BIO 201: Chapter 4.6 and 4.7 Special Senses and Autonomic Nervous System

sensation

detection of changes in the internal and external environments which may be conscious or subconscious

perception

integration and interpretation of information that one is consciously aware of

vision, hearing, equilibrium, taste, and olfaction

special senses

touch, pain, and temperature

general senses

chemosenses

olfaction and taste are sometimes referred to as _____ because they rely on chemoreceptors to relay information about the environment to the brain

olfactory epithelium

small patch in the roof of the nasal cavity in which chemoreceptor of olfaction can be found

olfactory receptor cells

about 10-20 million bipolar neurons contained in the olfactory epithelium

CN I olfactory nerve

made up of the axons of olfactory receptor cells that penetrate holes in the cribriform plate

olfactory bulb

sends the impulses down the axons of the olfactory tract to the olfactory cerebral cortex

taste buds

taste receptors are located on about 4000 of these

lingual papillae

projections from the tongue which include 4 types

filiform papillae

most numerous, located on the surface of the tongue, its spiky surface gives the tongue its rough appearance

• plays role in sensing if food is chewed enough to shallow and senses food texture

fungiform papillae

sporadically scattered over the surface of the tongue and kind of resembles a mushroom

• plays role in sensing food texture

circumvallate papillae

large papillae located at the posterior aspect of the tongue in a V shape arrangement

• contains most of the tastebuds

foliate papillae

translate to “leaf-like” and are parallel ridges located on the lateral aspects of the tongue

• contain taste buds primarily during childhood

true

true or false: of the four types of papillae, all but filiform papillae house taste buds

salty, sweet, sour, bitter, and umami

primary tastes sensed by the taste buds

outer ear

begins with the auricle/pinna and includes the external auditory canal and the tympanic membrane

auricle/pinna

shell-shaped structure composed primarily of elastic cartilage that surrounds the opening to the external auditory canal

external auditory canal

extends about 2.5 cm into the temporal lobe and ends in the tympanic membrane

tympanic membrane

thin sheet of pearly gray epithelium and connective tissue that separates the outer ear from the middle ear

middle ear

small air-filled cavity within the temporal bone that houses the auditory ossicles

auditory ossicles

tiny bones that include the malleus, incus, and stapes which all transmit vibrations from the tympanic membrane to the inner ear

oval window

opening to the inner ear where ossicles transmit vibrations

• stapes is attached here

pharyngotympanic tube

also known as the auditory tube and functions to connect the middle ear to the pharynx and equalizes pressure in the middle ear

inner ear

contains the sense organs for hearing and equilibrium

bony labyrinth

cavities of the inner ear that are filled with a fluid called perilymph

• has 3 regions: vestibule, semicircular canals, and cochlea

membranous labyrinth

series of membranes within the perilymph that contain a thicker fluid called endolymph

vestibule

egg shaped bony cavity that houses two membranous structures responsible for equilibrium:

• saccule (sac)

• utricle (bag)

saccule and utricle

structures in the vestibule that transmit impulses down the vestibular nerve and are responsible for static equilibrium

static equilibrium

refers to maintaining balance when the body is not moving

semicircular canals

3 round and bony canals that house the semicircular ducts and ampullae

semicircular ducts and ampullae

membranous structures that transmit impulses down the vestibular nerve and work together with the organs of the vestibule to maintain rotational/dynamic equilibrium

rotational/dynamic equilibrium

ability to maintain balance when the body or head is moving

cochlea

spiral bony canal that contains the cochlear duct

spiral organ/organ of corti

structure whose specialized hair cells depolarize and transmit sound impulses to the cochlear nerve in response to sound wave vibrations

round window

hole in the lateral wall of the cochlea which plays a role in allowing perilymph in the cochlea to vibrate

palpebrae

covers the eye and meet medially and laterally at the medial and lateral canti

lacrimal caruncle

gland at the medial canthus that lubricates the palpebrae and anterior surface of the eyeball

tarsal plate

dense connective tissue at each palpebea

tarsal gland

sebaceous gland associated with each tarsal plate

lacrimal apparatus

one of the most prominent external structures of the eye which functions to produce and drain tears

starts at the lacrimal gland → to the lacrimal ducts that drain tears → tears accumulated from the eye drain into lacrimal canals near medial canthus → drain into the lacrimal sac → tears travel through nasolacrimal duct → empty into the nasal cavity

pathway of tears

palpebral conjunctiva

thin mucous membrane that lines the internal surfaces of the palpebrae

bulbar conjunctiva

the palpebral conjunctive curls around to become this which functions to line much of the eyeball’s superficial surface

conjunctivities

pink eye or inflammation or swelling of the tiny blood vessels found in the mucous membrane

