- "jumping" of action potential to speed it up - Na+ ions push each other through myelinated sections, impulse is only truly propagated through nodes of ranvier

Intro to Anatomy Flashcards by Ethan Jones

What is a neuron’s resting membrane potential?

-65mv

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what is the threshold potential of a neuron?

-55mv

Na+ channels open at start of axon hillock
chain reaction down the axon
inside charge becomes around +40mv

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hyperpolarized: relative refractory period (charge?)

Na+ channels closed (not inactive), K+ channels still open
membrane is now -75 mv
once K+ channels close, membrane potential returns to -65

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Saltatory conductin

“jumping” of action potential to speed it up
Na+ ions push each other through myelinated sections, impulse is only truly propagated through nodes of ranvier

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Cranial Nerves Acronym

Oh Oh Oh To Try At Futbol
Victor Goes to Vagus And Hides

Only One Of The Two Athletes Felt Very Good, Victorious, And Healthy

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CN Functions Acronym

Some Say Marry Money But My Brother Says Big Brains Matter Most

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CN 1

Olfactory (S)

-smell
-test by having patient smell something strong with eyes closed (cinnamon)

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CN II

Optic (S)

-vision

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CN III

Oculomotor (M)

-movement of eye
-pupil constriction
-lens accommodation (follow finger)
-raises upper eyelid
-elevates and abduct (out), depress and adduct, and just adduct the eye

-drooping eyes? CN III might be the issue

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CN IV

Trochlear (M)

-movement of eye
-abduct, depresses and internally rotates eye

-test CN III, IV, and VI by following a finger

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CN V

Trigeminal (B)

-3 branches:
-V1: ophthalmic: sensory to upper eyelid, nose, forehead and scalp
-V2: maxillary: sensory to maxilla, nasal cavity, palate and skin of cheeks
-V3: Mandibular:
-Motor: chewing muscles
-sensory: lower lip, lower teeth, chin and temporal region of scalp, anterior 2/3 of tongue

-can you feel me touch your face and bite down?

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CN VI

Abducens (M)

-motor of the eye
-abduction (!) of the eye

-if everything else is okay except abduction in test, pinpoint VI

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CN VII

Facial (B)

-5 extracranial branches
-temporal
-zygomatic
-buccal
-mandibular
-cervical
-innervate muscles in charge of facial expression (smiling/frowning)
-bels palsy or stroke

(F-five, F-Facial)

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CN VIII

Vestibulocochlear nerve (S)

-2 branches:
-vestibular: equilibrium receptors
-cochlear: hearing receptors

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CN IX

Glossopharyngeal (B)

-motor: elevates pharynx during swallowing (parasympathetic motor fibers to salivary glands)

-Sensory: taste from posterior 1/3 of tongue
-touch and pain from pharynx (sore throat)

(more next chapter: also plays a role in chemoreceptors in the carotid bodies for respiration and baroreceptors of carotid sinus for BP monitoring)

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CN X

Vagus (B)

-Only CN that extends past the neck
-somatic motor innervation to muscles of pharynx and larynx involved in swallowing
-parasympathetic fibers to the heart, lungs and abdominal organs to help regulate heart rate, breathing, and digestion

-swallowing, uvula movement (if uvula is stuck in the right position, think issue is with the left side)

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CN XI

Accessory Nerve (M)

-Innervates trapezius and SCM muscles (sternocleidomastoid [large muscle in front of neck])

-shrug test

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CN XII

Hypoglossal nerve (M)

-motor: muscles of the tongue
-sensory: proprioceptive info from the tongue (movement, action, location)

-actually superior to CV XI

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Quadrants: RUQ

liver, gallbladder, head of pancreas, part of large intestine (transverse), duodenum, adrenal gland (ad to renal aka on top of kidney), kidney, ureter

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LUQ

Stomach, large/transverse, spleen, kidney/adrenal/ureter, pancreas

-epigastric: pancreas, stomach

RLQ & LLQ

Reproductive organs (uterus, ovaries), bladder, distal ureters, small intestine
-RLQ: appendix

Anterior and posterior are also known as:

Ventral and dorsal, respectively (dorsal fin)

ipsilateral/contralateral

same side/different sides

Superior/inferior are also known as:

cranial/caudal

abduction vs adduction

abduction: away from the body adduction: towards the body

palpation vs percussion

palpation: pressing on body surface percussion: tapping

Why are all cell bodies are found in the CNS (or near it)?

