The brain and CNS Flashcards
what 2 parts make up the CNS
brain and spinal cord
what does CNS stand for
central nervous system
what are the parts of the brain
cerebellum
medulla oblongata
cerebral; hemispheres
what is the purpose of the cerebral hemispheres
control voluntary movement, senses and memory/learning
what is the purpose of the medulla oblongata
do unconscious activities such as heart rate and breathing
what is the purpose of the cerebellum
coordinates precise and smooth movement
what are the 2 medical scans?
CT
PET
what does a CT scan stand for
computerised tomography scans
what does PET stand for
position emission tomography
how does a CT scan work
a patient is given a radioactive tracer which allows for different parts of the brain to show up, a CT scan will be carried out taking X-rays of the scull from different angles
a computer puts all these images together to give a 3-dimensional image
how does a PET scan work
the patient is given a radioactive form of glucose, which travels to the part of the body where rapid respiration is happening, the scanner detects the radioactivity and builds up images to show where the radioactive tracer is most concentrated
what are 3 reasons why it is hard to create the brain
- they are well protected by the skull
- capillaries around the brain are not as leaky so getting medicines to the brain is - difficult
- neurons are specialised so cannot divide to replace damaged cells
what are the 3 types of neurons?
sensory neurons
relay neurons
motor neurons
what is the purpose of a sensory neuron
carry impulses to the CNS
what is the purpose of relay neuron
carries impulses from one part of the CNS to another
what is the purpose of motor neuron
carry impulses from CNS to their effector organs
how does a sensory neuron work
the dendrites collect impulses from the receptor cells, and they travel along the dendron onto the axon and to the axon endings where the signal is passed to another neuron
why is a relay neuron different from other neurons
they have a small dendron with lots of short axon endings surrounding the cell body to pass signals on in all directions
what is the purpose of the myelin sheath
provides electrical insulation
what do you call the gap between 2 neurons
synapse
how does an electrical signal get across a synapse
- electrical nerve reaches the axon endings
- signal causes chemical neurotransmitters to be released
- the neurotransmitters diffuse across the gap and fit in receptors creating a new electrical impulse in the next neuron
what is a stimuli
a change in the environment
what are the 4 things about reflex arcs
they are:
immediate
involuntary
innate
invariable
why is the reflex arc important
it helps protect us from immediate arm
why is the reflex arc so effective
the impulses had to go to the brain to be processed, there would be many synapses so the response would take longer. while in the reflex arc, the impulse only has to go to the spinal cord
name the cycle for the reflex arc in steps
- receptor detects stimuli
- sensory neuron
- relay neurons in the spinal cord
- motor neuron
- effector organs such as muscle
