Unit 1 Flashcards
In _______ _______, the separation of charge across a membrane that would develop if the membrane were permeable to only one ion
Equilibrium (Nernst) potential
________ ______, the separation of charge across a membrane that develops in excitable cells that are permeable to MORE than one ion
Resting membrane potential
_______ _____, the local change in RMP that results from either an excitatory or inhibitory stimulus
local (receptor) potential
_____ ______, the propagation along the axon of a potential resulting from a threshold stimulus. Threshold may be reached by the summation of local potentials and is ALL-OR -NONE
Action potential
The equillibrium potential for a particular ion can calculated using ________
Nernst equation
The resting membrane potential in most large nerve fibers based on the factors in the Goldman equation is about _______ mV but with the Na/K pump the RMP in large neurons reaches _____mV
- 86mV
- 90mV
What contributes to the negativity of the interior of the cell
Na/K pump
3 Na out, 2 K in
The majority of the intracellular fluid and extracellular fluid is _________(charge)
Electrically neutral
Where does the resting membrane potential exist?
Only immediately inside and outside the cell membrane
What ion channels are responsible for the RMP?
K+ leak channels
K+ leak channels are permeable to what ions?
K+ and Na
What does the Goldman-Hodgkin-Katz equation address? 3 things
1) Concentration of ions inside and outside the cell
2) Permeability of the membrane to the ions
3) Valance of the ions (+ or -)
________ are always open, therefore sets up the baseline permeability of the membrane
K+ leak channels
What are examples of ion channels that are involved in maintaining the RMP?
K+ leak channels (main cause)
Na/K pump (necessary for maintenance and restoration
_________ is when potential becomes more negative
Hyperpolarization
What is hyperpolarization caused by?
Increasing permeability of the membrane to Cl- or K+
________ is when membrane potential becomes less negative
Depolarization
Describe local potentials
Local potentials are either depolarization or hyperolarization events that occur where stimuli are applied to an excitable cell
What are examples of stimuli
Synapse/neurotransmitter
Hormone or other chemical
Mechanical ( pressure, temperature, etc.)
Artificial (stimulating electrode)
Stimulus depends on what the excitable cell is sensitive to
A small stimulus causes a ______ depolarization of the cell membrane
A larger stimulus causes ______ depolarization
A stimulus of longer durations causes ______ depolarization but not of any greater ______ than the previous one
Small;
More;
Longer lasting; not of any greater strength
Local membrane potentials are _______. (The size of the stimulus is proportionate to the magnitude of the potential change)
Graded
What are local membrane potentials caused by?
Ligand-gated or mechanically gated ion channels
Do effects of local membrane potentials propagate far from the site of stimulus?
No they do not propagate
If a logical membrane potential meets or exceed __________ then an AP results
Threshold
AP are _________. They occur completely or not at all
All-or-none
What are the phases of the action potential?
Depolarization phase
Depolarization phase
Afterpotential/ hyperpolarization/ undershoot
Describe the depolarization phase
A threshold stimulus activates voltage-gated sodium channels
Threshold in the depolarization phase is usually ________mV above RMP
15-30 mV
During the depolarization phase, Na+ permeability therefore ________; Na+ _______ the cell causing depolarization
Increases; enters
Describe the repolarization phase
Voltage gated Na+ channels inactivate
Voltage gated K+ channels open increasing K+ permeability; therefore K+ leaves the cell causing repolarization
In the repolarization phase, voltage gated _____ channels open increasing _____ permeability; therefore ___ leaves the cell causes repolarization
K+, K+ and K+
Depolarization involves activation of the _____ voltage gated channels opening
Repolarization involves _____ voltage gated channels opening
Depolarization- Na+
Repolarization- K+
What is the Afterpotential/ hyperpolarization/ undershoot?
Transient hyperpolarization that occurs due to late closing of Voltage gated K+ channels
What is involved in restoring RMP?
Na/K pump
What are the 3 states of the V-gated Na+ channel?
Resting (closed)
Activated
Inactivated
What are the two states of the V-gated K+ channels?
Resting (closed)
Activated (opened)
The opening of voltage-gated channels increase _______ of the ions
Conductance
Describe an absolute refractory period
No stimulus no matter how strong can initiate another action potential
Describe a relative refractory period
A greater than threshold stimulus is required to initiate another AP
What are the differences between AP and local potentials?
