SENSORY ORGANS AND NERVOUS SYSTEM Flashcards
Structures of the eye
- conjunctiva
- sclera
- cornea
- choroid
- pupil
- iris
- lens
- retina
conjunctiva
a clear membrane that covers the outside of the front of the eyeball and the inside surface of the eyelids. It isn’t part of the eyeball itself.
extrinsic
outer
sclera
the outermost layer of the eyeball, or “the white of the eye”. It protects the eye and serves as the surface to which the extrinsic (outer) muscles attach.
Cornea
the clear area of the sclera. It allows light to pass through. It’s clear because it has no blood vessels, and it consists of five layers of flat cells. There are pain and touch receptors in the cornea.
Choroid coat
The middle layer of the eyeball. This is the vascular structure of the eye that provides blood and oxygen through blood vessels.
In humans, this coat is a dark color because of melanin.
The color causes minimal reflection of light within the eye so the clarity of sight is maintained.
Pupil
Small, circular opening in front of the choroid coat.
It appears as a black dot in the middle of the eye and lets light pass through.
Iris
Surrounds the pupil.
contains intrinsic, or inner, muscles that adjust the size of the pupil according to the amount of light in the environment.
In bright light, the muscles constrict the pupils to restrict the amount of light passing through.
In dim light, the muscles dilate the pupils to allow more light to pass through.
In stressful situations, the sympathetic nervous system causes these muscles to dilate the pupils.
Lens
The durable crystalline disc behind the iris and the pupil that focuses light on the retina.
The lens is biconvex, which means that it’s a disk with a convex surface of both sides.
The anterior surface, toward the front of the eye, has slightly less of a curve than the posterior surface, toward the back of the eye; however, these curves change with age.
biconvex
means that it’s a disk with a convex surface of both sides (it bulges out on both sides)
anterior surface
toward the front of the eye, has slightly less of a curve than the posterior surface, toward the back of the eye;
Fibrous tissue called suspensory ligaments connect the lens to the ___?
ciliary muscles
The space between the lens and the structures in front of it is called the
anterior chamber
The anterior chamber is filled with a watery fluid called the aqueous humor. You can remember this because “aqueous” means “watery”. The fluid is continuously replenished by the blood vessels behind the iris.
aqueous humor
Watery fluid that fills the anterior chamber. Continuosly replenished by the blood vessels behind the iris.
Posterior chamber
The space or cavity behind the lens.
The posterior cavity is filled with vitreous humor, a transparent, gelatinlike substance.
This structure maintains the spherical shape of the eyeball and aids in focusing light onto the retina.
Retina
The innermost layer of the eyeball, but it doesn’t extend to the front part of the eye. It detects light and transmits signals back to the brain; the optic nerve sends the signals back to the occipital lobe in the brain, which interprets them.
Rod cells
Specialized cells in the retina.
Sensitive to dim light and are used for peripheral vision.
Cone cells
Specialized cells in the retina.
Are sensitive to bright light and color.
Pale optic disc
The part of the retina around the optic nerve.
This area doesn’t contain any rod or cone cells, and without rods or cones, there’s no visual perception; thus, this area is known as the “blind spot”.
The ear is divided into three parts:
external ear or outer ear
middle ear or tympanic cavity
inner ear or labyrinth
pinna or auricle
The outer part that looks like a cup of rubbery tissue.
Collects sounds from the environment and focuses them into the auditory canal.
auditory canal
The wax-producing tunnel that curves into the temporal bone and ends at the eardrum.
Many short hairs and glands lie across the auditory canal. The glands secrete cerumen, or earwax.
The hairs and wax protect the ear by preventing dirt particles and insects from getting inside.
eardrum or tympanic membrane
The tight membrane that transmits the vibrations of sound waves from the auditory canal to the middle ear. The eardrum separates the outer ear from the middle ear.
tympanic membrane
earddrum
Function of the middle ear
After the sound waves strike the eardrum, the middle ear intensifies and transmits the sound. While the external ear conducts sound through the air, the middle ear conducts sound through its three bones- the malleus, the incus, and the stapes.
As sound enters the middle ear, the tiny bones work to transmit the sound and amplify it. The malleus is attached to the eardrum. As sound strikes the eardrum, the malleus vibrates, causing the incus and the stapes to vibrate.
