Unit 3 - Neurology and Immunobiology Flashcards
What is the central nervous system made up of?
Spinal cord
Brain
What are the three types of neurons involved in the nervous system?
Sensory
Inter Motor
What does the sensory neuron do?
Takes impulses from receptors in the sense organs to the CNS
What does the inter neuron do?
Carries impulses across spinal cord quickly during reflex actions
What does the motor neuron do?
Takes impulses from the CNS to effector muscles and glands
How are messages sent along neurons?
Electrical impulses
What is the gap between neurons called?
Synapse
What are the two divisions of the autonomic nervous control?
Sympathetic
Parasympathetic
How do sympathetic and parasympathetic division work?
Antagonistically (opposite actions)
How does the sympathetic affect the heart?
Increased heart rate and stroke volume
How does the parasympathetic affect the heart?
Decreases heart rate and stroke volume
How does the sympathetic affect breathing rate?
Increased rate and depth
How does the parasympathetic affect breathing rate?
Decreased rate and depth
How does the sympathetic affect peristalsis?
Decreased contractions
How does the parasympathetic affect peristalsis?
Increased contractions
How does the sympathetic affect intestinal secretions?
Decreased enzyme secretions
How does the parasympathetic affect intestinal secretions?
increased enzyme secretions
What are the three types of neural pathways?
Converging
Diverging
Reverberating
What does converging mean in terms of neural pathways?
Impulses sent from several neurons to one neuron
What is the purpose of converging neural pathways?
Increases sensitivity to excitatory or inhibitory signals which are responsible for whether or not the signal will be carried throughout the nervous system
Give an example of a converging neural pathway.
Eyes
Rod/cone cells sending light signals and converging into one signal around the optic nerve
What does diverging mean in terms of neural pathways?
When an impulse from one neuron travels to several neurons thus affecting more than one destination at the same time
Signals being sent to multiple sources to bring about a coordinated action/movement
When do diverging pathways occur?
IN tasks initiated by will
Signal from brain to move hand begins at one neuron being stimulated and ends with many neurons in the hand carrying out the action
Give an example of a diverging neuron pathway.
Walking, writing, lifting
Threading a needle
Typing
How do reverberating pathways work?
Neurons later in the pathway possess axon branches that form synapses with neurons earlier in the pathway
- Neurons at the end join to earlier neurons to create a continuous loop
What is the purpose of reverberating pathways?
Allows nerve impulses to be reused and repeatedly stimulated to create a continuous loop of action
Is stopped when process is no longer required
What is the difference between somatic and autonomic actions?
Somatic actions are voluntary actions/controlled by self. Brought about by skeletal muscle
Autonomic actions are involuntary actions controlled by the body. Brought about by smooth muscle/glands
What does antagonistic mean?
Work against each other / have opposite roles
One speeds things up, one slows things down
What is meant by localisation of brain functions in the cerebral cortex of the brain?
Specific functions are located in discrete areas/regions of the brain such as speech
Describe the function of converging neural pathways.
Allow low level stimuli to be summated causing an impulse to be passed on
Possible essay question : Describe the structure and functions of the autonomic nervous question (8)
What are the key things to include?
ANS controls involuntary responses
Impulses originate in the medulla
Made up of sympathetic and parasympathetic branches/systems
Sympathetic and Parasympathetic systems work antagonistically (or description)
Sympathetic system prepares body for fight or flight response
Parasympathetic system prepares the body for rest and digest response
Effect of the ANS on breathing rate/hart rate/peristalsis/secretions.
Where is their a localisation of brain functions?
In the cerebral cortex
What type of brain functions exist within the cerebral cortex?
Motor area Language area Auditory area Visual area Somatosensory area
What causes a stroke/ how does it happen?
Blockage in the blood vessels result in cells dying and as a result tissue dies
How is the cerebrum split?
Into two hemispheres - right and left
What does the left hand side of the cerebrum do?
Processes information from the right field of vision and controls the right side of the body
What does the right hemisphere of the cerebrum do?
Processes information from the left field of vision and controls the left side of the body
What is the corpus callosum?
The bundle of nerve fibres that connect the two hemispheres of the cerebrum
How are the two hemispheres of the cerebrum interconnected?
By corpus callosum
What is the purpose of the corpus callosum?
Enables information to be transferred between each hemisphere quickly allowing the brain to function as a whole
What is a split brain?
When the corpus callosum is severed
What happens in patients with a split brain?
2 Hemispheres cannot transfer information between each other
Where is speech located in the brain?
Left hand side
What is the effect of a split brain?