AP- propagate and dont dissipate over long distances
Local potentials do not propagate and dissipate over a short distance
What prevents retrograde conduction of the AP?
The refractory period
If an axon is ARTIFICIALLY stimulated in the middle of an axon, Action potentials propagate _____
Bidirectionally
Both directions
What are the conditions that require propagation?
Reaching threshold
Adequate numbers of funcitonal voltage gated channels
Describe the fibers of a typical nerve
There is a mixture of myelinated and unmyelinated nerve fibers
________ nerve fibers tend to be larger
Myelinated
________ nerve fibers are more numerous (2X more)
Unmyelinated
In myelinated axons in the PNS are myelinated via ______ and in the CNS by _____
Schwann cells -PNS
Oligodendrocytes -CNS
In UNmyelinated axons, ________ supports but doesnt myelinated these axons
Schwann cells
Schwann cell membrane contain the lipid ________ which is an excellent insulator which decreases ion flow by 5000X
Sphingomyelin
_______ increases the velocity of nerve transmission and conserves energy of the nerve
Saltatory conduction
During satlatory conduction, where does inflow through the membrane occur?
Only at the nodes of Ranvier
what increases conduction velocity of an AP?
Myelination
Increase in axon diameter
What does the PNS consist of?
12 pairs of cranial nerves
31 pairs of spinal nerves
_________ detect specific types of stimuli (light in the eyes, tactile in the body surface, etc.)
Sensory receptors
Muscles and glands are referred to as ______
Effectors
What do chemical synapses involve the release of?
The release of neurotransmitters into a synaptic cleft and postsynaptic receptors to respond to those NT leading to a change in membrane potential
How do electrical synapses work?
Use gap junctions to directly propagate action potentials to the post-synaptic cleft
_______ synapses secret NT to effect the post synaptic cell (excitatory, inhibitory, modify sensitivity)
Chemical synapses
______ synapses are unidirectional from presynaptic -> post synaptic membranes
Chemical
______ synapses are most often used in smooth muscle and cardiac muscle
Electrical synapses
How are electrical synapses connected?
Gap junctions
How do electrical synapses work?
Free movement of ions from one cell to another; bidirectional transmission
What type of receptor proteins are involved in direct neurotransmitter actions?
Ionotropic
What type of receptor proteins are involved in indirect neurotransmitter action?
Metabotropic receptors
Ionotropic receptors are ________ ion channels
Ligand gated
Ionotropic receptors effects are ___________ (longevity)
Short lived
Ionotropic receptors are ligand gated ion channels are can be ______ channels or ______ channels
Cation or anion channels
Na+ channels are ______ (excitatory or inhibitory). When open they tend to ______
Excitatory
When open tend to depolarize
K+ channels and Cl- channels are ______ (excitatory or inhibitory). When they are open they tend to _______
Inhibitory
When open tend to hyperpolarize and are therefore inhibitory
Metabotropic receptors by the use of _________ have more prolonged effects
G-proteins
Where are NT made?
In the cytosol of the presynaptic terminal and are actively transported into vesicles until released
What are the effects of NT’s?
Most often the effect is to increase or decrease conductance through ion channels
How are NT removed from the synaptic cleft?
Enzymatic destruction
Reuptake
Diffusion
Who secretes the NT Acetylcholine (Ach)?
Large pyramidal cells
Basal ganglia cells
Motor neurons to skeletal muscle
Many autonomic neurons
What is the effect of Ach?
Excitatory in most cases
Inhibitory in the heart and other parasympathetic targets
Who secretes norepinephrine (noradrenaline)?
Neurons in the brain stem and hypothalamus (locus ceruleus)
Most post gnaglionic neurons of the sympathetic NS
What is the effect of norepinephrine?
Excitatory or inhibitory depending on receptor/ target tissue
secretes dopamine and what is its effect?
Substantia nigra
Usually inhibition
Who secretes Glycine and what’s it effect?
Spinal cord neurons
Always inhibitory
Who secretes GABA and what’s it effect?
Nerve endings in the spinal cord, cerebellum, basal ganglia, and cerebral cortex
Effect: always inhibitory
Who secretes glutamate and what’s its effect?
Neurons in sensory pathways
Effect: always excitatory
Who secretes serotonin and what’s its effect?
