2A - intro to neuro Flashcards
neurons
a nerve cell; the basic building block of the nervous system
what are the two types of neurons
sensory and motor
neuroglia
non-excitable cells supporting, insulating, and nourishing neurons
-ex. Schwann cells
myelin sheath
a layer of fatty tissue segmentally encasing the fibres of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next
multipolar motor neuron
a neuron with a single axon and multiple dendrites; the most common type of neuron in the nervous system
pseudounipolar neuron
carry information from periphery to brain, whereas multipolar neurons carry information from brain to periphery
cell body
integrates all signals together, decides whether neuron will or will not send action potential
dendrites
collect information, synapse with other things
trigger zone
where action potential is generated. pieces of information are summed together. axon hillock
axon
the extension of a neuron, ending in branching terminal fibres, through which messages pass to other neurons or to muscles or glands
axon terminal
the endpoint of a neuron where synapses occur (with other neurons or with an end organ, such as muscle)
nodes of ranvier
gaps in the myelin sheath to which voltage-gated sodium channels are confined
peripheral process
sum the information collected by dendrites to decide whether there is an action potential worth sending or not
Sensory neurons
neurons that carry incoming information from the sensory receptors to the brain and spinal cord
motor neurons
neurons that carry outgoing information from the brain and spinal cord to the muscles and glands
ganglia
clusters of cell bodies in the PNS
oligodendrocyte
a type of glial cell that forms myelin in the central nervous system. Forms several myelin sheaths, and myelinated sections of several axons
Schwann cell
a type of glial cell that forms myelin in the peripheral nervous system. Forms one myelin sheath, and myelinated one section of an axon
what is multiple sclerosis
a chronic disease of the central nervous system marked by damage to the myelin sheath
- problems with oligodendrocytes, they can’t repair themselves
- secondary demyelination because many axons myelinated by a single oligodendrocyte
age range of onset of multiple sclerosis
20-50
how much does multiple sclerosis decrease life expectancy
7-14 years
what happens in the body when someone has multiple sclerosis
plaques occur in the brain and spinal cord causing tremor, weakness, incoordination, paresthesia, and disturbances in vision and speech
what is Guillain-Barre syndrome
inflammation of the myelin sheath of peripheral nerves
how is Guillain-barre syndrome characterized
rapidly worsening muscle weakness that may lead to temporary paralysis
recovery rate of Guillain-barre syndrome
80-90% recover within 2-4 weeks
progressive depolarization
the cause for electrical signal propagation (current)
resting membrane potential
-80mV
the outside of the cell is rich in which positively charged ion
sodium (Na+)
the inside of the cell is rich in this negatively charged ion
potassium (K)
conduction velocity
the speed at which an action potential is propagated along the length of an axon
what two factors does conduction velocity depend on?
- fibre diameter -> larger fibre diameter = faster conduction velocity
- myelination -> myelination means faster conduction velocity than unmyelinated
saltatory conduction
rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of ranvier to another, skipping the myelin sheathed regions of membrane
neuronal synapse
synapses that occur between two neurons, where transmission of nerve impulses occurs
presynaptic neuron
conducts impulses toward the synapse
postsynaptic neuron
transmits impulses away from the synapse
synaptic cleft
the narrow gap that separates the presynaptic neuron from the postsynaptic cell
step 1 of neuronal synapse
impulse arrives at end bulb
step 2 of neuronal synapse
voltage gated calcium (Ca2+) channels open, Ca2+ flows into cell
step 3 of neuronal synapse
increased concentration of Ca2+ causes neurotransmitter release
step 4 of neuronal synapse
Neurotransmitters cross synaptic cleft to bind receptors on postsynaptic membrane
step 5 of neuronal synapse
voltage gated channels open allowing Na+ to enter cell
step 6 of neuronal synapse
postsynaptic cell depolarizes
step 7 of neuronal synapse
nerve impulse initiated
anatomical nervous system
central nervous system and peripheral nervous system
functional nervous system
somatic nervous system and autonomic nervous system
central nervous system
brain and spinal cord
peripheral nervous system
the sensory and motor neurons that connect the central nervous system to the rest of the body
autonomic nervous system
a subdivision of the peripheral nervous system. Controls involuntary activity of visceral muscles and internal organs and glands
- divisions into sympathetic and parasympathetic
somatic nervous system
the division of the peripheral nervous. system that controls the body skeletal muscles
