4.2.2 Biopsychology Flashcards
What is the nervous system?
The nervous system is a body wide network of specialised nerve cells, that collects, processes, and responds to information in the environment, and co-ordinates organs and cells within the body.
What are the 2 functions of the nervous system?
-to collect, process and respond to information in the external environment
-to co-ordinate the workings of organs and cells within the body
(Done via the transmission of electrical impulses)
What are the 2 components of the nervous system?
The central nervous system (CNS) and the peripheral nervous system (PNS)
What is the central nervous system?
The central nervous system consists of the brain and spinal cord, and is the origin of all complex commands and decision-making.
What is the brain?
The brain is the centre of all conscious awareness, and is involved in all psychological processes.
What are the 6 areas of the brain and their functions?
Occipital lobe- processes visual information
Temporal lobe- processes auditory information
Parietal lobe- integrates information from senses
Frontal lobe- higher order functions eg. Logic
Brain stem- connects the brain to the spinal chord and controls involuntary processes
Cerebellum- controls muscular activity and balance
What is the spinal cord?
The spinal cord transfers messages to and from the brain and the rest of the body, and is responsible for reflex actions that do not involve the brain.
What is the peripheral nervous system?
The peripheral nervous system is a body wide network of neurones, that transmits messages to and from the central nervous system and the rest of the body.
What neurones are involved in the peripheral nervous system?
Sensory neurones- transmit messages to the CNS
Motor neurones- transmit messages away from the CNS
What are the 2 components of the PNS?
The somatic nervous system (SNS) and the autonomic nervous system (ANS)
What is the somatic nervous system?
-the primary means of communication between the CNS and the external environment
-made up of sensory receptors which carry information to the CNS, and motor pathways, which allow the brain to control muscle responses
-it is under conscious control
What is the autonomic nervous system?
-governs the vital functions that take place within the body, playing an important role in homeostasis (maintains internal processes)
-transmits information to and from internal organs
-it is an involuntary process
-consists only of motor pathways, and has 2 main components
What are the 2 components of the autonomic nervous system?
Sympathetic nervous system and parasympathetic nervous system
What is the sympathetic nervous system?
Involved in responses and physiological changes that prepare the body for fight or flight. The impulses travel from the CNS to organs in the body. Eg. Increased heart rate, breathing rate and blood flow, pupil dilation and inhibited digestion and urination.
What is the parasympathetic nervous system?
Involved in returning the body to a resting state, and restores normal physiological functioning after a period of stress. Eg. Decreased heart rate, breathing rate and blood flow, pupil contraction and restarts digestion and urination
What are neurones?
Neurones are nerve cells that process and transmit messages through electrical and chemical signals. They each have a different function depending on its location in the body and its role within the nervous system
What are the three types of neurones?
Sensory, relay and motor neurones
Describe the structure and function of a sensory neurone
Long dendrites, short axon
Pseudounipolar- axon is split into two branches
Found in receptors
Carry messages from receptors to the CNS
Describe the structure and function of a relay neurone
Many short dendrites and a short axon
Multipolar- one axon but several dendrite
No myelin sheath
Found in the CNS to allow communication between the other two neurones
Describe the structure and function of a motor neurone
Short dendrites, long axon
Multipolar- one axon but several dendrites
Found in the CNS and PNS
Transmit impulses to effectors to produce a response
What is the function of dendrites?
Receive signals from receptors or other neurones, and carry them towards the cell body
What is the function of the cell body?
To contain the genetic material of the cell in the nucleus, so controls its activities
What is the function of the axon?
To carry nerve impulses in the form of an electrical signal (action potential) towards the axon terminal
-it is insulated and protected by the myelin sheath
-the nodes of ranvier speed up transmission by forcing impulses to jump across the gaps
What is the function of the axon terminal?
To connect the neurone to other neurones and communicate with them over a synapse, through synaptic transmission
-sometimes they connect motor neurones directly to an effector
What is a synapse?
The gap between two neurones
In what form are impulses transmitted across the synapse?
Chemical (neurotransmitters)
What is the charge of a neurone at rest?
Negatively charged
Describe the process of synaptic transmission
When a neurone is at rest, the inside of the cell is negatively charged.
When it is activated by a stimulus, the inside of the cell momentarily becomes positively charged.
This causes an action potential to occur, creating an electrical impulse in the neurone, which travels down the axon.
When the electrical impulse reaches the presynaptic terminal, neurotransmitters are released from vesicles into the synapse.
The neurotransmitters diffuse across the synapse and bind to receptors on the post-synaptic terminal, which stimulates the receptors.
For the action potential to be passed onto the next neurone, the electrical charge needs to pass a threshold.
Some neurotransmitters are excitatory, so make the charge more positive (depolarisation). Whereas some are inhibitory, so and make the charge more negative (hyperpolarisation).
The excitatory and inhibitory effects of the binding neurotransmitters are summed through the process of summation.
If the net-effect is inhibitory, the neurone will not fire, but if it is excitatory, the neurone will fire.
The neurotransmitters detach and are reabsorbed by the presynaptic terminal to be released again (re-uptake), or undergo enzymatic degradation.
What are neurotransmitters released from?
Vesicles in the presynaptic terminal
What is the effect of excitatory neurotransmitters?
They make the charge more positive, so have a depolarising effect.
What is the effect of inhibitory neurotransmitters?
They make the charge more negative, so have a hyperpolarising effect.
What is summation?
The sum of the excitatory and inhibitory effects of neurotransmitters, to calculate the net-effect on the next neurone.
What happens to neurotransmitters when they detach from the receptors?
Re-uptake or enzymatic degradation
How do neurotransmitters travel across the synapse?
By diffusion
Describe the process which determines whether a neurone will fire or not
Neurones at rest are negatively charged compared to their surroundings.
For it to fire (trigger an action potential), it must momentarily become positively charged/ depolarised.
This means the excitatory effects of neurotransmitters binding to the next neurone must reach a threshold- after summation has occurred.
Excitatory neurones have a depolarising effect, known as EPSPs/ excitatory postsynaptic potentials: they increase the chance of the neurone firing
Inhibitory neurones have a hyperpolarising effect known as IPSPs/ inhibitory postsynaptic potentials: they decrease the chance of the neurone firing.
If the net-effect of the binding neurotransmitters is inhibitory, then the post-synaptic neurone will not fire.
If the net-effect of the binding neurotransmitters is excitatory, then the post-synaptic neurone will fire (action potential triggered).
Why do neurones only transmit information in one direction?
The synaptic vesicles that contain the neurotransmitter are only released from the presynaptic terminal.
The receptors that detect neurotransmitters are only present on the postsynaptic terminal.
It is the binding of the neurotransmitter that enables information to be passed on.
What is the endocrine system?
A network of glands across the body that secrete chemical messages known as hormones into the bloodstream. It works alongside the nervous system to control vital functions in the body.
What are hormones?
Hormones circulate in the bloodstream and travel to target organs where they produce a specific effect. Each gland produces and secretes different hormones.