Certain brain stem neurons
Effects- inhibitor (effects pain pathways, mood and sleep)
Who secretes NO?
Areas of the brain involved in memory and behavior
How is NO a unique NT?
It is not stored in vesicles but made as needed and has more of a metabolic function
What are the effects of NO?
Modifies neuronal excitability for seconds to minutes
______ are synthesized by ribosomes in the neuronal cell body, processed by the ER and golgi then packaged into transmitter vesicles
Neuropeptides
How are neuropeptide vesicles transported in the neuron?
By axonal streaming
_______ are very potent, small quantities are released at a time
Neuropeptides
A typical spinal cord neuron is _________ and have a RMP of ______ mV
Multipolar
-65mV
T/F: the resting membrane potential of neurons exists throughout the membrane, including the soma
True
The ______ has highly conductive intracellular fluid and has a large diameter.
Soma
Therefore any change in one part of the soma is spread quickly to the rest of the soma
What are two examples of local membrane potentials?
EPSP ( excitatory postsynaptic potential)
IPSP (inhibitory postsynaptic potential)
In EPSP’s what ion channels are involved?
Na+ channels
In IPSP’s what ion channels are involved
Cl- and K+
Both of these lead to hyperpolarization of the membrane therefore more inhibitory
Axon potentials are generated in the ______ when the RMP rises above _______
Initial segment ( axon hillock)
Threshold
The initial segment has a high density of __________ channels
Voltage gated sodium channels
T/F: A single EPSP from a single neuron is rarely big enough to hit a threshold
True
What are two ways in which threshold can be reached?
Spatial summation
Temporal summation
_________ summation, many presynaptic terminals stimulating APSP’s at the same time can summate to reach the threshold for firing
Spatial summation
_______ summation successive discharges of a single presynaptic terminal can also summate to reach threshold
Temporal
_______ summation of EPSPs and IPSPs May completely or in part cancel each other out
Simultaneous
________ is when a neurons presynaptic potential’s have summate toward threshold but has not heat reached it
Facilitation
80-95% of all presynaptic terminals end on ______ and the rest on ______
Dendrites; soma
Most dendrites cannot transmit AP bc they lack _________, therefore their threshold is ______
Enough voltage gated channels,
too high
_________ is the loss of excitability after experiencing a high frequency of firing for a period of time
Synaptic fatigue
Synaptic fatigue can also be due to ________ ______ _____ in the presynaptic terminals
Exhaustion of stores of NT
What are other possible causes of synaptic fatigue?
Progressive inactivation of postsynaptic receptors
Or
Development of abnormal concentrations of ions inside the postsynaptic cell
_________ may be a protective mechanism against excessive neuronal activity ( probably why seizures finally end)
Synaptic fatigue
What are the following’s effects on synaptic activity:
- acidosis
- alkalosis
- hypoxia
- drugs
Acidosis- depresses neuronal activity
Alkalosis- increases neuronal activity
Hypoxia- even for a few seconds can STOP nerve transmission in some neurons
Drugs - can be excitatory or inhibitory
What are the 3 steps common to all senses?
Physical stimulus
Set of events converts the stimulus into an AP
Response to the AP
What are the 5 ways sensory information is used?
Perception
Control of movement regulation of internal organs
Maintenance of arousal
Memory
Each sensation detected by sensory receptors is called a ________
Modality
What are examples of modality?
Pain, touch, cold, sound
Describe the labeled line principle
All sensory neurons transmit AP
The CNS differentiated different modalities based on cortical location of the tract termination
How does the CNS differentiate different modalities (sensations)?
Based on cortical location of the tract termination
Classification of the receptors can be based on location of stimulus. And the 2 are ________ and ______
Interoreceptor
Exteroreceptor
Classification of receptors can be based on structure. Three examples are
Simple
Encapsulated
Receptor cell associated
Classification of sensory receptors can be based on modality. What are the 5 examples?
