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87 Cards in this Set
- Front
- Back
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What are photoreceptors?
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Receptors that respond to light
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What do photoreceptors do in response to light?
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Hyperpolarize
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In photoreceptors, what generates the receptor potential?
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Cyclic guanosine 3-5 monophosphate (cGMP) second messenger cascade
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What signal stimuli causes tissue damage?
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Nociceptors.
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K+, Histimine, bradykinin, H+, ATP, serotonin are released by what?
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Noxious Stimuli
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When you are poked by a sharp object, what receptor is responsible for the pain?
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Mechanical nociceptors
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What activates Thermal nociceptors?
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heat extremes (>45C or 5C) and by strong mechanical stimuli
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What receptors innervate the tooth pulp?
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Polymodal nociceptors
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What receptor is responsible for a slow burning pain.
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Polymodal nociceptors
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In slow burning pain, are the fiber mylenated or unmylinated?
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Unmyelinated
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T or F
When discussion vision receptors, there are only one type of receptors responsible for all wavelengths of vision |
False
different photoreceptors are sensitive to different wavelengths |
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T or F
Hair cells and auditory nerves are tuned to specific frequencies |
True
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T or F
The SIZE of a stimulus effects the number of receptors stimulated |
TRUE
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Does the density of receptors in a given area matter in determining the number of receptors stimulated?
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Yes, of course if there are more receptors there are more that can be stimulated.
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What is the sensory threshold?
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The lowest stimulus strength a subject can detect. (in expierments this is defined as the amplitude detected in HALF trials)
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Why are changes in sensory threshold important?
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They can be used to DX diseases
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If a receptor responds to a wide range of stimulus intensities what will it perform?
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A log transformation- it will convert the initial stimulus engery into a receptor potential
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What will the range of response be for a receptor that operates over a narrow range?
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Linear fashion
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What happens to a slow adapting receptor?
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it will respond to a prolonged stimulus with a prolonged depolarization and action potential firing.
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What happens in the case of a rapidly adapting receptor?
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It will stop firing during a constant stimulus and it is only active when stimulus intensity increases or decreases
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What is the name of a rapidly adapting mechanoreceptor found in the skin, joint capsules, and the mesentery of the gut?
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Pacinian Corpuscle
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Where are Pacinian Corpuscle mechanoreceptors found?
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Skin, joint capsules, and the mesentery of the gut.
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In the pacinian corpuscle what surround the nerve terminal?
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Several layers of fluid filled connective tissue lamellae (like an onion)
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Referring to Pacinian Corpuscle what happens at a steady pressure?
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the receptors fire action potentials at the start and the end of a constant stimulus
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Refering to Pancian Corpuscle, what happens in response to vibrating stimulus?
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the receptor fires at each stimulus cycle.
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What will the timing of the action potential depend on?
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The threshold and refractory period
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What determines the speed at which signals are carried to the CNS?
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The size (diameter)
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Where do touch, proprioception, nocioception, and temperature sense project to?
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Dorsal Root Ganglion
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What does the Dorsal Root Ganglion neurons do?
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Convey all somatosensory information from the limbs and trunk.
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What do rods detect?
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dim light and low acuity
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T or F
Few rods synapse onto a bipolar cell |
False
MANY rods synapse onto a bipolar cell |
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Where are cones concentrated?
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Fovea
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What is the function of cones?
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color vision
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T or F
Few cones synapes onto a bipolar cell |
TRUE
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T or F
Rods and cones respond to light with graded changes in receptor potential |
TRUE
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What are the 3 parts of a photoreceptor?
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outer segment
Inner segment synaptic terminal |
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What portion of the photoreceptor contains photopigment rhodospin/cone pigment
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Outer segment
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What portion of the photoreceptor contains nucleus and biosynthetic machinery?
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Inner segment
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What portion of the photoreceptor makes contact with the target cell?
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synaptic terminal
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How many steps are in phototransduction?
