Unit 3 Test (From Winter 2013) Flashcards
What is the hyperpolarized membrane potential?
-90 mV
What is the membrane potential which triggers voltage-gated potassium channels to open?
+30mV
What is the membrane potential maintained by the sodium-potassium pump?
-70mV
What is the sub-threshold membrane potential?
-55 tp -50 mV
What is the membrane potential which triggers voltage-gated sodium channels to close?
+30
What is the membrane potential caused by an IPSP?
-90mV
What is an IPSP?
an “inhibitory postsynaptic potential” which is a kind of synaptic potential that makes a postsynaptic neuron less likely to generate an action potential
Does a strong stimuli cause the ampitude of a generated action potential to increase?
no, false
What happens to the action potential when there is a strong stimulis?
It fires more often; therefore stimulus strength is translated as action potential frequency.
Astrocytes function:
- most abundant, versalite, & highly branced gial cells
- cling to neurons and their synaptic endings, covering up capillaries
- support & brace neurons
- anchor neurons to their capillary nutrients
- guide migration of young neurons
- help control ion & neurotransmitter enviroment
Ependymal Cells:
- ciliated cells that range in shape from cuboidal/columnar
- line central cavities of brain & spinal column
- ciliated cells funtion to move CSF
Schwann Cells
- glial cells that wrap around a nerve fiber in the peripheal nervous system
- forms the myelin sheaths of peripheral axons (form from fatty tissue)
Oligodendrocytes
- branched cells wrap around CNS nerve fibers
- forms insulating covers aka myelin sheaths
acetylcholine
It is the excitatory neurotransmitter that is secreted by motor neurons innervating skeletal muscle
-excitatory neurotransmitter
dopamine
- a chemical released by nerve cells to send signals to other nerve cells
- involved in motor control and in controlling the release of several important hormones
- inhibitory neurotransmitter
- affects attention, learning, movement & pleasure
norepinephrine
- hormone and neurotransmitter most responsible for concentration - alertness
- role as the neurotransmitter released from the sympathetic neurons to affect the heart
- excitatory neurotransmitter
gamma aminobutyric acid (GABA)
- is a chemical neurotransmitter
- -inhibitory neurotransmitter
- contributes to motor control, vision, and many other cortical functions
Graded potentials:
- they may sum temporarally or spatially
- Stimulation of a neuron causes sodium gates to open and the membrane becomes partially depolarized as sodium ions enter the neuron
- called “graded” because the amount of depolarization depends on the strength of the stimulus
What is the absolute refractory period?
the period after an inital stimulus when the neuron is not sensitive to another stimulus
What is the refractory period?
-the amount of time it takes for an excitable membrane to be ready for a second stimulus once it returns to its resting state following an excitation
What is a threshold in an action potential?
The minimum stimulus needed to achieve an action potential
nuclei
cluster of nerve cell bodies in CNS
nerves
Any of the cordlike bundles of fibers made up of neurons through which sensory stimuli and motor impulses pass between the brain or other parts of the central nervous system and the eyes, glands, muscles, and other parts of the body. Nerves form a network of pathways for conducting information throughout the body
ganglia
cluster of nerve cell bodies in PNS
tracks
they are myelinated axons that are located within the central nervous system
efferent Neuron
Sends message away from CNS
Afferant neuron
sends message towards CNS
interneuron
connects messages within CNS pathway (inside of spintal cord)
Glial Cell
- supporting cells
- provide supportive framework for neurons
- segregate & insulate neurons
- guide young neuros to proper connections
- promote health & growth of neurons
What is the roll of acetylcholinesterase?
breaks down acetylcholine soon after its released into the synaptic cleft
What is saltatory conduction?
- When a current passes through a myelinated axon only at the nodes of Ranvier
- AP triggered only at nodes and “jump” from one node to the next
- much faster than unmyelinated axons
What are the neuroglia (gial cells) in the CNS?
astrocytes, microglia, ependymal cells and oligodendrocytes
What are the neuroglia (gial cells) in the PNS?
