Neurobiology And Immunology Flashcards
What is the central nervous system made up of?
The brain and spinal cord
What is the peripheral nervous system made up of?
The somatic and autonomic nervous systems
What does the somatic nervous system do?
Takes messages from the sense organs, along sensory neurones to the CNS
Motor neurones then take impulses from CNS along motor neurones to muscles and glands.
What does the autonomic nervous system contain?
Sympathetic and parasympathetic systems which are antagonistic to each other
What does the sympathetic system do?
Prepares body for action (fight or flight) by
•increasing heart rate,
•increasing breathing rate by allowing bronchioles to take in more air
•decreasing peristalsis
•decreasing production of intestinal secretions
What does the parasympathetic system do?
Calms body down returning to normal (rest and digest) by
•Decreasing heart rate
•Decreasing breathing rate by constricting bronchioles so less air is taken in
•Increases rate of peristalsis
•Increasing production of intestinal secretions allowing the body to conserve resources and energy
What is a converging neural pathway?
Impulses from several sources are channeled towards and meet at a common destination
This increases sensitive to excitatory or inhibitory signals
What is a diverging neural pathway?
The route along which an impulse travels and divides allowing information to be transmitted to several destinations at once
What is a reverberating neural pathway?
Neurones later in the pathway form synapses with neurones earlier in the pathway forming a loop enabling impulses to be cycled and stimulated repeatedly
What happens in the cerebral cortex?
It’s the centre of conscious thought
It’s where memories are recalled
It’s what alters behaviour in light of experience
What does localisation mean?
Distinct regions with a particular function
What does sensory do?
Receives information
What does motor do?
Sends signals to appropriate effector organs eg muscles
What do association areas do?
Concern language, personality, imagination, intelligence
Which side of the brain controls which side of the body?
The left cerebral hemisphere deals with information from the right visual field and controls the right side of the body and vice versa
What does transfer between the two hemispheres occur through?
The corpus callosum
What are the 3 stages of memory?
Encoding
Storage
Retrieval
What does your memory include?
Past experiences, knowledge and thoughts
What is the order or memories?
Sensory —-> short term —-> long term memory OR discarded
What does sensory memory do?
Retains all visual and auditory input and only lasts a few seconds
Only selected images and sounds encoded into short term memory
How much does short term memory hold?
Holds a limited capacity and holds information for a short time
How can memory capacity be improved?
Chunking (meaningful units of information)
Rehearsal
What is the serial position effect?
The items at the start of a list and end of a list are remembered better than those in the middle
How are items lost from short term memory?
Displacement (pushed out by new information)
Decay (breakdown of memory trace)
What is working memory?
STM can process data to a limited extent, as well as store it and is why STM can perform simple cognitive tasks
How much does long term memory hold?
Holds an unlimited amount of information for a long time
What is successful transfer to long term memory from short term memory promoted by?
Rehearsal
Organisation (into logical categories)
Elaboration of meaning (give meaning to an item)
How can information be encoded into long term memory?
Shallow encoding (rehearsal) Or Elaborative encoding (elaboration - deeper form of encoding leading to improved retention)
What is retrieval of items from LTM aided by?
Use of contextual cues (signals related to the time and place that were present when information was encoded)
What are the three types of neurones?
Sensory
Inter
Motor
What is the basic structure of a neuron?
Cell body
Axon
Dendrites
What does the cell body of a neuron do?
Contains nucleus so is the control centre
What does the axon of a neuron do?
Single nerve fibre that carries nerve impulses away from a cell body
What does the dendrite of a neuron do?
Pass impulses towards cell body
What are axons surrounded by?
A myelin sheath
What is a myelin sheath?
A layer of fatty material that insulates the axon, greatly increasing the speed of impulse conduction
What is myelination?
The development of myelin
It continues from birth to adolescence
What is the difference between responses to stimuli in the first 2 years of life compared to the rest of life?
They are not as rapid or coordinated as those of an older child or adult.
What destroys the myelin sheath and what effect does this have?
Certain diseases, causing a loss in coordination
What do glial cells do?
Produce the myelin sheath and support neurones
What is the region of functional contact between the axon ending of one neurone and a dendrite of another called?
A synapse
What is the tiny gap between two neurones called?
Synaptic cleft
How are messages relayed across the synaptic cleft?
By neurotransmitters
Where are neurotransmitters?
In vesicles on the presynaptic neurone
What is an example of a neurotransmitter?
Acetylcholine
Noradrenaline
What happens when an impulse passes through the presynaptic neurone?
It stimulates several vesicles to move to the synapse, fuse with the membrane and discharge the neurotransmitters which diffuse across the synaptic cleft and bind to receptors of the post synaptic neuron
What is done to prevent continuous stimulation and precise control in neurones?
The post synaptic neurone must remain excited for only a brief moment to pass on the impulse
How are neurotransmitters removed?
Enzyme Degeneration
Enzyme Re-Uptake
What is enzyme degeneration?
Enzyme breaks down neurotransmitters which is then reabsorbed and synthesised into new neurotransmitter
What is enzyme re-uptake?
Neurotransmitter is stored in vesicles
What do the receptors present on the postsynaptic neurone determine?
Whether the signal is excitatory or inhibitory
What must happen in order for an impulse to be transmitted?
