bio psycho Flashcards
The nervous system
- Network of cells in the human body
- Electrical and chemical signals
Endocrine
- Based on hormones
Nervous system has two functions
- To collect process respond to information in the environment
- To co-ordinate the working of different organs and cells in the body
The nervous system is divided into two subsystems
- Central nervous system
- Peripheral nervous system
The CNS
- Brain is divided into two hemispheres
- Spinal cord is an extension of the brain.
- Passes messages to and from the brain and connects to the PNS
Peripheral nervous system
- Autonomic nervous system- vital functions in the body eg breathing
- Somatic nervous system- -muscle movement and receiving info from sensory receptors
Types of neurons
- Sensory
- Relay
- Motor
Structure of neuron
- Cell body includes a nucleus- genetic material
- Dendrites- branchlike structure, carries nerve impulses towards cell body
- Axon- carries the impulse away from the cell body
- Axon is covered in a fatty layer of the myelin sheath – protects and spends up transmission
- Nodes of Ranvier speed up transmissions by forcing it to jump across the gap along the axon
- End of axon is terminal button communicate with the next neuron – synapse.
Location
- Motor maybe be in CNS or the PNS
- Sensory neurons are located outside the CNS in the PNS in clusters known as ganglia
- Relay found in the brain and the visual system
electric impulse
Electrical transmission- the firing of a neuron
Neuron in a resting stare- negatively charged
Neuron is activated the inside of the cell becomes positively charged for a split second causing an action potential.
This creates an electrical impulse
Synaptic transmission
Chemical transmission
Neuron communicates within groups known as neural networks
Each neuron is separated by a gap called synapse
Signals within neurons are transmitted electrically
Signals between neurons are transmitted chemically across the synapse
When the electrical impulse reaches the end of the neuron the presynaptic terminal it triggers the release of neurotransmitters from tiny sacs called synaptic vesicles.
Neurotransmitters
Chemicals diffuse across the synapse to the next neuron.
Once a neurotransmitter crosses the gap it is taken up by a postsynaptic receptors site on the dendrites of the next neuron
The chemical message is converted back into an electrical impulse
One way only
Neurotransmitters are released from the presynaptic neuron terminal and received by the postsynaptic neuron.
Neurotransmitter has it own specific molecular structure that fits perfectly into the post synaptic receptor sites.
Neurotransmitter- special function
Excitation and inhibition
Neurotransmitters have either an excitatory or inhibitory effect.
Serotonin- inhibition in the receiving neuron results in the neuron becoming more negatively charged and less likely to fire
Adrenaline- excitation of the post synaptic neuron by increasing its positive charge and making it more likely to fire.
Summation
Whether a postsynaptic neuron fire is decided by the process of summation
If the net effect of the postsynaptic neuron is inhibitory then the postsynaptic neuron is less likely to fire.
If the net effect is excitatory, it is more likely to fire
Therefore, the action potential of the postsynaptic neuron is only triggered if the sum of excitatory and inhibitory signals at any one time reaches the threshold.
Competition between two neurotransmitters
If theres more of one eg excitation and meets the threshold excitation effect faster rate.
Verse visa for inhabitation
Localisation of function
Local vs holistic theory
Broca and Wernicke argued for localisation of function
The idea that different parts of the brain perform different tasks and are involved with a different part of the body
If a certain area of the brain becomes damaged through illness or injury the function associated with that area will also be affected
Hemispheres of the brain
The cerebrum is divided into two halves
Activity on the left hand side of the body is controlled by the right hemisphere
Activity on the right hand side of the body is controlled by the left hemisphere
Eg language is linked with the left hemisphere
structure of the brain
The motor somatosensory visual and auditory centres
The cortex is the outer layer of both hemisphere
The cortex is subdivided into four centres
The frontal lobe the parietal lobe the occipital lobe and the temporal lobe
front of head Auditory broca area motor somatosensory back of head visual wernicke
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where and what do they do?
Each lobe is associated with a different function
Frontal lobe in both- motor area controls voluntary movement in opposite sides of the body damage to this area= loss of control over fine movements
Parietal lobes- somatosensory area where sensory info is represented
Occipital lobe- visual cortex eye sends info-> right visual field left visual cortex verse visa
Temporal lobes- auditory area analyses speech-based information
Languages centres of the brain
Language is only on the left side
Left frontal love- speech production -> broacs areas
Damage- slowed laboriously and lacking in fluency
Understanding speech- it was fluent but meaningless-> Wernicke area
Evidence from brain scans
Strength- supports idea that many everyday brain functions are localised
Brain scans to show how active wernickes area was during a listening task and broca area was active during a reading task.
Long term memory study- semantic and episodic memories reside in different parts of the prefrontal cortex
Counter point
rats brain maze
Removed areas of the cortex 10%-50% in rats that were learning the routes through a maze.
No area was more important than any other area in terms of the rat’s ability to learn the routes.
The process of learning requires every part of the cortex to be confined to a particular area. Suggest higher cog processes eg learning -> holistic
Language localisation question
weakness
Language not just localized to Broca and Wernicke’s areas.
2% of language is completely controlled by broca and wernicke area
fMRI neural processes in the brain can be studied
the language function is distributed for more holistically
language may be organized more holistically in the brain.
Case study evidence
Phineas gage- personality and temperament resides in frontal lobe
weakness
Difficult to make generlisations
Evidence supporting localisation may lack validity, oversimplifying the brain processes
Early studies of brain damage poor controlled and lack of the objectivity.
Hemispheric lateralisation
Localisation and lateralisation
For some functions the localised areas appear in both hemispheres eg vision the visual area is in the left and right occipital lobe.
