bbb 2 Flashcards
How much does the brain weigh on average?
1.5 kg,
Which neurone is most frequently found in the brain?
Interneurons (Relay neurons),
What are the two neuron ‘processes’? (2)
- Axons 2. Dendrites,
What is the function of axons?
Transmit information from the neuron onto the others to which it is connected.,
What is the function of dendrites?
They receive the information being transmitted by the axons of other neurons.,
What are the functions of the spinal cord? (2)
- Simple and complex reflexes 2. It forms a highway between the body and the brain for information travelling in both directions.,
What is the diencephalon is divided into? (2)
- Thalamus 2. Hypothalamus,
Function of the basal ganglia
Has a central role in the initiation and control of movement.,
How are the left and right hemispheres connected?
Corpus Callosum,
Who drew the first pictures of neurons and denrites?
Ramon y Cajal in 1890,
How do dendrites change shape?
They sprout new connections and withdraw others,
What are dendritic spines?
Tiny protuberances that stick out from the dendrites,
Function of dendritic spines
These are where incoming axons make most of their connections.,
What do the end-points of the axons respond to?
Growth factors,
How do growth factors influence axons?
These factors are taken up inside and then transported to the cell body where they influence the expression of neuronal genes (manufacture of new proteins). These enable the neuron to grow longer dendrites or make dynamic changes to its shape or function.,
Where does the word ‘synapse’ stem from?
Classical Greek words that mean “to clasp together”.,
What happens when the dendrite receives a chemical messenger? (2)
Miniature electrical currents are set up inside the receiving dendritic spine these are either: 1. Currents that come into the cell (excitation) 2. Currents that move out of the cell (inhibition),
What does the myelin sheath do?
It prevents the ionic currents from leaking out in the wrong place,
What do clusters of ion channels serve to do?
Boost and maintain the action potential as it skips along the nerve.,
Where are neurotransmitters found?
Synaptic vesicles in the endings of axons.,
What happens after neurotransmitters are released into the synaptic cleft? (2)
- Attaches to post-synapse receptors 2. Returns into the synaptic cleft by transporters on glial cells,
What are ionotropic receptors?
When the attachment of the transmitter (the key) to the receptors (the lock) causes the opening of an ion channel,
What is the main excitatory neurotransmitter in the brain?
Glutamate,
What are the names of the inhibitory neurotransmitters? (2)
- GABA 2. Glycine,
What are the characteristics of metabotrophic receptors? (3)
- Do not contain ion channels 2. Are not localised in the region of the synapse 3. Do not lead to the initiation of action potentials,
What is the action of metabolic receptors called?
Neuromodulation,
What receptors neuromodulate?
Metabotrophic receptors,
Where are metabotrophic receptors found?
In complex particles linking the outside of the cell to enzymes inside the cell that affect cell metabolism.,
What effects can neuromodulation cause? (4)
Changes in: 1. Ion channels 2. Receptors 3. Transporters 4. Expression of genes,
Which messengers act on G-protein coupled receptors? (3)
- Acetylcholine 2. Dopamine 3. Noradrenaline,
What is noradrenaline?
Noradrenaline is released in response to various forms of novelty and stress and helps to organise the complex response of the individual to these challenges. Lots of networks may need to “know” that the organism is under stress.,
How does acetylcholine work ionically?
It uses ionic mechanisms to signal across the neuromuscular junction from motor neurons to striated muscle fibres.,
What receptors does actylcholine work on?
Ionotropic and metabotropic receptors.,
How can actylcholine act as a neuromodulator?
When you want to focus attention on something - fine-tuning neurons in the brain to the task of taking in only relevant information.,
What ability do addictive drugs share?
They promote the release of the chemical messenger dopamine in certain brain regions.,
How does alcohol work?
Alcohol acts on neurotransmitter systems in the brain to dampen down excitatory messages and promote inhibition of neural activity.,
How does nicotine work?
Nicotine acts on brain receptors that normally recognise the neurotransmitter acetylcholine; it tends to activate natural alerting mechanisms in the brain.,
Consequence of alcoholism (2)
- Damages the body (liver and brain) 2. Pregnant mothers who drink run the risk of having babies with damaged brains and low IQ’s.,
Consequence of a nicotine addiction
Tobacco smoke is extremely damaging to the lungs and long-term exposure can lead to lung cancer and also to other lung and heart diseases.,
What two neurotransmitters do amphetamines release? (2)
- Dopamine (strong arousal and pleasurable effects) 2. Serotonin (sense of well-being and a dream-like state that can include hallucinations).,
What are the consequences of amphetamine use? (3)
- Permanent reduction of serotonin cells. 2. Death 3. Schizophrenia-like psychosis,
How does heroin work?
It hijacks a system in the brain that employs naturally occurring neurotransmitters known as endorphins (pain control).,
How does cocaine work?