Mechanoreceptors Thermoreceptors Nociceptors Electromagnetic receptors Chemoreceptors
________ receptors respond to mechanical pressure or distortion
Mechanoreceptors
______ receptors respond to heat or cold
Thermoreceptors
_________ receptors respond to noxious (painful) stimuli
Nociceptors
_________ receptors respond to photons (sight)
Electromagnetic receptors
________ receptors respond to chemical stimuli
Chemoreceptors
What are examples of cutaneous Mechanoreceptors in the epidermis and dermis
Meissners corpuscle Merkels receptor Ruffini’s corpuscle Pacinian corpuscle Hair receptor Free nerve endings
________ receptors are neurons with free nerve endings
Simple receptors
_______ receptors have nerve endings enclosed in connective tissue capsules
Encapsulated (complexes neural)
_________ are cells that release NT onto sensory neurons, initiating an AP/
Receptor cell associated (most special senses receptors)
What are examples of deep tissue mechanoreceptor types?
Muscle spindles
Golgi tendon organs
What are examples of special senses mechanoreceptor types
Hair cells (cochlea, vestibular apparatus)
What are the locations of the following chemoreceptor modalities?
- taste
- smell
- arterial oxygen
- osmolality
- blood CO2
- blood glucose, amino acids, FA’s
Taste- taste buds
Smell- olfactory cells
Arterial oxygen- Aortic and carotid bodies
Osmolality- neurons in supraoptic nuclei
Blood CO2- aortic and carotid bodies, medulla
Blood glucose, amino acids, fatty acids - hypothalamus
What are examples of chemoreceptors? (6)
Taste Smell Arterial oxygen Osmolality Blood CO2 Blood glucose, aminoacids and FA’s
What are examples of thermoreceptors, cold and heat receptors?
Free nerve endings
What are examples of electromagnetic receptors?
Vision - rods and cones
Nociceptors are _____ receptors
Pain
T/F: pain receptors are a strange modality in that more than one type of stimulus can elicit pain
True
Nociceptors (pain receptors) are called _______ because more than one type of stimulus can elicit pain
Polymodal
What are 3 examples of stimuli that can elicit pain through nociceptors?
Chemical
Temperature
Mechanical
Local potentials in sensory endings are called _________
Receptor potentials
Mechanical deformation and chemical binding of a stimulus ________
Opens ion channel
Temperature alters ______ when responding to a specific modality
Permeability to ions
Light directly or indirectly leads to ________ when responding to a specific modality
Ion flow
The greater the sustained stimulus strength, the _____ the AP frequency
Greater
Local membrane potentials or receptor membrane potentials in sensory endings are ______
Graded
The greater the frequency of the AP, means more _______ release
NT release
A weak stimulus releases ______ NT
A strong stimulus causes more AP and releases _____ NT
Little NT
More NT
The stimulus intensity is equivalent in both the ______ and _______ adapting neurons
Rapidly and slowly
In _____ adapting neurons, the frequency of firing decreases quickly
Rapidly adapting (phasic receptors)
Rapid adaptation = ______ receptors
Slow adaptation = ________ receptors
Phasic receptors
Tonic receptors
Why are rapidly adapting (phasic) receptors important?
Bc they punctuate our sensory experience by highlighting stimuli that changes (input of new stimuli)
Sensory adaptation is useful in ______ and _____ cases
Smell and temperature
________ are cutaneous mechanorecptors that sense tickle, itch, and pain. Their adaptation rates are tonic or phasic
Free nerve endings
_______ are cutaneous mechanoreceptors sense stretching of skin and deep pressure. Their adaptation rate is tonic
Ruffini endings
______ are cutaneous mechanoreceptors that sense fine touch and pressure. Their adaptation rate is tonic
Merkel discs
________ are cutaneous mechanoreceptors that sense fine touch, pressure and slow vibration. Their adaptation rate is phasic- moderate.
Meissners corpuscle
________ is a cutaneous mechanoreceptor that sense crude touch, and movement of hair. It’s adaptation rate is ______
Hair follicle
Phasic -moderate
_____ are cutaneous mechanorecptor4s that sense fast vibration. Their adaptation rate is phasic -fast
Krause bulbs
________ are cutaneous Mechanoreceptors that sense pressure, fast vibration and tickling. Their adaptation is phasic -fastest
Pacinian corpuscle
Describe the predictive value of phasic receptors
If a receptor detects the rate of change of a sensory input, it can predict the status of the stimulus in the future
Ex: semincirular canals sense head rotation. Can predict where the head will be in the next few seconds so that balance can be maintained
What is the function of fiber type Aalpha? Is it fast or slow?
Proprioception; somatic motor
Fastest bc thickest myelination and axon of diameter is large
What are the functions of fiber type Abeta?
