Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
170 Cards in this Set
- Front
- Back
|
How are voltage gated K+ channels triggered?
|
they are triggered to open with depolarization but they open much more slowly than voltage gated Na+ channels. They do not open until Na channels are closed and point of potential inside the cell=+30mv
|
|
|
What are the characteristics of action potentials?
|
1. Changes in membrane potential caused by time dependent opening and closing of voltage gated channels.
2. always excitatory 3. do not summate 4. all or none response 5. do not travel decrementally |
|
|
refractory period
|
a period of reduced excitability during and immediately after an action potential
|
|
|
absolute refractory period
|
coincides with time period when Na+ channels are either already open and will not be affected by a second stimulus or when inactivation gates are closed and cannot be opened. encompasses all of depolarization and most of repolarization
|
|
|
relative refractory period
|
occurs immediately after the absolute refractory period when it is impossible to generate an action potential. it is due to increased permeability of K+. Na gates are closed but can be opened
|
|
|
when a cell membrane is depolarized...
|
Na+ channels are open allowing + charge into cell
the further away from the stimulus, the less depolarization |
|
|
because of absolute refractory period...
|
action potential will only travel in one direction.
|
|
|
myelin
|
a phospholipid substance that forms an insulating sheath around many nerve cells
it serves to increase rate of conduction of action potential |
|
|
nodes of ranvier
|
spaces between myelin which increases the speed of propagation
|
|
|
salutatory conduction
|
when action potentials jump from node to node which increases the speed of propagation
|
|
|
how are conduction velocities increased in myelinated and unmyelinated nerves?
|
when the diameter of the nerve is larger because it is less resistant to flow of current
|
|
|
synapse
|
the junction between the neuron and target cell
|
|
|
presynaptic neuron
|
neuron that conducts an action potential toward the synapse
|
|
|
postsynaptic neuron
|
neuron that conducts its action potential away from the synapse
|
|
|
synaptic cleft
|
space between presynaptic and postsynaptic neurons
|
|
|
axon terminal
|
end of the axon involved with the synapse
|
|
|
synaptic vesicles
|
vesicles within the axon terminals which store neurotransmitters
|
|
|
voltage gated Ca++ channels
|
axon terminals have an abundance of these
voltage gated channels open allowing Ca++ into the cell which causes the synaptic vesicles to fuse with docking proteins of the inner surface of the cell membrane |
|
|
how are neurotransmitters released?
|
by exocytosis from the synaptic vesicles
|
|
|
how is the neurotransmitter cleared from the synaptic cleft?
|
diffuses away
broken down by specific enzymes active re-uptake by the presynaptic neuron |
|
|
what are excitatory synapses?
|
any stimulus taht makes a neuron more likely to fire
generate excitatory post synaptic potential EPSP moves a cell membrane potential closer to threshold Na moves in and depolarizes the cell closure of K channels also result in EPSP may be slow or fast channels at work |
|
|
what are inhibitory synapses?
|
any stimulus that makes a cell less likely to fire an action potential
inhibitory post synaptic potential IPSP IPSP moves membrane potential further from threshold by opening K or Cl channels |
|
|
efferent neuron
|
transmit information away from the CNS out to the effectors
cell body located in the CNS |
|
|
afferent neuron
|
functions to bring sensory information back to the CNS
typically psuedo unipolar cell body located outside of CNS and central axons project into the CNS |
|
|
interneuron
|
located almost entirely in the CNS
interconnect neurons with to CNS to integrate sensory information and motor output account for 99% of neurons in the body |
|
|
ganglia
|
a collection of cell bodies outside of the CNS
|
|
|
what does the efferent division consist of?
|
somatic nervous system (voluntary)
autonomic- sympathetic, parasympathetic, enteric |
|
|
what does the afferent division consist of?
|
somatic senses
special senses visceral senses (sensations from internal organs or blood vessels) |
|
|
glial cells
|
most numerous cells
provide physical and biochemical support for neurons make up differs from central and peripheral nervous systems |
|
|
schwann cells
|
create myelin for peripheral nerves
one schwann cell to one nerve one nerve typically has many schwann cells secrete neurotrophic factors which help maintain neurons and guide them during repair and development |
|
|
oligodendrocytes
|
create myelin for neurons in the CNS
differ from schwann cells in that 1 oligodendrocyte creates myelin for several nerves |
|
|
astrocytes
|
induce changes in CNS capillaries to form blood-brain barrier
secrete neurotrophic factors which help direct developing neurons modulate synaptic activity by secreting factors and/or by removing substances from synaptic clefts help maintain electrolyte composition of extracellular fluid |
|
|
microglia
|
scavengers
able to perform phagocytosis |
|
|
ependymal cells
|
create selectively permeable barrier which lines the ventricular sysem of the brain
cilia on the ependymal cells may have potential to serve as neural stem cells |
|
|
meninges
|
connective tissue layers encasing the brain and spinal cord
|
|
|
dura mater
|
outermost layer closest to the bone
thick, dense inelastic consistency of parchment paper |
|
|
arachnoid
|
middle filmy layer
|
|
|
subarachnoid
|
lies beneath the arachnoid and contains cerebrospinal fluid
attached to underlying pia mater by strands that resemble a cob web arteries and veins are within the subarachnoid space |
|
|
pia mater
|
closely adheres to the surface of the brain
resembles tissue paper |
|
|
what is the down side to the blood-brain barrier?
