HEENT A&P Flashcards
What is sensation?
Conscious or subconscious awareness of changes in the external or internal environment
What are the special senses?
Tactile, thermal, pain and proprioceptive sensations
What are visceral sensations?
Sensations from internal organs
What 4 conditions must be satisfied for sensation to occur?
- Stimulus
- Receptor converts stimulus into electrical signal
- Nerve pathway conducts the information to the brain
- Brain translates or integrates impulse into sensation
What is perception?
Conscious awareness and interpretation of sensations
Perception is primarily a function of what part of the brain?
Cerebral Cortex
What is adaptation?
Decrease in strength of sensation during prolonged exposure
What are the types of receptors?
- Mechanoreceptors
- Thermoreceptors
- Nociceptors
- Photoreceptors
- Chemoreceptors
-Osmoreceptors
What receptor detects mechanical information?
Mechanoreceptors
What receptor detects changes in temperature?
Thermoreceptors
What receptor detects pain?
Nociceptors
What receptor detects light?
Photoreceptors
What receptor detects presence of chemicals?
Chemoreceptors
What receptor detects osmotic pressure of fluids?
Osmoreceptors
Somatic sensations arise from where?
Sensory receptors in skin, mucous membranes, muscles, tendons and joints
How are sensory receptors for somatic sensations distributed through the body?
Widely and unevenly so that some are more sensitive to others (ex. Fingertips, lips, tip of the tongue)
What are the receptors for somatic senses?
Tactile, thermal and pain
What sensations do tactile receptors detect?
Touch, pressure, vibration, itch and tickle
Where are tactile receptors located?
Skin or subcutaneous tissue
What sensations do thermal receptors detect?
Warm, cold
Where are thermal receptors located?
Epidermis and dermis
Where are pain receptors located?
Everywhere, except the brain
What are the 2 thermal receptors?
Cold and warm
What temperatures do cold receptors detect?
10-40C (50-105F)
Where are cold receptors located?
Epidermis
What temperatures do warm receptors detect?
32-48C (90-118F)
Where are warm receptors located?
Dermis
Temperatures below cold receptor range and above warm receptor range are perceived as what?
Pain
Do nociceptors adapt to pain?
No
What is fast pain?
Acute, sharp, picking, can be precisely located
What is slow pain?
Chronic, aching, burning, more diffuse
Where are proprioceptors located?
Skeletal muscles (muscle spindles), tendons (tendon organs), in and around synovial joints (joint kinesthetic receptors), and inner ears (hair cells)
What is proprioception?
Kinesthetic sense or the perception of body movements
What do muscle spindles detect?
Inform which muscles are contracting
What do tendon organs detect?
Amount of tension in our tendons
What do joint kinesthetic proprioceptors detect?
Position of joints while doing work
What do hair cells detect?
Orientation of head relative to ground and positioning
What is the sense of smell called?
Olfaction
What type of sense is smell?
Chemical sense
How many receptors are located in the olfactory epithelium?
10 million-100 million receptors
Where are the olfactory receptors located?
Superior aspect of the nasal cavity
What are the 3 types of cells in the olfactory epithelium?
Olfactory receptor cells, supporting cells and basal cells
What must happen to odorants to be smelled?
Must be dissolved
At what speed does adaption to odors occur?
Quickly
What is the threshold of smell?
Low
What forms the olfactory tract?
Axons from olfactory nerve and olfactory neurons
What does the olfactory tract project to the cerebral cortex?
Awareness of smell
What does the olfactory tract project to the limbic system?
Emotional response to odors
What is gustation?
Sense of taste
What are the primary tastes?
Salt, sweet, bitter, sour and umami
Where are the gustatory cells located?
Taste buds on the surface of the tongue
What are the raised bumps on the tongue?
Fungiform papillae
What must happen to tastants to be tasted?
Must be dissolved in saliva
At what speed does adaptation to taste occur?
Quickly
What is the threshold for taste adaptation?
Varies for each of the primary tastes
Which nerves are responsible for taste?
