The brain and behaviour Flashcards
who was Phineas Gage?
he was a construction worker who got a steel pipe through his skull in 1848 and survived. however, his personality changed and therefore people started to assume that the brain was directly related to thoughts and behaviours.
what are neurons?
the functional building blocks of the nervous system. cells which transmit the electrical activity which underlies psychological processes
what is a glial cell?
from the greek for ‘glue’. cells surrounding neurons, holding them in place, providing nutrients neurons need and isolating toxins that would harm the neuron.
what is a synapse?
a connection between neurons
what is a sensory neuron?
neurons that carry input messages from the sensory organs to the spinal cord and brain
what is a motor neuron?
neurons that transmit output impulses from the brain and spinal cord to the bodies muscles and organs
what are interneurons?
neurons that perform connective or associative functions within the nervous system - they connect sensory neurons to motor neurons
what is the peripheral nervous system?
contains the neurons outside the brain and spinal cord. it has two major divisions, the somatic and autonomic nervous systems
what is the somatic nervous system?
a subdivision of the peripheral nervous system that controls voluntary movements
what is the autonomic nervous system?
a subdivision of the peripheral nervous system that controls involuntary movement. it has two subdivisions, the sympathetic and parasympathetic nervous systems
what is the sympathetic nervous system?
a division of the autonomic nervous system that controls activation and arousal. it is responsible for the ‘fight or flight’ reaction and tends to act as a ‘total unit’ (effects multiple different areas of the body.
what is the parasympathetic nervous system?
a subdivision of the autonomic condition which opposes the sympathetic branch. it is generally responsible for the ‘rest and digest’ processes that reverse arousal.
define homeostasis
a delicately balanced or constant internal state
what is the central nervous system?
a system which contains the brain and spinal cord, it connects the peripheral nervous system with the brain.
what are the dimensions of the spinal cord?
40.5-45.5 cm long and 2.5cm in diameter.
what tissues does the spinal cord consist of?
white matter and grey matter
what are spinal reflexes?
reflexes which do not require input from the brain. for example if you touch something hot your hand will immediately pull away as the message does not need to travel to the brain which would slow it down and increase the amount of damage done to the body.
how does the make up of the brain and spinal cord differ?
spine = grey matter on the inside white on the outside brain = grey matter on the outside, white matter on the inside
what is the difference between grey matter and white matter?
grey matter is made of up of the cell bodies of neurons
white matter is made up of the axons of neurons
what is a neuron?
a specialised cell that forms the basic building blocks of the nervous system
what is the structure of a neuron?
electrical impulses are conducted from the dendrites to the soma (cell body) this then sends messages down the axon (which is insulated by a myelin sheath).
what are dendrites?
specialised receiving units like antennae that collect messages from neighbouring neurons and send them on to the cell body
what is an axon?
conducts electrical impulses away from the cell body to other neurons, muscles or glands
what are found at the end of axons?
axon terminals which are connections to other dendrites or muscles or glands etc.
what are the three stages of an electrical impulse travelling through a neuron?
- the neuron maintains a resting potential through the distribution of positive and negatively charged ions inside and outside of the cell membrane
- when stimulated the cell membrane depolarises (the charge reverses) which produces an action potential
- the resting potential is recovered
what is a resting potential?
an internal difference of around -70mv
what is an action potential?
an electrical shift across the neural membrane, which lasts about a millisecond and propagates an electrical signal down an axon
how is an action potential created?
- resting potential = the 10:1 ratio of sodium ions outside the neuron and the negative protein ions inside create a resting potential of -70mv
- action potential created = if the neuron is stimulated, sodium channels open and sodium ions flood into the axon
- resting potential restored = sodium channels close and potassium channels open so potassium ions exit the neuron and the resting potential is restored
what is the refractory period?
the period of time after an action potential where the balance of ions is being restored and so another action potential cannot be created.
what are graded potentials?
changes in the negative resting potential that do not reach the -50mv action
what is a myelin sheath?
a whitish, fatty, insulation layer that covers axons. it is derived from glial cells. it is interrupted by nodes of ranvier which allow electrical activation to jump from one node to another and speed up the rate of transmission.
the myelin sheath develops throughout childhood and adolescence so explains why muscle control and coordination gets better with age.
what does damage to the myelin sheath do?
it can be caused by conditions such as MS resulting in jerky, uncoordinated movement or paralysis.
what is a synaptic cleft?
the tiny gap between one axon terminal and the next neuron
why is synaptic connectivity important for development?
changes in synaptic connection in early life leads to psychological development, synaptic connecting and pruning plays an important part in adult psychological functions
what are neurotransmitters?
chemical substances that carry messages across the synaptic cleft to other neurons, muscles or glands
what is a synaptic vesicle?
chambers within the axon terminal
what are receptor sites?
large protein molecules embedded in the receiving neurons cell membrane
outline the steps of synaptic transmission
1) the action potential triggers the presynaptic neuron to release neurotransmitter into the synaptic cleft
2) neurotransmitter defuses across the synaptic cleft
3) neurotransmitter molecules bind to the receptor sites on the postsynaptic neuron
4) this binding triggers an action potential in the postsynaptic neuron
what is meant by excitatory and inhibitory neurotransmitters?
excitatory = make the postsynaptic neuron more likely to fire an action potential inhibitory = make the postsynaptic neuron less likely to fire an action potential
what is meant by re-uptake in the synapse?
the transmitter molecules are taken back into the presynaptic axon terminal
what are the two methods of deactivation?
1) re-uptake into the presynaptic neuron
2) breakdown by other chemicals found in the synaptic cleft
what is acetylcholine and what is it involved with?
it is a neurotransmitter found in the brain that is involved with memory and muscle activity
how is ACh involved with Alzheimers?
underproduction of ACh is thought to cause the memory problems and lack of muscle control in ALezheimers disease
what effect does ACh have on muscles?
it is excitatory
what is botulinum bacteria?
toxin forming bacteria, a mild form of which is town as botox. it blocks the action of ACh
what are neuromodulators?
neurotransmitters with a more widespread and generalised influence on synaptic transmission. they increase or decrease the sensitivity of many neurons. an example is endorphins
what is noradrenaline?
a neurotransmitter released from the adrenal medulla, it has both excitatory and inhibitory effects and is involved in learning, memory, wakefulness and eating. an undersupply causes depression
what is serotonin?
a neurotransmitter involved in mood, sleep, eating and arousal. may also play a key role in pleasure and pain. an undersupply can lead to depression, eating and sleeping disorders.
what is dopamine?
an excitatory neurotransmitter that is involved in emotional arousal, learning, memory, pleasure and pain. an undersupply can lead to Parkinson’s disease.
what is GABA?
it is inhibitory in the motor system. lack of GABA leads to loss of motor control in Huntington’s disease
what is an endorphin?
a neuromodulator that decreases sensitivity to pain