Nervous system Flashcards
What is the central nervous system made up of?
The spinal cord and the brain
Describe the brains role in the central nervous system
Involved in most consious and unconsious processing
Describe the spinal cords role in the central nervous system
Relays information between the brain and the rest of the body, allowing the brain to regulate and monitor bodily processes e.g digestion and to coordinate voluntary movements. The spinal cord also has pairs of spinal nerves which connect to specific muscles or glands, and the spinal cord also has circuits of nerve cells that enable us to perform some simple reflexes without the direct involvement of the brain.
What may happen if the spinal cord gets damaged?
Areas supplied by spinal nerves below the damaged site will be cut off from the brain and stop functioning
List the 4 main areas that the brain divides into
The cerebrum, the cerebellum, the diencephalon and the brain stem
Describe the cerebrums structure and function in the brain
This is the largest part of the brain and is further divided into 4 different lobes which each have their own function, eg the frontal lobe which is involved in thought and speech processing. The cerebrum is divided into two hemispheres which are specialised for particular behaviours, and each half communicates via the corpus callosum.
Describe the structure and function of the cerebellum in the brain
This sits at the back of the cerebrum and this is involved in controlling a persons motor skills and balance, coordinating the muscles to allow specific movements.
What may damage done to the cerebellum cause?
Speech and motor problems and epilepsy
What is the structure and function of the diencephalon in the brain?
This lies beneath the cerebrum and on top of the brain stem, and within this area there are 2 important structures which are the thalamus and the hypothalamus.
Thalamus- Acts as a relay station for nerve impulses coming from the senses routing them to appropriate part of the brain where they can be processed
Hypothalamus has a number of important functions including regulation of body temperature, hunger and thirst, and also acts as the link between the endocrine sustem and the nervous system controlling the release of hormones from P gland
What is the function of the brain stem?
Responsible for regulating the automatic functions that are essential for life, including breathing, heartbeat and swallowing. Motor and sensory neurons also travel through the brain s
What is the peripheral nervous system
All the nerves outside of the CNS make up this nervous system, and the function of this is to relay nerve impulses from the CNS to the rest of the body and from the body back to the CNS
When does synaptic transmission take place?
When an action potential has arrived at the terminal button at the end of the axon, and it needs to be transferrred to another neuron or a tissue, it must cross a gap between the presynaptic neuron and the postsynaptic neuron which is a synapse.
Describe the process of synaptic transmission
At the end of the axon of the nerve cell are a number of sacs called synaptic vesicles, which contain the neurotransmiters tha. When the action potential reaches the synaptic vesicles it causes them to release their contents through a process called exocytosis. The released neurotransmitter will then diffuse across the synaptic gap and will bind to specialised receptors on the surface of the cell that recognise it and are activated by that particular neurotransmitter. Once they have been activated they will either produce a excitaory or inhibitory effects on the post synaptic neuron
What determines the effects on the postsynaptic neuron during synaptic transmission?
How quickly the presynaptic neuron re-uptakes the neurotransmitter from the synaptic cleft ( where it is stored and made available for later release) The quicker it is taken back, the shorter the effects on the post synaptic neuron
Give examples of excitatory neurotransmitters
Noradrenaline and acetylcholine
What is an excitatory neurotransmitter
They are the nervous systems on switches and they increase the likelihood that an excitatory signal is sent to the post synaptic cell which is then more likely to fire. When they bind to a post synaptic receptor it causes an electrical change in the membrane of that cell, resulting in an excitatory post synaptic potential meaning the post synaptic cell is more likely to fire an action potential
What is an inhibitory neurotransmitter?
These are the nervous systems off switches and they decrease the likelihood of that neuron firing. They are generally responsible for calming the mind and body, including sleep, and filtering out any unneccasary excitatory signals. When they bind to a post syanptic receptor this results in an inhibitory postsynaptic potential meaning it is less likely the cell will fire an action potential
What happens when a nerve cell receives both excitatory post synaptic potential and inhibitory?
The likelihood of a cell firing this therefore determined by adding up the excitatory and the inhibitory synaptic input, the net result of this summation determines wether or not the cell fires
How may the strength of an EPSP be increased?
- By spatial summation when a large number of EPSPs are generated at many different synapses on the same postsynaptic neuron at the same time
- In temporal summation, a large number of EPSPs are generated at the same synapse by a series of high frequency action potentials on the pre-synaptic neuron
What does the rate at which a cell fires at depend upon?
BY what goes on in the synapses , if excitaory synapses are more active, the cell will fire at a higher rate, if inhibitory synpases are more active the cell will fire slowly if not at all
Define synapse
The conjunction of the end of the axon of one neuron and the dendrite or cell body of another.
Define neurotransmitter
Chemical substances that play an important role in the workings of a nervous system by transmitting nerve impulses across a synapse
Define synaptic transmisssion
The process where a nerve impulse passes across the synaptic cleft from one neuron ( pre synaptic) to the other (post synaptic)
