Brain and Behaviour Flashcards
What two things are the nervous systems made up of?
Neurons and glial cells
What is the definition of a neuron?
Functional building blocks of nervous system – cells which transmit electrical activity which underlies psychological processes
What is the definition of a glial cell – name three of it functions in the definition?
Cells surrounding the neurons holding them in place, providing nutrients and isolating toxins that would harm the neuron
How many neurons in an average human brain?
86 million neurons
What are neurons connected by?
A synapse
Define a synaptic cleft/space
A tiny gap between the axon terminal and the next neuron (the pre-synaptic neurons send messages and the post-synaptic neurons receive messages)
Define a sensory neuron
Carry input messages from the sense organ to the spinal cord and the brain
Define a motor neuron
Transmit output impulses from brain and spinal cord to the body’s muscles and organs
Define an inter-neuron
Perform connective or associative functions within the nervous system – these outnumber sensory and motor neurons
Define the peripheral nervous system
Contain all the neural structures that lie outside of the brain and the spinal cord
What two functions does the PNS perform? (one is sensory input and the other motor output)
- Sensory input functions that enable us to sense what’s going on inside and outside of our bodies
- Motor output function that enable us to respond with our muscles and glands
What are the two subdivisions of the PNS, and define them
• Somatic nervous system – a system of sensory and motor neurons that allow us to sense and respond to our environment
• Autonomic nervous system – senses the body’s internal functions and controls the glands and the involuntary muscles that form the heart, blood vessels and lining of the stomach and intestines
o Involved in respiration, digestion, circulation, motivation, emotional behaviour and stress responses
Name and define the two subdivisions of the ANS
• Sympathetic nervous system – has an activation or arousal function and tends to act as a total unit –
o Flight or fight response
o When you encounter a stressor your sympathetic nervous system helps you in a number of ways e.g. speeds heartrate, dilates pupils, slows digestion
• Parasympathetic nervous system – slows down the body processes and maintain a sense of tranquillity
o Slows down heart rate, allows digestion, contracts pupils
What is homeostasis?
A delicately balanced or constant internal state
Define the central nervous system
Contains the brain and the spinal cord, which connects most parts of the peripheral nervous system with the brain
What is it called when a response is triggered without the involvement of the brain and give an example of it
A spinal reflex or simple withdrawal reflex – touching a hot plate and dropping it immediately – by bypassing the brain there is a reduction of potential tissue damage
Name the three main parts of a neuron – and define each part
o Cell body – also known as soma – contain biochemical structures needed to keep the neuron alive, and its nucleus carries the genetic information that determine how the cell develops and functions
o Dendrite – branch-like structure protruding from the cell body – specialised receiving unit like antennae that collect messages from neighbouring neurons and send them onto the cell body
o Axons – extends from one side of the cell body – conducts electrical impulses away from the cell body to the other neurons, muscles or glands
What are all neurons covered by and what does it do?
Cell membrane – controls the exchange of chemical substances between the inside and outside of the cell
Name the three stages of electrical activity of neurons
Resting potential -> action potential -> resting potential
Explain what resting potential is – mention polarization
When neuron isn’t involved in creating impulses – when inner ions are more negatively charged than outer ions, so a net negative charge (this is polarization)
Explain what action potential is – mention depolarization
An electrical shift occurs when the neuron is stimulated and positive sodium ions enter the neuron, this causes a brief moment of depolarization
What happens after an impulse?
A recovery period called absolute refractory period – a period during which the membrane is not excitable and cannot discharge another impulse
What is the limit of human impulses (per second)
300 pulses per second
Explain the concept ‘All or nothing’
The fact that action potential can either occur at a uniform maximum or not at all – the electrical stimulation needs to meet a certain intensity or the neuron will not fire
What is a graded potential?
Changes in the negative resting potential that do not reach the action potential threshold – sometimes graded potential add up and trigger an action potential
Define myelin sheath
A whitish fatty insulation layer derived from glial cells during development
What are nodes of Ranvier?
Interruptions in the myelin sheath – they are at regular intervals and speed up transmission
Is myelin sheath present at birth?
It isn’t completely formed at birth, fully developed sometime in later childhood
Name a disorder that damage to the myelin sheath can cause – name the symptoms
Multiple sclerosis – when individual’s own immune system attacks the myelin sheath – disrupts the timing of nerve impulses to muscles – results in jerky and unco-ordinated movements and the paralysis
What is a neurotransmitter?
Chemical substance that carry messages across the synaptic cleft to other neuron, muscles or glands
Name the 5 steps of communication of a neurotransmitter and expand on each step
I. Synthesis – transmitter molecules formed inside neuron
II. Storage – molecules are stored in synaptic vesicles (chambers within the axon terminal)
III. Release – action potential causes the vesicles to move to the surface of axon terminal and release molecules into synaptic cleft between presynaptic and postsynaptic neuron
IV. Binding – transmitter molecules bind themselves to receptor sites – each neurotransmitter fits like a lock and key
V. Deactivation – a neurotransmitter molecule continues to excite or inhibit a neuron until deactivated
Name two ways deactivation can occur
o The neurotransmitter broken down by other chemicals
o Re-uptake so the neurotransmitter molecules are taken back into the presynaptic terminal
Explain excitatory neurotransmitters
A neurotransmitter that causes the action potential to fire
Explain inhibitory neurotransmitters
A neurotransmitter that prevents the neuron from firing
Give an example of a neurotransmitter
Acetylcholine – a neurotransmitter involved in muscle activity and memory – an underproduction involved in Alzheimer’s
Define neuromodulators
Neuromodulators have a more widespread and generalised influence on synaptic transmission
Give an example of a neuromodulator
Endorphins – they travel through the brain circulatory system and inhibit pain and enhances neural activity which produces pleasurable feelings
Define neuropsychology
The study of the function in the brain by investigating the effects of brain damage on mental functions - often in forms of case studies
Name the six types of brain lesions and try and expand on each of them
- Vascular – disruption to blood flow – this may be caused by blockages or enlarged arteries (stroke/aneurysm)
- Tumour – mass of tissue with no physiological function – this grows and disrupts functioning
- Degenerative diseases – breakdown of neurological material – each disorder presents different symptoms e.g. Alzheimer’s or Parkinson’s
- Trauma – violent assault to the head
- Infectious diseases – a virus can result in neurological symptoms e.g. HIV, AIDS, herpes
- Epilepsy – brief loss of consciousness resulting from excessive electrical activity in the brain – this can be triggered by trauma and can disrupt activity over wide areas
What is the difference between single association and double association?
Single association is just when observations are made from one patient and when they show a struggle in a certain action or behaviour, this suggests that there could be a link between the part of the brain that is damaged OR it could be explained by problems with the design. BUT double association is where two people with different brain lesions complete two different tasks. If patient A is impaired at task A, but performs well on task B and patient B performs well on task A, but is impaired on task B then we can say with much more confidence that the differences in performance are seen due to the brain abnormalities.
Explain Wenicke’s aphasia
Results from damage in the temporal lobe and is primarily manifested as difficulties with speech comprehension.
Explain Broca’s aphasia
Results from damage in the frontal lobe and is primarily manifested as difficulties with the production of speech.
Brian function partly consists of __________
The answer is ‘electrical activity’ - measuring this can be used to infer brain functions
Name a method of measuring electrical activity in the brain
Electoencephalography (EEG) - measures the activity of large groups of neurons through a series of large electrodes placed on the scalp
