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