The Brain And Behaviour Flashcards
Approximately how much does the brain weigh
1400g
What are the basic building blocks of the nervous system
Neurons
What are the three main parts of neurons
Soma
Dendrites
Axon
Where is the soma in a neuron
The cell body
What are dendrites
Specialised receiving units that collect messages from neighbouring neurons and send them on to the cell body
What do axons do
Conduct electrical impulses away from the cell body to other neurons, muscles or glands
What do neurons do
Generate electricity that creates nerve impulses
Release chemicals to communicate with neurons, muscles and glands
What are the three stages neurons go through
Resting potential
Action potential
Resting potential again
What occurs during resting potential
Neuron is separated from surrounding fluid by a cell membrane; substances pass through ion channels
What causes polarisation
Inner ions are more negatively charged that outer ions, resulting in a net negative charge for the resting neuron
What is action potential
An electrical shift that occurs when a neuron is stimulated
What causes depolarisation
Positive sodium ions entering the neuron
When does polarisation occur
During resting potential
When does depolarisation occur
During action potential
What is the absolute refractory period
The recovery period that occurs after the action potential passes along each point on the axon
What is the all or none law
Action potentials occur either at uniform and maximum potential, or not at all
Define graded potentials
Changes in the negative resting potential that do not reach the action potential threshold
What is the myelin sheath
A layer of fatty insulation that surrounds the axon
What colour is myelin
White
What does the myelin do
Allows electrical conduction to take place at a higher speed than unmyelinated axons
When does the myelin completely form in many neurons
Some time after birth
What can damage to the myelin sheath cause
Multiple sclerosis
How do neurons communicate with other cells
Through synapses
What are synapses
The conjunction of an axon terminal of one neuron and the membrane of another cell
What is the synaptic space
A tiny gap between the axon terminal and the next neuron
What are pre synaptic neurons
Neurons that send messages
What are post synaptic neurons
Neurons that receive messages
What are neurotransmitters
Chemical substances that carry messages across the synaptic space to other neurons, muscles or glands
What are the 5 steps neurotransmitters go through
Synthesis Storage Release Binding Deactivation
What occurs during the synthesis stage of neurotransmitters
The transmitters are formed
What occurs during the storage stage of neurotransmitters
Transmitter molecules are stored in synaptic vesicles in axon terminals
What happens during the release stage of neurotransmitters
Action potential causes transmitter molecules to move from synaptic vesicles across the gap
What happens in the binding stage of neurotransmitters
Transmitter molecules bind themselves to receptor sites embedded in the receiving neurons cell membrane
What are the two ways deactivation of neurotransmitters occur
Broken down by other chemicals
By reputake
What occurs in reputake
Transmitters are taken back into the presynaptic axon terminal
What is the first stage neurotransmitters go through
Synthesis
What is the second stage neurotransmitters go through
Storage
What is the third stage neurotransmitters go through
Release
What is the forth stage neurotransmitters go through
Binding
What is the fifth stage neurotransmitters go through
Deactivation
What are the two types of chemical reactions that can occur when a neurotransmitter binds to a receptor
Excitatory
Inhibitory
What does an excitatory reaction cause
It causes the action potential to fire
What does an inhibitory reaction cause
Prevents the neuron from firing
What does ACh stand for
Acetylcholine
What us acetylcholine
A neurotransmitters involved in muscle activity and memory
What is underproduction of acetylcholine a cause of
Alzheimer’s
What drugs block acetylcholine
Botulism
Botox
What can cause overproduction of acetylcholine
Black widow spider bites
What are neuro modulators
Chemicals which modulate sensitivity of 1000s of neurons to their specific transmitters
What is the best known category of neuro modulators
Endorphins
What do endorphins do
They travel through the brain inhibiting pain transmission while enhancing pleasurable feelings
What are the three main types of neurons in the nervous system
Sensory neurons
Motor neurons
Inter-neurons
What do sensory neurons do
Carry input messages from the sense organs to the spinal cord and brain