Chapter 23 + 24- General & Special Senses Flashcards
What are general sense receptors?
Temperature- free nerve ending (most widely distributed)
Pressure/touch
- tactile (Meissner corpuscle)
- Lamellar (Pacini Carpuscle)
Pain- free nerve ending
Free nerve endings are nerves ending in small hairs without organs
What are the 5 special senses?
Smell (olfaction)
Taste (gustatory)
Sight
Hearing
Equilibrium
What is the olfaction purpose and how does it work?
Smell
Chemoreceptors on roof of nasal cavity detect chemical changes and fire action potential by the Cranial Nerve I to the brain
What is the gustatory sense?
Taste
What are the three kinds of papillae and what are their purpose? Where are they found?
Fungiform- front of tongue. Taste buds
Circumvallate- back of tongue. Taste buds
Filiform- between fungiform and circumvallate. No taste buds. Perceive texture
What is the purpose of taste buds?
Taste buds house the gustatory chemoreceptors whose hairs are stimulated when chemicals dissolve in saliva
Each taste bud responds most effectively one of the five primary taste sensations
- sour
- sweet
- bitter
- umami (savoury)
- salty
What nerves are part of the gustatory sense?
Facial nerve- CN VII
Glossopharyngeal nerve- CN IX
Vargas nerve- CN X
What is a sense organ and what are their purpose?
Organs that enable the body to respond to stimuli caused by changes to internal or external environment
Two types- general and special
Which organ is responsible for two senses?
Ear
Hearing and equilibrium
What are the sensory receptors in the ear?
Mechanoreceptors
Respond to touch and sound
What are the components of the outer ear?
Pinna (auricle)- cartilage part
External auditory canal
- narrow chamber lined with skin
- location of ceremonious glands
- ends at tympanic membrane (ear drum)
Outer ear is responsible for hearing only, not equilibrium
What are the components of the middle ear?
Air filled cavity
Three auditory ossicles
-Malleus moves when ear drum vibrates and strangers sound to inner ear through ossicles
Middle ear opening
What are the three auditory ossicles called?
Malleus (hammer)
Incus(anvil)
Stapes (stirrup)
What are the openings of the middle ear?
Opening from external acoustic Mateus (ear canal) is covered by tympanic membrane
Oval window- stapes sits over this
Round window- covered by membrane. Below oval window
Auditory tube- opening that connects middle ear with throat (allows for pressure equalization during yawning and swallowing)
What is the fluid that fills the inner ear called?
Perilymph
What Is The bony labyrinth?
Maze of bony chambers in the inner ear, making up the
Vestibule (balance)
Cochlea (hearing)
Semicircular canals (balance)
What is the membranous labyrinth?
Within bony labyrinth.
Inside vestibule (balance) Cochlea (hearing) Semicircular canals (balance)
What is the fluid that fills the membranous labyrinth called?
Endolymph
What is the organ of corti?
Hearing organ within the membranous cochlea
Walls of cochlea membrane (basilar membrane) in the organ of corti have hairs that move to detect sound
What are the two nerves in the inner ear that help with hearing and what nerve do they make up?
Vestibular and cochlear
Make up the vestibulocochlear nerve CN VIII
Nerve impulses sent to auditory cortex
What are the two types of equilibrium and what is their purpose?
Static equilibrium- ability to sense position of head relative go gravity as well as acceleration/deceleration
Dynamic equilibrium- balance while moving
What are the macula and how do they work?
Receptors in the vestibule of the inner ear
- reports position of the head
- hairs embedded in gelatinous otolithic membrane move/bend when pressure changes and relay information via vestibular nerve
What is the sense organ with the most sensory receptors?
The eye- 70% of all sensory receptors
What is the mucous membrane that sits in the eyelid?
Conjunctiva
connects to surface of eye and secretes mucous for lubrication
What is the lacrimal apparatus?
Consists of gland above the eye that produces lacrimal fluid (tears)
And lacrimal canals that drain lacrimal fluid from eyes
To lacrimal sac (tube connecting lacrimal canal and nose)
Eventually out the nasolacrimal duct (hole from lacrimal sac to nose)
-protects, moistens, and lubricates the eye
What are the extrinsic muscles of the eye?
The muscles connecting to the eyeball allowing movement.
Controlled by cranial nerves
What are the intrinsic muscles of the eye and what part of the nervous system controls them?
Autonomic nervous system
Iris
Ciliary Muscle-controls shape of lens
Lens-biconvex. Focuses light rays on retina
What is the outermost layer of the eyeball and what does it include?
Fibrous layer
- sclera (protective tissue)
- cornea (transparent bulb in front of iris and lens)
What forms the white of the eye?
Sclera- fibrous layer
What two types of photoreceptors make up the retina?
Rods and cones
What are cones and what is their purpose?
Allow for colour vision
Located in centre of retina
At the location of the optic nerve there is the optic disk- no rods or cones (blond spot)
What is the fovea centralis?
Are of the retina with only cones
What are rods and what is their purpose?
Allow for dim light vision, peripheral vision
Black and grays
Which cranial nerve is the optic nerve?
CN II
What are the different cavities of the eyeball?
Anterior cavity - divided into anterior chamber and posterior chamber. Located in cornea and around lens
Filled with aqueous humour
Posterior cavity- larger cavity. Entire space behind lens.
Filled with vitreous humor (gel)
What is the purpose of the cavities in the eye?
To maintain pressure and shape
To provide nutrients to eye
What is the process of sight?
Light is first refracted onto retina by cornea, aqueous humour, lens , and vitreous humor
(Lens flat when seeing far- ciliary muscles relaxed
Lens round when seeing near- ciliary muscles contracted)
Photoreceptors respond to light and sent neural impulse through CN II
Visual cortex of occipital lobe processes
What is the middle layer of the eyeball and what is its purpose?
Vascular layer
- choroid (blood rich nutrient layer)
- ciliary body/muscles (changes shape of lens)
- Iris
What is the innermost layer of the eye and what are its components ?
Inner layer
- retina
- optic nerve
- blood vessels