7, 9, 10
Which cranial nerve is responsible for tasting sweet and salty?
CN 7
Which cranial nerve is responsible for tasting bitter and sour?
CN 9
Which portion of the tongue is sweet and salty tasted?
Anterior 2/3
Which portion of the tongue is responsible for tasting bitter and sour?
Posterior 1/3
CN X carries taste information from where in the body?
Epiglottis
Where do taste buds impulses propagate?
Midbrain
From the mid brain, where is the final destination of primary gustatory area for conscious perception of taste?
Parietal lobe of the cerebral cortex
What are the accessory structures of the eye?
- Eyebrows and eyelashes
- Eyelids
- Lacrimal apparatus
What protects the eye from foreign objects, perspiration and sun rays?
Eyebrows and eyelashes
What shades the eyes during sleep, protects it form excessive light and spreads lubrication by blinking?
Eyelids
What is the group of glands, duct and canals that produce and drain tears?
Lacrimal apparatus
What is the path of a tear?
Lacrimal gland->lacrimal duct->lacrimal canaliculi ->nasolacrimal duct->nasal cavity
In short, tears start at the lacrimal gland, through the duct to the nose cavity
What muscles move the eyeball?
- Superior/Inferior Rectus
- Lateral/Medial Rectus
- Superior/Inferior Oblique
What are the main layers of the eyeball?
- Fibrous Tunic (outer)
- Vascular Tunic (middle)
- Retina (inner)
What are the 2 regions of the fibrous tunic?
- Posterior Sclera
- Anterior Cornea
What structure is nonvascular and bends light rays onto the retina?
Anterior Cornea
What is the white of the eye?
Sclera
What are the 3 portions of the vascular tunic?
- choroid
- ciliary body
- iris
What is the thin membrane that lines the inner portion of the sclera?
Choroid
What alters the shape of the lens for near and far vision (accommodation?
Ciliary muscle in the ciliary body
What is the colored portion of the eye?
Iris
What structure does light enter through?
Pupil
The retina is located where?
Posterior 3/4 of the eye
What does the neural layer of the retina consist of?
- photoreceptor layer
- bipolar cell layer
- ganglion layer
What are the photoreceptors?
Rods and Cones
Which receptor allows us to see shades of gray in dim light?
Rods
Which photoreceptor allows us to see in color?
Cones
Where are the cones located?
Fovea Centralis
Which area has the sharpest vision?
Fovea Centalis due to high concentration of cones
The eye’s interior is divided into what structures?
- Anterior cavity
- Vitreous chamber
What helps maintain the shape of the eye and nourishes the lens and the cornea?
Aqueous Humor
What maintains the shape of the eye and holds of retina in place?
Vitreous Chamber
What is the difference in material between the aqueous humor and vitreous chamber?
Aqueous= watery fluid
Vitreous= jellylike
What structures maintain IOP?
Aqueous humor (mainly)
Vitreous body
What is the normal measurement for IOP?
16mm Hg
What are the processes involved in the formation of vision?
- image on the retina
- stimulation of rods and cones
- pathway to the brain
The cornea carries out percentage of refraction?
75%
In what orientation are images focused on the retina?
Upside down
Refraction abnormalities can result in what?
- myopia (nearsightedness)
- hyperopia (farsightedness)
- astigmatism (change in curvature of the eye)
Convergence of both eyes so that they are being directed on the object allows for what kind of vision?
Binocular
What is nonfunctional in day light?
Rods
What vitamin deficiency can cause night blindness?
Vitamin A
In colorblindness, what color cones are missing?
Red or green
Rods and cones convey impulses on to what cell?
Bipolar cells of the retina
What cells initiate nerve impulses?
Ganglion cells
Impulses from ganglion cells are conveyed along axons through the retina to which Cranial Nerve?
CN 2
What percentage of neurons cross the optic chiasm?
50%
Where do neurons cross to reach the opposite side of the brain?
Optic Chiasm
Where is sight perceived in the brain?