cranial nerves
12 pairs of nerves that carry messages to and from the brain
spinal nerves
31 pairs of nerves arising from the spinal cord
sympathetic nervous system
the division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations. fight, flight, or fright
parasympathetic nervous system
the division of the autonomic nervous system that calms the body, conserving its energy
white matter
nervous tissue of the CNS consisting of neurons and their myelin sheaths. Inside the brain, outside the spinal cord
grey matter
the portions of the central nervous system that are abundant in cell bodies of neurons rather than axons. Unmyelinated. Outside the brain, inside the spinal cord
cerebral hemispheres
the right and left halves of the cerebrum
brainstem
the oldest part and central core of the brain, responsible for automatic survival functions
midbrain
important for hearing and sight
pons
a brain structure that relays information from the cerebellum to the rest of the brain
medulla oblongata
part of the brainstem that controls vital life-sustaining functions such as heartbeat, breathing, blood pressure, and digestion
spinal cord
nerves that run up and down the length of the back and transmit most messages between the body and brain
diencephalon
thalamus and hypothalamus
cerebellum
a large structure of the hindbrain that controls fine motor skills
longitudinal fissure
separates cerebral hemispheres
corpus callosum
the large band of neural fibres connecting the two brain hemispheres and carrying messages between them
fissure
deep groove
sulcus
shallow groove
gyrus
ridge
central sulcus
separates frontal lobe from parietal lobe
precentral gyrus
the strip of frontal cortex, just in front of the central sulcus, that is crucial for motor control
postcentral gyrus
the strip of parietal cortex, just behind the central sulcus, that receives somatosensory information from the entire body
lateral fissure
the fissure that separates the temporal lobe from the overlying frontal and parietal lobes. AKA Sylvian fissure
parietal lobe
a region of he cerebral cortex whose functions include processing information about touch
frontal lobe
associated with reasoning, planning, parts of speech, movement, emotions, and problem solving
occipital lobe
a region of the cerebral cortex that processes visual information
temporal lobe
a region of the cerebral cortex responsible for hearing and language
insula
regions of cortex located at the junction of the frontal and temporal lobes. Taste
brocas area
part of frontal lobe that if damaged, cannot speak/make language
wernicke’s area
part of parietal lobe that if damaged, cannot understand language
thalamus
relays messages between lower brain centres and cerebral cortex. Gatekeeper for sensory information
hypothalamus
brain region controlling the pituitary gland, maintains homeostasis
cauda equina
collection of spinal nerves below the end of the spinal cord
dorsal horn
crescent shaped projection of gray matter within the spinal cord where sensory neurons enter the spinal cord
ventral horn
somatic motor neurons whose axons exit the cord via ventral roots
cerebrospinal fluid
fluid in the space between the meninges that acts as a shock absorber that protects the central nervous system
meninges
three protective membranes that surround the brain and spinal cord
ventricles
canals in the brain that contain cerebrospinal fluid
lateral ventricle
a complex C-shaped lateral portion of the ventricular system within each hemisphere of the brain
third ventricle
the ventricle located in the centre of the diencephalon
fourth ventricle
the ventricle located between the cerebellum and the dorsal pons, in the centre of the metenephalon
dura mater
thick, outermost layer of the meninges surrounding and protecting the brain and spinal cord
arachnoid mater
weblike middle layer of the three meninges
pia mater
thin, delicate inner membrane of the meninges
dural sinuses
spaces that collect blood that has circulated through the brain
dural folds
folded inner layer of dura mater
- Extend into cranial cavity
- Stabilize and support brain
- contain collecting veins (dural sinuses)
falx cerebri
separates the two vertebral hemispheres
tentorium cerebelli
separates cerebrum from cerebellum
falx cerebelli
separates the two hemispheres of the cerebellum
extracerebral hemorrhages
hemorrhages from the blood vessels of the meninges or on the surface of the brain, bleeding is outside the brain
epidural hematoma
pooling of blood located on top of the dura
subdural hematoma
pertaining to below the dura mater, tutor of blood
subarachnoid hematoma
pooling of blood in the subarachnoid space (between pia mater and arachnoid membrane)
spinal tap
placement of a needle through an intervertebral space into the subarachnoid space to withdraw CSF
epidural
pertaining to the layer upon the dura mater
conus medullaris
tapered, inferior end of spinal cord
lumbar cistern
subarachnoid space inferior to medullary cone that contains caudal equina and CSF
