Neurons and Synaptic transmission Flashcards
1
Q
what are neurons??
A
- nervous system contains 100 billions of these and 80% are located in the brain.
- these cells must relay info around the brain and nervous system by using electrical impulses and chemicals called neurotransmitters
- electrical impulses travel from one end of a neuron to the others and relaease a neurotransmitter and if not functioning properly this will effect our behaviour
2
Q
how does a neuron work??
A
- when a message travels down a neuron, it is in the form of an electrical impulse called an action potential
- to be passed to next neuron, the message has to cross a small gap called the synaptic cleft. As electrical impulses cannot pass over this gap, it is converted into a chemical message thru neurotransmitters
- if the next neuron is activated by these neurotransmitters, the message is converted back into an electrical impulse that travels down the neuron
3
Q
what is the structure of neurons?
A
- dendrites
- nucleus
- axon
- myelin sheath
- nodes of ranvier
terminal buttons
4
Q
what are dendrites?
A
appendages that are designed to recieve communication from other cells and have a tree like structure - form projections that stimulate other neurons and conduct electrochemical charge to cell body
5
Q
what does the nucleus do?
A
contains genetic material of info for cells development and sysnthesis of proteins for cell maintenance and survival
6
Q
what does the Axon do?
A
- after dendrites have passed electrical impulse to cell body, the cell body passes the electrical impulse along the axon until it reaches the terminal buttons
7
Q
what does the myelin sheath do?
A
- protective layer that wraps around the axons of neurons to aid insulating neurons and increase electrical signals
8
Q
what do the nodes of ravier do?
A
- the 1-2 micrometer gap between the gial cells - help facilitate rapid conduction of nerve impulses
9
Q
what do the terminal buttons do??
A
terminal buttons - send the signal on to other neurons
10
Q
what are the three different types of neurons?
A
sensory, motor and relay
11
Q
describe sensory neurons??
A
- carry messages from the PNS to the CNS
- they only transmit messages and known as unipolar
- tell the brain about external and internal environment by processing info from one of the fire sets of snesory receptors which are quickly inverted into electrical impulses
- in the brain these impulses are translated into sensations so we can react appropriately
- have long dendrites and short axons
12
Q
describe relay neurons?
A
- most common type of neuron in the CNS
- allow sensory and motor neurons to communicate and connect with each other = carry nerve impulses between neurons
- they are multipolar as they send and recieve info from many sources
- only carry messages from one part of the CNS to the other, they are not founf in other parts of the nervous system
13
Q
what are motor neurons?
A
- these connect the CNS to effectors like muscles and glands
- they are multipolar since they send and recieve info from many sources
- project axons outside the CNS to directly or indirectly control mucsles and glands
- form synapses within muscles and when stimulated they relaease neurotransmitters to triggar response in uscles to make them contract
- strength of contraction depnds on the rate of nerve impulses.
- inhibition of these nerve impulese causes muscle relaxation
- have short and long axons
14
Q
how do neurons communicate with each other?
A
- communicate within groups known as neural networks and each neruon is sperated from each other by a tiny gap called a synapse
- signals are turned into chemicals using neruotransmitters and carry signals across synaptic gap and increase or deacrease likelihood of further activity
15
Q
how does the process of a synaptic gap go?
A
- when the dendrite pick up message it sends impulse thru cell body and along axon to terminal buttons
- once an action potential has arrived at terminal buttons at the end of the axon, it needs to be transferred to another neuron. to achieve this it needs to cross a synaptic gap
- at the end of the terminal buttons there are synaptic vesicles that contain and store neurotransmitters. these are chemical messengers that convert the impulse to a chemical message thats transferred to next neruon
- as the impulse travelling to the end of the neruon it reaches the synpatic vesicle which they release the NT that then crosses the gap
- as the NT diffuses across the synaptic gap it binds to specialised recpetors on the surface of a diff cell (dendrites) that recognise it and match that particular cell
- once the next cell is activated the receptor molecules produce either an excitatory effect that strengthens furhter impulses or an inhibiotry effect that weakens further impulses
- synaptic transmission is completed by a process called re-uptake. this is where the NT is taken back up/ recycled by the pre-synaptic neuron