Better protected compared to arms and legs

Why are there no nodes of ranvier in the CNS? (??????????????) was ruzga wrong

No Schwann cells (oligodendrocytes) -White matter is found in the brain/spinal cord and appears white due to myelin (which is the result of oligodendrocytes)

Polarization is what kind of potential?

Resting

What stops a neurotransmitter from repeatedly firing?

Enzyme might break it down (cholinesterase) or reuptake and reuse

What would you notice about a patient who has damaged myelin?

Slower moving

Are most synapses excitatory or inhibitory?

Excitatory (causes action potential)

What happens at an inhibitory synapse?

neurotransmitter causes the postsynaptic neuron to hyperpolarize -neuron membrane becomes more positive outside as K+ ions leave or Cl- enter the cell (no impulse) (essentially keep the neuron below threshold level)

Why are inhibitory synapses important?

For slowing the heart rate balancing the excitatory impulses transmitted to skeletal muscles prevents excessive contraction

types of neurotransmitters in PNS // CNS

PNS: Ach, NE, Epi CNS: Dopamine, GABA, NE/Epi, Glutamate, Serotonin, Substance P

Within the CNS, a bundle of pathway axons is called a BLANK (white matter)? In PNS?

CNS: Tract PNS: Nerves (ex. spinal nerves/cranial nerves)

Where do neurons exit in different spinal regions?

C1-C7 exit OVER corresponding vertebrae C8 exits below C7 (no C8 vertebrae) T1-S5 and coccyx exit below

If you do not know where your limbs are in space and can’t use sensory receptors to send information, could be injury in which root?

Dorsal (afferent/sensory)

what are the optimal spots for reflex testing?

Biceps Brachioradialis Triceps patellar Achilles

Classification of reflexes

1. development -innate reflex or acquired reflex 2. response -somatic (deep or superficial) or autonomic (visceral) 3. complexity -monosynaptic (somatic, stretch reflex) or polysynaptic (visceral) 4. processing site -Spinal cord reflex -Cranial reflex

Muscle tone and efferent nerves

If efferent nerve is damaged/severed, the muscle will be flaccid/hypotonic If efferent nerve is continuously stimulated (no inhibition) the muscle will be hypertonic (spastic)

Polysynaptic reflex example:

Withdrawal reflex (painful stimulus to foot, plantar surface) -multiple interneurons (stimulatory and inhibitory) -stimulates the hamstring to contract, inhibits the quadriceps from contracting

Why is prescribing medication to a poor metabolizer dangerous?

Meds can buildup in the body

What general factors might induce or inhibit metabolic enzyme systems, particularly CYP 450

Meds, food, and diet supplements

Phase I of drug metabolism (CYP 450)

CYP 450 enzymes carry out oxidation, hydrolysis, or reduction to convert non-polar, lipid-soluble meds into more polar, water-soluble metabolites (preparing for excretion)

Phase II

Conjugation reactions (joined with another compound, like methyl group, acetyl group, etc.) creating highly polar, water-soluble metabolites that are trapped in urine and excreted

T or False: Phase I and Phase II can occur together, in either order, or separate (not necessarily both need to occur)

CYP 450 inhibition example: Warfarin

CYP 450 inhibitors (ex. grapefruit juice) can block the metabolism of Warfarin and cause buildup in the blood Since warfarin is an anti-coagulant, this can cause severe bleeding

Clarification about myocyte action potential

When the charge inside the cell reaches about +20, and Phase 1 aka initial depolarization occurs, K+ ions leave the cell while calcium ions rush in. Calcium ions are responsible for initiating and maintaining contraction of the heart, so the K+ ions can be thought of as a counterweight to the Ca2+ ions to maintain a heart beat