Satellite cells, schwann cells
What is a chemical synapses?
specialized for release and reception of chemical neurotransmitters (2 parts, axon terminal & receptor region)
Group A Fibers
- have greatest amount of myelination & fastest (300mph)
- cary sensory signals from skin and joints
- carry motor signals to skeletally muscles
Group B Fibers
- lightly myelinated (30 mph)
- carry sensory & motor signals for internal (visceral) organs and some skin
Group C Fibers
- unmyelinated (2mph)
- not wrapped by but can be supported by Schwann cells
- cary sensory & motor signals for internal organs only
Synaptic Cleft
- it is the chemical synapses that convers electric signals into chemical signals (via neurotransmitters)
- it is the fluid filled space separating the presynaptic & postsynaptic neurons
What is there to know about a information transfer for a synaptic cleft? (6 steps)
1) action potential arrives at axon terminal
2) voltage gated CA 2+ channels open & CA2+ enters axon terminal
3) when CA2+ enters it causes neurotransmitter-containing vesicles to release their contents by exocytosis
4) neurotransmitters diffuses across synaptic cleft & binds to specific receptors on postsynaptic membrane
5) binding of neurotransmitter opens ion channels resulting in graded potentials
6) neurotransmitters effects are terminated
what does the termination of a neurotransmitter effect?
- blocks reception of additional messages
- must be removed from receptor to stop effect (enzymatic degradation, reabsorption by astrocytes or presynaptic terminals, by diffusion)
EPSP
excitatory postsynaptic potentials:
-local depolarization of postsynaptic membrane that brings neuron closer to AP threshold
What is a neurotransmitter?
-chemical signal used for neuronal communication with the body & brain
What are the two types of myelinated cells in the PNS & CNS?
Schwann cell (PNS) Oligodendrocytes (CNS)
Where is the fourth ventriccle located (in the brain)?
under the cerebreal aquaduct which connects it to the 3rd ventricle
What is the decussation of the pyramids?
-it is the crossing point of the fibers of the corticospinal tracts from one side of the central nervous system to the other
What is the optic chiasma?
where the optic nerves cross below the hypothalamus
What is the pons nuclei?
involved in conveying information from the motor cortex to the cerebellum regarding intended movement
Funtions of midbrain:
-breathing, heartbeat, blood pressure
Cingulate gyrus
- Coordinates Sensory Input With Emotions
- Emotional Responses to Pain
- Regulates Aggressive Behavior
prefrontal cortex
planning complex cognitive behavior, personality expression, decision making, and moderating social behavior
temporal lobe
the temporal lobes are involved in the retention of visual memories, processing sensory input, comprehending language, storing new memories, emotion, and deriving meaning
hippocampus
long term memory
Primary Motor Cortex
Initiation of voluntary movement
Primary Somatosensory Cortex
Receives tactile information from the body
sensory Association Area
Processing of multisensory information
visual association area
Complex processing of visual information
visual cortex
Detection of simple visual stimuli
Wernicke’s Area
- sounding out unfamiliar workds
- language comprehension
- damage causes an inability to speak sensible or understand spoke worlds or written language
auditory association area
Complex processing of auditory information
auditory cortex
Detection of sound quality (loudness, tone)
Broca’s area
- present in one hemisphere (usually left)
- motor speach, directs muscles of tongue, lips, & pharynx requred for word formation
- Damage causes difficutly in motor speech (apraxia) but they can still read & understand
if there is a hematoma in the subacrachnoid space where does the blood pool?
subarachnoid mater & pia mater
What are the different levels of protection of the brain? (furthest away to closest)
Bone
Mengiges
CSF
What are the different levels of Mengiges?