If patient sees a word written with his right eye, then the visual is processed on the left hand side of the brain where the speech is located and the patient can see what he saw
If the patient sees the word with his left eye, it is processed on the right and as information cannot be passed to the left hemisphere, they cannot voice their vision
LEFT controls the RIGHT, RIGHT controls the LEFT
What are the three levels of memory in the brain?
Sensory
Short Term
Long Term
What are the three basic processes carried out for something to be committed to memory?
Encoding
Storage
Retrieval
What is classed as a memory?
Past events
Experiences
Knowledge
Thoughts
What are the three ways to extend short term memory?
Chunking
Rehearsal
Serial Position Effect
What is the capacity of short term memory?
7-10 Items, lasts 30 seconds
How can information in short term memory be lost?
Displacement
Decay
What is displacement in terms of memory?
Information being pushed out by new incoming information
What is decay in terms of memory?
Breakdown of briefly activated neuron connections
What is chunking?
Breaking something down to remember it / grouping small pieces of information together into single items
What is rehearsing?
Repeating it again and again – practising it
What is elaboration?
Elaboration is a form of deeper encoding leading to better retention. Essentially the more you know about something the more likely to remember it.
What is the capacity of long term memory?
Unlimited
Store info for a long time
What is the requirement for information in short term memory to go to long term memory?
Has to be encoded in the brain to a form that is easily stored and recalled
What ways can information be encoded?
Rehearsal
Organisation
Elaboration
How is the retrieval of information aided?
Through the use of contextual cues (setting, place, time, etc)
What is organisation in terms of memory?
Compartmentalising it
What is elaboration in terms of memory?
Adding value to a piece of information
What is Alzheimer’s disease?
The most common form of dementia (mental deterioration)
What are the symptoms of Alzheimer’s?
Confusion Mood swings Irritability Aggression Loss of long term memory Loss of speech Can’t recall recent memories
How does Alzheimer’s affect the brain?
Cell connections in the brain begin to breakdown – unknown cause
Think it might be to do with reduced synthesis of acetylcholine which is a neurotransmitter substance
What region of the brain co ordinates voluntary movements?
Cerebral cortex
What is the cerebral cortex and what is its function?
Outer layer of the cerebrum
Retrieves sensory information, co ordinates voluntary movements, recalls memories, makes decisions based on experience
What is the function of the corpus callosum?
Allows the exchange of information between the right and left hemispheres of the brain
Connects both halves
What region of the brain is in charge of involuntary control of intercostal muscles and diaphragm?
The medulla
What is meant by a memory ‘cue’?
A stimulus which helps retrieve information from long term memory/a link to the time and place in which the memory was created
What is the purpose of sensory memory?
What are the basic components of neurons?
Cell Body
Axon
Denrites
What neurons have insulation?
Sensory and motor
Where is the insulation of neurons and what form is it in?
Around the axon
Form = Myelin Sheath
What is the direction of electrical impulses in neurons?
Dendrites -> neuron -> cell body
What is myelination?
Process which enables a fatty layer to form around neurons by special glial cells in the body
When is myelination of neurons completed?
At adolescene
What is the point in insulating the axon?
Ensures that the speed of electrical transmission from node to node is increaced
How might unmyelinated neurons in babies and toddler’s affect them?
Delayed responses to stimuli
Can’t control body temperature
What is the effect of the destruction of myelination?
Nerve impulses slow down/stop
What are the symptoms of MS?
fatigue vision problems numbness and tingling muscle spasms, stiffness and weakness mobility problems pain problems with thinking, learning and planning depression and anxiety
What is MS/What happens in MS?
Multiple Sclerosis
In MS, the immune system attacks the myelin sheath. This damages and scars the sheath, and potentially the underlying nerves
What is the myelin sheath?
The protective layer that forms around nerves
Can the myelin sheath be repaired?
Myelin is repaired or replaced by special cells in the brain called oligodendrocytes
What is the long term prognosis of someone suffering from MS?
Is chronic
Disabilities
Decreased life span by 5-10 years
Decreased quality of life
Is MS a degenerative condition? Why?
What is the synaptic cleft?
The space between two neurons at a synapse
What is the neuron before the synaptic cleft called?
Presynaptic neuron
What is the neuron after the synaptic cleft called?
Postsynaptic neuron
What are the messages relayed across the synaptic cleft called?
Chemical neurotransmitters
Where are chemical neurotransmitters stored?
In the vesicle in the axon endings of the presynaptic neuron
Why do vesicles have many mitochondria?
To produce, store and release chemical neurotransmitters
What determines the type of signal response from the postsynaptic membrane?
The receptor present
What are the two types of signals?
Excitatory
Inhibitory
What must happen for an impulse to be carries on?
The minimum number of neurotransmitter molecules attach to a receptor in order to reach the membranes threshold and transmit the impulse
How do synapses respond to weak stimuli?