A certain threshold of neurotransmitter molecules must attach to receptors otherwise they are filtered out due to being weak
What is summation?
When a postsynaptic neurone receives information via several synapses (convergent pathway), this collective of weak stimuli could be enough to fire an impulse
What are endorphins?
Neurotransmitters that stimulate neurones involved in reduced intensity of pain by combining with receptors synapses and blocking the transmission of the pain signal
What are endorphins produced by?
The hypothalamus
What are increases levels of endorphins produced in response to?
Severe injury
Prolonged and continuous exercise
Physical and emotional stress
Certain foods such as chocolate
What are increases levels of endorphins linked with feelings from?
Eating
Sex
Prolonged exercise
What is dopamine?
Neurotransmitters that induce feelings of pleasure by stimulating the reward pathway which reinforces certain behaviour to satisfy a need that is beneficial - such as hunger or thirst
What are examples of neurotransmitter related disorders?
Alzheimer’s
Schizophrenia
Depression
How are neurotransmitter related disorders treated?
By agonists and antagonists
What do agonists work?
Binds to and stimulates specific receptors on post synaptic neurone mimicking action of naturally occurring neurotransmitters, triggering normal cellular response
How do antagonists work?
Bind to specific receptors on postsynaptic neurone and blocking the action of the neurotransmitter inhibiting normal cellular response
How do inhibitor drugs work?
By preventing the removal of the neurotransmitter (by degrading the enzymes or preventing re-uptake) causing an enhanced effect
What can recreational drugs act like?
Agonists and antagonists
What do recreational drugs affect?
Transmission at synapses in the brain
What do recreational drugs alter?
Mood - happier, more confident, more aggressive
Cognition - can’t carry out complex mental tasks such as problem solving and decision making
Perception - misinterpretation of stimuli
Behaviour - stay awake for longer, talk endlessly about themselves
How can recreational drugs cause overstimulation?
By affecting neurotransmission in the reward circuit of the brain
How is drug addiction caused?
By repeated use of drugs that act as antagonists
How do antagonists lead to drug addiction?
They block specific receptors causing the nervous system to compensate by increasing both the number and sensitivity of these receptors
What does the increased sensitivity to receptors (sensitisation) lead to?
Addiction, where the individual craves more of the drug
What is drug tolerance caused by?
Repeated use of drugs that act as agonists
How do agonists cause drug tolerance?
They stimulate specific receptors causing the nervous system to compensate by decreasing both the number and sensitivity of these receptors?
What does the decreases sensitivity to receptors (desensitisation) lead to?
Drug tolerance, where the individual must take more of the drug to get an effect
What are the four types of non-specific body defences?
Physical defence
Chemical defence
The inflammatory response
Phagocytes
What does the physical defence consist of?
Closely packed epithelial cells found on the surface of skin and lining the body’s digestive and respiratory systems
What does the physical defence offer a barrier against?
Bacteria and viruses
What does the chemical defence consist of?
Secretions including tears, saliva, mucus and stomach acid
What does the chemical defence work against?
Invading pathogens
What is a pathogen?
A disease causing microorganism
What is the inflammatory response caused by?
A physical injury such as a cut or invasion of microorganisms
What happens to mass cells following an injury?
They become activated, releasing large quantities of histamine
Where are mast cells found?
Connective tissues
What is histamine?
A chemical which causes vasodilation and capillaries to become more permeable
What does the increased blood flow during the inflammatory response lead to?
Accumulation of phagocytes and clotting elements at the site of infection
What do phagocytes do?
Recognise pathogens, engulf them and destroy them using digestive enzymes contained in lysosomes through phagocytosis
What do phagocytes release and what is the effect?
Cytokines - attracting more phagocytes to the area of infection
What are cytokines?
Protein molecules which act as a signal
What is body’s specific defence?
Lymphocytes
What are lymphocytes?
The white blood cells involved in the specific immune response
What do lymphocytes do?
Respond to specific pathogens because they have a single type of membrane receptor which is specific for one antigen on the invading pathogen
What is an antigen?
Molecules, often proteins, located on the surface of cells which trigger the immune response
What does the binding of the membrane receptors of a lymphocyte and the antigen lead to?
The lymphocyte repeatedly dividing, resulting in a clinal population of identical lymphocytes
What are the two types of lymphocyte?
B Lymphocytes
T Lymphocytes
What do B lymphocytes do?
Produce antibodies which bind to antigens inactivating the pathogen
What are antibodies?
Y shaped proteins that have receptor binding sites which are specific to a particular antigen or pathogen
What is formed when antibodies bind to antigens?
Ab antibody antigen complex
How can an antibody antigen complex be destroyed?
By phagocytosis
How do B lymphocytes cause allergic reactions?
They can respond to antigens on substances that are harmless to the body
What is it called when B lymphocytes respond to antigens on substances that are harmless?
Hypersensitivity
What do T lymphocytes do?
Destroy infected body cells by recognising antigens of the pathogen on the membrane and inducing APOPTOSIS
What is apoptosis?
Programmed cell death
How does apoptosis work?
T Lymphocytes attach onto infected cells and release a protein which diffuses into the cell causing production of self-destructive enzymes
The remains of the cell are then removed my phagocytosis lib
