Biopsychology – Revision Sheet
The Nervous System
What does the CNS do?
- Controls behaviour and regulates the body’s physiological processes
(breathing and digestion)
- Processes info from the PNS and prepares responses
- Brain, spinal cord and relay neurons (only found here)
What does the PNS do?
- Transmits messages to and from the CNS to the rest of the body
What does the SNS do? (PNS)
- Transmits info from the sense organ to the CNS (sensory pathways)
and from the CNS to effectors (motor pathways) to control voluntary
movement and allow for the reflex action
- Controls skeletal muscles, consists of sensory and motor pathways,
uses the motor cortex
What does ANS do? (PNS)
- Transmits info to and from the internal bodily organs to regulate
involuntary bodily processes (breathing and heartrate)
- Controls internal organs and glands, consists of motor pathways,
uses the brain stem
What does the SANS do?
- Works alongside the endocrine system to bring about physiological
arousal in the fight or flight response
- Mobilises bodily activity
What does PANS do?
- Works alongside the endocrine system to return the body to its
resting state in the rest and digest response
- Decreases bodily activity
Neurons
What is a neurons function and structure?
, - Neurons enable communication within the nervous system
- The soma includes a nucleus, which contains the genetic material of
the cell.
- Dendrites are branch-like structures which extend from the cell body
- Dendrites carry nerve impulses from neighbouring neurons towards
the cell body (they receive information from other neurons)
- Axons can be myelinated to speed up the transmission of the
impulse (through nodes of Ranvier which force the impulse to ‘jump’
along the gaps of the axon)
- Axons carry the nerve impulses away from the cell body down the
length of the neuron
- Terminal buttons are at the end of the axon
- Terminal buttons communicate with the next neuron across the
synapse (make synaptic connections with other cells)
What is a sensory neuron?
- Processes info received from the sensory receptors and converts this
info into neural impulses which are then translated to sensations
when they reach the brain
- Only transmits info from the body to the brain (unipolar)
- Long dendrites, short axon (no dendrites on cell body)
What is a relay neuron?
- Connect motor and sensory neurons
- Both send and receive messages from different parts of CNS
(multipolar)
- only found in brain and spinal cord
- short dendrite and axon (looks most distinctive)
What is a motor neuron?
- Carry signals from the CNS to organs, glands and muscles
- Form synapses with muscles to control their contractions through
releasing neurotransmitters which trigger a response (muscle
movement) and through inhibiting the motor neuron which causes
relaxation
- Both send and receive messages (multipolar)
- Shorts dendrites, long axon (looks most typical)
Sensory receptor PNS CNS Motor neuron effector
Sensory neuron Relay neuron
,How is an apply question on neurons answered?
- The sensory receptors in… sense…
- This information is sent from the PNS to CNS via sensory neurons
- Relay neurons based solely in the CNS receive the message, analyse
the sensations and decide how to respond
- Motor neurons receive this message from the relay neurons and a
take it from the CNS to effector muscles
- The message instructs… muscles to…
Synaptic transmission
What is a synapse?
, - The area between the axon of one neuron and the cell body/dendrite
of another
What is a neurotransmitter?
- Chemical messengers that carry signals across the synaptic cleft to
receptor sites on the post-synaptic neuron
- They can be excitatory or inhibitory
How does synaptic transmission work?
- Synaptic transmission is the process of transferring an action
potential from one neuron to the next across a synapse
- The action potential reaches the presynaptic neuron
- When stimulated by the action potential vesicles (located in the end
of the axon of the nerve cell, in the presynaptic neuron) travel
towards the presynaptic membrane and fuse with it (exocytosis)
- This causes the release of neurotransmitters into the synaptic cleft
- Neurotransmitters travel across the synaptic cleft and bind to
receptor sites on the postsynaptic membrane
- The neurotransmitters produce either excitatory or inhibitory effects
on the postsynaptic neuron, depending on the net effect
(summation)
- Excitatory neurotransmitters increase the likelihood of the
postsynaptic neuron firing an impulse, whereas inhibitory
neurotransmitters decrease the likelihood.
Why does synaptic transmission only occur in one direction?
- The synaptic vesicles containing the neurotransmitter are only
present on the presynaptic neuron
- The receptor cites for the neurotransmitters to bind to are only
present on the postsynaptic membrane
- It is this binding of the neurotransmitters to receptor sites which
enables the information to be transmitted to the next neuron
- Diffusion of the neurotransmitters mean they can only go from high
to low concentration, so can only travel from the presynaptic to the
postsynaptic neuron
How are excitation and inhibition involved in synaptic transmission?
- Excitatory neurotransmitters (like dopamine) are the nervous
system’s ‘on-switches’
- If excitatory then the post synaptic neuron is more likely to fire
an impulse
The Nervous System
What does the CNS do?
