Neurophysiology Flashcards
Which receptor cell type is responsible for the ff stimullus:
- Tap, Flutter 5-40 Hz
- Deep pressure, Vibration 60-300 Hz
- Motion
- Sustained pressure
- TOUCH– Flutter 5-40 Hz: Meissner
- TOUCH– Vibration 60-300 Hz: Pacinian
- TOUCH– Motion: Hair follicle
- TOUCH– Sustained pressure: Ruffini corpuscles
Which receptor cell type is responsible for the ff stimullus:
- Vestibular– Balance: Angular acceleration
- Vestibular– Balance: Linear acceleration
- Vestibular– Balance: Angular acceleration
Hair cells SC canal - Vestibular– Balance: Linear acceleration
Hair cells Otolith organs
What kind of pain is elicited?
- Glutamate for rapid localization
- Glutamate and substance P, dull, intense, unpleasant
- First/ fast/ epicritic pain
2. Second/ slow/ protopathic pain
What kind of pain is mediated by:
- ASIC
- TRPM8
- P2X, TRPA1
- TRPV1
- ASIC: Acid pain
- TRPM8: Cold
- P2X, TRPA1: Mechanical
- TRPV1: Acid and Heat
Differentiate:
- Hyperalgesia
- Allodynia
Hyperalgesia is an exaggerated response to a noxious stimulus, and allodynia is a sensation of pain in response to a normally innocuous stimulus
Where is the only place in the body where arterioles are readily visible?
Retina during fundoscopy
What are the components of the extrafoveal portion of the retina?
- Outer nuclear layer: Rods and cones
- Outer plexiform layer
- Inner nuclear layer: Bipolar cells, amacrine cells
- Inner plexiform latyer
- Ganglion cell layer: Midget and diffuse ganglion cells
- Outer nerve fibers
What kind of photoreceptor cell is most prominent in the fovea?
Cones
What induces hyperpolarization in cones? Light or dark?
Light.
In the dark what is the movement of the Na+?
From the inner to the outer segment
What are the two components of rhodopsin? Which one is an aldehyde of vitamin A?
Retinal and opsin
Retinal
When light hits what happens to retinal?
The only action of light is to change the shape of the retinal, converting it to the all-trans isomer from an all cis isomer.
What is the process of bleaching?
After 11-cis retinal is converted to the all-trans configuration, it separates from the opsin in a process called bleaching. This changes the color from the rosy red of rhodopsin to the pale yellow of opsin.
Where do the axons of a group of ganglion cells in the retina that contain melanopsin go? 2 answers.
The axons of these melatonin-containing photosensitive retinal ganglion project via at least two pathways. One, their axons can travel via the optic nerve, optic chiasm, and optic tract (bypassing the lateral geniculate nucleus, LGN) to terminate in the olivary pretectal nucleus. From here neurons synapse on parasympathetic preganglionic neurons in the Edinger—Westphal nucleus to mediate the pupillary light reflex (described below). Two, the axons of melatonin-containing photosensitive retinal ganglion cells can project to the suprachiasmatic nucleus of the hypothalamus, where they form connections that synchronize a variety of endocrine and other circadian rhythms with the light-dark cycle (Chapter 14).
Fill in
- Change in retinal due to light
- Activation in phosphodiesterase
- Decrease in cGMP
- Decreased release of synaptic transmitter
- Response of bipolar cells and other neural elements
- Change in retinal due to light
- Activation of transducin
- Activation in phosphodiesterase
- Decrease in cGMP
- Closure in Na channels
- Hyperpolarization
- Decreased release of synaptic transmitter
- Response of bipolar cells and other neural elements
What is the range of wavelength of visible light?
397 to 723 nm
When should strabismus be corrected before complete loss of visual acuity occurs in the suppressed eye? The cortical phenomenon called “Suppression scotoma”
6 years old
Why can occipital lesions spare macular central vision?
because the macular representation is separate from that of the peripheral fields and very large relative to that of the peripheral fields. Therefore, occipital lesions must extend considerable distances to destroy macular as well as peripheral vision.
There are 6 layers of the lateral geniculate nucleus. Which layers are part of the magnocellular pathway? Which layers are from the contralateral eye?
Magno 1, 2
Contralateral eye 1,4,6
Which layers of the LGN detect movement depth and flicker? Which are for color, texture, shape and fine detail?
Depth: 1-2 MAGNOCELLULAR
Color: 3-6
PARVOCELLULAR
Blindness with preservation of the pupillary reflex is usually due to a lesion in which visual pathway?
Bilateral lesions posterior to the optic tract
Which visual projection area?
