- Created by: arusa11
- Created on: 28-04-17 08:29
Nervous and Endocrine system
Nervous-collect,process&respond to info in the environment+coordinate working of all different organs in the body. Made of CNS and PNS.CNS=made of brain and spinal cord.brain made up of two hemispheres.Spinal cord is responsible for reflex actions.PNS made of autonomic nervous system which governs vital funtions eg breathing and somatic nervous system which controls muscle movement and receives info from sensory receptors.
Endocrine- regulate bodily functions.glands&hormones-gland=group of cells specialised to secrete useful substance like hormone.hormones=chemical messages.Glands produce hormones which are then secreted into the blood and affect any cell in the body that has a a receptor for that particular hormone.Endocrine and ANS working together= especially through stressful event.When stressor percieved, the hypothalamus triggers activity in the sympathetic branch of the of the ANS. ANS changes from resting (parasympathetic state) to physiologically aroused sympathetic state. Adrenaline is then released which triggers physiological changes eg increased heart rate which creates physiological arousal needed for flight or fight response.The endocrine and ANS owrk together because this response is automatic.Once threat has passes the parasympathetic nervous system returns the body to resting state
Structure&function of a neuron- process&send messages through electric&chemical impulses.Three types.sensory- carry messages from PNS to CNS.Have long dendrites and short axons. relay- connects the sensory neuron to the motor. Have short dendrites and short axons. motor- connect CNS to effectors(glands and muscles). Have short dendrites and long axons.Neurons all have:
- cell body- includes a nucleus which contains the genetic material of the cell
- dendrites- carry never impluses from other neurons to the cell body
- axon- carry nerve impulses away from the cell body and to other neurons
- myeline sheath- fatty layer protecting axons&increases eletrcial transmissionofnerveimpulse
- nodes of ranvier- if myeline sheath all the way= slow down electrical impulse.Nodes of Ranvier segment myeline sheath into gaps called nodes of ranvier=increases transmission by forcing the impulse to 'jump across' the gaps along the axon
- terminal buttons- at the end of the axon which commuicates the the next neuron in the chain across the synapse.
Electrical tansmission(firing of neuron)- Neuron in resting state-inside of the cell is negativley charged.When neuron is activated by a stimulus inside become positvley charged for a spilt second&causes action potential-creates an electrical impulse that travels down the axon toward the end of the neuron.
Chemical transmission- neurons are seperated by a synapse.Signals withing neurons are transferred electrically but between=chemically by synaptic transmission.when electric impulse reaches presynaptic terminal it triggers the release of neurotransmitters from from synaptic vesicles.
Neurotransmitters are chemicals that diffuse from one neuron to the next across the synapse. Once it reaches the next neuron it is taken up by postsynaptic receptor sites where the chemical message is converted back to an electrical impulse and electric transmission process starts again.
Excitation and inhibition- neurons either have a exhibitory of inhibitory effect on neighbouring neurons. Excitatory neurotransmitters increase likelihood that an electrical impulse will be triggered by the postsynaptic neuron.Inhibitory neurotransmitters decrease the likeliood that an electrical impulse will be triggered in the post synaptic neuron.
Localisation of brain function
Localisation of brain-different areas of the brain are responsible for different things.Broca and Wernicke discovered that specific areas are associated with specific functions.before this people thought all parts of the brain were involved in the processing of thought and action. This means if a part of the brain is damaged the functions thats the part played will also be affected.
Brain has two parts;right and left hemisphere. Some of our physiological and psychological funstion are controlled by a certain hemisphere known as lateralisation. Activity on the left hand side of the body is controlled by the right hemisphere&vice versa
At the back of the frontal lobe is the motor area which control volountary movements in the opposite side of the body.Damge= loss of control over fine movements.At the front of the parietal lobe is the somatosensory area which is seperated from the motor area by a valley called the central sulcus. Its where sensory info is represented.damaged =may not be able to feel pain.In the occipital lobe is the visual area.right eye sends info to the left visual cortex &vice versa.The temporal lobe keeps the auditory area.analayses speech based info.damage can lead to hearing loss or unable to speak.Language centres-Language restricted to left hemisphere.Broca identified Broca's area which was a small area in the left frontal lobe responsible for speech production.Damage can cause Broca aphasia(slow speech,and lacking in fluency). Wernicke found an area in the left temporal lobe that was responsible for language comprehension. if damaged Wernicke's apahasia(nonsense words)-ao3=look at pack
Platicity=brains tendency to adapt as a a result of experince and new learning.funtional recovery=Brains ability to transfer function usually done by damaged areas to undamaged areas.in infacy= lots of synaptic connections and as we age we delete the connections we rarely use& strengthen frequently used ones = synaptic pruning.thought that once a critcal point has been reached,=the adult brain fixed but research has suggested that at any time if life,neural connections can change,be formed as a result of new experiences and learning'brain plasticity'.Macguire et al-studued brains of taxi drivers+found more grey matter in posterior hippocampus than in matched control group.This part of the brain is associated with the devolopment of spatial skills.As part of their training they needed to take a knowledge quiz of the quickest ways to get to places.It appears that this spatial learning alters the strucutre of the taxi driversbrain. Postive correlation-the longer a taxi driver= more damage butcorrelation isn't causation.Functional recovery of the brain:following physical injury/trauma the unaffected areas of the brain are able to adapt and compensate.Healthy brain areas may take over the functions of those areas and neuroscientists have suggets that this process can occur quickly after traumaand then slow down after some weeks.what happens during recovery? Brain is able to rewire and reorganise itself by making new synaptic connections close to the area of damage.Secondary neural pathways that aren't usually used are activated to let functioning continue.Supported by structural changes eg axonal sprouting- new nerve ending joining to other undamaged nerve cells to form new neural pathways,Increased brain stimulation and reformation of blood vessels.