Unit 5: Peripheral Nervous System (PNS)

epineurium

surrounds entire nerve with multiple fascicles and blood vessels

perineurium

surrounds a set of nerve fiber bundles

endoneurium

surrounds individual nerve fiber

shingles

viral infection caused by chickenpox's virus

analgesia with ibuprofen vs. aspirin

pain relief through analgesics

Aspirin inhibits prostaglandins and production to reduce pian signals' intensity. Used commonly for headaches

cerebral palsy

damage to developing brain due to meningitis

Parkinson's disease

progressive loss of dopaminergic neurons leads to tremors

reflex

automatic/predictable response to stimulus for homeostasis/protection

somatic reflex

voluntary reflex that controls Skeletal muscles

autonomic reflex

involuntary reflex that controls smooth muscle, cardiac muscle, and glands (I.e., heart rate)

monosynaptic reflex arc

1 synapse with sensory neurons directly synapsing onto the motor neurons

polysynaptic reflex arc

2+ synapses with interneurons (slower)

stretch reflex

a muscle contracts in response to a stimulus (I.e., quads contract when the patella is tapped)

flexor reflex

a limb is withdrawn for protection (I.e., hand on hot stove or foot on sharp) & polysynaptic

reasons to test reflex

to test for abnormalities of the PNS, spinal cord, and nerves → abnormality = spinal cord injury, nerve damage, or neurological disorder

patellar reflex

tests L2-L4 & femoral nerve function, is monosynaptic

1) The knee is tapped.
2) The quads stretch, sending a signal to muscle spindles/stretch receptors.
3) Sensory neuron carries signal to the spinal cord.
4) Sensory neuron directly synapses to motor neuron.
5) Motor neuron sends signal to quads to contract and kick up.

autonomic NS

AAUT (autonomic = automatic, unconscious, targets organs)

has 2 neurons in a chain (pre/post ganglionic), using both ACh and norepinephrine

controls behavior & the endocrine system, maintains homeostasis

** contains both the sympathetic & parasympathetic NS

somatic NS

SAME (somatic = ACh, motor control, exact movement)

1 motor neuron from CNS to muscle with direct synapse from ACh

sympathetic NS (belongs to autonomic NS)

for fight/flight (Stress, Speed up)
efferents exit CNS from spinal cord b/w T1 & L2

pupils: dilate
heart rate: increases
inhibits: secretion of gastrointestinal tract glands
bronchi: dilates for air
triggers: orgasm
inhibits: pee

has antagonistic and cooperative effects with the parasympathetic NS

parasympathetic NS

rest/digest (Poo, Pee, Peace)

efferents exit CNS via CN3, 7, 9, 10, or from sacral spinal cord

pupils: constrict
heart rate: decreases
stimulates: secretion of gastrointestinal tract glands
bronchi: constrict for air
stimulates: erection
stimulates: pee & poo

SLUDD (saliva, lacrimation, urination, digestion, defecation)

conjunctivitis

inflammation of the conjunctiva caused by bacterial/viral infections, allergies, or irritants that cause redness, swelling, & discharge

glaucoma

eye condition that leads to optic nerve damage, common in 60+ year olds with gradual effects of loss on side vision in later stages

cataracts

when crystallin proteins in eye break down & clump together to cloud vision (due to eye injuries, diseases, or genetics) and can progress over time w/ issues of night vision, astigmatism, sensitivity to light/glare,and double vision. It can only be treated through surgery with aging and diabetes as highest risk factor

detached retina

retina separates & causes blurred vision -> blindness. Symptoms are increases in floaters, flashes of light, darkening of FOV, and peripheral vision loss. Occurs due to age, eye injury, myopia (nearsightedness), eye surgeries, etc.

myopia

cornea too curve or eyeball too long, causing light to focus in front of retina & not on

diverging lens spreads light out before they enter eye

myopia = minus lens

see close clearly, can’t see far

hyperopia

cornea too flat or eyeball too short, light focuses behind retina

converging lens bends light in to help focus on retina

hyperopia = plus lens

can see far, not close

astigmatism

cornea/lens shaped like football causing uneven focus → blurred edges around lights

cylindrical lens compensates for football shape

color blindness

1+ cones are absent/not working most likely due to genetics w/ red-green color blindness being most common

night blindness

damaged/insufficient rods → bad night vision b/c of Vitamin A deficiency, retinitis pigmentosa, or genetic disorders

corneal transplants’ success

cornea is immune-privileged with no blood/lymphatic vessels, so transplanted cornea can’t be rejected or attacked by immune system despite being foreign

eyelids, eyelashes, and eyebrows’ function

protect eyeballs from foreign objects, perspiration, and sun rays (eyelashes/eyebrows)

eyelids shade/protect & spread lube over eye

pupil size regulation

iris regulates how much light enters by adjusting pupil size

constriction = parasympathetic NS & for bright light
dilation = sympathetic NS & for low light

Vertebrae & nerves

“Come to learn smart concepts”

Cervical (8) - C8 exits above C7

Thoracic (12) - exits below each

Lumbar (5) - exits below each

Sacral (5) - exits through sacral foramen

Coccyxgeal (1) - near coccyx

root

2 branches connecting spinal nerve to cord (not mixed)

dorsal root takes sensory information, ventral root takes motor output

ramus

branches derive individually after roots exit spinal column (dorsal = posterior, ventral = anterior)

connects spinal nerves to autonomic ganglia

plexus

networks formed by ventral Rami of spinal nerves (cervical, brachial, lumbar, and sacral plexuses)

sensation

conscious/subconscious detection of changes internally/externally

perception

conscious awareness and interpretation

sensory modality

type of sensation (two types: general & special senses) & brain distinguishes which senses based off where the sensory neurons synapses

sight = occipital lobe
hearing = temporal lobe
touch = postcentral gyrus

general modality

somatic and visceral senses (from touch, pressure, pain, temperature)

special senses

specialized receptors for 5 senses and for equilibrium & spread throughout the head, complex organs, eyes, nose, ear, and tongue

how a sensation turns into a perception

“Silly turtles get cold in Canada”

Sensation: A sensation is detected by the receptors.

Transduction: Receptor converts stimulus into a graded potential.

Generation: Graded potentials are generated. If threshold is reached, an action potential is generated.

Conduction: Action potential travels to the central nervous system.

Integration: Central nervous system integrates and it leads to a perception if it’s a conscious change resulting from the actin potential.

Receptors for sensation

free nerve endings are for pain, touch, temperature, tickle, and itch sensations → AP generated

encapsulated nerve endings are dendrites wrapped in connective tissue for pressure, vibration, and touch → AP Generated

separate cells are specialized to synapse with the sensory neurons (hair, gustatory, and photoreceptors) → triggers neurotransmitters to diffuse with sensory neurons

Other receptors for sensation

exteroreceptors - external changes
interoreceptors - internal changes
proprioceptors - within muscles, joints, and inner ear
mechanoreceptors - mechanical energy
thermoreceptors - thermal energy
nociceptors - detection of pain
photoreceptors - changes in light
chemoreceptors - chemical energy
osmoreceptors - osmotic changes

adaptation