Nervous Systems and Endocrine System - Ear and Eye Flashcards
What is the function of the pinna?
-Collect and direct sound waves into auditory canal.
-Unique shape helps brain determine which direction a sound is coming from.
-Outer ear
What is the function of the auditory canal?
-Transmits sound waves from pinna to the tympanic membrane.
-Can regulate temperature and humidity levels within the ear.
-Outer ear
What is the function of the ossicles?
-3 tiny bones in the middle ear, malleus (hammer), incus (anvil), and stapes (stirrup).
-Transmits sound vibrations of the tympanic membrane to the inner ear.
-Amplifies the sound vibrations.
-Muscles that join the bones protect against excessive noise. Excessive noise causes the muscles to contract which resists the movement of the malleus and pulls the stapes away from the oval window (dampens the sound).
What is the functions of the tympanum (tympanic membrane)?
-Hearing begins when sound waves push against it.
-Converts sound waves from the air into mechanical vibrations.
-Vibrations are then sent to the ossicles.
-Middle ear
What are the functions of the oval window?
-Receives mechanical vibrations from the ossicles and transmits them to the fluid filled cochlea of the inner ear.
-Helps convert pressure from the air filled middle ear to the fluid filled inner ear.
-Middle ear
What are the functions of the eustachian tube?
-Equalizes pressure on both side of the tympanic membrane (tympanum).
-Helps drain mucus and other secretions from the middle ear into the nasopharynx.
-Helps protects middle ear from pathogens, reducing infections.
-Middle ear
What are the functions of the vestibule?
-For static equilibrium (horizontal or vertical).
-Contains the utricle and saccule which are filled with fluid and lined with hair cells. Cilia from the hair cells are suspended in a material containing calcium carbonate granules called otolits. Otolits only move when head is not in a normal position.
-Maintains balance, detects gravity, spatial orientation, and coordinating eye movements with head movement.
-Inner ear
What is the function of the semicircular canals?
-For dynamic movement (acceleration).
-While in movement 3 filled semi circular canals maintain balance.
-Each canal contains an ampula (pocket).
-Movement causes fluid to move and the cilia attached to the hair cells in the ampulla to bend.
-Nerve impulses are initiated and carried to the brain.
-helps maintain balance, coordinate eye movement with head movements, and contributes to spatial orientation.
-Inner ear
What are the functions of the cochlea?
-Receives fluid vibrations and converts them into electrical impulses.
-The organ of corti is the hearing apparatus within the cochlea.
-Fluid movement causes the hair cells to bend.
-Basilar membrane is attached to the hair cells (mechoreceptors) which are synapses to the auditors nerve.
-Auditory nerve sends message to the temporal lobe of the cerebrum.
-Inner ear
How do sound waves travel?
-Sound energy must first be converted into electrochemical impulses (nerve impulses) before it can be interpreted.
-Sound must travel through a medium, air is the most common but can travel through water and solids.
Describe the part of the ear that identifies both loudness and pitch
-Inner ear identifies both loudness and pitch.
-High pitch noises stimulate cilia in the first parts of the cochlea.
-Low pitched noises move farther along the cochlea and stimulate cilia there.
-Each neuron terminates in a specific part of the auditory section of the brain.
What is one thing that can result in hearing loss?
-Damage to cilia.
What does is the function of the sclera?
-Protects and supports the eyeball.
What is the function of the cornea?
-Bends light rays into the eye.
-First bends light towards the pupil which causes refractions.
What is the function of the choroid?
-Asborbs scattered light and contains blood vessels.
What is the function of the iris?
-Regulates the amount of light that enters the eye.
What is the function of the pupil?
-Opening for light to enter the eye.
-Pupil dilates in low light to allow more light to enter.
-Pupil constricts in bright light to limit light entering.
What is the function of the ciliary muscles?
-Changes the shape of the lens in order to focus.
What is the function of the lens?
-Focuses light rays onto the fovea centralis.
What is the function of the fovea centralis?
-Contains a high density of cones, provides acute vision.
-When image is bent to a focal point on the fovea centralis the image is smaller, upside down and reversed.
What is the function of the optic nerve?
-Transmits sensory info to the brain.
What is the function of the retina?
-Contains 2 types of photoreceptors (rods and cones) that detect light.
-The photoreceptors convert light into electrochemical signals which are sent through the optic nerve to the thalamus and then to the occipital lobe.
Describe rods
-Very sensitive to dim light.
-Allows for black and white vision.
-Detects motion and peripheral vision.
-Concentrated at the outside edges of the retina.
Describe cones
-3 types of cones that detect red, blue and green wavelengths of light.
-Requires intense light.
-Concentrated at the fovea centralis.
What is the function of the aqueous humor?
-Maintains shape of the cornea, and provides oxygen and nutrients for the surrounding cells.
-Aqueous and vitreous humor are placed in order of ABCs, aqueous first, then vitreous.
What is the function of the vitreous humor?
-Maintains the shape of the eye as a whole, and supports surrounding cells.
How does the lens focus on objects at different distances?
-Focusing is also known as accommodation, which are reflexes and adjustments made by the lens and pupil for near and distant objects.
For distant objects the ciliary muscles relax and suspension ligament exerts tension on lens. (Lens becomes thinner and light is bent).
For near objects the ciliary muscles contract and suspensory ligaments exert less tension on the lens (lens gets rounder).
In what order does light go through the eye?
-Cornea -> iris -> pupil -> lens -> retina -> rods/cons -> fovea centralis -> optic nerve.
Why is there a blind spot?
-There can’t be photoreceptors at the back of the eye because that’s where neurons come and go, which results in a blind spot.
In what order do sound waves travel through the ear?
-Pinna -> auditory canal -> tympanic membrane -> ossicles -> oval window -> cochlea -> auditory nerve -> brain.