Proprioception, touch, pressure
What are the functions of fiber type Agamma
Motor to muscle spindles
What are the functions of fiber type Adelta?
Fast pain, cold, touch
Less fast than gamma, beta and alpha
What is the function of fiber type B?
Preganglionic autonomic
What are the functions of C type fibers?
Slow pain, temperature, some mechanoreceptors, postganglionic sympathetic
For the functions of proprioception: muscle spindle (annulospiral ending), what are the general and numerical classification of those sensory nerves?
General: Aalpha
Number: 1a
Sensory classification sometimes used for sensory neurons is a ______ classification
Numerical classification (Ia, Ib, II, III, IV)
What is a numerical and general sensory classification for the neurons that functions in proprioception in the Golgi tendon organ?
Ib- numerical
Aalpha- general
What is a numerical and general sensory classification for the neurons that functions in proprioception: muscle shingle (flower-spray ending), fine touch, pressure?
II-numerical
Abeta - general
What is a numerical and general sensory classification for the neurons that functions in pain and cold, crude touch?
III- numerical
Adelta - general
What is a numerical and general sensory classification for the neurons that functions in pain, temperature, itch crude touch?
IV - numerical
C- general
_______ is the area of skin a neurons dendritic zone is sensitive to
Receptive field
The bigger the _________, the harder it is to pinpoint the location of a stimulus
Receptive field
Describe spatial summation of receptive fields
Overlapping receptive fields of neighboring neurons are “recruited” with stronger stimuli
Describe temporal summation of signals in nerve tracts
Increased frequency of nerve impulses in fiber resulting from stronger stimuli
What is the spatial and temporal summation effect on the CNS
A strong stimulus will excited neurons to fire with high frequency and will recruit fibers innervating neighboring receptive fields
What is a neuronal pool/ circuit/ pathway?
A collection of communicating neurons, large or small
Neuronal pools interconnect in a variety of ways to process ________ and create ______
Process incoming sensory input
Create patterns of output
Divergence of stimuli can occur in _______ or _______
In the same pathway
Or
Multiple tracts
In _____, input neurons can be originating form the same tract or diffent tracts of the NS and end up on one neuron.
Convergence
In _________ Circuit one mechanism by which input signals can be prolonged.
Reverberating (oscillatory) circuit
Reverberating (oscillatory) circuits can be stoped by _______ or _______
Incoming inhibitory signals
Or
Synaptic fatigue
Reverberating circuits may be sped up by _______
Facilitation (excitatory signals)
_______ is another mechanisms by which a signal can be prolonged. When long-acting neuropeptides are used, the postsynaptic neuron May continue for many milliseconds after the input neuron fired
Synaptic after- discharge
________ refer to the sensations that are common throughout the body. They are also referred to as _____
Somatic sensations
General senses
______ are tactile touch receptors located in the epidermis and corneal epithelium. Their modality is crude touch,pressure, tickle and itch
Free nerve endings
What is the location of free nerve endings and their modalities?
Location: everywhere in the epidermis and corneal epithelium
Modality: crude touch, pressure, tickle, itch
________ are uncapsulated and have no complex sensory structures
Free nerve ending
_______ are the most common type os nerve endings and have a varying degree of adaptation
Free nerve ending tactile receptors
what are the fiber types of free nerve endings?
Adelta or C
What is the location and modalities of Meissners corpuscles?
Location: glabrous (non-hairy like on palms or soles) skin, the dermis and particularly dense areas that have the keenest sense of touch (fingers and lips)
Modality: stroking, fluttering
________ are encapsulated, made of flattened supportive cells arranged in horizontal lamella surrounded by CT. A single ________ branches throughout
Meissner’s corpsucles
Nerve ending
________ are rapidly adapting so they respond well to movement of objects over the surface and low frequency (10-50Hz)
Meissners corpuscle
What is the fiber type of Meissner’s corpuscles?
Abeta
What is the location of Merkel’s discs and their modality?
Location- epidermis and hair follicles
Modality- static pressure, texture
________ is a tactile receptor that has multiple expanded tip endings each associated with a ______ cell
Merkel’s disc
Merkel cell
______ are slowly adapting and work with Meissner’s corpsucles
Slowly adapting
Merkel’s discs together with Meissner’s they are great at _________ sensations and determining ______
Great at localizing touch sensations and determining texture
What is the fiber type of Merkel’s discs?