Can either filter it out if it is a result of insufficient secretion of neurotransmitters
OR
the summation of weak stimuli can also trigger a response
What kind of pathways are neurotransmitters involved in?
Pathways that directly affect a persona mood/behaviour
What is the effect of dopamine and what pathway is it a part of?
Feelings of satisfaction and pleasure
Rewards pathways
What is the effect of endorphins?
Released to bring about a reduction of pain or increased euphoria depending on the receptor the bind to
How can endorphin production be increased?
Response to severe injury, prolonged/continuous exercise, stress and certain foods
Why is it essential to remove neurotransmitters from the synaptic cleft?
Prevent continuous stimulation of postsynaptic neurons
What are the two ways to remove neurotransmitters from the synaptic cleft?
Enzyme controlled degradation (with acetylcholine)
Reuptake into the presynaptic neuron (with noradrenaine)
Give some reasons for the occurrence of a neurological disorder.
Over production of a particular neurotransmitter
Under production of a particular neurotransmitter
An imbalance in the production of neurotransmitters
Give examples of some common neurological disorders.
Alzheimer’s
Schizophrenia
Depression
How can neurological disorders be treated?
Drugs
What are the three distinct categories of drugs used to treat neurological disorders?
Agonists
Antagonists
Inhibitors
How do recreational drugs alters a persons state of consciousness?
By altering the neurotransmitters in the brain
What category of drug do recreational drugs fall under?
Agonists or antagonists
What neurological pathway do recreational drugs often effect?
The reward pathway of the brain
How do agonistic drugs work?
Bind to and stimulate specific receptors mimicking the action of a neurotransmitter
How do antagonistic drugs work?
Are chemicals that bind to specific receptors blocking the actions of a neurotransmitter
Overall, what do antagonistic and agonistic drugs acta as?
Synapse
What is drug addiction?
A chronic disease that causes the sufferer to compulsively seek out and use drugs regardless of the consequences
What changes occur in the nervous system as a result of drug addiction?
Over-ridden self control
With agonistic drugs - desensitisation
With antagonistic drugs - sensitisation
What happens in desensitisation?
the number of neurotransmitters decrease, become less sensitive to drugs increasing the drug tolerance
What happens in sensitisation?
Increased number of neurotransmitters and sensitivity
What changes occur to the nervous system as a result of drug tolerance?
Decrease in number and sensitivity of receptors as a result of repeated exposure to a drug acting as an agonist
What causes addiction?
Repeated use of an antagonist drug that increases sensitivity and the number of receptors leading to a craving for more of the drug
What causes tolerance?
Repeated use of an agonist drug which decreases the receptor sensitivity and numbers so more of the drug is needed to get a hit
What is the purpose of the immune system?
To defend the body against infection or act to destroy the invading pathogen
What are the the two main immune responses?
Non=specific and specific
What is the purpose of epithelial cells?
Provide a physical barrier pf protection against foreign pathogens
Where are epithelial cells found?
In the skin and the inner linings of the digestive and respiratory tracks
Give examples of chemical secretions that play a role in the defence against foreign pathogens
Mucus Sweat Tears (containing lysozyme) Saliva ^ Stomach Acid Sebum
Why is the stomach lining not digested by protein digesting enzyme pepsin?
Pepsin is inactive in the stomach
Mucus provides protective layers
What causes inflammation?
The release of chemical histamine from mast cells
What does histamine do?
Promotes the vasodilation of blood vessels
Increases the permeability of surrounding capillaries
Why does histamine vasodilate the blood vessels?
Increased blood flow -> accumulation of phagocytes and clotting elements at the site of infection
What produces histamine?
Mast cells
What are the signs of an inflammatory response?
Heat Redness Swelling Pain Loss of function
What are phagocytes?
Specialised white blood cells involved in non specific response
How to phagocytes work?
Recognise foreign pathogens
Engulf and digest them using digestive enzymes contained in lysomes
What is the ‘engulf and digest’ process done by phagocytes referred to as?
Phagocytosis
How do phagocytes attract more phagocytes to a site of infection?
By releasing cytokine
What is cytokine?
A protein signalling molecule
A chemical messenger
How does the inflammatory response work?
Mast cells activate and release large quantities of histamine
Histamine vasodilates the blood vessels and the capillaries swell with blood
The additional blood in the vessels makes the area red and inflammed
Where are mast cells found?
Connective tissue all around the body
When is the immunes systems final line of defence brought on?
When non specific responses have been insufficient at controlling the spread of infection
What brings about a specific immune response?
Lymphocytes in bone marrow
What are the two main cell types which are involved in specific response?
T Lymphocytes (T Cells) B Lymphocytes (B Cells)
Where do T cells mature?