- Primary visual cortex
- Motion
- Shape, color, texture
- Direction of movement
- Direction and speed
- Shape
- Color vision
- Primary visual cortex V1
- Motion V3
- Shape, color, texture V4
- Direction of movement V5
- Direction and speed V6
- Shape LO
- Color vision V8
Vision from V1 divides roughly to a dorsal parietal pathway and a ventral temporal pathway. What are the functions of these?
Dorsal: Motion
Ventral: Shape and recognition of faces
What are the primary colors?
Red Green Blue
What region of the visual projection area is responsible for color vision? Can lead to achromatopsia?
V8
How is color blindness inherited?
X-linked
The young helmhotz theory of color vision indicates that there are how many types of cones?
The Young–Helmholtz theory of color vision in humans postulates the existence of three kinds of cones, each containing a different photopigment and that are maximally sensitive to one of the three primary colors, with the sensation of any given color being determined by the relative frequency of the impulses from each of these cone systems.
What are the functions of the superior colliculi?
The superior colliculi, which regulate saccades, are innervated by M fibers from the retina.
The superior colliculi are constantly active positioning the eyes, and they have one of the highest rates of blood flow and metabolism of any region in the brain.
What type of astrocytes are in white and gray matter?
White: fibrous
Gray: Protoplasmic
What proteins that lock onto one another compacts the myelin sheaths?
Po or Myelin protein zero
The myelin is then compacted when the extracellular portions of a membrane protein called protein zero (P0) lock to the extracellular portions of P0 in the apposing membrane.
What proteins are attached to microtubules to help with the orthograde and retrograde transport of substances?
Dynein and kinesin
At rest what is them membrane potential? Which is more negative inside or outside? Close to the resting potential of which ion?
How is resting membrane maintained?
-70mV
Inside negative
Potassium
Because there are more open K+ channels than Na+ channels at rest, the membrane permeability to K+ is greater.
Steady ion leaks cannot continue forever without eventually dissipating the ion gradients. This is prevented by the Na, K ATPase, which actively moves Na+ and K+ against their electrochemical gradients.
Determine which fiber type
- Largest diameter and fastest
- For touch and pressure, second largest
- For proprioreception and somatic motor
- Pain and temperature (2 answers)
- Motor to muscle spindles
- Preganglionic autonomic
- Post ganglionic sympathetic
- Most susceptible to local anesthetics
- Most susceptible to pressure
- Largest diameter and fastest A alpha
- For touch and pressure, second largest A beta
- For proprioreception and somatic motor A alpha
- Pain and temperature (2 answers) A delta and C
- Motor to muscle spindles A gamma
- Preganglionic autonomic B
- Post ganglionic sympathetic C
- Most susceptible to local anesthetics C
- Most susceptible to pressure A
How does lidocaine and cocaine work in local anesthesia?
This usually occurs as a result of blockade of voltage-gated Na+ channels on the nerve cell membrane.
Nociceptive fibers (unmyelinated C fibers) are the most sensitive to the blocking effect of local anesthetics. This is followed by sequential loss of sensitivity to temperature, touch, and deep pressure. Motor nerve fibers are the most resistant to the actions of local anesthetics.
Correlate the numerical with the letter classification of nerve fibers
Ia
Muscle spindle, annulo-spiral ending
Aα
Ib
Golgi tendon organ
Aα
II
Muscle spindle, flower-spray ending; touch, pressure
Aβ
III
Pain and cold receptors; some touch receptors
Aδ
B has no number correlate (preganglionic autonomic)
IV
Pain, temperature, and other receptors
C
Which proteins are attached to:
- Z-line
- M-line
- Z-line: Actin
2. M-line: Myosin
The overlap of myosin and actin forms which band?
How about the lighter bands between these?
A band, in the middle of which is the M line
DONT FORGET A (H) BAND M LINE MYOSIN
Lighter bands are I bands bisected by the Z line
What are the functions of the ff troponins?
T
I
C
T: Bind actin to tropomyosin
I: Inhibit binding of actin to myosin
C: Bind to calcium– facilitates contraction
Which muscle protein?
- Binds actin to the Z line
- It connects the Z lines to the M lines and provides scaffolding for the sarcomere. It contains two kinds of folded domains that provide muscle with its elasticity.
- It adds structure to the Z lines in part by binding the Z lines to the plasma membrane.
- Actinin
- Titin
- Desmin
What does dystrohpin bridge?
F actin and the dystroglycan sarcoglycan complex. This dystrophin–
glycoprotein complex adds strength to the muscle by providing
a scaffolding for the fibrils and connecting them to
the extracellular environment.
What is the resting membrane potential of skeletal muscle?
-90mv
Regarding calcium in muscle contraction:
- What two receptors must interact for it to be released?
- Where is it released from?
- What pumps it back into the #2?
- Where does it bind to enable muscle contraction?
