Sense organs Flashcards

Question

Outer ear is and pinna

Answer 1

Extends from the exterior to the eardrum Pinna - fleshy part of ear Functions to catch sound Cartilage covered with skin Very mobile Varies widely depending on species and breed (especially in dogs)

Answer 2

Transmits sound Soft membrane-lined passageway from pinna to eardrum In most domestic species, it is a L-shaped tube Has a vertical and horizontal component Ends blindly at the eardrum or tympanic membrane In some dog breeds, like poodles, it can be full of hair Has ceruminous glands which secrete wax – protects against infection

Answer 3

(eardrum) - thin, semitransparent membrane Tightly stretched across the opening between the external auditory canal and the middle ear cavity Thin and delicate Vibrates with the same frequency as sound waves that strike it.

Answer 4

Transmits and amplifies sound A hollowed-out area of the temporal bone, lined by soft tissue membranes Separated from the external ear by the tympanic membrane Separated from the inner ear by the membranes of the oval and round windows of the cochlea Filled with air Connected to pharynx by the EUSTACHIAN or AUDITORY tube

Answer 5

Middle ear infections can cause Horner's syndrome Signs are Ptosis Miosis Enophthalmos

Answer 6

a system of levels that transmit and amplify sound vibrations of the tympanic membrane to the cochlea Malleus (hammer) - attached to the tympanic membrane Incus (anvil) – forms synovial joints to link other 2 bones Stapes (stirrup) - attach to membrane of the oval window of the cochlea (don’t MISs the order)

Answer 7

(auditory tube) functions to equalize pressure on both sides of the tympanic membrane, protecting it from rupture Ears pop when changing altitude- air moving through auditory tube Swallowing or yawning opens auditory tube allowing air to middle ear and equalizes pressure

Answer 8

diverticulum of auditory tube found in equine only Large, air-filled space Dorsocaudal to the nasopharynx Contains a branch of the carotid artery A heat regulation device to cool the horse's brain during exercise CN VII and IX to XII pass along the wall of the pouch

Answer 9

Functions as site where hearing and balance is sensed Three parts Cochlea (hearing) Vestibule (equilibrium) Semicircular canals (equilibrium)

Answer 10

The cochlea contains a tube called the cochlear duct, filled with a fluid(endolymph) The duct divides, but does not fill, the bony cavity. There is a fluid filled channel on either side of the cochlear duct. The two arms communicate at the apex to form a U shaped tube The U-shaped tube has 2 openings – one at either end, both covered by membranes: The oval window attaches to the staoes The round window bulges in and out as fluid moves within the U-shaped tube

Answer 11

The cochlear duct houses the sensory cells called the Organ of Corti Houses hair cells The receptors for hearing Have cilia (hairs) on their surface and nerve endings at their base The hair cells are covered by a gelatin-like tectorial membrane

Answer 12

Sound waves (changes in air pressire) cause the tympanic membrane and the ossicles of the middle ear to vibrate Loud sounds cause greater displacement of the membranes than soft sounds As the stapes vibrates back and forth it pushes and pulls on the membrane covering the oval window of the cochlea Vibrates the fluid surrounding the cochlear duct Vibrations are transferred to the organ of Corti This bends the sensory hairs Generates nerve impulses that travel to the brain via the vestibulocochlear nerve (CN VIII) and are interpreted as sound Different frequencies are felt at different locations along the organ of Corti so the brain differentiate frequencies Partly due to the different lengths of the ‘hairs’ on the hair cells. The slight asymmetry to ears helps localize sound better

Answer 13

Receptors are in portions of the inner ear called the vestibule and semicircular canals Sensory inputs also come from proprioceptors and vision Conflicting signals from vision and vestibular system cause motion sickness.

Answer 14

Static Equilibrium Usually gravity to determine position on a linear plane (like walking) Part of the inner ear between the cochlea and the semicircular canals Gelatinous matrix containing crystals of calcium carbonate, called otoliths, sits above hair cells in a path of equilibrium Tilting the head shifts the otoliths due to the pull of gravity, which bends the cilia on the hair cells Generates nerve impulses which are sent to the brain

Answer 15

Made up of 2 saclike spaces Utricle Saccule

Answer 16

Dynamic Equilibrium Consists of three semicircular canals, at right angles to each other Sense head rotation by their different planes of orientation: Horizontal Frontal Sagittal Work like the vestibule but there are no otoliths Hair cells occur in patches The hairs stick up into a gelatinous, free-floating structure which moves with the fluid in the canals As the head rotates the fluid lags due to inertia Causes the sensory hairs to bend, generating nerve impulses which are sent to the brain