Fiber type Abeta
What is the location of the hair end organ (AKA. Hair follicle receptor or hair plexus) and their modalities?
Location: hair follicles
Modality: stroking, fluttering
In _______ the nerve ending wraps around the based of the hair follicle
Hair end organ (hair follicle receptor, hair plexus)
______ are rapidly adapting and mainly detects movement across the body surface
Hair end organ
What are the fiber types of hair end organ?
Type Abeta and Adelta
What is the location and modality of ruffini ending (bulbous corpuscle)?
Location: deep skin and joint capsules
Modality: skin stretch, degree of joint rotation
_______ are enlarged dendritic endings encased in elongated capsules
Ruffini ending (bulbous corpuscle)
_______ are very slowly adapting. And have fiber type Abeta
Ruffini ending (bulbous corpuscle)
What is the location And modality of pacinian corpsucles (lamellar corpsucles)?
Location- dermis and fascia
Modality - vibration
______ are large oval shaped structures with 20-60 concentric epithelial membranes encased in a CT
Pacinian corpuscle
Most specialized receptors transmit their signals using _____ nerve fibers. Free nerve fiber use slower fibers _____ or ______
Abeta
Adelta or C
Receptors that detect certain sensations with precision use ______ fibers. (Fast or slow?)
Faster
Faster fibers are good in detecting what?
Precise localization
Minute gradations in intensity
Rapid changes
Vibration is best detected by _______ and ________ tactile receptors
Pacinian corpuscles and meissner’s corpuscles
How can a signal be prolonged? (2 possibilities)
Using a reverberating or oscillatory circuit AND
Synaptic After-discharge
All sensory information for the somatic segments of the body enters the Spinal cord through the __________
Dorsal roots of the spinal nerves
Incoming sensory nerves form ______ that ascend the spinal cord
Tracts
What are the two principle tracts (sensory pathways) in the spinal cord?
Dorsal-column- medial lemniscal system (MLS)
Anterolateral (spinothalamic) system
Describe the dorsal column MLS tract (fibers and modalities)
Larger myelinated fibers High degrees of spatial localization Touch sensations with fine gradations of intensity Phasic sensations (vibrations) Movement against skin Joint position sense Fine gradations of pressure intensity
Describe the anterolateral (spinothalamic) system (fibers and modalities)
Smaller myelinated fibers Pain sensation Thermal sensations Crude touch and pressure sensations Tickle and itch Sexual sensations
__________ sensory pathway tract modalities include, touch, vibration, two point discrimination and proprioception
Dorsal column medial lemniscal pathway
The general layout of most somatic sensory pathways:
First order neuron _______-> ______
Second order neuron _____-> ______
Third order neuron ____ -> _____
First order: receptor -> cord/brain stem
Second order: cord/brainstem-> thalamus
Third order: thalamus -> cortex
What are the areas/ divisions of the grey matter (5)
Marginal zone Gelatinous substance Nucleus proprius Lateral motor neurons Medial motor neurons
________ are large myelinated fibers form specialized mechanoreceptors enter the SC
First order neuron
First order neuron in the dorsal column - MLS, divides into ______ and _______
Medial and lateral branch
Medial branch ascends the dorsal column
Lateral branch synapses with interneurons
The first order neuron continues to ascend the dorsal column the _________ if originating from T6 or up.
OR
________ if originating from source below T6
Fasciculus cuneatus
Fasciculus gracilis
The fibers from the lowest part of the body project to the most _______ part of the __________
The fibers from the uppermost part of the body project the most _____ part of the ________
Medial; fasciculus gracilis
Lateral; fasciculus cuneatus
The first order neuron of the dorsal column -MLS terminates/ synapses in the __________ or ________ in the _________
Nucleus gracilis or nucleus cuneatus in the medulla oblongata
The second order neuron of the anatomy of dorsal column-MLS decussates to ascend in the ___________. Continues up the ___________ of the pons and midbrain and terminates in the ______
Medial lemniscus
Medial lemniscus
Thalamus (ventroposterolateral (VPL) nucleus)
The third order neuron of the dorsal column -MLS projects from the thalamus to the _________
Somatosensory cortex (post-central gyrus)
Third order neuron of the dorsal column MLS terminates in the _______ arranged such that the lower body projects to the __________ cortex and the upper body in the ________ cortex
Post central gyrus
Lower body-> superior medial cortex
Upper body -> inferior medial cortex
Post central gyrus is also known as the __________ cortex and corresponds to brodmanns areas __, ___, ___.