|
in the case of an infection to the brain, antibiotics cannot get to the infected area easily
|
|
|
cerebrospinal fluid
|
watery fluid that surrounds the brain and spinal cord produced by the choroid plexus
surrounds the CNS and fills cavities within CNS (ventricles) |
|
|
what are the functions of cerebrospinal fluid?
|
shock absorber
provides route for nutrients/messengers to CNS removal of waste |
|
|
arachnoid villi
|
specialized areas in the arachnoid layer that absorbs cerebrospinal fluid
|
|
|
hydrocephalus
|
condition in which the flow of cerebrospinal fluidis obstructed causing an accumulation that may be harmful
|
|
|
blood-brain barrier
|
created by tight junctions between capillary endothelial cells
restricts movement of hydrophilic substances into the CNS lipophilic molecules can diffuse directly to CNS through plasma membranes |
|
|
glucose and the CNS
|
only source of ATP=metabolism of glucose
brain stores glycogen in order to ensure adequate resources for glucose, blood flow to the brain must be maintained |
|
|
stroke (cerebrovascular accident)
|
results from inadequate supply of blood to the brain which results in neural damage
|
|
|
cerebral cortex (cerebrum)
|
contains grey and white matter
ridges (gyri) and grooves (sulci) acts as an integrating center for sensing environment, emotions, intiating movement carries out the highes level of neural processing |
|
|
corpus callosum
|
connects two 2 hemispheres of the cerebrum
|
|
|
frontal lobe
|
primary motor cortex
|
|
|
parietal lobe
|
primary somatosensory cortex
|
|
|
occipital lobe
|
visual cortex
|
|
|
temporal lobe
|
auditory cortex
|
|
|
homunculus
|
"little man"
|
|
|
central sulcus
|
separates the frontal and parietal lobe
|
|
|
primary motor cortex
|
located anterior to central sulcus
|
|
|
primary somatosensory cortex
|
located posterior to central sulcus
|
|
|
somesthetic sensations
|
sensations from the surface of the body such as touch, pain, temperature, vibration etc.
|
|
|
proprioception
|
awareness of ones body position
|
|
|
limbic system
|
part of the cerebrum
consists of loose association of cortical regions and subcortical nuclei that function together in learning and emotions |
|
|
basal ganglia
|
consists of subcortical nuclei
plays a role in modifying movement inhibits muscle tone suppresses useless patterns of movement maintains posture dopamine is important in this region |
|
|
what would happen if the limbic system was affected in any way?
|
difficulty with learning and sensing emotions
loss of motivation |
|
|
parkinson's disease
|
associated with a deficiency of dopamine
3 abnormalities- increased muscle tone, resting tremors, and slowness in initiating movements. |
|
|
thalamus
|
cluster of nuclei receiving all sensory information from the body (except smell)
relay and integrating center helps direct attention to important sensory imput and filter less important stimuli |
|
|
hypothalamus
|
link between endocrine and nervous system
regulates homeostasis regulates hunger and thirst |
|
|
cerebellum
|
motor coordination and balance
receives information from everywhere and processes influences rate, range, force and direction of movement procedural memories |
|
|
what would happen with damage to cerebellum?
