Srnsory Organs

What is the function of receptors?

Receptors sense changes in their environment and trigger nerve impulses.

What are mechanoreceptors and where are they located?

Mechanoreceptors sense changes in pressure or movement of fluid.

What do chemoreceptors sense?

Chemoreceptors are stimulated by changes in chemical concentrations and are associated with the senses of smell and taste.

What do thermoreceptors detect?

Thermoreceptors sense temperature changes, including heat and cold.

What is the role of nociceptors?

Nociceptors sense pain and tissue damage.

What are photoreceptors and where are they found?

Photoreceptors are light receptors located in the eye.

How is sensation defined?

Sensation is the interpretation of sensory nerve impulses by the brain, resulting in awareness of internal or external events.

What is the role of the thalamus in sensation?

The thalamus receives crude sensory information and relays it to the cortex.

What is referred pain?

Referred pain occurs when visceral pain neurons share somatic pathways, leading to confusion in the cortex about the source of pain.

Where are olfactory receptors located?

Olfactory receptors are located in the upper nasal cavity.

How does the process of smell occur?

Smells trigger nerve impulses that travel to the olfactory bulb and then to the limbic system and cortex for interpretation.

What are taste buds and where are they located?

Taste buds are sensory receptors located on the tongue.

What are the four basic taste sensations?

The four basic taste sensations are sour, sweet, bitter, and salty.

How does taste work with smell?

Taste works hand in hand with smell, as aromas assist in the judgment of taste.

What role do temperature and texture play in taste?

Temperature and texture significantly influence the perception of taste.

What happens during sensory adaptation?

Sensory adaptation occurs quickly, reducing sensitivity to constant stimuli.

Which of the following picks up sensations of light touch?

Meissner corpuscles

Where is sensory information sent following reaching the thalamus?

Cerebral cortex

Which of the following describes the basis for referred pain (e.g. the pain of a heart attack radiates to the left shoulder and arm)?

The same nerves that carry sensory information from the heart also carry sensory information from the shoulder

The sense most closely related to taste is:

Smell

"Tastebuds" that contain clusters of chemoreceptors are found within:

Papillae.

After a smell triggers a olfactory receptor, the signal is passed first to:

olfactory bulb.

Recall the cranial nerve responsible for hearing and equilibruim

(8) VIII - vestibulocochlear (hearing and balance)

Cerebellum

Balance

Sensory impulses from VIII cranial nerve

Connect with the cerebellum

Proprioceptors

Receptors located in muscles, tendons, joints which allow the body to recognize its position

What are the three divisions of the ear?

The ear is divided into three parts: external, middle, and internal.

What is the function of the external ear?

The external ear is funnel-shaped and collects sounds.

What is the auditory meatus?

The auditory meatus is an S-shaped tube that leads inward from the external ear.

How are sounds transmitted in the ear?

Sounds are collected through vibration and transmitted through matter as sound waves.

What role does the auricle play in hearing?

The auricle directs sound waves inward towards the ear.

What separates the external ear from the middle ear?

Tympanic membrane

Endolymph is located where?

In the membranous labyrinth

External Ear – Auricle (Pinna)

Funnel shaped; collects sounds

External Ear – Auditory Meatus

S-shaped tube that leads inward

Sound Transmission (External Ear)

Sounds are collected through vibrations transmitted through matter as sound waves and directed inward because of the auricle

Middle Ear Includes

Tympanic cavity, tympanic membrane, auditory ossicles

Tympanic Membrane (Eardrum)

Separates the external and middle ear

Tympanic Membrane Structure

Semi-transparent membrane; interior is mucous membrane

Tympanic Membrane Shape

Cone-shaped because of attachment to the auditory ossicles (malleus)

Sound Waves in Auditory Meatus

Create pressure changes causing the eardrum to move

Vibration Pathway

Vibrations progress inward to the auditory ossicles

Auditory Ossicles (Order)

Malleus, Incus, Stapes

Oval Window

Opening that relays sound from the tympanic cavity into the inner ear

Inner Ear Response

Vibrations produce fluid motion and stimulate hearing receptors

Auditory Tube (Eustachian Tube)

Also called the Eustachian tube

Auditory Tube Connection

Connects the middle ear to the throat

Auditory Tube Function (Air Movement)

Allows air to pass between the inside and the outside

Auditory Tube Function (Pressure)

Allows equal pressure to be maintained on either side of the eardrum

Inner Ear

Consists of communicating sets of tubes and chambers called a labyrinth

Inner Ear Labyrinths

Two labyrinths: osseous and membranous

Labyrinth Relationship

One sits inside the other like an “inner tube”

Inner Ear Fluids

Two different fluids

Perilymph

Secreted by the bony canal (outside tire)

Endolymph

Secreted by the membranous labyrinth (inner tube)

Semicircular Canals

Lay at right angles in different planes and function in equilibrium

Cochlea

Snail-shaped structure with internal spaces and membranes

Organ of Corti

Located in the cochlea; hearing receptors live here

Function of Organ of Corti

Functions in sound transmission

Sound Pathway (Start) →

Vibrating object makes sound

External Ear Function →

External ear collects sound

Eardrum (Tympanic Membrane) →

Vibrates in response to sound

Auditory Ossicles →

Amplify vibration

Oval Window →

Vibrates

Inner Ear Response →

Inner ear fluid moves

Organ of Corti →

Detects sound

Cranial Nerve VIII →

Vestibulocochlear nerve sends signal to the brain

The semicircular canals are involved in:

balance during movement

What is located in the utricle and is responsible for static equilibrium?

Otoliths

Endolymph in the semicircular canals moves what when you turn your head?

Cupula

Equilibrium

Maintained by two forces: static and dynamic

Static Equilibrium

Senses the position of the head

Vestibule

Has two chambers: utricle and saccule

Macula

Structure within the vestibule that contains sensory receptors

Macula Receptors

Hair cells embedded in the otoliths

Head Movement (Static)

As the head turns, otoliths roll and pull on hair cells

Static Equilibrium Signal

Stimulates impulses to CN VIII (vestibulocochlear nerve)

Brain Area Informed

Cerebellum is informed of the position of the head

Dynamic Equilibrium

Maintains balance when the head or body is rotated or suddenly moved

Dynamic Equilibrium Control Site

Crista ampullaris

Crista Ampullaris Location

Located in the semicircular canals