Grey Matter Flashcards
Difference between endocrine and nervous system
nervous system: acts faster
targets specific parts/cells
has a short lasting effect
electrical impulses sent
Endocrine system: slower but long-lasting
affects through chemical control
What is a phytochrome Which phytochrome in plants is active?
Phytochrome absorbs and detects light Pfr is active in plants
What converts Pr to Pfr what converts Pfr to Pr
When red light is absorbed by Pr it is converted to Pfr When far-red light is absorbed by Pfr it is converted to Pr
Benefits of plant responses to light
ensures that flowering happens at the right time so same species flower at the same time and they flower when insects are available since length of days varies short days in winter and long days in summer
Which phytochrome stimulates flowering?
Low levels of Pfr
explain role of neurotransmitters
comes from pre-synaptic neurone diffuses across synaptic gap affects post-synaptic neurone
special structure in sensory neurone
cell body in middle
how structure of neurone helps conduct impulses
Schwann cell convers axon Schwann cell contains myelin which provides insulation So Action potential only occurs at nodes of ranvier (gaps between schwann cells) undergoes saltatory conduction and jumps from node to node
how does structure of axon membrane help with impulses
phospholipids restrict ion movement proteins span membrane sodium potassium pump punmps ions across membrane protein gates allow for diffusion of ions
advantages of having mylelinated neurone
myelin sheath provides electrical insulation except at nodes of ranvier where neurone is exposed because nodes are site of sodium-gated channel proteins these open when impulse arrives causing depolarisation of nodes impulse jumps from node to node this is known as saltatory conduction only occurs between Schwann cells this is faster than non-myelinated neurones
Why are neurones not affected by a second stimulus that occurs to quickly
they are still undergoing action potential neurone hasn’t reached resting potential Sodium ion gates are closed
what are the events leading to depolarisation of membrane
depolarisation of adjacent membrane this changes PD across membrane opens sodium gates and sodium ions move into axon
Which type of neurone is found in the central nervous system
Relay neurone
direction of impulse in sensory neurone direction of impulse in motor neurone
away from receptor towards effector
What is A?
What is B?
What is C?
What is D?
A- nucleus
B- Cytoplasm
C- Myelin Sheath
D- Axon
How is an action potential generated?
Stimulus occurs
This causes Na+ voltage gated channels to open
Allowing Na+ to diffuse into axon down concentration gradient
More Na+ channels are stimulated to open (positive feedback)
Axon PD becomes positive due to increase of Na+ in axon and is depolarised and AP generated
Wave of depolarisation is passed through axon
Sodium ion gates then close and K+ channels open
K+ permeablility increases
K+ diffuse out down the electrochemical gradient
it repolarises the axon, making it more negative
Hyperpolarisation occurs and K+ channels are closed
Sodium-potassium pump returns axon to resting potential
Events that occur at synapse
Impulse arrives at synaptic knob
Ca2+ channels in pre-synaptic membrane open
Ca2+ diffuse into synaptic knob
Synaptic vesicles containng neurotransmitters move towards pre-synaptic membrane
Vesicles fuse with membrane ad neurotransmitter is released into synaptic cleft
Neurotransmitter diffuse across synaptic cleft and
attach to specific protein receptors
on post-synaptic membrane
Na+gated-channels on post-synaptic membrane open
Na+ diffuse in to post-synaptic neurone
PD across mombrane changes and it is depolarised
AP generatedin post-synaptic membrane
Could be spatial or temporal summation
Enzyme breaks down neurotransmitter and it is reabsorned through pre-synaptic membrane
So there is no prolonged stimulation of post-synaptic membrane
Difference between spatial and temporary summation
Spatial is when potentials from many pre-synaptic neurones cause post-synaptic neurone to reach threshold potential
Temporal is when a single presynaptic neurone fires many times in succession causing postsynpatic neurone to reach threshold potential
Describe structure and role of choroid
It is at back of eye, contains black pigment which absorbs all light
Where are Rod Cells found?
Where do neurones of the optic nerve begin?
Which direction is light moving in?
C
A
from bottom to top
What happens when light hits eye
Rhodopsin is bleached
retinal changes shape
and rhodopsin splits into opsin and retinal
The cell that links a rod cell to snesory neurone is
bipolar neurone
How is light observed?
When there is a light intensity
the light is absorbed by the rod cell
retinal changes shape
the rhodopsin splits into opsin and retinal
opsin binds to cell surface membrane
Na+ gated channels close
Na+ ions are still being pumped out
Rod becomes negatively polarised , hypepolarisation occurs
Rod id depolarised and AP is generated
How is rhodopsin regenerated after bleaching?
In the dark
Na+ diffuse back in as gates reopen
ATP is used to resynthesise rhodopsin
Where is rhodopsin located?