The three bones of the middle ear
Malleus
Incus
Stapes
Eustachian tube
Connects the middle ear to the pharynx, or throat, which explains the frequent spread of throat infection to the ear.
The Eustachian tube also equalizes the air pressure on both sides of the eardrum.
This tube is usually closed, but it opens when you swallow or yawn.
Inner ear
The most complicated part of the ear. In addition to its role in hearing, the inner ear also helps to maintain a sense of equilibrium and balance. Due to its complex, maze like design, the inner ear resembles a bony labyrinth.
Three structures of the inner ear :
Cochlea
Semicircular Canals
Vestibule
Cochlea
Bony, snail-shaped, filled with fluid and contains a compartment called the organ of Corti, which is lined with nerve endings.
Organ of Corti
Sensitive element of the inner ear and houses about 20,000 sensory hair cells; each hair cell has 40 to 100 hairs.
Tactile receptors
Bring you information about pressure, touch, and vibration. They’re located throughout your skin but are more abundant in areas such as the fingertips and the lips.
Temperature receptors
Enable you to sense changes in temperature. Although they’re found throughout the body, they’re concentrated in the lips, the mouth, and the anus.
Pain receptors
Located throughout the skin and within certain internal organs. Some organs, however, are poorly supplied with pain receptors, making it difficult for you to determine where it actually hurts. An example of that is a headache; headaches can be felt due to the pain in the brain, the skull, the neck, or the blood vessels.
Proprioception or kinesthesia
The sense of positioning.
The receptors are located within muscles, joints, and tendons. Once the receptors detect a stimulus such as pain, pressure, or touch, the stimulus is converted into an electrical signal or nerve impulse. The signal then travels the nerve pathways to the brain, where the sensation is interpreted. After the brain interprets the stimulus, it sends orders back along the nerve pathways to the organs and/or other muscles to react appropriately to the receptor.
Special Sense Organs
Eyes
Ears
Nose
Taste Buds
How do special sense organs function?
They receive sensory signals and transmit them to the brain by way of cranial nerves. Although sensory organs don’t appear to be similar to nerves, they can be considered appendages of the nervous system. Each of these organs has unique sensory cells that pick up data and then transmit it to the brain for decoding of the collected data.
How many different smells can the nose detect?
About 10,000
What enables your nose to smell ?
A highly specialized collection of nervous tissue, the olfactory bulb (or olfactory epithelium) enables your nose to smell.
The part of the brain that analyzes scents works closely with memory and emotion.
That’s why the sense of smell can evoke powerful feelings and memories.
Olfactory nerves are never replaced; once they’re damaged, the sense of smell is impaired forever.
They also tire quickly, which explains why a pungent odor seems to dull after it has been sensed for a while.
papillae
bumpy, hair-like projections on the tongue
Taste buds function
Clusters of taste buds surround the papillae and also cover the roof of your mouth.
The taste buds themselves aren’t visible.
For a taste to be stimulated, the food must be solubilized.
The mouth does this by providing saliva through the salivary ducts. The stimulus of food prompts the ducts to release saliva so the food can start to be dissolved. Specialized cells in the taste buds, gustatory cells, can detect the basic sensations of sour, salty, bitter, and sweet.
The information is then converted to impulses and transmitted to the brain.
The sweet and salty tastes are sensed mainly at the tip of the tongue.
The sour taste is sensed at the sides of the tongue, and the bitter taste is sensed at the back of the tongue.
Glaucoma
AA disease caused by increased pressure in the eye, which results in a damaged optic nerve. Increased pressure may be caused by factors such as high blood pressure, obesity migraines, and heredity.
Since there are usually no symptoms until there’s a decrease in vision, annual eye exams are extremely important to detect this disease during the early stages.
If untreated, glaucoma can lead to blindness.
The most common form of glaucoma is called open-angle glaucoma.
Open-angle glaucoma is treatable with medications, Lasik, and surgery.
Eyedrops commonly used to treat glaucoma:
Pilocarpine (Isopto Carpine)
Carbachol (Isopto Carbachol)
Latanoprost (Xalatan)
Travoprost (Travatan)
Timolol (Timoptic)
Dorzolamide (Trusopt)
Betaxolol (Betoptic)
Acetazolamide (Diamox)
Cataract
A cloudiness of the eye’s lens due to increased age.
