the nerve cell membrane rather than the movement of electrons
what is potential difference?
the voltage across part of a circuit
what is action potential?
the difference of voltage created when a nerve is excited
what is resting potential?
the difference in voltage across the nerve membrane when a nerve is not excited
what do neurons have on either side of their membrane?
neurons have a rich supply of both positive and negative ions on either side of their membrane
what charge can not pass the neuron membrane?
negative ions are largely impermeable and therefore have little affect on the overall charge
what does the generation of an electrochemical gradient result from?
an electrochemical gradient results from the uneven distribution of positive ions on either side of the nerve membrane
what is the easiest way to change membrane potential of Vm?
transport ions across the nerve cell membrane via specific channels
how are sensory channels opened?
channels are opens mechanically form in response to physical forces of pressure and light
how are gated ion channels opened?
gated ion channels open in response of the secreting of neurotransmitters
how are voltage gated channels opened?
open in response to electrical potential of the membrane
