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Nervous system functioning - Coggle Diagram
Nervous system functioning
roles of different divisions in the nervous system
central nervous system
the brain
cerebral cortex is the outer layer of the brain.
made of interneurons
cerebral cortex is divided in two halves: cerebral hemispheres
-corpus callosum allows communication between two halves
the spinal cord
cable like column of nerve fibers that extends from the base of the brain to the lower back and is made of interneurons.
major functions:
-receive sensory info from the body via the PNS and transmit them to the brain.
-receive info from the brain and relay it to the body via the PNS to control muscles, glands, and internal organs.
peripheral nervous system
the entire network of nerves located outside of the CNS
two main functions:
-carry information from the sensory and internal organs to the CNS via sensory neurons.
-convey info from the CNS to the muscles, organs and glands via motor neurons
somatic nervous system
voluntary actions
transmits sensory information recieved by sensory receptor cells inwards towards the CNS, and motor messages from the CNS to the bodys voluntary skeletal muscles.
example
feel heat of a wood fire on hands
sensory receptors in hands recieve heat sensation
sensory neurons in PNS transmit info to spinal cord
interneurons in spinal cord send info to the brain for processing
brain processes info then action is carries to the muscle by motor neurons in PNS
neurotransmitters released into muscle, cause muscle to expand or contract
somatic nervous system initiates all skeletal muscle activity.
autonomic nervous system
transmits motor messages from the brain to the bodies internal organs and glands, resulting in involuntary activity of internal organs and glands.
transmits messages back to the brain about activity levels of organs
keeps vital organs and systems in the body functioning, while also maintaining survival.
sympathetic nervous system
activates internal muscles, organs and glands to prepare the body for vigorous activity, stressful or threatening situations.
enhances survival
split second response
pupils expand, heart rate accelerates, decreased salivation
parasympathetic nervous system
counterbalances the activity of the sympathetic nervous system.
keeps bodily systems functioning efficiently.
keeps body in homeostatic state
restores body back to a state of calm after sympathetic roles are no longer needed.
decreased heart rate, pupils contract, increased salivation in salivary glands
sensory, motor, and interneurons
sensory neurons
: carry info from sensory receptor organs through the PNS to the CNS. info is recieved externally through the environment and internally through muscles, organs and glands.
motor neurons
: carry info from CNS to muscles, organs, and glands
interneurons
: neurons found in the CNS only, transmits info from sensory neurons to motor neurons.
role of the neuron
individual nerve cell specialised to receive, process, and/or transmit information in the form of a neural impulse
neurons communicate with eachother, and also with mucles and glands
-if even one part of the neural process breaks down, it can lead to Parkinson's disease or alzheimers
dendrites
thin extensions of a neuron that recieve information from other neurons and transmit it to the cell body.
axon
part of a neuron that sends information away from the cell body (soma) to other neurons.
myelin sheath
white protective coating of the axon which insulates the neural message, making it quicker.
axon terminals
the end of the branches that protrude out of the axon, release neurotransmitters into the synaptic gap.
synaptic gap
the gap between neurons
neurotransmitters
chemicals released from axon terminals that carry chemical information from one terminal to another through the synapse
conscious and unconscious reponses to stimuli
conscious responses
awareness
conscious responses to sensory stimuli involves awareness. requires paid attention to the stimulus and therefore know about it.
eg: when you step outside and feel the air temperature, there will be a conscious response to decide whether to put on a jacket
unconscious awareness
not aware
unconscious responses to sensory stimuli is a reaction that doesnt involve awareness.
involuntary, unintentional, automatic and its occurence cannot be controlled
eg: autonomic nervous system is constantly regulating the function of pumping blood from the heart, digesting food, etc.
spinal reflex
info goes straight from sensory receptor sites to the spinal cord. spinal cord sends motor neurons back with an immediate action.
information is then taken to the brain for interpretation
a survival/ evolutionary development.
eg: touching a hot stove
role of neurotransmitters
neurotransmitters are chemical substances produces by a neuron that carries a message to other neurons or cells in muscles, organs, or other tissue. - when carrying a message to another neuron, the neurotransmitter works by attaching itself (binding) to receptor sites of postsynaptic neurons that are specialised to receive that specific neurotransmitter.
neurotransmitters that do not bind to receptors in the post synaptic neuron is absorbed back into the terminal buttons in a process called re uptake.
excitatory and inhibitory effects
excitatory: neurotransmitters with an excitatory effect will consequently stimulate or activate post synaptic neurons to perform their functions.
inhibitory: neurotransmitters with an inhibitory effect will block or prevent postsynaptic neurons from firing
glutamate
the main excitatory neurotransmitter in the CNS. makes postsynaptic neurons more likely to fire.
the release of glutamate is highly associated with enhanced learning and memory.
GABA
the primary inhibitory
neurotransmitter in the CNS. makes postsynaptic neurons less likely to fire.
without the inhibitory effect of GABA, the activation of postsynaptic neurons might go out of control.
neurotransmission as a lock and key process
when released by the presynaptic neuron, neurotransmitter searches for the correctly shaped receptor site on the dendrites of postsynaptic neurons.
neurotransmitter is the key and the receptor site is the lock, but only for a specific key.
how interference to neurotransmitter function can affect neurotransmitter functioning
parkinsons disease
little or too much of a specific neurotransmitter can have a significant impact on how we think, feel, or behave because of its effect on nervous system functioning.
parkinsons disease is a CNS neurodegenerative disorder characterised by both motor and non motor symptoms. motor symptoms result from the degeneration and loss of dopamine producing neurons in the substantia nigra.
the substantia nigra has a role in the control of voluntary muscle movements so they can be executed in a smooth and coordinated matter, such as balance, walking, talking, and writing.
continued
when the substantia nigra is diseased or damaged, the amount of dopamine available for motor activities reduces and neurons gradually die over many years.
motor symptoms:
tremor involving continous, involuntary shaking of the body.
bradykinesia, slowness of voluntary movement, particularly when initiating and executing movement and in performing repetitive movements.
muscle rigidity
non motor symptoms:
-speech problems
pproblems with cognitive functions, eg slowed thinking, memory loss