|
put finger in front of patients face and have them touch it then their nose- they wouldn't be able to do that easily
|
|
|
brainstem
|
consists of medulla, pons and midbrain
origin of most cranial nerves contains reticular formation received information from spinal cord location of major integrating centers |
|
|
reticular formation
|
reticular activating system which consists of a network of nuclei important for arousal, sleep-wake cycles
|
|
|
grey matter
|
containing cell bodies and interneurons
occupies the center of the spinal cord |
|
|
dorsal horn of spinal cord
|
some sensory (afferent) fibers come into CNS and synapse here
sensory fibers have cell bodies in the dorsal root ganglia |
|
|
ventral horn of spinal cord
|
cell bodies of efferent neurons originate here
|
|
|
lateral horn of spinal cord
|
location of cell bodies for autonomic neurons
|
|
|
white matter
|
contains myelinated axons
axons are highly organized into bundles (tracts) |
|
|
ascending tracts of white matter
|
carry information to the brain
contralateral |
|
|
descending tracts of white matter
|
tracts that carry information away from the brain to the spinal cord
contralateral |
|
|
ipsilateral
|
a pathway that stays on the side of its origin
|
|
|
contralateral
|
a pathway that crosses to the opposite side of its origin
|
|
|
spinal nerves
|
just outside of the spinal cord information is seperated out into afferent (sensory) and efferent (motor)
|
|
|
where is afferent information transmitted?
|
fibers located in the dorsal root
|
|
|
where are efferent information transmitted?
|
fibers contained in the ventral root
|
|
|
reflexes
|
a reflex is an automatic, patterned response to a sensory stimulus
i.e.- patellar tendon reflex |
|
|
what are the five components of a reflex arc?
|
sensory receptor--> afferent neuron--> integrating center--> efferent neuron--> effector
|
|
|
withdrawal reflex
|
responsible for withdrawing from a painful stimulus
|
|
|
nocioreceptors
|
detect painful stimuli, send information via afferent pathway to the spinal cord
efferent signals are sent out causing contraction of the muscles effecting withdrawal at the same time inhibitory signals are sent to the antagonistic muscles |
|
|
crossed-extensor reflex
|
enhancement of withdrawal reflex
occurs as withdrawal reflex but entails a simultaneous response from the opposite leg in order to maintain balance i.e. when stepping on a tack the other leg with have its extensor muscles activated to support the body as the other leg is withdrawn |
|
|
pupillary light reflex
|
shining light into the eye refelexively causes the pupil to constrict
|
|
|
what are the 4 components of voluntary muscle control?
|
1. an intention to move- cerebral cortex
2. program of motor commands- primary motor cortex, pre motor area and supplemental motor area 3. execution of motor commands-pyramidal tract, extrapyramidal tract, and motor neurons 4. continuous feedback to CNS to adjust |
|
|
motor neurons
|
aka- somatic motor neurons
provide efferent signals causing muscles to contract only excitatory |
|
|
lower motor neurons
|
can be excited or inhibited by input from afferent neurons as well as from input from higher centers descending via tracts to motor nuclei
|
|
|
what are the two tracts that descend to exert an effect on motor control?
|
pyramidal tracts (coritcospinal tracts)
extrapyramidal tracts |
|
|
pyramidal tracts
|
important in controlling discrete movements of the distal portion of extremities
fine movement |
|
|
extrapyramidal tracts
|
important in controlling large groups of muscles important for posture
upper motor neurons nuclei of the brainstem projects into the spinal cord via these tracts which are involved with involuntary control of posture and balance |
|
|
acetycholine
|
ligand
its receptors=cholinergic receptors |
|
|
what are the two types of cholinergic receptors?
|
nicotinic
muscarinic |
|
|
nicotinic cholinergic receptors
|
interact with nicotine
responses=fast onset, short duration and excitatory ionotropic opens channels allowing Na and K to flow more Na enters the cell |
|
|
muscarinic cholinergic receptors
|
muscurine
metabotropic- G protein coupled receptors responses activated by second messengers excitatory or inhibitory |
|
|
what enzyme breaks down acetylcholine?
|
acetylcholinesterase
|
|
|
norepinephrine
|
receptors= adrenergic
|
|
|
adrenergic receptors
|
metabotropic- G protein coupled receptors
|
|
|
what enzyme breaks down norepinephrine?
|
monoamine oxidase
|
|
|
what are the two classes of adrenergic receptors?
|
alpha (1 and 2)
beta (1 and 2) |
|
|
somatic division
|
only innervates skeletal (voluntary) muscle
neurons= somatic motor neurons or lower motor neurons |
|
|
somatic motor neurons
|
cell bodies located in ventral horn of spinal cord
exit spinal cord via ventral root and travel entire distance innervates muscle cells stimulation results in activation of all the muscle fibers in motor unit |
|
|
neuromuscular junction
|
the synapse involving a somatic motor neuron and a muscle fiber
|
|
|
what is the neurotransmitter at all somatic neuromuscular junctions?
|
acetylcholine
motor end plate= on the muscle fiber side of the junction, the specialized area of the cell membrane containing ACH receptors |
|
|
what type of ACH receptors are at neruomuscular juncitons?