Cocaine makes more dopamine and serotonin available in the brain.,
What aspect of touch do the Pacinian and Meissner corpuscles respond to? (2)
Sense of: 1. Vibration 2. Flutter,
What aspect of touch does Merkel’s disk respond to?
Sense of pressure,
What aspect of touch do Ruffini endings respond to?
Slowly changing indentations,
Which corpuscle has the largest receptive field?
Pacinian,
What happens once a somatosensory receptor detects a stimulus?
The receptors send impulses along the sensory nerves that enter the dorsal roots of the spinal cord.,
How is touch involved in the active control of movement?
Neurons in the motor cortex controlling the muscles in your arm that move your fingers get sensory input from touch receptors in the finger tips.,
Why is it unsurprising that touch has a relationship with motor?
The primary sensory and motor cortices are right beside each other in the brain.,
What is a pain receptor called?
Nociceptor,
What types of stimulus do nociceptors respond to? (3)
- Heat above 46C 2. Tissue acidity 3. The active ingredient of chilli peppers.,
What peripheral afferent fibres repond to noxious stimuli? (2)
- Αδ fibres 2. C fibres,
What is noxious stimuli?
An actually or potentially tissue damaging event,
Which parts of the brain deal with pain? (2)
- Anterior cingulate (ACC) 2. Insular,
Why is pain important? (2)
- Allows us to learn and avoid threatening situations 2. Inhibit activity to allow healing,
How is pain supressed in a survival situation?
Via the release of endogenous analgesics,
What can be done to elevate the pain threshold?
Electrically stimulate the aqueductal grey matter,
What chemical transmitters are involved in pain mediation?
Endogenous opioids,
What is an example of an endogenous opioid?
Met-enkaphalin.,
What receptors does morphine act on?
The same receptors at which some the endogenous opioids act.,
What is enhanced pain called?
Hyperalgesia,
What are the symptoms of hyperalgesia? (4)
- Lowering of the pain threshold 2. An increase in the intensity of pain 3. A broadening of the area over which pain is felt 4. Pain in the absence of noxious stimulation.,
What causes hyperalgesia?
Sensitisation of the peripheral receptors as well as complex phenomena at various levels of the ascending pain pathways.,
How does the human eye detect light?
Light entering the eye is focused by the lens onto the retina located at the back. Receptors there detect the energy and by a process of transduction initiate action-potentials that travel in the optic nerve.,
Which photoreceptor is more sensitive to light?
Rods are 1000 times more sensitive to light than cones.,
Which photoceptor do you use during the day and which at night?
You see at night with your rods but by day with your cones.,
What is phototransduction?
The conversion of light into electrical signals in the rods and cones,
What feature of the eye projects to the brain?
The optic nerve,
Where do the fibres of the optic nerve meet?
At the optic chiasm,
What happens to the fibres of the optic nerve once they’ve met at the optic chiasm?
Half of them “cross” to the other side where they join the other half from the other optic nerve that have stayed “uncrossed”.,
What are the connected pathways of the optic nerves called?
Optic tracts,
How do optic tracts project to the cerebral cortex?
Via a synaptic relay in a structure called the lateral geniculate nucleus,
What is it called since the occipital lobe reponds to imput from either eye?
Binocularity,
What is a receptive field (vision)?
The region of retina over which the cell will respond to the prefered kind of image.,
Which is the first stage of cortical processing (vision)?
V1,
What do the V1 neurones respond to?
Lines or edges in a particular orientation.,
How does blind sight work?
It is probably mediated by parallel connections from the eyes to other parts of the cortex.,
What does the activity of the cells in V5 reflect?
It reflects the strength of the movement signal.,
What does V5 do? (2)
- Register the motion of visual stimuli 2. Register perceived motion,
What does ‘EMGs’ stand for?
Electro-myographic recordings,
How can EMGs be used?
To measure the level of activity in each muscle,
What is a population code?
Actions are specified by the firing of an ensemble of neurons. (such as with movement),
What is the function of the pre-motor cortex? (3)
- Planning actions 2. Preparing spinal circuits for movement 3. Establish links between seeing movements and understanding gestures.,
Why are mirror neurones important?
They are important in imitating and understanding actions.,
What is behind the motor cortex?
Parietal lobe,
Where do the basal ganglia send impulses?
Motor cortical areas,
What area of the brain causes Parkinson’s disease?
Degeneration of neurons in an area of the brain called the substantia nigra,
What part of the brain does alcohol have a big effect on?
Cerebellum,
Functions of the cerebellum (3)
- Skilful smooth movements 2. Motor learning and adaptation 3. Optimal adjustment (timing),
What symptoms occur when there is damage to the cerebellum? (4)
- Poorly coordinated movements 2. Loss of balance 3. Slurred speech 4. Cognitive difficulties,
What areas are in the anterior half of the cortex? (4)
- Sensory 2. Motor 3. Prefrontal 4. Limbic regions,
Which structure does the brain form from in early embryonic development?
Neural plate,