Dura mater
arachnoid mater
Pia mater
Dura Mater
-leathery strong outer meninx composed of two fused fiberious CT layrs
outermost layer of meningies..
dural venous sinuses
where two layers of dura matter seperate
-sinuses collected venous blood from brain & direct it to jugular veins
superior sagittal sinus
-sinus within longitudinal fissure
Falx cerebri:
dura mater that fold & dips into the longitudinal fissure
What sense does the temporal lobe control?
smell & hearing
What sense does the occipital lobe control?
sight
What sense does the parietal lobe control?
pain, pressure, temperature, touch, and part of taste
What does the frontal lobe control?
consciousness and primary body movements
What is the diencephalon?
Thalamus, Hypothalamus, Epithalamus, Retina
What does the transverse fissure seperates?
seperates cerebrum & cerebellum
What does the Central Sulcus sperates?…
seperates precentral gyrus of frontal lobe & post central gyrus of parietal lobe
What does the parietooccipital sulcus seperate?
parietal lobe & occipital lobe
What does the lateral sulcus seperate?
seperates temporal lobe from frontal & parietal lobes
What is the blood brain barier?
a filtering mechanism of the capillaries that carry blood to the brain and spinal cord tissue, blocking the passage of certain substances. (ie metabloic waste)
Microglia Cell
small avoid cells with thorny processes
-transform into local macrophages that clean up microbes or neuronal debris
Schwann Cells
surround majority of nerve fibers in PNS
- form myelin sheaths
- important for regeneration of damaged nerves
- increas nerve condution speed
Satellite Cells
surround ganglionic neuron cell bodies (similar to astrocyte in CNS
Passive Ion Channels
leaky, always open
Chemically gated ion channels
open with binding of a specific neurotransmitter
voltage-gated ion channels
open & close in responce to specific membrane potential
Mechanically gated ion channels
open & close in responcse to physical deformation of receptors
Depolarization
inside of membrane is less negative
Repolarization
membrane returns to its resting membrane
Hyperpolarization
inside of membrane becomes even more negative than the resting potential
What is the all-or-none phenomenon
action potentials either happen completely or not at all
What is the Absolute refractory period?
- prevents neuron from generating an action potential
- ensures each action potential is seperate
- enforces one-way transmission of nerve impulses
What is the relative refractory peroid?
- it is the interval following the absolute refractory period when the:
- sodium gates close *potassium gates open *repolization is occuring
What is a synapses?
It is a juntion that mediates info transfered from one neuron to another
presynaptic neuron
axon conduting impulses towards the synapse
postsynaptic neuron
axon transmits impusel away from synapse
What do excitatory neurotransmitters do?
cause depolarization
What do inhibitory neuotransmitters do?
cause hyperpolarization
Biogenic Amines:
- distributed in brain
- plays role in emotional behaviors & sleep/wake cycle
“gut-brain” peptides
involved with appetite, anxiety, growth hormone released
Neuronal pools
it is a group of neurons that function together to integrate information & forward prossed info to the appropriate destination
What is a covergent circute?
many incoming fibers stimulate one fiber, which then is carried out by only one circut
What is a divergent circute?
one incoming fiber stimulates multible fibers, which then amlifys many circuts.
What is parallel processing of a neuron?
when input travels along several pathways
-one stimulus promotes numeruous responces (ie smell- remind us of something then associate experiences)
Longitudinal Fissure
sperates the right & left hemispheres
transverse fissure
seperates caranium from cerebellum
Corpus callosum
it allows communication between the two hemispheres that is done via myelinated tracks
Funtion of frontal eye field:
controls voluntary eye movement; skeletal muscles attached to eyeball
What is spacial discrimination?
recognition of what body part stimulus is coming from…
What do commissure fiber tracts do?
connect corresponding gray areas of the two hemispheres
What do association fibers do?
they connect different parts of the same hemisphere
what do projection fibers do?
enter the hemispheres from hindbrain or spital cord centers
what is the basal ganglia?
it is a mass of gray matter found deep within the brain that cortical white matter
What neurotransmitter is requred for propper funtion of basal ganglia?
dopamine
