Bio 240 Test 5 Spring 2024 Study Sheet

Flashcards covering the Peripheral Nervous System, Cranial Nerves, Sense Organs and related topics from Bio 240 Test 5 lecture notes.

Cranial Nerves

Nerves connected directly to the brain or brainstem, numbered by the order in which they emerge from anterior to posterior; can be sensory, motor, or both.

Trigeminal Nerve

Cranial nerve V; Sensory: skin of head & face, gums & teeth; Motor: muscles of mastication; Disorder: Trigeminal Neuralgia / Tic Douloureux [painful twitch]

Facial Nerve

Cranial nerve VII; Sensory: taste buds / anterior ⅔ of tongue; Motor: muscles of facial expression; Disorder: Bell’s Palsy / drooping of ½ face / facial paralysis

Vagus Nerve

Cranial nerve X; Longest cranial nerve: stretches from brain stem to intestines; Sensory & Motor to: pharynx, larynx, trachea, heart, lungs, esophagus, stomach, intestines & gallbladder

Cranial Nerve Zero

Detects pheromones; Sexual signals, social signals, dormitory syndrome in the absence of males.

Acetylcholine

All preganglionic neurons release this neurotransmitter.

Norepinephrine

Most sympathetic postganglionic neurons release this neurotransmitter.

Fight or Flight

Response to physical danger, job or relationship stress involving sympathetic effects such as increased heart rate, constricted skin blood vessels, and dilated skeletal muscle blood vessels.

Cortisol

Hormone released in stressful situations; e.g., Smoking: ↑ Cortisol by 77% >> Immune problems; ↑ Adrenalin by 84% >> ♥ Heart attack

Sense Organs / Receptors

Specialized structures of the nervous system able to respond to external or internal stimuli by producing an action potential.

Somatic Senses / General

Distributed throughout the body densely or sparsely; Relay sensations of touch, pressure, temperature, pain.

Special Senses

Grouped in the tongue, nose, eyes, ears; Produce sensations of taste, smell, sight, sound, and balance /imbalance.

Sensory Adaptation

In response to continuous stimulation, the magnitude of the receptor potential decreases, sensory impulse conduction slows down, and intensity of the sensation decreases.

Fast Adapting

Touch, temperature, smell, light, sound, pressure, taste

Slow Adapting

Pain, proprioceptors / stretch receptors

Mechanoreceptors

Respond to mechanical force that in some way moves or changes the shape or position of receptors. e.g., hearing & touch, pressure / blood vessels, skin; stretch / muscles, tendons, lungs, balance.

Chemoreceptors

Respond to amount or changing concentration of chemicals e.g., taste & smell (tastants & odorants) also monitor blood levels of glucose, CO2, O2, H+ / Hydrogen ions (acidic)

Thermoreceptors

Found everywhere; respond to changes in temperature.

Photoreceptors

Located only in eyes; respond to light, if enough is present.

Baroreceptors (Osmoreceptors)

Concentrated in the hypothalamus; detect osmotic pressure or osmolarity (ionic concentration or concentration of electrolytes in body fluids).

Nociceptors/Pain Receptors

Respond to “noxious” stimuli (intense stimuli of any type that results in tissue damage) due to toxic chemicals, intense light, sound, pressure, or heat.

Referred Pain

Originates from deep structures and is referred to surface areas; Theory: Somatic neurons & sensory autonomic neurons share same interneurons / synapses in spinal cord

Free Nerve Endings

Simplest, most common receptors; Respond to pain, itching, tickling, touch, temperature, movement, stretch.

Encapsulated Nerve Endings

Touch & pressure receptors, e.g, Meissner’s corpuscles: light touch; fingertips; Pacinian corpuscles: deep pressure& stretch; deep dermis of skin; Merkel’s disks: light touch, 2 point discrimination.

Golgi Tendon Organ

Proprioceptor / prevents muscle & tendon injury

Muscle Spindle

Proprioceptor / prevents muscle & tendon injury

Olfactory Receptors

Chemoreceptors for our sense of smell; specialized bipolar neurons, only neurons to regenerate throughout adult life.