This disease may be caused by trauma or radiation exposure. Symptoms include blurred vision, faded colors, and sensitivity to light.
Common risk factors include increased age, diabetes, smoking, prolonged exposure to sunlight, and alcohol.
A mainstay of the cataract treatment is the surgical removal of the cataract lens and replacement with a new lens. Cataract surgery is a minor outpatient surgery performed routinely to treat cataracts. Medicated eye drops are normally used prior to surgery to dilate pupils and post-surgery for inflammation and infection.
Eye Drops that dilate pupils are called
mydriatic
The following is a list of mydriatic medications:
Tropicamide (Mydriacyl)
Atropine (Isopto Atropine)
Cyclopentolate (Cyclogyl)
Phenylephrine (Mydfrin)
The following eyedrops are used for inflammation and infection:
Bacitracin, Neomycin, and Polymyxin B (Polysporin)
Ketorolac (Acular)
Conjunctivitis
The inflammation or irritation of the conjunctiva, is the most common infection of the eye.
Conjunctivitis is also referred to as “pink eye”.
The infection can be caused by a virus, bacteria, or an allergen.
The common cold, an upper respiratory infection, or a sore throat may lead to conjunctivitis. Symptoms include swollen, scratchy, red, and extremely watery eyes.
The following antibiotic eye drops are commonly used to treat “pink eye” or conjunctivitis:
Ciprofloxacin (Cipro)
Ciprofloxacin and dexamethasone (Ciprodex)
Tobramycin (Tobrex)
Trimethoprim/polymyxin (Polytrim)
external otitis
Outer ear infections “swimmer’s ear”
otitis media
middle ear infections
Otitis media is a common type of ear infection in children that’s often treated with oral antibiotics.
Cerumen
Earwax
If your ear produces too much earwax…..
It can collect in the auditory canal. When this happens, the cerumen absorbs or blocks the passage of sound waves.
This blockage impairs hearing. Treatment for this includes irrigation of the ear canal and the use of lubricating drops. Carbamide peroxide (Debrox), over-the-counter (OTC) eardrops, is commonly used to remove excess earwax.
Which medications have to be sterile, ear or eye?
Eye
Discard opened eye drops after how many days?
28 days
The average human brain weighs about?
3 lbs
The brain processes information about our
Heart rate
blood pressure
respiration rate
temperature
muscle tone
blood chemistry
The four major anatomical parts of the brain:
cerebrum
diencephalon
cerebellum
brain stem
The largest and most complicated part of the brain is the
cerebrum
Cerebral Cortex
Thin outer lay of gray matter that covers the cerebrum.
Basal Ganglia
White matter that covers cerebrum (lies under the cerebral cortex)
The cerebrum controls?
motor activities
interprets sensations
serves as the center of intellect, memory, language, and consciousness
What is the cerebrum divided by?
A deep groove, or longitudinal fissure, into two fleshy lobes called the right and left cerebral hemisphere.
Each hemisphere is further divided into four lobes
The four lobes of each hemisphere of the cerebrum?
frontal
parietal
temporal
occipital lobes
left hemisphere governs:
logic
language
reasoning
numbers
linearity
analysis
academic activities
right hemisphere is responsible for
rhythm
music
images
imagination
color
parallel processing
daydreaming
face recognition
pattern or map recognition
The cerebral lobes are named after
the bones that protect them.
The frontal lobe controls?
body movements
speech
judgment
intelligence
problem solving
The parietal lobe receives and integrates information from various sensory receptors, including vision and hearing. It plays a part in
language interpretation as well as spatial and visual perception
The occipital lobe receives information from the
thalamus about what you see and uses the information to help you formulate an appropriate response. This lobe is the primary visual area.
The temporal lobe receives and responds to
sound; it also formulates emotion, personality, and behavior.
cerebellum has ____ lobes
two- right and left
The narrow ridges in the cerebellar cortex are known as
folia
The cerebellum is located?
at the posterior aspect of the brain, underneath the occipital lobe of the cerebrum.
three main functions of the cerebellum
- it coordinates and refines voluntary movements such as running, walking, writing, and talking
- it helps to maintain muscle tone and posture
- because it receives impulses from the inner ear, it helps maintain equilibrium, or a sense of balance.