- Controls behaviour and regulates the body’s physiological processes
(breathing and digestion)
- Processes info from the PNS and prepares responses
- Brain, spinal cord and relay neurons (only found here)
What does the PNS do?
- Transmits messages to and from the CNS to the rest of the body
What does the SNS do? (PNS)
- Transmits info from the sense organ to the CNS (sensory pathways)
and from the CNS to effectors (motor pathways) to control voluntary
movement and allow for the reflex action
- Controls skeletal muscles, consists of sensory and motor pathways,
uses the motor cortex
What does ANS do? (PNS)
- Transmits info to and from the internal bodily organs to regulate
involuntary bodily processes (breathing and heartrate)
- Controls internal organs and glands, consists of motor pathways,
uses the brain stem
What does the SANS do?
- Works alongside the endocrine system to bring about physiological
arousal in the fight or flight response
- Mobilises bodily activity
What does PANS do?
- Works alongside the endocrine system to return the body to its
resting state in the rest and digest response
- Decreases bodily activity
Neurons
What is a neurons function and structure?
, - Neurons enable communication within the nervous system
- The soma includes a nucleus, which contains the genetic material of
the cell.
- Dendrites are branch-like structures which extend from the cell body
- Dendrites carry nerve impulses from neighbouring neurons towards
the cell body (they receive information from other neurons)
- Axons can be myelinated to speed up the transmission of the
impulse (through nodes of Ranvier which force the impulse to ‘jump’
along the gaps of the axon)
- Axons carry the nerve impulses away from the cell body down the
length of the neuron
- Terminal buttons are at the end of the axon
- Terminal buttons communicate with the next neuron across the
synapse (make synaptic connections with other cells)
What is a sensory neuron?
- Processes info received from the sensory receptors and converts this
info into neural impulses which are then translated to sensations
when they reach the brain
- Only transmits info from the body to the brain (unipolar)
- Long dendrites, short axon (no dendrites on cell body)
What is a relay neuron?
- Connect motor and sensory neurons
- Both send and receive messages from different parts of CNS
(multipolar)
- only found in brain and spinal cord
- short dendrite and axon (looks most distinctive)
What is a motor neuron?
- Carry signals from the CNS to organs, glands and muscles
- Form synapses with muscles to control their contractions through
releasing neurotransmitters which trigger a response (muscle
movement) and through inhibiting the motor neuron which causes
relaxation
- Both send and receive messages (multipolar)
- Shorts dendrites, long axon (looks most typical)
Sensory receptor PNS CNS Motor neuron effector
Sensory neuron Relay neuron
,How is an apply question on neurons answered?
- The sensory receptors in… sense…
- This information is sent from the PNS to CNS via sensory neurons
- Relay neurons based solely in the CNS receive the message, analyse
the sensations and decide how to respond
- Motor neurons receive this message from the relay neurons and a
take it from the CNS to effector muscles
- The message instructs… muscles to…
Synaptic transmission
What is a synapse?
, - The area between the axon of one neuron and the cell body/dendrite
of another
What is a neurotransmitter?
- Chemical messengers that carry signals across the synaptic cleft to
receptor sites on the post-synaptic neuron
- They can be excitatory or inhibitory
How does synaptic transmission work?
- Synaptic transmission is the process of transferring an action
potential from one neuron to the next across a synapse
- The action potential reaches the presynaptic neuron
- When stimulated by the action potential vesicles (located in the end
of the axon of the nerve cell, in the presynaptic neuron) travel
towards the presynaptic membrane and fuse with it (exocytosis)
- This causes the release of neurotransmitters into the synaptic cleft
- Neurotransmitters travel across the synaptic cleft and bind to
receptor sites on the postsynaptic membrane
- The neurotransmitters produce either excitatory or inhibitory effects
on the postsynaptic neuron, depending on the net effect
(summation)
- Excitatory neurotransmitters increase the likelihood of the
postsynaptic neuron firing an impulse, whereas inhibitory
neurotransmitters decrease the likelihood.
Why does synaptic transmission only occur in one direction?
- The synaptic vesicles containing the neurotransmitter are only
present on the presynaptic neuron
- The receptor cites for the neurotransmitters to bind to are only
present on the postsynaptic membrane
- It is this binding of the neurotransmitters to receptor sites which
enables the information to be transmitted to the next neuron
- Diffusion of the neurotransmitters mean they can only go from high
to low concentration, so can only travel from the presynaptic to the
postsynaptic neuron
How are excitation and inhibition involved in synaptic transmission?
- Excitatory neurotransmitters (like dopamine) are the nervous
system’s ‘on-switches’
- If excitatory then the post synaptic neuron is more likely to fire
an impulse