- What two receptors must interact for it to be released? Dihydropyridine receptor and ryanodine receptor
- Where is it released from? Terminal cisterns of the sarcoplasmic reticulum
- What pumps it back into the #2? SERCA– Sarcoplasmic endoplasmic reticulum Ca++ ATPase
- Where does it bind to enable muscle contraction? Troponin C on actin fiber
What receptor is pathologic in malignant hyperthermia?
Ryanodine receptors
Determine which type of muscle: Type 1, 2a, 2b
- Fast oxidative glycolytic
- White
- Red
- Fast myosin atpase activity
- Large
- High calcium pumping capacity
- Low oxidative capacity
- Motor unit fast but resistant to fatigue
- Most susceptible to atrophy with inactivity
- Fast oxidative glycolytic: 2a
- White: 2b
- Red: 1 and 2a
- Fast myosin atpase activity: 2a and 2b
- Large diameter: 2a and 2b
- High calcium pumping capacity of SR: 2a and 2b
- Low oxidative capacity: 2b
- Motor unit fast but resistant to fatigue: 2a
- Most susceptible to atrophy with inactivity 1
Besides glucose and lipids what other energy rich phosphate compound can the muscles use for contraction?
Phosphorylcreatine
Regarding ATP in muscle:
- How many kcal are brought about by hydrolysing ATP and H2O
- Glucose + 2ATP via anaerobic pathway results in?
- Glucose +2ATP via aerobic pathway results in?
- How many kcal are brought about by hydrolysing ATP and H2O –> 7.3
- Glucose + 2ATP via anaerobic pathway results in? –> Lactic Acid + 4 ATP
- Glucose +2ATP via aerobic pathway results in? –> 40ATP + 6 CO2 and 6 H2O
End to end adhesion of cardiac muscle fibers are called?
Intercalated disks
Identify the ion channel most responsible for the following phases cardiac muscle contraction
- Phase 0
- Phase 1
- Phase 2
- Phase 3
- Phase 4
- Phase 0: Upstroke– opening of voltage gated Na+ channels
- Phase 1: Closure of Na and opening of K channel
- Phase 2: Prolonged plateau phase– Slower but prolonged opening of Ca++ channels
- Phase 3– final repolarization: closure of the Ca++ channel and slow delayed K efflux
- Phase 4: Resting membrane potential– open K with NaK ATPase maintaining gradient
What are the equivalent structures of Z lines in smooth muscles?
Dense bodies
Whereas in striated muscles Ca++ binds to troponin C– where does it bind for smooth muscle?
Calmodulin– Smooth muscle
What type of smooth muscle has “pacemaker activities”?
Unitary (single-unit) smooth muscle similar to uterus, GI tract, ureter and bladder
What is another name for the substance secreted by endothelial cells to relax smooth muscles– EDRF endothelial derived relaxing factor?
Nitric oxide
What are the contents of these synaptic vesicles
- Small clear synaptic vesicles
- Small with dense core
- Large with a dense core
- Small clear synaptic vesicles: ach, glycine, GABA, glutamate
- Small with dense core: catecholamines
- Large with a dense core: neuropeptides
Before a vesicle fuses with a presynaptic cell membrane to release contents what proteins must lock together?
Synaptotagmin-1 is localized to synaptic vesicles and is the trigger for their calcium-induced exocytosis. Activation causes the fusion of the SNARE complex detailed below
Synaptobrevin (V SNARE) in the vesicle membrane locks with syntaxin and SNAP 25 (T SNARE) in the terminal cell membrane; GTPases regulate a multiprotein complex that includes Rab and Sec1/Munc18-like proteins as part of the fusion process.
How does the MOA of the two clostridium species vary?
Tetanus toxin binds irreversibly to the presynaptic membrane of the neuromuscular junction and uses retrograde axonal transport to travel to the cell body of the
motor neuron in the spinal cord. From there it is picked up by the terminals of presynaptic inhibitory interneurons. The toxin
attaches to gangliosides in these terminals and blocks the release of glycine and GABA.
Botulinum
toxins A and E cleave synaptosome-associated protein-25 (SNAP-25). This is a presynaptic membrane protein needed for fusion of synaptic vesicles containing acetylcholine to the terminal membrane, an important step in transmitter release.
Botulinum toxin B cleaves synaptobrevin, a vesicle-associated membrane protein (VAMP). By blocking acetylcholine release at the neuromuscular junction, these toxins cause flaccid paralysis.
Slow post synaptic potentials are usually due to manipulation of the conductance of which ion channel?
Potassium
What is the inhibitory neuron in the spinal cord and what does it secrete? How about in the cerebellum?
Renshaw cell– glycine
Basket cells
The entry of what ion triggers the release of Ach from the vesicles of the presynaptic junction?
Calcium (Voltage gated ion channels open when motor neuron action potential is activated)
What ion channels are blocked in Lambert Eaton Syndrome?
Presynaptic voltage gated Calcium ion channels