Anosmia

Loss of sense of smell from infection, injury (concussion), cigarette smoking (immobilizes cilia), cocaine use, zinc deficiency, genetics.

Gustatory Receptors

Chemoreceptors for our sense of taste

Ear Receptors

Receptors: hair cells / mechanoreceptors; shape is changed by stimulus of sound waves or movement of otoliths; Mediate both hearing & balance (equilibrium)

Auricle/pinna

Outer ear

External Auditory Meatus

Ear canal

Tympanic Membrane

Eardrum

Ossicles

Malleus, incus, stapes

Auditory Tube/ Eustachian Tube

Connects ear to throat & equalizes pressure around eardrum

Semicircular Canals, Vestibule, Utricle, Saccule

Structures involved with equilibrium (balance)

Utricle & Saccule

Detects head position and movement

Organ of Corti

Contains hair cells (mechanoreceptors), tectorial membrane

Conduction Deafness

Problem anywhere in sound conduction pathway from: Damage to eardrum, Buildup of earwax, Fluid buildup, Otosclerosis, Scarring, Tumors, Disease, Infection, Injury

Nerve Deafness

Damage to hair cells, organ of Corti or neurons (cochlear nerve); Hair Cell Damage can be from: Loud noises, Excessive nicotine or caffeine, Infections of the ear, nose, throat; meningitis, Aging

Static Equilibrium

Vestibule; maintenance of body position relative to the force of gravity (Utricle & Saccule)

Dynamic Equilibrium

Semicircular Canals; maintenance of body position in response to sudden movement such as rotation, acceleration, deceleration

Sclera

Outer/Fibrous Layer

Cornea

Most anterior transparent part of the eye

Choroid

Middle/Vascular Layer containing blood vessels, pigments, ciliary body, suspensory ligaments, lens & iris.

Iris

Muscle controlling (pupil size & thus) amount of light entering the eye. The colored part of the eye.

Retina

Inner/Nervous Layer containing Photoreceptors (rods & cones); continuous with Neurons & optic nerve (CN II); fovea centralis & retinal blood vessels

Aqueous Humor

Clear, watery fluid that fills the space between the cornea and iris.

Vitreous Humor

Gel-like substance that fills the large space behind the lens; maintains shape of eye / interocular pressure & holds retina against the choroid

Conjunctiva

Mucous membrane lining that keeps eyes moist; can become inflamed (conjunctivitis/pink eye)

Lacrimal Apparatus

Produces “tears” constantly; contains lysozymes that clean the eyes.

Refraction

Bending of light by passing in order through the cornea, aqueous humor, pupil, lens, vitreous humor.

Accommodation of Lens

Lens shape, curvature is changed by the muscles of the ciliary body thus focusing the image on the retina’s fovea centralis.

Constriction or Dilation of Pupil

Circular fibers of iris constrict pupil for near vision; radial fibers of iris dilate pupil for far vision

Rhodopsin

Rods contain a photopigment/visual purple made by vitamin A; broken down by bright light.

Rods

Responsible for night vision; sensitive to dimly lit images, black & white images, movement, peripheral vision

Fovea Centralis

Small depression in the retina with a high concentration of cones

Optic Disk

Where the nerves and blood vessels exit/enter the eye, causing a normal “blind spot”

Vitamin A

Blindness due to _ deficiency causes loss of transparency of cornea

Cataracts

Degenerated lens proteins / makes lens cloudy

Glaucoma

Fluid pressure buildup under the cornea because the aqueous humor can’t drain

Floaters

Calcium granules floating in vitreous humor casting shadows on retina

Lens

Key concepts: Changes shape to focus images on fovea centralis of retina

Vitreous Humor

Key concepts: Maintains interocular pressure & eye shape

Retina

Key concepts: Contains photoreceptors & neurons and is continuous with the optic nerve to receive light input and send messages to brain