Sense Organs

Conjunctiva

Conjunctiva

• stratified squamous epithelium

• inferior eyelid and the superficial layer of the eyeball

• not over the cornea

• contains goblet cells that lubricate and moisten the eye

Subconjunctival Hemorrhage

• blood vessel rupture

Conjunctivitis

• inflammation of the conjunctiva

• bacterial or viral infection

• caused by rubbing eyes with dirty hands

Eyelids (Palpebrale)

• moveable anterior protective covering

Eyelashes and Eyebrows

• protection of the eye

Sty

• typically caused by an infection of the sebaceous glands associated with eyelash follicles

Lacrimal Apparatus

• cleans and protects the eye surface

• fluid produced in the lacrimal gland, collects in the lacrimal sac and drains into the nasal cavity

• dispersed across the eye surface

Two Main Functions of the Eyeball

• protect/support photoreceptor cells

• gather, focus and process light

Fibrus Tunic

• most external layer of the eye consisting of two regions

Sclera

• apart of the fibrous tunic

• dense collagen connective tissue

• "whites of the eye"

Cornea

• apart of the fibrous tunic

• anterior transparent region of the sclera

Corneal Transplants

• if the cornea becomes clouded, it can be produced by another

• no blood supply, therefore no problem with rejection

Vascular Tunic (Uvea)

• made up of three regions

• middle layer of the eye

Choroid

• apart of the vascular tunic

• highly vascularized layer

Ciliary Body

• apart of the vascular tunic

• blood supply

• suspensory ligaments

• ciliary muscle

Iris

• apart of the vascular tunic

• coloured portion of the eye

• eye colour is correlated with the amount of melanin in this region

Retina

• the inner layer of the eye

• responsible for the conversion of light into nerve signals

• often used for diagnostic purposes

• pigmented layer and neural layer

Macula

• apart of the retina

• directly posterior to the centre of the lens

Optic Disc

• apart of the retina

• where nerve fibers of the retina converge into the optic nerve

• blindspot

Detached Retina

• when the retina is pulled from its normal position

• usually treated with laser surgery or cryotherapy

Lens

• made up of proteins arranged like layers of an onion

• fully transparent with no blood vessels

• ciliary muscle controls the shape

Ciliary Body

• suspensory ligaments that extend from the lens to this region

• responsible for the production of the aqueous humor

• over time the condition of the musculature/lens deteriorates and people lose the ability to focus on close objects

Pupil

• defined by the inner margin of the iris

• 2 muscles that control the diameter of the pupil activated by light intensity

Sphincter Pupillae Muscles

• controlled by the parasympathetic system

• constriction of the pupil

Dilator Pupillae Muscles

• controlled by the sympathetic system

• dilation of the pupil

Vitreous Humor

• inferior area of the eye

• transparent jelly that fills the space behind the lens

• "floaters" are found in this region

Aqueous Humor

• watery solution secreted into the space between the iris and the lens

Extrinsic Eye Muscles

• six muscles that move the eye

• originate from a common tendinous ring in the posterior orbit and attach onto the outer surface of the eye

Outer Ear

• consists of the pinna, auricle, auditory canal and tympanic membrane

Pinna

• apart of the outer ear

• made up of elastic cartilage

Auditory Canal

• leads from the auricle to the tympanic membrane

• apart of the outer ear

Tympanic Membrane

• apart of the outer ear

• partition between the outer ear and middle ear

Ruptured Eardrum

• typically caused by infection or trauma

• heals on its own

Middle Ear

• air filled space in the temporal bone

• consists of the three smallest bones in the body the malleus, incus and stapes

The Eustachian Tube

• selective valve that allows air to enter behind the sealed eardrum

• if air pressure is not equal on both sides of the eardrum, it will not vibrate efficiently

Inner Ear

• also called the labyrinth

• consists of the semicircular canals and the cochlea

Semicircular Canals

• apart of the inner ear

• important for balance

Cochlea

• apart of the inner ear

• vibrations passed from the tympanic membrane, along the ear ossicles to the oval window

• nerve impulses generated that travel along the vestibulocochlear nerve, transporting sound through electrical impulses to the brain

Utriculus and Sacculus

• apart of the semicircular canals

• position of the body with respect to gravity

Canals

• apart of the semicircular canals

• involved in the motion of the body

• filled with endolymph

• triggers neural signals as it moves

Olfaction

• receptors found on the olfactory epithelium lining on top of the nasal cavity

• bathed by the swirling air that enters the nose

• has three cell types: olfactory receptor cells, support cells and basal stem cells

Olfactory Tissue

• individual receptor cells are replaced once a month

• each cranial nerve (I) consists of about 20 groups of nerve fibers

Taste

• chemicals for taste and smell must be dissolved

• receptors for taste are found in taste buds

• found on tongue and elsewhere in pharynx

Gustatory Hair

• molecules first attach

• taste

Receptor Cells

• transmit signals

Sensory Neurons

• merge together to form the facial (VII) or glossopharyngeal (XI) nerves

Individual Taste Buds Can Detect

• sweet

• sour

• bitter

• salty

• umani

Filiform Papillae

• no taste buds

• body of the tongue

Fungiform Papilla

• taste buds on the dorsal surface of the tongue

Vallate Papilla

• taste buds

• upper area of the tongue

Foliate Papilla

• taste buds

• side of the tongue