12.3 Mechanoreception and Chemoreception Flashcards
What do Mechanoreceptors in the ear do?
Convert the energy of sound waves into electrochemical energy
What are the major divisions of the ear?
Outer ear, Middle ear, inner ear
What does the outer ear consist of?
The Pinna and auditory canal
What is the Pinna?
The outside flap of the ear made of skin and cartilage
Why is the Pinna shaped the way it is?
To enhance sound vibrations and focus them in the ear
What is the Auditory Canal?
A 2.5 cm long tube that leads to the eardrum in the middle ear
What does the Auditory Canal do?
Amplifies sound waves
What do the hairs and glands in Auditory Canal do?
Prevent dust, insects, bacteria, and foreign particles from proceeding deeper into the ear
What is the Middle ear?
An air filled space that is bordered on one side by the tympanum
What is the Tympanum?
A round elastic structure that vibrates in response to sound waves
What happens when sound waves push the Tympanum?
It vibrations are passed on an amplified by the neighboring Ossicles
What are the Ossicles?
Three tiny interconnected bones in the middle ear
What does each bone in the Ossicles act like?
A lever for the next. So as vibrations pass from each bone to the next, they are amplified
What are the bones of the Ossicles?
Malleus, Incus, Stapes
What does the Stapes do?
Concentrates vibrations into a membrane covered wall of the inner ear, called the oval window
What does the Eustachian tube connect?
Connects the middle ear to the throat
What is the purpose of the Eustachian tube?
Allows air pressure to equalize when there is a difference in air pressure
What does the Inner ear consist of?
The semicircular canals, vestibule, and the cochlea
What do the Semicircular canals and vestibules contain?
Sensors for balance
What is the Cochlea used for?
Hearing
What happens in the Cochlea?
Mechanical energy is converted into electrochemical impulses that are transmitted to the brain
What does the middle chamber of the ear contain?
The organ of Corti
What is the Organ of Corti?
The Organ of hearing
What is along the base of the Organ of Corti?
The basilar membrane which sensory receptors called hair cells are attached and have thin projections called stereocilia
Where are the far ends of stereocilia embedded?
Within the tectorial membrane
What happens when stapes strike the Oval Window?
It vibrates the window and creates pressure waves in the fluid of cochlea
What do the pressure waves in the fluid of the cochlea do?
Make the basilar membrane move up and down, which causes the stereocilia of the hair cells to bend against the tectorial membrane
What happens when the hair cells bend against the tectorial membrane?
The nerve cells sense this movement and send an impulse to the brain
What are the hair cells in the Organ of Corti able to do?
Distinguish the frequency (pitch) and amplitude (intensity) of sound waves
What is Frequency?
The number of waves that pass through a specific point every second and is measured in Hertz
What does the Frequency of speech usually range from?
100 to 4000 hz
Which hair cells do high frequencies stimulate?
Hair cells closests to the oval window
Which hair cells do low frequencies stimulate?
Hair cells farthest from the oval window
What does hearing loss usually result from?
Nerve damage of the hair cells or damage to the outer or middle ear
What is the amplitude of a sound wave?
The intensity or volume of sound
What happens when a sound is loud?
It puts pressure on the fluid of the cochlea which puts pressure on the hair cells which are very sensitive
What dBs can damage the ears?
80 dBs
Where do sensory neurons in the ears send information to?
The auditory nerve which sends the information to the thalamus, brain stem, and temporal lobes
Which structures in the inner ear help us stand upright?
The semicircular canals, utricle, and saccule
What do the Semicircular Canals contain?
Mechanoreceptors that detect head and body rotation
What are the Semicircular Canals?
Three fluid filled loops arranged in different planes
What happens inside the semicircular canals?
The stereocilia of the hair cells stick into jelly like covering called a cupula. When the head rotates the fluid inside the canals bend the stereocilia causing the hair cells to send information to the brain
What is Gravitational Equilibrium?
The balance required while moving the head forwards and backward
What does Gravitational equilibrium depend on?
The Utricle and the Saccule which make up the fluid filled vestibule of the inner ear
What do the Utricle and the Saccule contain?
Calcium carbonate granules called otoliths
What happens when the head moves forward or back?
Otoliths that lie over the layers of hair cells causing them to send a neural impulse to the brain
What are Proprioceptors?
Another type of mechanoreceptor involved in coordination
Where are Proprioceptors found?
In muscles, tendons, and joints throughout the body
What do Proprioceptors do?
Send information about the body position to the brain
What are the 4 basic tastes?
Salty, Sour, Sweet, Bitter
What happens when we eat?
Saliva dissolves some of our food and specific molecules are detected by the taste buds
Where does information from the tongue get sent to?
The brainstem, thalamus then to the gustatory centre of the parietal lobe
What are the Chemoreceptors in the nose?
The olfactory cells that line the upper nasal cavity
What happens to particles bind to the olfactory cells?
Ion channels in the cell membrane open which generates an action potential in the olfactory cells which are linked to the olfactory bulb in the brain
What part of the brain does perception of odour occur?
The frontal lobe
What are pheromones detected by?
By a structure in the nose called the vomeronasal organ
When is pain sensed?
When specialized sensors or nerve endings are activated by mechanical pressure or chemical signals
What do Nociceptors do?
Release chemicals that trigger pain receptors to send impulses to the brain