In the Thymus
Where do B cells mature?
In the Bone marrow
What is the relationship between lymphocytes and antigens?
Lymphocytes are specific and can only be activated by one antigen
What is an antigen?
An antibody generator
What happens when an lymphocyte is activated?
Will divide repeatedly to form a population of clones
What is a lymphocyte?
A type of white blood cell
What activates T cell responses?
Fragments of foreign antigens displayed on phagocytic immune cells
What is the purpose of T cells and how do they carry out their function?
Destroy infected body cells by causing apoptosis
What is apoptosis?
A way of killing cells
What happens when proteins are secreted from the T cell?
Self destructing enzymes are created within the infected cells leading to cell death
What happens to the remains of an infected cell?
Cleared by phagocytic cells
How are B cells activated?
By antigen presenting cells and produce antibodies against foreign antigens which are displayed on pathogens
What is the structure of B cells and how is it suited to its purpose?
Y shaped protein molecules
Have a receptor binding site that is specific to one type of antigen on a pathogen
How do B cells get rid of foreign antigens?
Antibodies bind to pathogens, inactivating them so that the antigen-antibody complex is cleared from the immune system by phagocytic cells.
How long can it take for a full immune response to react to a new foreign invader?
Up to Seventeen days
What happens when a foreign invader returns?
Antibody production is rapid due to memory cells
Antibody concentration is higher
Antibodies are maintained for longer in the bloodstream
Have a greater ability to bind to antigens
Would would a graph for antibody production against time for the first and second attack?
Small peak, long build up
Tall peak, short build up
How do T cells recognise self from non-self antigens?
Cells have a combination of cell surface proteins (an antigen signature) unique to a person
During maturation lymphocytes bearing a receptor for the bodies antigen signature are removed
When do T cells tell the difference between self and non self cells?
What are the consequences of a T cells being unable to tell the difference between self and non self cells?
Autoimmune disorders
How is autoimmunity different to an allergic response??
Autoimmunity is an attack against the bodies own cells
Allergies are when the immune system mistakes a harmless cell for an invader and triggers a response to fight it
Is there a difference between immunisation and vaccination? If yes, what is it?
Immunisation is when the body becomes immune to a disease
Vaccination is
What is immunisation?
The process which brings about protection against a disease causing microorganism
What are the two ways to achieve immunisation?
Naturally and Artificially
How does natural immunisation occur?
Your body comes into contact with a pathogen and fights against the infection ensuring memory cells have formed for future encounters
How does artificial immunisation occur?
Vaccinations
What is in a vaccine?
A form of the foreign antigen
NOT the full disease causing the pathogen
Why do vaccines not contain the full disease?
For safety and control purposes
What kind of forms of antigen can be found in vaccines?
Dead pathogens
Inactivated pathogens/toxins
Fragments
Attenuated (weakened)
Give examples of vaccines with dead pathogens.
Hepatitis A
Polio
Give examples of vaccines with inactivated pathogens.
Diphtheria
Tetanus
Give examples of vaccines with fragments.
Hepatitis B
HPV
Give examples of vaccines with attenuated diseases.
MMR
Smallpox
What is herd immunity?
When the majority of a population are immunised so the risk of an unimmunised person coming into contact with the disease decreases and increases their protection against said disease
When does herd immunity occur?
When a threshold limit of immunised people is met
Why are mass vaccinations designed?
To establish herd immunity to a particular disease
Why does mass vaccination not always work?
Factors such as poverty or people refusing a vaccine
What is antigenic variation?
When genetic mutations and DNA recombination arise allowing new antigens to be displayed on pathogenic surfaces ensuring a sufficient disguise from the immune system
Why does antigenic variation occur?
Is a survival technique o ensure selective advantage over previous strains of a disease causing pathogen
What does antigenic variation apply primarily too?
Viruses adapting
How does antigenic variation work?
Virus adapt and change their antigen signature so they cannot be recognised by memory cells
How is antigenic variation combatted?
Updated vaccinations every year
What has to happen before clinical trials?
Rigorous testing stages
Where are vaccines usually first tested?
On cell cultures and on animal models
Why are initial vaccine tests carried out on animals and cell cultures first?
To allow side affects to be determined
Can take up to 10 years
How allows a clinical trial to be tested on humans?
Countries regulatory authority
What is included in the design of clinical trials?
Group sizing
Randomisation of test subject
Placebo control
Double bind trial
What is the point in randomisation in a clinical trial?
Ensures a reduced bias in the distribution of characteristics such as age and gender
What is meant by a double bind procedure?
Neither the subject nor the researchers know which group of subjects are in (drug or placebo) to prevent bias
What happens to the majority of new vaccinations?
Don’t pass the initial preclinical stage
