Physiology 2 Exam 1

Rods

Low threshold, function in low light conditions, Use Rhodopsin

Cones

High threshold, 3 wavelengths; red, blue, green, Use photopsin

4 layers light passes through to reach cones and rods

Cornea, Aqueous humor, Lens, Vitreous humor

Light Transduction

Light energy converted into electrical signal

what does depolarization of Bipolar cells do

Stops inhibition so that action potential can occur

Pigmented cells

Utilize melanin to absorb light

Photoreceptor cells

Rods and Cones

Bipolar cells

relaty information to ganglion cells

Ganglion cells

axons make up the optic nerve

Horizontal vison cells

provide for lateral inhibition, increasing contrast

Where do ganglionic cells exit

Optic Disc

Where does the vision pathway synapse in the thalamus

Lateral geniculate nucleus, Primary visual cortex

T/F Temporal visual field crosses in optic chiasm

TRUE

T/F Nasal visual field crosses in optic chiasm

FALSE

which eye muscle is innervated by CN 6

Lateral rectus

Which eye muscle is innervate by CN 4

Superior Oblique

Convex Lens

Focuses light

Concave lens

Diverges or spreads light

Hyperopia

farsighted, fixed with convex lens

Myopia

Nearsighted, fixed with concave lens

Frequency

pitch of the sound

Amplitude

volume of sound

Order that vibrations cross in the Cochlea

VMT, Scala vestibuli-media-tympani

Human Hearing Range

20-20,000 Hz

Presbycusis hearing range

50-8,000 Hz

Does the tectorial membrane move

No, stays stationary

Does the Basilar membrane move

Yes, in optimal range

would it take a higher frequency to hear at the base or at the apex

BASE

Hearing Pathway

CN 8, SIMP

Utricle

horizontal acceleration

Saccule

vertical acceleration

Semicircular canals

angular acceleration, not affected by gravity

If steriocilia bends toward kinocilium is it excitatory or inhibitory

Excitatory

Crista Ampullaris

Houses hair cells which do the transduction in semicurlular canals

What stimulates hair cells found in the crista ampullaris

Endolymph movement

Anterior Semicircular ducts

Flexion and extension

Posterior Semicircular ducts

Lateral bending, most effected in Vertigo

Lateral Semicircular duct

Rotation left and right

Control centers for the vestibular pathway

CN 3,4,6,11 Spinal cord, cerebellum, Thalamus

Salty taste

Rely on Na+ (sodium)

Sour taste

Rely on H+ (acidic)

Sweet/bitter/umami taste

Rely on G protein receptors

T/F olfaction is more specific than taste

TRUE

Chemoreceptors of Olfaction

Rely on g-protein receptors

Does the olfactory pathway synapse in the thalamus

NO

Lateral tract of olfactory pathway

Goes to ipsilateral cortex and limbic system

Medial tract of olfactory pathway

Goes to contralateral cortex

Somatic Sensation

The route nerves take to relay sensory info from the body

Sensory Transduction

Conversion of an environmental stimulus to electrical impulse

Where does sensory transduction occur?

At the receptor, 1st order neuron

does activation occur during Depolarization or hyperpolarization?

Depolarization, Na+ influx to meet threshold

Will a Cl- influx or a K+ exit cause an activation to occur?

NO, only Na+ influx

Pacinian (Lamellar) Corpuscle

Fasted adapting, sense vibration, large receptive field, and located in dermis

Meissner (Tactile) Corpuscles

Rapidly adapting, sense precise touch, small receptive field, located on fingertips and lips

Ruffini Corpuscle

Slowly adapting, found in joint capsule, sense stretch, large receptive field

Merkel Receptors (Discs)

Slowly adapting, found in dermis-epidermis junction, senses light touch/pressure, small receptor field

difference between a strong and weak stimulus

Strong stimulus has a high frequency of action potentials firing

Free nerve endings common features

Non-encapsulated, present everywhere in body, Connected to TYPE A-DELTA, and C fibers

When do we find dense concentrations of nociceptors

Skin, joints, periosteum, arterial walls(headaches)

Where do we find low concentrations of nociceptors

Deep tissue (Visceral), Brain, GI tract

Fast Pain (first pain)

sharp and well localized, Travels in A-delta fibers, small receptor fields

Slow Pain (Aching)

Poorly localized, travels in C fibers of Paleo-spinothalamic tract, large receptor fields

Examples of Fast pain

skin cut, bone fracture, heavy impact of an object

Examples of Slow pain

inflammation, burned skin, ischemia

Warmth Thermoreceptors

Transduce temperature between 86-120 degrees, TRPV transduces heat, also transduces capsaicin in spicy foods

Cool Thermoreceptors

Transduce warm temperatures between 42-109 degrees, TRPM transduces cool, also transduces menthol and topical pain relievers

What fibers are cool stimuli found in

A-delta fibers

What fibers are warm stimuli found in

C-fiber

Tickle free nerve endings

located exclusively to superficial skin, very low threshold

Example of tickle receptors

Mosquito landing on arm and swatting it away

Itch free nerve endings

Respond to chemical stimuli, most importantly Histamine

Which sensory fiber classification uses both motor and sensory information

Erlanger's

Which sensory fiber classification is used for proprioception

LLoyd's

Erlanger's A alpha fibers

Muscle spindles- sensory, alpha motorneuron

Erlanger's A beta fibers

(fine) touch and vibration

Erlanger's A gamma fibers

muscle spindles, Motor (intrafusal muscle fibers)

Erlanger's A delta fibers

fast pain, crude touch, deep pressure, cold temp

Erlanger's B fibers

Preganglionic autonomic

Erlanger's C fibers

Slow pain, heat, tickle, olfaction, postganglionic autonomic

Lloyd's Ia fibers

muscle spindle afferents (nuclear bag)

Lloyds Ib fibers

Golgi tendon organ afferents

Lloyds II fibers

discriminative touch, vibration, muscle spindle afferents (nuclear chain)

Lloyds III fibers

crude touch, pressure, fast pain, temp

Lloyd's IV fibers

Slow pain, olfaction

T/F Lloyd's sensory system sense both motor and sensory

False, only sensory

Modalities carried in Dorsal Column-Medial Lemniscal pathway

Fine touch, Vibration, Conscious proprioception

Infow coming into dorsal column-medial pathway below T6

Gracilis, lower extremities

Info coming into dorsal column-medial pathway above T6

Cuneatus, Upper Extremities

In DCML pathway characteristics of sensory info

Composed of A-beta fibers, Rapid Speed, well localized (except vibration)

1st order neuron in DCML pathway

originates in dorsal root ganglion, ascends to either nucleus gracilis or cunaetus

2nd order neuron in DCML pathway

Crosses in medial lemniscus, synapses VPL of thalamus

3rd order neuron of DCML pathway

goes from VPL of thalamus to primary somatosensory cortex

4th order neuron of DCML pathway

synapses in somatosensory cortex

Fibers carried in Anterior Spinothalamic pathway

Mostly A-delta fibers, C-fibers(tickle and itch)

Modalities carried in Anterior Spinothalamic pathawy

Crude touch, tickle and itch, sexual sensation

1st order neuron in Anterior spinothalamic tract

Originate in dorsal root ganglion, synapse in dorsal horn

2nd order neuron in Anterior Spinothalamic tract

Immediately crosses to other side and synapses in VPL of thalmaus

3rd order neuron in Anterior Spinothalamic tract

VPL of thalamus to primary somatosensory cortex

Fibers used in Lateral spinothalamic tract

A-delta, C- FIbers

Modality carried in Lateral spinothalamic tract

Pain and temperature