Answer 17

Normal (Positional) Jerky movement of the eyes that occurs when the head is rotated from side to side During head rotation, the eye moves slowly in the opposite direction, remaining "fixed" on a stationary object After the head has rotated a considerable distance, the eyes move rapidly in the direction of rotation and then become fixed again

Answer 18

Nystagmus when there is no head movement Slow and fast phases (like positional) Usually in the horizontal plane Seen during certain stages of general anesthesia and with vestibular disease Animals with vestibular problems also have head tilt and circle or fall (may even roll) in one direction Pendular nystagmus is a lifelong condition of minor significance

Answer 19

Organ of sight: consists of the eyeball and its accessory structures Vision Electromagnetic stimulus is used to generate an image that is transmitted to the brain

Answer 20

transparent anterior part that lets light into the eyeball No blood vessels, but lots of sensitive nerves Very painful to have a scratch! Becomes opaque if it dries out or becomes edematous

Answer 21

- the white of the eye Gives shape and protects the inner structures

Answer 22

The junction of the cornea and sclera

Answer 23

pigment and blood vessels between sclera and retina Some species have a reflective tapetum Allows light to bounce back through the retina a second time for better night vision Not in pigs or humans

Answer 24

colored, donut shaped part of eye

Answer 25

central opening of iris which lets light in, can constrict or dilate to regulate light entry

Answer 26

holds and helps focus the lens Muscles of the ciliary body attach by processes to the lens Focuses the lens by contraction or relaxation of the ciliary muscle Produces aqueous humor that fills the eye

Answer 27

functions to collect image Contains the photoreceptors, rods and cones

Answer 28

origin of optic nerve, which goes to the brain to interpret visual images Optic disc is the point at which the nerve leaves the eye to transmit visual information to the brain Has no photoreceptors, so any light hitting it will not contribute to the image Creates a blind spot in vision Normally the brain fills in the gap in detail The artery and vein also enter and leave the eye at this point

Answer 29

between cornea and lens. Subdivided into a large anterior chamber in front of the iris and a small posterior chamber between the iris and the lens. Filled with a clear watery fluid called aqueous humor that is produced by the ciliary body Fluid circulates through aqueous compartment then is reabsorbed into blood stream Excess accumulation of fluid= high intraocular pressure Primarily responsible for maintaining internal pressure of the eye

Answer 30

located between lens and retina Filled with a jelly-like substance called vitreous humor Maintains the shape of the eye and holds the retina in place

Answer 31

Soft, transparent, elastic, biconvex Composed of layers of tiny protein fibers Lacks blood vessels and nerves Accommodation- ciliary muscles adjust the shape of the lens to focus light on the retina depending on distance of images Ciliary muscles are contracted for close-up vision- test them by looking at a distance objects to prevent eye strain

Answer 32

Innermost sensory layer of the eye Composed of several layers of cells The actual photoreceptor cells are near the outside (towards the choroid) The inner layer is nerve fibers that converge on the optic disc to form the optic nerve The surface of the retina is sometimes called the FUNDUS of the eye

Answer 33

Rods: function well in dim light, but do not detect color and have poor sensitivity to detail Cones: function well in bright light, see color, and have excellent sensitivity to detail -Our domestic animals have few cones. Therefore, they see washed-out colors with poor detail -Macula/fovea in primates- high density of cones allows precise vision

Answer 34

Refraction is the bending of light rays as they pass from one medium to another at an oblique angle Occurs in the eye to focus light on the retina Air → cornea → aqueous humor → lens → vitreous humor → RETINA Cornea most important refraction point Image is upside down- the brain interprets it as right side up!

Answer 35

Impulses form the retina travel on the optic nerves (CN II) and merge at a place in the brain called the optic chiasm Some fibers cross over to the other side of the brain Others continue to the same side Processing of image form different sides on the same part of the brain allows for stereoscopic (biocular) vision

Answer 36

The visual image may be 2-dimensional, or 3-dimensional Depends on the field of vision Need binocular vision to see 3-D images Predatory animals tend to have good binocular vision Allows them to stalk and calculate distances for attack Prey animals tend to have a narrower area of binocular vision Instead, emphasis is on wider RANGE of vision, even if it is monocular

Answer 37

Special mucous membrane lining eyelid and eyeball Palpebral - lines inner surface of eyelid Bulbar - reflection of palpebral conjunctiva onto eyeball Blood vessels are close to the surface of the area Checked during PE Pale = anemia , shock Yellow/orange = jaundice

Answer 38

Upper, lower, and third Lateral junction Lateral Canthus Medial junction Medial canthus Meibomian (tarsal) glands line the lid margins Secrete waxy substance to contain tears in eye Can become plugged and enlarge, or may become cancerous Can sometimes relieve plugging with hot compresses or by pulling associated eyelash

