B2 | cells and control Flashcards
which part of the eye detects coloured light?
cones
which part of the eye controls pupil size and how much light enters the retina?
iris
which part of the eye focuses light rays onto the retina?
lens
which part of the eye refracts/bends light?
cornea
which part of the eye carries impulses between the eye and the brain?
optic nerve
which part of the eye contains light receptors?
retina
how are light rays focused to give normal vision?
light rays refracted at the cornea onto the retina
what happens to the lens when the eye changes from focusing on a distant object to focusing on a near object?
the lens gets thicker to bend the light rays more
what is another name for a convex lens?
converging lens
what is another name for a concave lens?
diverging lens
how do electrical impulses travel across the synapse?
- an electrical impulse travels along an axon
- this triggers the nerve-ending of a neuron to transmit neurotransmitters
- neurotransmitters diffuse across the synapse and bind with the receptor molecules on the membrane on the next neuron
- this stimulates the second neuron to transmit an electrical impulse
- the process repeats
what is the reflex arc?
- a receptor detects a stimulus
- sensory neurones send electrical impulses to relay neurones which are located in the spinal cord
- the impulse is passed from the sensory neurone to the relay neurone to the motor neurone across synapses
- motor neurones send electrical impulses to the effector cell
- effector produces a response
what is the function of the cell body?
where all cell reactions take place
what is the function of the effector cell?
receives electrical impulses to generate a response to a stimulus
what is the function of the receptor cell?
receives sensory information from a stimulus
what is the function of dendrite?
carries electrical signals from the synapse to the cell body
what is the function of the axon?
carries electrical impulses
what is a synapse?
the gap between two neurons where electrical signals travel across
what are the risks when operating on the brain/CNS?
- can leave other parts of the brain permanently damaged
- could cause damage to the spinal cord leading to permanent paralysis due to electrical impulses from the brain being unable to reach the motor neuron via the spinal cord
what is the function of the myelin sheath?
insulates the axons which speeds up travel of electrical impulses
how do depressants affect the synapse?
they cause less neurotransmitters to diffuse across the synapse which slows down electrical impulses and increases reaction times
how do stimulants affect the synapse?
they cause more neurotransmitters to diffuse across the synapse which speeds up electrical impulses and decreases reaction times
what is the function of sensory neurones?
send electrical impulses from the receptor to the CNS
differences between mitosis and meiosis:
- mitosis produces diploid cells, meiosis produces haploid cells
- mitosis produces 2 cells, meiosis produces 4 cells
- mitosis produces genetically identical cells, meiosis produces genetically different cells
- mitosis produces body cells, meiosis produces gametes
what happens during interphase?
- DNA is duplicating
- production of cell components
- cell growth occurs
what happens during prophase?
- the DNA in the chromosomes and their copies condense (they get shorter and fatter and become more visible)
- the nuclear membrane breaks down and disappears
what happens during metaphase?
chromosomes line up in the centre of the cell
spindle fibres attach to the centromeres of each chromosome
what happens during anaphase?
- spindle fibres shorten and pull the chromosomes apart
- each half of the chromosome (chromatid) is moved to opposite ends of the cell
what happens during telophase?
- new membranes form around each set of chromosomes forming nuclei of the two cells
- chromosomes get longer and thinner
- the cell starts to divide
what happens during cytokinesis?
cell membrane pinches in and eventually the cell divides into two genetically identical daughter cells
what happens in a chloroplast?
oxygen is produced and sunlight is absorbed by chlorophyll
what is cytoplasm?
a jelly-like material where chemical reactions occur
what is the difference between a prokaryotic and eukaryotic cell?
a prokaryotic cell has no nucleus (e.g bacterial cell) and a eukaryotic cell does have a nucleus (e.g plant, fungi and animal cells)
what is the difference between animal and plant cell growth?
- plants grow continuously whilst animals stop growing once they reach adulthood
- plant cells continuously differentiate whilst animal cells differentiate at an early stage (embryo)
what are meristems?
stem cells found in plants found in roots/shoots that can differentiate throughout the plants entire life
what are the advantages of using stem cells?
- can be used to repair/replace all parts of the body
- can cure hundreds of diseases
- can be used to research diseases and test drugs for safety/effectiveness
what are the disadvantages of using stem cells?
