Biopsychology Flashcards
The parts of the nervous system
- Central nervous system (CNS)
- Peripheral nervous system (PNS)
The Central nervous system (CNS)
-consists of the brain and spinal cord.
Function of the Central nervous system
-It has two main functions:
the control of behaviour
the regulation of the body’s physiological processes.
- In order to do this the brain must be able to receive information from the sensory receptors (eyes, ears, skin etc.) and be able to send messages to the muscles and glands of the body in response.
Areas of the brain
- Cerebrum
- Cerebellum
- Diencephalon
- Brainstem
Cerebrum
- This is the largest part of the brain.
- It has four lobes, and is spilt down the middle into two halves, called hemispheres.
- cerebrum controls voluntary movement, intelligence and memory.
Cerebellum
Responsible for motor skills, balance and coordinating muscles to allow precise movement
Diencephalon
Contains the thalamus (regulates consciousness, sleep and alertness) and the hypothalamus (regulates body temperature, stress response and hunger and thirst).
Brain stem
Regulates breathing and heart rate
The spinal cord
- The main function of the spinal cord is to relay information between the brain and the rest of the body.
- This allows the brain to monitor and regulate bodily processes, such as digestion and breathing, and co-ordinate voluntary movement.
- The spinal cord is connected to different parts of the body by pairs of spinal nerves, which connect to specific muscles and glands.
What happens if the spinal cord is damaged?
Body areas connected to it by nerves below the damage will be cut off and stop functioning
The peripheral nervous system (PNS)
- consists of the nervous system throughout the rest of the body (e.g. not the brain or spinal cord).
- The PNS transmits messages via neurons (nerve cells) to and from the CNS.
Divisions of the PNS
- Somatic nervous system
- Autonomic nervous system
The somatic nervous system
- controls voluntary movements and is under conscious control.
- It connects the senses with the CNS and has sensory AND motor pathways.
- It controls skeletal muscles.
- The somatic nervous system is controlled by the motor cortex.
The autonomic nervous system
- is involuntary (i.e. not under conscious control).
- It ONLY has motor pathways and it controls smooth muscles and the internal organs and glands of the body.
- The ANS is controlled by the brain stem.
- Has two divisions
Divisions of the Autonomic nervous system
- Sympathetic nervous system
- Parasympathetic nervous system
Sympathetic nervous system
- This is activated when a person is stressed.
- Heart rate and breathing increase, digestion stops, salivation reduces, pupils dilate, and the flow of blood is diverted from the surface on the skin (fight or flight response).
Parasympathetic nervous system
-This is activated when the body is relaxing and so conserving energy. -Heart rate and breathing reduce, digestion starts, salivation increases, and pupils constrict.
Neurons
specialised nerve cells that move electrical impulses to and from the Central Nervous System (CNS).
Parts of a neuron
- Cell body
- Nucleus
- Dendrites
- Axon
- Myelin Sheath
- Schwann cells
- Nodes of Ranvier
Cell body as a part of a neuron
Is the control centre of the neuron
Nucleus as a part of a neuron
Contains genetic material
Dendrites as a part of a neuron
Receives an electrical impulse (action potential) from other neurons or sensory receptors
Axon as a part of a neuron
A long fibre that carries the electrical impulse from the cell body to the axon terminal.
Myelin Sheath as a part of a neuron
Insulating layer that protects the axon and speeds up the transmission of the electrical impulse
Schwann cells as a part of a neuron
Make up the myelin sheath
Nodes of Ranvier as part of a neuron
Gaps in the myelin sheath.
They speed up the electrical impulse along the axon.
Three types of neuron
- Consist of similar parts but their structure, location and function are different.
- Sensory neuron
- Motor neuron
- Relay neuron
Where are Sensory neurons found?
Found in sensory receptors
E.g. eyes, ears, tongue and skin
Sensory neuron function
- They carry electrical impulses from the sensory receptors to the CNS (spinal cord and brain) via the Peripheral Nervous System (PNS).
- Sensory neurons convert information from sensory receptors into electrical impulses.
- When these impulses reach the brain they are converted into sensations, such as heat, pain etc. so that the body can react appropriately.
- Some sensory impulses terminate at the spinal cord.
- This allows reflexes to occur quickly without the delay of sending the impulses to the brain.
Where are motor neurons found?
Located in the CNS but project their axons outside the CNS.