Answer 39

Third eyelid (nictitating membrane) - fold of conjunctiva, reinforced by T-shaped cartilage located at medial canthus of eye between upper and lower eyelids and eyeball. retraction of eyeball, by muscle or pressing on the eyeball, causes the 3rd eyelid to passively move across the cornea to protect it

Answer 40

Group of structures that produce and drain tears Lacrimal glands - pink glands located on dorsolateral aspect of eyeball, Releases tears onto surface of eye

Answer 41

Inner mucous layer: from the conjunctiva Has antibacterial substances to fight infection Middle tear layer: from the lacrimal glands Moisturize the cornea Outer oily layer: from the tarsal glands Minimizes tear evaporation and spillage over lid

Answer 42

openings which drain away excess tears On the upper and lower eyelid near medial canthus Drain into the lacrimal canaliculi → lacrimal sac → nasolacrimal duct → nasal cavity

Answer 43

Six muscles attach to the sclera and control delicate eye movement 4 straight (rectus) muscles – on 4 sides of eye 2 oblique – dorsal and ventral Often a 7th – the retractor bulbi which pulls the eye deeper into the socket and protrudes the third eyelid.

Answer 44

An inversion of the lid margins Eyelashes irritate the corneal and conjunctival surfaces

Answer 45

An eversion of the lid margins causing chronic conjunctival exposure

Answer 46

Genetic weakness in attachment of gland to third eyelid Inflammation and/or prolapse of the accessory lacrimal land of the third eyelid and associated nictitating membrane Common in young dogs, particularly the "droop-eyed" breeds - spaniels, basset hounds etc

Answer 47

Acute prolapse of the eye is a result of trauma and is most common in the canine and feline An emergency Prognosis for retention of vision is poor (50% in dogs, much less in cats) but prognosis retention of globe is good

Answer 48

Ocular Squamous Cell Carcinoma (Cancer eye) Most common in white faced, outdoor, animals (exposed to sun more). White faced cattle and horses Has a hereditary basis Usually occurs in older animals Tumour may originate from eyelids, conjunctiva or 3rd eyelid The cancerous or precancerous lesions can be multiple and present in one or both eyes

Answer 49

Many, MANY causes Often start as trauma and then become infected Often become infected, which leads to deep ulcer or ruptured cornea Diagnosed with fluorescein stain A corneal ulcer means the epithelium is destroyed Shallow ulcers heal rapidly by epithelialization Deep ulcers granulate in – needs blood vessels to grow in from limbus

Answer 50

Inflammation of the cornea with resulting edema, vascularization, scarring and pigmentation May include ulceration of the cornea Seen in all species because of mechanical damage, keratoconjunctivitis sicca, entropion, ectropion, and bacterial and viral infections such as pinkeye in cattle

Answer 51

Inflammation and/or infection of the conjunctiva Eyes are red, have discharge and are squinting (blepharospasm) Common in all species Associated with a multitude of conditions from physical irritation to bacterial and viral infection

Answer 52

Keratoconjunctivitis sicca (The disease "Dry Eye") Mainly seen in SA Due to a tear deficiency Usually results in conjunctivitis,cloudiness of the cornea (=corneal edema), corneal ulceration and/or corneal scarring

Answer 53

Increased intraocular pressure that damages the retina and optic nerve, leading to blindness Damages the retina and optic nerve, leading to blindness Painful - often the only presenting complaint is a behavioural change Genetic or secondary to other ocular disease

Answer 54

White opacity of the lens, any species May cause blindness Can develop in younger animals due to heredity or disease such as Infection or trauma to the eye/lens Diabetes mellitus Treat through surgical lens removal (can place a prosthesis)

Answer 55

The lens may become opaque with age Old fibers harden and lose transparency Gives a blue haze to lens Doesn’t interfere with vision much

Answer 56

An inherited disease complex seen in Irish Setters and Collies as young as 4-6 months and in Miniature Poodles as old as 5 years Night blindness leading to total blindness

Answer 57

Inflammation and/or infection of the pinna and external auditory meatus (auditory canal) May be caused by ALLERGIES, trauma, excessive amounts of wax, moisture and hair, or the presence of ear mites Most common in "flop-eared" breeds of dogs and in cats infested with mites Ears are painful, itchy and "smelly"

Answer 58

Usually progressing from otitis externa or from an infection tracking via the auditory tube from the nasopharynx Animals exhibit head shaking, head tilt, circling and loss of balance, Horners syndrome May lead to meningitis and death

Answer 59

A soft swelling of the pinna Seen in dogs, cats and pigs The result of trauma (bite wounds), may be self-inflicted from scratching and rubbing in association with otitis

Answer 60

Equine disease Can get infected by fungi These like to grow on the carotid artery Can damage adjacent nerves or cause massive blood loss