|
nicotinic cholinergic
|
|
|
discuss signal transmission at the neuromuscular junction
|
always excitatory
|
|
|
end plate potential
|
the graded potential at the neuromuscular junction that develops in response to ACH binding to its nicotinic cholinergic receptor
always strong enough to elicit action potential always excitatory |
|
|
sympathetic pathways
|
cell bodies originate in the lateral horn of the spinal cord
fibers originate in the thoracic and lumbar regions fibers exit ventral root |
|
|
what are the 3 general anatomic arrangements for sympathetic fibers?
|
1. short preganglionic fibers exit ventral root and mix with spinal nerve (most common)
2. long preganglionic fibers travel to and synapse on cells within the adrenal medulla of adrenal gland 3. preganglionic fibers exit the ventral root, exit white ramus but do not synapse in sympathetic ganglia but synapse in collateral ganglia |
|
|
parasympathetic pathways
|
cell bodies of preganglionic neurons are in the brainstem or sacral spinal cord
|
|
|
parasympathetic cell bodies of preganglionic neurons in the brainstem
|
cell bodies are in cranial nerve nuclei III, VII, IX, X
X cranial nerve (vagus nerve) provides parasympathetic input to heart, lungs, stomach, liver, small intestine |
|
|
parasympathetic cell bodies of preganglionic neurons in the sacral spinal cord
|
cell bodies in lateral horn
parasympathetic pregaglionic fibers do not run in spinal nerves they run in their own distinct nerves |
|
|
what is the neurotransmitter released from preganglionic fibers at sympathetic ganglia?
|
acetylcholine
|
|
|
what are the receptors on postganglionic cells at sympathetic ganglia?
|
nicotinic cholinergic
|
|
|
what neurotransmitter is released from postganglionic sympathetic fibers?
|
norepinephrine
except the sympathetic fibers innervating sweat glands release ACH post ganglionic cells in adrenal medulla secrete promarily epinephrine |
|
|
what neurotransmitter is released from preganglionic fibers at parasympathetic ganglia?
|
acetylcholine
|
|
|
what are the receptors on postganglionic cells of the parasympathetic system?
|
nicotinic cholinergic
|
|
|
what neurotransmitter do postganglionic parasympathetic fibers release?
|
acetylcholine
|
|
|
what are the 3 general anatomic arrangements for sympathetic fibers?
|
1. short preganglionic fibers exit ventral root and mix with spinal nerve (most common)
2. long preganglionic fibers travel to and synapse on cells within the adrenal medulla of adrenal gland 3. preganglionic fibers exit the ventral root, exit white ramus but do not synapse in sympathetic ganglia but synapse in collateral ganglia |
|
|
parasympathetic pathways
|
cell bodies of preganglionic neurons are in the brainstem or sacral spinal cord
|
|
|
parasympathetic cell bodies of preganglionic neurons in the brainstem
|
cell bodies are in cranial nerve nuclei III, VII, IX, X
X cranial nerve (vagus nerve) provides parasympathetic input to heart, lungs, stomach, liver, small intestine |
|
|
parasympathetic cell bodies of preganglionic neurons in the sacral spinal cord
|
cell bodies in lateral horn
parasympathetic pregaglionic fibers do not run in spinal nerves they run in their own distinct nerves |
|
|
what is the neurotransmitter released from preganglionic fibers at sympathetic ganglia?
|
acetylcholine
|
|
|
what are the receptors on postganglionic cells at sympathetic ganglia?
|
nicotinic cholinergic
|
|
|
what neurotransmitter is released from postganglionic sympathetic fibers?
|
norepinephrine
except the sympathetic fibers innervating sweat glands release ACH post ganglionic cells in adrenal medulla secrete promarily epinephrine |
|
|
what neurotransmitter is released from preganglionic fibers at parasympathetic ganglia?
|
acetylcholine
|
|
|
what are the receptors on postganglionic cells of the parasympathetic system?
|
nicotinic cholinergic
|
|
|
what neurotransmitter do postganglionic parasympathetic fibers release?
|
acetylcholine
|
|
|
what are the receptors for postganglionic parasympathetic fibers?
|
muscarinic cholinergic
|
|
|
what does the sensory nervous system include?
|
sensory receptor cells that receive information from the external or internal environment
afferent pathways that transmit this information to the CNS parts of the brain that process the information from the sensory receptors |
|
|
sensory information
|
information detected by sensory receptors
may or may not be conscious detection |
|
|
sensation
|
when sensory information is brought to the level of consciousness
|
|
|
perception
|
a person's understanding of the sensation
|
|
|
visceral receptors
|
sensory receptors that detect information from within the body
i.e. monitoring blood pressure |
|
|
visceral afferents
|
afferent fibers which transmit information from these receptors
|
|
|
what are the general categories of the sensory system?
