ASCI 4438 Lab Midterm

T or F: Nerves can be both sensory and motor

True

What section of the nervous systems is the cranial nerves in?

Peripheral nervous system

What is a nerve?

A bundle of neurons

Sensory neurons are...

Afferent

Motor neurons are...

Efferent

Afferent neurons have their cell bodies and dendrites located _____

peripherally

Afferent neuron's nerve terminal is located in _____

spinal cord

Efferent neuron's have their cell bodies located in the ______ and their nerve terminals located ______

spinal cord, peripherally

What happens when you block a nerve?

Prevention of an action potential

Where is sensation perceived?

Somatosensory cortex

T or F: The spinal cord in the fore and hind limbs is thicker and therefore need less innervation

False

T or F: The plexus is a interweaving mix of nerves

True

What plexus is in the forelimb?

Brachial plexus

What plexus is in the hindlimb?

Lumbosacral plexus

What nerves are in the brachial plexus?

C6-T2

What tears nerves in the brachial plexus?

Getting hit by a car (overextension)

What are pain receptors called?

Nociceptors

What nerve block did we give the horse?

Lidocaine

What does the palmar digital nerve block stop innervation to?

back 1/3 of hoof

What does abaxial nerve block stop innervation to?

All of hoof

What class is lidocaine in?

local anesthetic (class 1B antiarrhythmic)

What is the MOA of lidocaine?

Blocks voltage-gated Na+ channels so action potential cannot be produced

Name two others in Lidocane drug class?

Novacaine, Naropin

How is capillary refill assessed?

Blanching

How fast should capillary refill be?

Less than or equal to 2 seconds

What is skin turgor?

Skin elasticity

What is skin turgor assessing?

Hydration status

What is high heart rate called?

Tachycardia

What is a low heart rate called?

Bradycardia

What is a high respiratory rate called?

Tachypnea

What is a low respiratory rate called?

Brachypnea

What is pupillary constriction called?

miosis

What is pupillary dilation called?

mydrosis

What are the four cranial nerves involved with the eye?

optic, oculomotor, trochlear, abducens

What are the three layers of the eye?

Fibrous tunic, vascular tunic/uvea, nervous tunic

What is in the fibrous tunic?

Sclera + cornea

What is in the vascular tunic/uvea?

Choroid, ciliary body, iris

What type of tissue makes up the sclera and cornea?

Dense fibrous connective tissue that is rich in collagen

Why is the cornea clear?

Collagen fibers are uniform so light passes through

Why is the sclera white?

Collagen fibers are interwoven in random patterns that scatters light

What is the function of the cornea?

Refracts light to help focus on the retina

What is the condition called when there is an abrasion or scrape on the corneal surface?

Corneal ulcer

What is the function of the pupil?

Allow light to enter the eye

What is the difference between pupillary light reflex and accommodation?

the light reflex adjust pupil size based on light level and the accommodation changes pupil size based on if an object is far or near

What did you have to snip to remove the lens?

Suspensory fibers

What does the image look like when you look through the lens?

Inverted + upside down

Where are images processed?

Visual cortex of the occipital lobe

What is the clear jelly in the back of the eye?

Vitreous body

What are the 3 layers of cells in the retina?

Ganglion cells, bipolar cells, photoreceptors

What are the two types of photoreceptors in the retina?

Rods and cones

Where is the optic nerve headed?

Ganglion cell layer

What direction, with regard to AP, is it headed?

To the CNS, afferent

Where does vision actually take place?

Visual cortex in the occipital lobe of the cerebrum

What type of cell formed the myelin sheath in these axons making up the optic nerve?

Oligodendrocytes formed the myelin sheath

What is the colorful thing under the retina?

Tapetum

What layer is under the retina (meaning it is the forward-most layer of what)?

Vascular tunic

What are two species that don't have a tapetum?

Humans, squirrels/pigs

What cranial nerve drives tear production?

Facial

What is crying called?

lacrimation

What sedative was given during the ophthalmology lab?

Detomidine

MOA of Detomidine

alpha-2 adrenergic agonist, decreases norepinephrine release which decreases neurotransmitter firing resulting in sedation

Where are the alpha-2 adrenergic receptors?

Presynaptic neurons of CNS

Where is the nictitating membrane located?

medially between the eyeball and the eyelid

Three branches of trigeminal

opthalmic, maxillary, mandibular

Is the maxillary branch of the trigeminal afferent or efferent?

afferent sensory

Is the opthalmic branch of the trigeminal afferent or efferent?

afferent sensory

what is the efferent limb of the palpebral reflex?

Facial nerve stimulates blinking

What part of the brainstem is tested in the palpebral reflex?

Pons

What nerve near the eye did we block in the ophtamology lab?

auriculopalpebral nerve

What branch is the auriculopalpebral part of?

Facial nerve

What cranial nerves are tested through the menace response?

Optic and facial

What has the drug given for dilation of the eye

Tropicamide

What was the MOA for tropicamide?

parasympathetic muscarinic antagonist, blocks ACh