Chapter 3: Biology and Behaviour Flashcards
What does the nervous system consist of?
Central nervous system (CNS)
Peripheral nervous system (PNS)
What does the CNS consist of?
The spinal cord and the brain
What does the PNS consist of?
All the other nerve cells in the rest of the body
What are the 2 nervous systems that the PNS has?
Somatic nervous systems
Autonomic nervous systems
What is the responsibility of the somatic nervous system?
Responsible for voluntary behaviour
What is the responsibility of the autonomic nervous system
Responsible for involuntary behaviour (eg: controlling the heartbeat)
What do neurons do?
Receive, integrate and transport information in the nervous system
What is a neural network?
Neurons communicate selectively with other neurons
This forms a circuit, which is also called a neural network
What happens in the receiving phase?
Neurons receive and absorb chemical signals from other neurons
What happens in the integration phase?
These signals are evaluated
What happens in the transmission phase?
The neurons send out their own chemical signals to there neurons
What do sensory neurons do?
Receive information from the physical world and transit this information to the brain via the spinal cord
What is an example of a sensory neuron?
Somatosensory nerves
What do somatosensory nerves do?
Receive information from the skin and muscles
What do motor neurons do?
Send signals from the brain to the muscles to contract or relax
What are reflexes
Automatic motor responses that occur without thinking
What are the 4 parts of a neuron?
Dendrites
Cell body
Axon
Terminal buds
What is the basic unit of the nervous system?
A neuron
Dendrites
Detect chemical signals form surrounding neurons
They are short and branched
Cell body (soma)
The information form the dendrites is collected and integrated here
Axon
After incoming information is processed, electrical impulses are sent from the cell body to the terminal buds via the axon
Axons are long and thin
Terminal buds
These are branches at the end of the axon
They send chemical signals to the next neuron
What is the synapse?
Where chemical communication between neurons takes place
With what is a neuron covered?
A membrane
What is a membrane?
A fatty protective layer that is insoluble in water
It is also semi permeable
What is an action potential?
The electrical signal that passes along the axon
This causes the terminal buds to release chemicals that transmit signals to other neurons
What is the resting potential?
When the membrane of the neuron is stable, there are more negatively charged ions on the inside of the cell than on the outside
What is the charge at the resting potential?
-70 millivolts (mV)
Inhibitory signals
Hyperpolarise the cell membrane by increasing the negative charge int he cell
This makes it less likely that a neuron will fire
Excitatory signals
Depolarise the cell membrane by reducing the negative charge in the cell
Meks it more likely that a neuron will fire
What happens when the toal input of the neuron exceeds the threshold value (-55 mV)?
An action potential is generated
What are the first 3 steps when a neuron fires?
Sodium channels in the cell membrane open and sodium ions flow into the neuron
Potassium channels in the cell membrane open and potassium ions flow out of the neuron
The neuron is now more positively charged inside than outside
What are the first 3 steps when a neuron fires?
- Sodium channels in the cell membrane open and sodium ions flow into the neuron
- Potassium channels in the cell membrane open and potassium ions flow out of the neuron
- The neuron is now more positively charged inside than outside
What are the 4, 5, 6, 7 steps when a neuron fires?
- The sodium channels close again
- The neuron begins to repolarise
- Potassium channels close
- The neuron eventually regains its original negative resign potential
What is the myelin sheath made of?
Glial cells
What is the myelin sheath?
Accelerates the transmission of electrical signals
Where are Ranvier’s nodes?
The myelin sheath is made up of segments and between these are Ranvier’s nodes
What is the function of Ranvier’s nodes?
It is where the action potential can take place
What is the presynaptic neuron?
The neuron that sends the signal
What is the postsynaptic neuron?
The neuron that receives the signal
What does the terminal button contain?
Neurotransmitters
What doe neurotransmitters do?
Chemicals made in the axon and stored in vesicles
When the action potential has reached the terminal button, the vesicle attaches to the presynaptic membrane and releases neurotransmitters into the synapse
Autoreceptors
Autoreceptors on the presynaptic neuron control the amount of neurotransmitter in the synapse
When there is enough neurotransmitter in the synapse, autoreceptors signal the presynaptic neuron to stop releasing the neurotransmitter
What are agonists?
Substances that enhance the action of the neurotransmitter by, for example, mimicking the neurotransmitters and binding to receptors as if they were the real thing
What are 7 important neurotransmitters for thinking, feeling and behaviour?
Acetylecholine (ACh)
Noradrenaline
Serotonin
Dopamine
Gamma aminobutyric acid (GABA)
Glutamate
Endorphins
Acetylcholine (ACh)
Responsible for motor control between nerves and muscles
Botox suppresses ACh release, paralysing the muscles and reducing wrinkles
ACh antagonists cause temporary memory loss
Noradrenaline
Involved in excitement, attention and alertness
Serotonin
Involved in various psychological activities, mainly in emotional states, impulse control and dreams
Low levels of serotonin cause sad and anxious moods, hunger and aggressive behaviour
Drugs that block the reuptake of serotonin cause more serotonin to remain in the synapses
Dopamine
Helps direct behaviour towards rewards
Low levels of dopamine cause problems with movement (eg: Parkinson’s disease)
Gamma aminobutyric acid (GABA)
The primary inhibitory neurotransmitter
Low levels of GABA can cause synaptic excitation to go out of control and lead to epileptic seizures
Glutamate
The primary excitatory neurotransmitter
Glutamate is important for learning and memory by strengthening synaptic connections
High levels of glutamate can lead to overmstiumuation of the brain resulting in epileptic seizures an brain damage
What is the phrenological system?
The function that is most often used would result in an enlarged brain in a certain location related to that functions
It is therefore possible to feel from the outside what kind of personality someone had