• caused by viral or bacterial infection or an allergic reaction

levator palpebrae superioris muscle

elevates the upper eyelid to open it

orbicularis oculi muscle

closes the eyelid

lateral rectus muscle

moves the eyeball laterally (abduction)

• innervated by CN VI abducens nerve

medial rectus muscle

moves the eyeball medially (adduction)

• innervated by CN III oculomotor nerve

superior rectus muscle

moves the eyeball superiorly

• innervated by CN III oculomotor nerve

inferior rectus muscle

moves the eye inferiorly

• innervated by CN III oculomotor nerve

superior oblique muscle

rotates the eyeball inferiorly and slightly lateral

• innervated by CN IV trochlear nerve

inferior oblique muscle

rotates the eyeball superiorly and laterally

• innervated CN III oculomotor nerve

eyeball

hollow organ that is divided into two main portions of the anterior and posterior cavity

lens

crystalline structure that is the boundary of the anterior and posterior cavities in the eye which refracts light coming into the eye to focus it

anterior cavity

anterior to the lens and filled with a watery fluid called aqueous humor

scleral venous sinus

structure contained in the sclera that functions to drain aqueous humor

posterior cavity

posterior to the lens and contains thick fluid called vitreous humor which is present at birth and remains unchanged throughout life

fibrous tunic

outermost layer of the eyeball made mostly of dense irregular collagenous connective tissue, avascular, and consists of the sclera and cornea

sclera

white part of the eyeball that makes up 5/6 of the fibrous tunic and has numerous collagen fibers

cornea

clear structure that makes up 1/6 of the fibrous tunic and is deep/posterior to the conjunctiva

vascular tunic

also called the uvea, functions to carry most of the blood supply to the tissues of the eye, and consists of the choroid, ciliary body, and iris

choroid

highly vascular and makes up posterior part of the vascular tunic

• brown/black in color to prevent light scattering in the eye and provides oxygenation, nourishment, and waste removal to retina

ciliary body

thickened extension of the choroid at the anterior aspect of the vascular tunic that produces aqueous humor

ciliary muscle

smooth muscle that controls the shape of the lens via its fingerlike projections called ciliary processes which attach to the lena via suspensory ligaments

iris

pigmented and adjustable structure at the most anterior portion of the vascular tunic

iris sphincter muscles

make up the iris and are arranged around the pupil

• contract to perform pupillary constriction or pupillary dilation

anterior and posterior segments

the iris divided the anterior cavity into two smaller subdivisions where aqueous humor travels to called …

sensory/nervous tunic

deep layer that consists of the retina and the optic nerve

retina

thin, delicate structure that contains three layers of neurons

• photoreceptors, bipolar neurons, and ganglion cells

photoreceptors

detect light

• rods: responsible for vision in dim light, peripheral vision, and black and white vision

• cones: responsible for color and high-acuity vision in bright light

macula lutea

area with high numbers of cones

fovea centralis

center of the macula lutea that only contains cones

bipolar neurons

receives input from photoreceptors

ganglion cells

its axons converge to form the CN II optic nerve

optic chiasma

optic nerves exchange axons at this X-shaped before diverging into the two optic tracts

blind spot

also known as the optic disc, area with no rods or cones at the posterior most aspect of the eyeball where the optic nerve leaves the eyeball

first light hits the cornea → through the aqueous humor → through the lens → through the vitreous humor

light has to pass through this 4 refractive media before it hits the retina

cornea and lens

which refractive media have the greatest refractive power?

2/3

the cornea itself accounts for about __ of the eye’s refractive power

accommodation

adjustment in which the lens become rounder for additional “fine-tuning” when viewing nearer objects

autonomic nervous system

largely involuntary branch of the peripheral nervous system charged with maintaining homeostasis of different physiological variables

• two branches: sympathetic nervous system and parasympathetic nervous system

sympathetic nervous system

• its cell bodies are located in the thoracic and lumbar regions of the spinal cord

• “fight-or-flight” so its activated by any excitation, emotion, or exercise

• axons release epinephrine, norepinephrine, and ACh

parasympathetic nervous system

• cell bodies are location in cranial nerve nuclei and sacral portion of spinal cord

• “rest and digest” so it promotes functions associated with digestion, defecation, and diuresis

• axons release ACh