- mutations may occur and cause cancer
- unethical to use embryonic stem cells
- unwanted differentiation could occur meaning stem cells might differentiate into an unwanted/wrong cell
where is the frontal lobe? what is it responsible for?
- behind forehead
- changes thoughts into speech
- starts and coordinates movement
- responsible for problem solving and critical thinking
what problems might someone experience if the frontal lobe is damaged?
- inability to express language
- motor weakness
- personality and behavioural changes
- inability to focus
- difficulty with problem solving
where is the parietal lobe? what is it responsible for?
- under the crown of the head
- processes reading and maths
- primary sensory area of the brain
- processes sight, touch, taste, smell, hearing, temperature and movement
what problems might someone experience if the parietal lobe is damaged?
- inability to name objects
- difficulties reading and drawing
- difficulty differentiating left and right
- difficulty with maths
- difficulty with hand eye coordination
where is the occipital lobe? what is it responsible for?
- back of the skull
- where all visual information is processes such as colour, shape and distance
what problems might someone experience if the occipital lobe is damaged?
- difficulty locating objects in visual field
- visual hallucinations
- inability to recognise words
- difficulty distinguishing colours
where is the temporal lobe? what is it responsible for?
- behind the temple above the ears
- processes what we hear
- involved with how we learn and organise information
- responsible for emotion and emotional memory
- plays a crucial role in forming and retrieving memories
what problems might someone experience if the temporal lobe is damaged?
- auditory hallucinations
- difficulty recognising faces
- short term memory loss
- personality changes
- difficulty understanding spoken words
where is the cerebellum? what is it responsible for?
- back of the skull under the occipital lobe
- controls balance and fine motor coordination
what problems might someone experience if the cerebellum is damaged?
- inability to walk
- impaired balance
- poor muscle coordination and control
- dizziness
- slurred speech
- inability to make rapid movements
where is the medulla oblongata? what is it responsible for?
- bottom of the brain stem just above the spinal cord
- most important part of the brain
- helps transfer neural messages from the brain to the spinal cord
- controls involuntary functions
- regulates respiratory, digestive and circulatory systems
what problems might someone experience if the medulla oblongata is damaged?
- difficulty swallowing
- loss of gag and cough reflex
- vomiting
- changes in respiratory pattern
where is the pons? what is it responsible for?
- top of the brain stem under the temporal lobe
- helps to replay messages from to the cerebrum and cerebellum
- plays a key role in sleep and dreaming
what problems might someone experience if the pons is damaged?
- loss of sensation in the face
- corneal reflex loss
- facial muscle dropping
describe the route of an impulse through a reflex arc
- receptor detects a stimulus
- sensory neurone passes impulse to relay neurone in the spinal cord
- relay neurone passes impulse to motor neurone
- motor neurone passes impulse to effector muscle which initiates a response
advantage of taking computerised tomography (CT) scans?
they are non-invasive meaning they do not cause the patient any harm
what is the limitation of CT scans?
they can show the structures of the brain but can’t distinguish between their functions
how do positron emission tomography (PET) scans work?
- patients injected with radioactive tracer
- tracer moves around the body and collects in areas with more active cells by attaching to glucose (high energy = more glucose needed)
- positrons are produced when the tracer decays
- positrons and electrons annihilate which produces gamma rays in opposite directions
- gamma rays are detected by the PET scanner and a computers builds an image of what is being scanned for
advantages of PET scans
- more detailed than CT scans
- both the structure and functions of the brain can be investigated in the real time
what do the bright areas represent in a PET scan?
areas of high cell activity
why would a cell need more mitochondria and ribosomes during mitosis?
more mitochondria = increase in respiration = increase in energy produced
more ribosomes = increase in protein synthesis for production of DNA
how do stimulants and depressants affect the synapses between neurones?
stimulants cause MORE neurotransmitters to diffuse across the synapse which SPEEDS UP electrical impulses and reaction times
depressants cause LESS neurotransmitters to diffuse across the synapse which SLOWS DOWN electrical impulses and reaction times
how does laser eye surgery correct eye defects?
it uses lasers to reshape the corners so that it can focus better
what causes colour blindness?
missing or faulty cones
can colour blindness be cured?
no because cone cells can’t be replaced