Motor neuron function
- They send electrical impulses via long axons to the glands and muscles so they can affect function.
- Glands and muscles are called effectors.
- When motor neurons are stimulated they release neurotransmitters that bind to the receptors on muscles to trigger a response, which leads to movement.
Where are relay neurons located?
Found in the CNS
Function of the relay neuron
- They connect sensory neurons to motor neurons so that they can communicate with one another.
- During a reflex arc (e.g. you put your hand on a hot hob) the relay neurons in the spinal cord are involved in an analysis of the sensation and decide how to respond (e.g. to lift your hand) without waiting for the brain to process the pain.
Synaptic transmission
- Process by which one neuron communicates with another.
- Neurons transmit electrical impulses, known as action potentials, between the pre-synaptic neuron and the post-synaptic neuron
What is the pre-synaptic and post-synaptic neuron?
- Pre-synaptic neuron is the neuron transferring the action potential
- Post-synoptic neuron is the neuron receiving the action potential.
Process of synaptic transmission
- When the action potential reaches the pre-synaptic terminal it triggers the release of neurotransmitters from sacs on the pre- synaptic membrane known as vesicles in a process called exocytosis.
- The released neurotransmitter diffuses across the synaptic cleft where it binds to specialised post-synaptic receptor sites.
Neurotransmitters
Chemical messengers
Synaptic cleft
physical gap between the pre-synaptic membrane and post-synaptic membrane
How long does synaptic transmission take?
Fraction of a second
How are the effects of synaptic transmission terminated?
- Terminated by a process called re-uptake .
- The neurotransmitter is taken back by the vesicles on the pre-synaptic neuron where they are stored for later release.
- The quicker the neurotransmitter is taken back the shorter the effects.
Why can information only travel in one direction in the synapse?
- The vesicles containing neurotransmitters are ONLY present on the pre-synaptic membrane.
- The receptors for the neurotransmitters are ONLY present on the post- synaptic membrane.
- It is the binding of the neurotransmitter to the receptor 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 pre-synaptic to the post-synaptic membrane.
Psychoactive drugs in synaptic transmission
- (medication that affects brain function to alter perception, mood or behaviour), -such as SSRIs
- work by affecting (increasing or inhibiting) the transmission of neurotransmitters across the synapse
Excitatory and Inhibitory neurotransmitters
Neurotransmitters can be excitatory or inhibitory (most can be both but GABA is purely inhibitory).
Excitatory neurotransmitters
-cause an electrical charge in the membrane of the post-synaptic neuron resulting in an excitatory post-synaptic potential (EPSP), meaning that the post-synaptic cell is more likely to fire an impulse
Inhibitory neurotransmitters
cause an inhibitory post-synaptic potential (IPSP), making it less likely that the neuron will fire an impulse.
If a neuron receives both ESPs and ISPs at the same time, how can you determine whether an impulse will fire?
- A neuron can receive both EPSPs and IPSPs at the same time.
- The likelihood that the cell will fire an impulse is determined by adding up the excitatory and the inhibitory synaptic input.
- The net result of this calculation, known as summation, determines whether or not the cell will fire an impulse.
- If the net effect is inhibitory the neuron will not fire, and if the net effect is excitatory, the neuron will fire.
Endocrine system
provides a chemical system of communication in the body via the blood stream.
Endocrine glands
produce and secrete hormones into the bloodstream which are required to regulate many bodily functions.
Major glands of the endocrine system
- Pituitary glands
- Adrenal glands
Target cells
- The cells that are affected by hormones
- Target cells respond to a particular hormone because they have receptors for that hormone.
- When enough receptor sites are stimulated by that hormone there is a physiological reaction.
Where is the pituitary gland located?
Brain
Function of pituitary gland
produces hormones whose primary function is to influence the release of other hormones from other glands in the body.
What is the pituitary gland controlled by?
- Hypothalamus
- Above the pituitary gland
How does the pituitary gland function?
- The hypothalamus receives information from many sources about the basic functions of the body.
- The hypothalamus then sends a signal to the pituitary gland in the form of a releasing hormone.
- This causes the pituitary gland to send a stimulating hormone into the bloodstream to tell the target gland to release its hormone.
- As levels of this hormone rise in the bloodstream the hypothalamus shuts down production of the releasing hormone and the pituitary gland shuts down secretion of the stimulating hormone.