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4
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Referring to steps in phototransduction:
In photoreceptors what gates the cation channel? |
cGMP
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In phototransduction, what happens in step one when the cation channel opens?
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Allows Na+ to flow into the cell.
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In Step 1 of Photoreception, when is cGMP concentration high?
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In the dark
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In Step 1 of Photoreception, when the cGMP concentration is high, what happens to the channels?
Is cell depolarized or hyperpolarized? |
it keeps them open.
This is called the DARK CURRENT depolarized (-40mV) |
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What happens in step 2 of Phototransduction?
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Light stimulates cGMP phosphodiesterase and cGMP concentration decreases
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Name the 3 methods used to control channel gates
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Voltage, mechanical, and chemical
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What are symptoms of Ca2+ channel defect?
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Migrains, malignant hyperthermia, and neuromuscular disease
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Name the defects linked to K+ channel defects
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deafness and cardiac abnormalities
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What disease is related to Cl- channel mutations?
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cystic fibrosis
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What is responsible for the opening and closing of channels?
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Gates
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When referring to diffusion, which way do the molecules travel?
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High concentration to low concentration
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What kind of molecules can cross the membrane by diffusion?
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lipid soluble
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What acts as a carrier in facilitated diffusion?
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protein
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Is facilitated diffusion active or passive?
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Passive
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What occurs when a substance reaches a maximum level?
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Saturation
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What does Tm mean?
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Maximum rate of transportation in facilitated diffusion (all binding sites are occupied)
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What is the function of a protein in primary active transport?
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they serve as pumps
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What direction are molecules transported in primary active transport?
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Uphill
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T or F
When referring to Active Transport saturation occurs at high concentration |
true
due to lack of additional protein |
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How many Na+ ions are pumped out or every 2 K+ pumped in?
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3
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What do cardiac glycosides do?
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Block Na+/K+ pump
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Where is Ca2+ATPase found?
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sarcoplasmic reticulum, mitochondrial membrane, and plasma membrane
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What does the Ca2+ATPase do?
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maintains intracellular Ca+ low by pumping it against electrochemical gradient
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How many Ca2+ are transported per molecule of ATP?
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1-2
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What initiates muscle contraction?
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Ca2+
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What is responsible for release of neurotransmitter at the synapse?
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Ca2+
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What regulates gene expression and cytoplasmic enzymes?
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Ca2+
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Where is H+/K+ ATPase found?
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In gastric mucose (parietal cells)
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What is found in the renal collecting duct?
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H+/K+ ATPase
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What pumps H+ into stomach?
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Parietal cells
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What does Omeprazole do?
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Blocks the parietal cells from pumping H+ into stomach
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What happens to H+ in the renal tubes?
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it is secreted into the urine from the blood
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What is the transport of 2 or more solutes , which indirectly use ATP called?
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Secondary Active Transport
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What is typically needed in secondary active transport to transport the ion?
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Moving Na+ down its electrochemical gradient
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Symport is also know as what?
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Cotransport
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What is it called when solutes are transported in the same direction as Na+?
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Symport
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What is it called when solutes move in the opposite direction as Na+?
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Countertransport
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When referring to countertransport, what must the carrier protein bind to on the outside of the cell?
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Na+
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When referring to countertransport, what must the carrier protein bind to on the inside of the cell?
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Ca2+
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What is the resting membrane potential?
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electrical potential gradient across the cell membrane
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What is the usual measurement of RMP?
What are the exceptions? |
-70mV
Retinal -40mV Skeletal muscle -90mV |
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What does it mean to be osmotically balanced?
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At RMP the solutes outside=solutes inside
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What is the net movement of ions at RMP?
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NONE
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If 2 solutions are separated by semi-permeable membrane what causes the movement of the solutes?
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osmotic pressure
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What is it called when 2 solutions have the same osmolarity?
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isosomotic
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What is an Action Potential?
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rapidly propogating electrical wave
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It referring to action potential, what does it mean to become depolarized?
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less negative
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