Week3 Nervous System Flashcards
The basic building blocks of the nervous system
Neurons
Three main parts of neurons.
Soma: the cell body
Dendrites: specialised receiving units that collect messages from neighbouring neurons and send them onto the cell body
Axons: conducts electrical impulses away from the cell body to other neurons, muscles or glands
Two important functions of neurons
- Generate electricity that creates nerve impulses.
- Release chemicals to communicate with neurons, muscles and glands
Describe resting potential
Neuron is separated from surrounding fluid by a cell membrane ; substances pass through ion channels
Inner ions are more negatively charged than outer ions, resulting in a net negative charge for the resting neuron
(Polarisation)
What is action potential? How does it occur?
Electrical shift that occurs when a neuron is stimulated
Positive sodium ions enter the neuron, causing brief depolarisation
It begins at one end of the axon and moves down along it
When does the absolute refractory period occur? What happen to the membrane during this period?
After the action potential passes along each point on the axon
The membrane is not excitable, and cannot discharge another impulse during this period
What are All or None events
Action potentials occur, either at a uniform, and maximum intensity, or not at all
What are Graded Potentials? What may happen to them?
Changes in the negative resting potential that do not reach the action potential threshold
They may combine to trigger an action potential in certain circumstances
What is myelin sheath? What colour does it have? What does it allow? If damaged, what would happen?
A layer of fatty insulation that surrounds the axon
White
Allows electrical conduction to take place at a higher speed than in unmyelinated axons
Multiple sclerosis
Myelin sheath is completely formed at birth. True or false?
False
In many neurons, the myelin sheath is not completely formed until some time after birth
What are synapses and what is synaptic space?
The conjunction of an axon terminal of one neuron and the membrane of another cell
A tiny gap between the axon terminal, and the next neuron
Five stages of synaptic transmission.
- Synthesis - formation of neurotransmitters
- Storage - transmitter molecules are stored in synaptic vesicles in axon terminals.
- Release - action potential causes transmitter molecules to move from synaptic vesicles across the gap.
- Binding - transmitter molecules find themselves to receptor sites embedded in the post-synaptic neuronal membrane
- Deactivation - broken down of transmitted by other chemicals or reuptake (transmitter molecules are taking back into the pre-synaptic axon terminals)
Two types of chemical reactions that can occur when a neurotransmitter molecule binds to a receptor
Excitatory: causes the action potential to fire
Inhibitory : prevents the neuron from firing
What is Acetylcholine? Underproduction and overproduction causes?
A neurotransmitter involved in muscle activity and memory
Underproduction is involved in Alzheimer’s
Overproduction occurs with black widow spider bites
What are neuromodulators? A best know category?
Chemicals that modulate sensitivity of many neurons to their specific transmitters, exerting behavioural and physiological effects
Endorphins - inhibit pain transmission while enhancing pleasurable feelings
Three major neurons and their functions
How many of them does a simple withdrawal reflex require?
Sensory- carry input messages from the sense organs to the spinal cord and brain
Motor - transmit output impulses from the brain and spinal cord to the body’s muscles and organs
Inter- perform connective or associative functions within the nervous system
All three!
What does PNS contain?
All the neural structures that lie outside of the brain and spinal
PNS consists of two nervous systems…
Somatic: a system of sensory and motor neurons that allows us to sense and respond to the environment
Autonomic: a system that senses the body’s internal functions, and controls many glands and muscles
Two subdivisions of the autonomic nervous system and their functions
Sympathetic: activation or arousal function(fight or flight)
Parasympathetic : slows down the body; maintaining state of internal equilibrium
CNS consists of …
Spinal cord and the brain
What is the spinal cord
A densely packed bundle of nerve fibres that run along the spine, and which transmit messages from sensory and motor neurons
Ways to study the structure and functions of the brain
- Measuring, verbal and non-verbal behaviours of brain damage sufferers
- Lesion studies in animals
- Electrical recording such as EEG
How does EEG work
Electrodes are attached to the scalp and record the activity of groups of thousands of neurons
Seen in the form of line tracings or readouts
Brain imaging for structures? For activity?
MRI and DTI
PET, fMRI, fNIRS