In the outer segment
inner membrane
What do the muscles do to dilate and constrict eyes?
Dilate: radial contract, circular relax
Constrict: radial relax, circular constrict
How do neurones change pupil size?
Impulse generated
Sent through bipolar neurone
to sensory neurone and to optic nerve
motor neurone receives impulse
it is connected to muscles and cause them to contract
Biochemistry of habituation
The high frequency of impulses depletes neurotransmitter
Calcium ion channels on pre-synaptic membrane become less responsive
Post-synaptic membrane is not depolarised
Impulses do not reach muscle
Benefits to habituation?
Less energy wasted on non-threatening stimuli
There are naturally frequent stimuli in animal’s habitat
(e.g. for underwater it is wave action)
Ethics against animal testing
Absolutist view - all use of animals is unacceptable
Animals have rights
Haven’t given consent
Will feel pain
Causes stress
Research topic may not be essential
Ethics for Animal testing
Rationalist view - overall good outweighs harm done
Few animals as possible being used
Welfare of animals being considered
A - Medulla
B - Temporal Lobe
C - Cerebellum
D - Occipital Lobe
E - Parietal Lobe
F - Temporal Lobe
G - Hypothalamus
H - Pituitary Gland
Role of Cerebellum
Maintain balance
Co-ordination of movement
Muscle movement
Role of Medulla Oblongata
Regulate heart rate and ventilation rate
Occipital Lobe role
Processes info from eyes
Visual center
Frontal Lobe role
Decision Making
Planing
Emtotions
Behaviour
Includes primary motor cortex (controls most body movements)
Role of hypothalamus
controls thermoregulatory centre:
monitors body and skin temp
initates -ve feedback
Parietal Lobe
Orientation
Movement
Sensation
Calculation
Temporal Lobe
Processes auditory info
Why is MRI better than CT?
MRI has higher image resolution
MRI can identify smaller structures than CT
MRI uses radio waves, CT uses X-Ray
Less risk of damage to tissues with MRI
So it can be used more often
How does fMRI work?
uses radio waves
allows brain activity to be seen in real time
active areas have high levels of oxygenation
that reflects the signal
and is seen as a bright spot
What is fMRI used for?
increased flow means increased activity in that part of the brain
Study brain activity related to tasks, find which parts of brain required for what
How can we analyse CT and MRI scans?
How can they be used?
ID location of abnormality
Size of abnormality
ID type of abnormality
Can monitor growth of tumours (or anything else)
Can identify any other problems such as accessibilty for surgery
What can having eyes closed during critical window do to viual cortex?
Lack of visual stimulation means less impulses to visual cortex
so less neurotransmitter released
the synapses are weakened
neurones are lost
lack in connections made in visual cortex
occular columns wont develop and are small
brain cannot interpret visual information correctly
Deine human genome
all the DNA of the human species
Ethics of human genome
Insurers might have access to a person’s DNA and discriminate
Who decides on whether a person gets tested
Needs to be confidential
Expensive medical treatments might be restricted
how genome project aids in drug synthesis
Identifies allele related to disease
Drug developed targets this allele
So mutant allele can no longer express itself
Drug may prevent translation, protein not synthesised
drug is more effective than the typical treatments
Effect of MDMA on brain
Higher levels of serotonin released
reabsorption of serotonin is inhibited in synapse
pumps may be reversed to release more serotonin
How SSRI works
Serotonin is not reabsorbed
SSRI binds to reuptake proteins
high level of serotoin remains in synapse
Serotonin continues to bind to receptors on post-synaptic membrane and AP still generated
How does L-Dopa work
It can pass through blood-brain barrier and enter brain
It’s converted to dopamine
Dopamine triggers action potential at synapses
This alleviates symptoms
Symptoms of Parkinson’s
Stiffness of muscles
Tremor of muscles
Slowness of movement
Lack of balance
Walking problems
Depression
Soeech problems
Swallowing problems
Describe + Explain Hubel and Weisel’s experiment with kittens
Investigated development of visual cortex
Closing one eye in kittensto deprive vision for over a period of time led to smaller ocular dominance columns forming in that eye
where as the eye that was left open developed large ocular dominance columns
there are less impulses fired in neurones in the closed eye
this leads to a loss in neurones
this suggests that there is a critical period for brain development during which it needs to be stimulated regularly
closing the kittens eye before or after the critical period has no effect
Describe gene therapy
Use restriction endonuclease to cut out healthy gene
Healthy gene inserted in to plasmisd
This is then inserted into cells using a vector such as liposomes
Why is small sample size bad?
Or else results would not be reliable or valid
Conclusion would also be unreliable
insufficient data for statistical test