Primary Visual areas of the Occipital Lobe
What are the 3 anatomical subdivisions of the ear?
- External (outer) ear
- Middle Ear
- Internal (inner) ear
What is the basic function of the external ear?
Collect/direct sound waves
Sound is mechanical
What are the structures of external ear?
- Auricle
- External Auditory canal
- TM (ear drum)
What is the function of the auricle?
Collects sound waves and directs them to the auditory canal
The hairs and glands in the External auditory canal secrete what substance?
Cerumen
What is the TM?
- Thin semi-transparent partition between the external auditory canal and middle ear
What effect does sound have on the TM?
TM vibrates
What is the middle ear?
Small, air filled cavity between the eardrum and internal ear
The middle ear is connected to the throat via what?
Auditory tubes (Eustachian tubes)
What function do the Eustachian tubes have?
Opens to equalize pressure on both sides of TM, preventing rupture
What is the general name for the 3 tiny bones that extend across the middle ear?
Auditory Ossicles
What are the names of the 3 tiny bones within the middle ear?
Malleus, Incus, Stapes
Which bone touches the TM?
Malleus
Where are the receptors for hearing and equilibrium located?
Internal Ear
What are the 2 general regions of the internal ear?
Outer bony labyrinth and inner membranous labyrinth
What are the structures of the bony labyrinth?
Cochlea, Vestibule, Semicircular canal
Where is perilymph found?
Bony Labyrinth
Where is endolymph found?
Membranous labyrinth
What structures make up the oval portion of the bony labyrinth?
Vestibule
The 3 bony semicircular canals are arranged how?
Right angles to each other. 2 of them are vertical while the other is horizontal
The enlargement at the end of the semicircular canals are known as what?
Ampulla
What is the principle organ of hearing?
Cochlea or “Spiral Organ”
What is the structure of the cochlea?
Spiral bony canal
Where is the cochlea located?
Resting on basilar membrane inside the cochlear duct
What cells are located inside of the cochlea?
Hair cells
What covers the hair cells in the cochlea?
Tectorial Membrane
Which CN do hair cells synapse with?
CN 8 (Acoustic)
What is the path of sound waves?
External ear->external auditory canal->strikes TM->conduction to ossicles
What structures does the stapes repeatedly strike in the middle ear?
Oval window
Pressure changes within the cochlea causes movement of what membrane?
Tectorial membrane
Movement of the tectorial membrane moves what cells?
Hair cells
Movement of hair cells fire action potential to travel up via what structure?
Cochlear branch of CN 8
Nerve impulses from the cochlear branch of CN 8 pass to which parts of the brain?
Midbrain and thalamus, ending in primary auditory area of temporal lobe
Why does the left and right temporal lobes receive impulses from both ears?
Auditory axons cross form both ears
What is static equilibrium?
Maintenance of body position during speeding up and slowing down
“Forward and back”
What is dynamic equilibrium?
Maintenance of body position during rotation
“Bring it aroooouuuunnnnd tooowwwwnnn”
What are the receptor organs for equilibrium in the internal ear?
Saccule, Utricle and Semicircular ducts
What do saccule and utricle contain?
Macula with hair cells and supporting cells
What membrane sits on the macula?
Otolithic membrane containing otolithic crystals
What does the otolithic membrane do in response to movement of the head?
Slides as head moves
Nerve impulses originating from hair cells transfer via what branch of CN 8?
Vestibular branch
What structure maintains dynamic equilibrium?
3 semicircular ducts located within semicircular canal
Semicircular ducts are positioned on 3 planes to detect what?
Imbalance in 3 planes
Where does the nerve impulse from the Vestibular branch of CN 8 enter on the brain?
Medulla or Cerebellum
Where do the CN impulses that control eye/head/neck movement originate?
Medulla
What brain structure is primarily responsible for maintaining equilibrium?
Cerebellum via links with the Medulla and Cerebrum
How is equilibrium maintain?
Cerebellum continuously works in conjunction with the Cerebrum to make continuous adjustments to coordinate movement