Primary somatosensory cortex
3,1,2
_________ tract discriminates touch/pressure from the face
Trigeminothalamic tract
How many layers are there of the somatosensory cortex?
Six layers
In which of the 6 layers are there incoming 3rd order neurons synapse here first then branch to a more superficial and deep layers
Layer four
Somatosensory cortex layers ______ , project to neighboring cortical areas
I-III
layers ____ and _____ of the somatosensory cortex contain outgoing neurons to more distant areas
5 and 6
Functionally, the neurons of the somatosensory cortex form ________ _______ each serving a sensory modality
Vertical columns
________ columns respond to proprioception
Brodmans 3a columns
As you move posterior in the cortical columns from 3a -> 2. What occurs in the neurons?
Rapidly adapting -> slowly adapting
Texture and movement -> deep pressure
The farther posterior in the column
3b-> 1 -> 2
Based on ________ you would be able to take a corre sample from a part of the post-central gyrus, you would be able to predict the modality, body part, and input/output patterns from that core sample based on location
Cortical columns
Brodmann’s areas _____ and ____ combine information from multiple sources including the thalamus, visual cortex and auditory cortex
Brodmanns areas 5 and 7
Brodmanns areas 5 and 7 combine information from multiple sources including ______, ______ and _____
Thalamus
Visual cortex
Auditory cortex
What brodmanns areas decipher deeper meanings such as is this a ball or a pencil?
Areas 5 and 7
________ is the ability to determine shape and texture based on feel and not just by sight
Stereognosis
What is the dorsal column system composed of?
Divergent circuits
The dorsal column system is composed of divergent circuits which helps with ________
Distinguishing weak vs strong stimuli
The dorsal columna system is important in _______ and _______
Two point discrimination and
Vibration and rapidly changing stimuli sensations
________ is used to increase the degree of contrast between two stimuli
Lateral inhibition
What is an important component in two point discrimination?
Lateral inhibition
______ and _____ neurons respond to vibrations and rapidly changing stimuli sensations
Pacinian and Meissners neurons
______ proprioception is the orientation of the different parts of the body with respect to one another
Static
_______ proprioception is the rate of movement (kinesthesia)
Dynamic
_______, _____ and _____ are examples of receptors tha relay to the dorsal column and are involved in proprioception
Skin tactile receptors, deep joint receptors and muscle spindles
The anterolateral pathway modalities are ___? (6)
Pain Heat Cold Crude tactile Tickle and itch Sexual sensations
What is the anatomy of the anterolateral pathway in terms of the first order neuron
First order neuron enter dorsal horn grey matter and synapse there
What is the anatomy of the anterolateral system in terms of the second order neuron?
Decussate immediately through the anterior commissure
Enters the anterior or lateral spinothalamic tract and terminat in reticular nuclei of the brain stem or the thalamus VPL and intralaminar nuclei
The second order neuron in the anterolateral pathway enters into the anterior or lateral spinothalamic tract and terminates in what locations? (3 possible)
Reticular Nuclei of the brain stem
Thalamus VPL and the intralaminar nuclei
What is the anatomy of the anterolateral pathway in terms of the third order neuron?
It ascends from VPL to the primary somatosensory cortex
The _______ spinothalamic tract receives inputs from nociceptors, thermal receptors, visceral afferents, itch receptors
Lateral
The ______ spinothalamic tract contains A delta and C fibers
Lateral
_______ spinothalamic tract receives mixed information from visceroreceptors, nociceptors and low threshold Mechanoreceptors (free nerve endings)
Anterior
The anterolateral pathway velocities of transmission is slower (______ and _____ fibers); spatial localization is ______; gradations of intensities are _____ accurate; rapidly changing signals and vibration sense is ______.
A delta and C types
Poorer
Less accurate
Poor
In the anterolateral pathway the fibers from the lowest part of the body project to _________ pathway
Anterolateral
Anterolateral pathway, the fibers from the uppermost part of the body project to the most ___________ part of the pathway
Posteromedial
Dendrites do transmit electronic current toward the soma, however the more distance that needs to be covered, the weaker the signal gets. This is why it is called __________ conduction
Decremental