|
1. somatosensory- monitors sensations associated with the skin
2. special senses 3. visceral sensation |
|
|
sensory receptors
|
specialized structures which detect a specific form of energy
may be specialized at the peripheral end of an afferent neuron my be a separate cell that communicates with an afferent neuron via chemical synapse |
|
|
stimulus
|
a change detectable by the body
this change is in the form of energy which impinges upon and activates a sensory receptor |
|
|
modality
|
refers to the type of stimulus energy (temperature, light, pressure etc)
|
|
|
adequate stimulus
|
the type of energy to which a particular receptor responds in normal functioning
|
|
|
law of specific nerve energies
|
states that a given sensory receptor is specific for a particular modality
a specific receptor is most sensitive to a specific stimulus but it can respond to other stimuli if strong enough |
|
|
sensory transductions
|
the process of converting energy of a sensory stimulus into changes of membrane potential
|
|
|
receptor potentials
|
the changes in membrane potential which are created by activation of a sensory receptor
graded potentials triggered by sensory stimuli |
|
|
slowly adapting receptors (tonic receptors)
|
these receptors show little adaption to constant stimulation
will signal CNS as long as stim present this stimuli must be closely monitored |
|
|
rapidly adapting receptors (phasic receptors)
|
these receptors adapt quickly and function best in detecting changes in stimulus intensity
fire when stimulus begins and ends allow brain to ignore non threats |
|
|
labeled-line
|
level of organization that is also seen in the fact that specific neural pathways which transmit information for a particular sensory modality follow this particular pathway
|
|
|
sensory unit
|
a single sensory neuron and all the receptors associated with it.
all of these receptors will be of the same type |
|
|
receptive field
|
typically denotes an area of skin in which a stimulus can cause a response in an afferent neuron
this area corresponds to the area covered by receptors innervated by a single afferent neuron |
|
|
sensory coding
|
the mechanism by which the nervous system identifies the type, strength, and location of a stimulus
|
|
|
coding for type
|
the type is coded for by the type of receptor that is stimulated
|
|
|
coding for intensity
|
is coded by the total number of action potentials sent to the integrating center
|
|
|
how can the number of action potentials vary?
|
altering the frequency of action potentials
population coding-stronger stimulus acitvates more receptors |
|
|
coding for location
|
receptive field that is activated will give a general sense of location
processing information from overlapping fields lateral inhibition-functions to increase acuity by increasing contrast in signals to CNS |
|
|
acuity
|
the precision with which the location of a stimulus is perceived
|
|
|
two point discrimination
|
minimal distance at which two points can be felt
|
|
|
first order neuron
|
afferent neuron serving the sensory receptor
carry information to the CNS and synapse with second order neurons |
|
|
second order neurons
|
cross over the midline at some point either at the spinal cord level or at the medulla synapse in thalamus with third order neurons
|
|
|
third order neurons
|
project into somatosensory region of the cerebral cortex
|
|
|
dorsal column pathway
|
transmits info from mechanoreceptors and proprioceptors to thalamus
first order neurons ascend the spinal cord vial dorsal columns |
|
|
dorsal column nuclei
|
in the medulla where first and second order neurons synapse
|
|
|
medial lemniscus
|
second order nuerons cross over at the level of the medulla via this route
|
|
|
spinothalamic tract
|
transmits information from thermoreceptors and nocioreceptors to the thalamus (pain and temp)
first order synapse with second order in the dorsal horn second order cross over and travel up spinothalamic tract to the thalamus where they synapse with the third order which project to somatosensory cortex |
|
|
pain
|
sign of tissue damage
teaches us to avoid things |
|
|
what are the responses associated with perception of pain?
|
autonomic response
increase BP, HR sweating dialation of pupils emotional response fear, anxiety reflexive withdrawal from pain |
|
|
gate control theory
|
based on understanding that there are interneurons on the spinal cord level that can modulate the information as it is passed along the spinal cord
some respond to non painful stimuli |
|
|
periaqueductal gray matter
|
site of origin of signals which eventually are transmitted to the spinal cord and block communication between nociceptive afferents and second order neurons
enkephalin during illness hyperalgesia |
|
|
wernicke's area
|
language comprehension
damage= wernicke's aphasia which is a difficulty in understanding language aka receptive aphasia posterior temporal and inferior parietal |
|
|
broca's area
|
frontal lobe
language expression broca's aphasia= difficulty in speaking aka expressive aphasia |
