lesson 1 Flashcards
autonomic nervous system
def
not under individuals control
includes sympathetic (fight or flight) & parasympathetic (rest and digest) nerves
explain how stem cells can develop into specialised neuron cells (link to topic 3)
-stem cell recieves external stimulus in the form of a hormone
-hormone enables activation of specific genes
-RNA polymerase transcribes genes into MRNA
-mRNA is translated at the ribosome into proteins
-the protein produced differenciates the stem cell into a neuron cell
difference between grey and white matter
grey matter contains the cell bodies of neurons (nerve cells) and their local connections to each other, white matter contains bundles of nerve fibres that connect distant brain regions to each other
difference between neurones and glia
neurones carry electrical impulses, glia insulate the axons of neurons and speed up impulse transmission
q for olivia, what is saltatory conduction
2) Describe the roles of:
a) Schwann cells/myelin sheath
schwann cells form a myelin sheath (fatty layer) around axons wrap around axons, insulate them and increase speed of impulse transmission.
role of the axon
extension sending impulse away from cell body
role of dendrites
form connections with many other neurons
short branched extensions of a neurone which recieve impulses from other cells at synapses and transmits them to the cell body.
role of the nodes of ranvier
uninsulated gaps between schwann cells where the axon membrane is exposed, ion exchange happens here
Electrical impulses in myelinated cells dont travel down the whole axon, but jump from one node to the next, speeding up impulse transmission
role of cell body
Contains neuron nucleus and eukaryotic cellular structures
whatre sensory neurones
they carry impulses from receptors to the brain and spinal chord in the CNS
describe sensory neurone structure
A cell body that branches off in the middle of the axon
The dendrites are attached to a receptor cell
The section of neurone that links the axon terminal (at the receptors) with the cell body is known as a dendron; it delivers the electrical impulse to the cell body
The section of neurone that connects the cell body with the CNS is the axon
whatre relay neurones
connect sensory and motor neurones-found entirely in CNS
describe relay neurone structure
short neurones with long axons and highly branched dendrites
Whatre motor neurones
carry impulses from the CNS to effector muscles or glands
describe motor neurone structure
A large cell body at one end that lies within the spinal cord or brain
Many highly-branched dendrites extending from the cell body, providing many connections with the axon terminals of other neurones
whats an axon terminal
The end of the axon, the axon terminal, has many nerve endings
The nerve endings at the axon terminals allow neurones to connect to and receive impulses from other neurones, forming a network for easy communication
contains neurotransmitters and makes synaptic contact with next neuron in the chain
what direction does the nerve impulse go in? (in terms of axons and dendrites)
from dendrites to axon
how can water move across a cell membrane
dispite its polarity it can diffuse across a phospholipid bilayer and also move using channel proteins (aquaporins)
what part of an electrical impulse can vary, its strength , speed or frequency
frequency
how is it ensured that action potentials continue in one direction only?
after a section of an axon has been depolarised and the action potential has been spread further from it it will be temporarily unresponsive to depolarisation as its in a phase of repolarisation, cant be depolarised again by the next section of the axon that is just spread the wvae of depolarisation to.
what is membrane potential
difference in electric potential between the interior and exterior of a biological cell/ the bigger the difference between + and - areas the higher the voltage & larger the potential
what is voltage
the measure of potential energy generated by separated charges
what is current
the flow of electricity from one point to another
current= voltage/resistance
