Sensory System Overview

Sensory receptors convert various stimuli into electrical signals that can be interpreted by the nervous system.

The area where a sensory receptor responds to a stimulus.

Sensory receptors become less responsive to a constant stimulus over time, leading to a diminished perception.

The process where strongly activated sensory neurons inhibit nearby neurons, enhancing the sharpness and clarity of perception.

The process of converting sensory information (light, sound, pressure, etc.) into electrical signals that the brain can understand.

The type of sensory receptor that detects changes in light intensity and wavelength, enabling vision.

The type of sensory receptor that detects changes in pressure, vibration, and touch, enabling the sense of touch and hearing.

The type of sensory receptor that detects dissolved chemicals, enabling the senses of smell and taste.

A single olfactory receptor cell is only sensitive to one specific smell.

The process begins when an odorant molecule binds to an odorant receptor on the olfactory receptor cell.

The activated G-protein triggers Adenylate cyclase, which converts ATP into cAMP.

Cyclic AMP (cAMP) opens Na+/Ca2+ channels, allowing sodium and calcium ions to enter the cell.

The influx of sodium and calcium ions depolarizes the cell, generating an action potential that travels to the brain.

A small, onion-shaped sensory organ containing taste receptor cells.

The five basic tastes are: salty, sour, sweet, bitter, and umami.

Light waves enter the eye through the cornea, pass through the pupil and lens, and reach the retina.

A water-like substance that helps maintain the shape of the eye, cleans the lens, and is produced by the ciliary processes. It flows through the posterior and anterior chambers before being recycled through the scleral venous sinus.

The muscle that constricts the pupil in bright light, making the opening smaller.

The muscle that dilates the pupil in low light, making the opening wider.

The ability to see distant objects clearly but not near objects.

The ability to see near objects clearly but not distant objects.

The central part of the retina responsible for sharp, detailed vision, containing only cones.

The point where the optic nerve leaves the eye, containing no photoreceptor cells, creating a blind spot.

Specialized light-sensitive cells in the retina that convert light into electrical signals.

A protein located in rod photoreceptors; it's responsible for detecting light and initiating the visual transduction process.

The retinal molecule can change shape based on the presence or absence of light. In the dark, it is in a 'cis' form and inactive. When light hits it, it changes to a 'trans' form, activating the phototransduction process.

An enzyme that plays a crucial role in the phototransduction pathway. It breaks down cyclic GMP (cGMP), a molecule that keeps sodium channels open in the dark. This closure of sodium channels reduces the release of neurotransmitters from the photoreceptor.

A protein that acts as a messenger in the phototransduction pathway. It is activated when light causes rhodopsin to change shape, and it in turn activates phosphodiesterase.

The process of converting sound waves into electrical signals that can be interpreted by the brain. It involves the transduction of sound energy through the ear and the firing of action potentials in auditory neurons.

The tube that connects the middle ear to the pharynx (throat). Its primary function is to equalize air pressure between the middle ear and the outside environment, ensuring proper functioning of the eardrum.

The thin membrane that separates the external ear from the middle ear. It vibrates in response to sound waves, transferring the vibrations to the ossicles in the middle ear.

Three tiny bones in the middle ear (malleus, incus, stapes) that amplify and transmit sound vibrations from the eardrum to the inner ear.

A hormone released by the anterior pituitary gland that stimulates growth, especially of bone and muscle.

Signaling molecules produced in the liver in response to growth hormone, which further stimulate growth of bone, muscle, and organs.

A hormone produced by the thyroid gland that regulates metabolism in the body, affecting every cell.

A condition where the thyroid gland is enlarged, often due to lack of iodine.

A condition characterized by high levels of thyroid hormone and low levels of thyroid-stimulating hormone (TSH).

A condition characterized by low levels of thyroid hormone and high levels of thyroid-stimulating hormone (TSH).

A hormone produced by the adrenal medulla that triggers the 'fight or flight' response during stressful situations.

A hormone secreted by the posterior pituitary gland that regulates water balance in the body by controlling reabsorption in the kidneys.

In children, the ear tube is positioned horizontally. This makes it more likely for bacteria or viruses to enter the tube, potentially leading to ear infections. In adults, the tube is slanted, reducing the risk of infections.

Sound waves cause the eardrum to vibrate, which in turn vibrates the tiny bones in the middle ear (malleus, incus, and stapes). The stapes then transmits vibrations to the oval window, setting the fluid in the cochlea into motion. This fluid movement creates waves that signal the brain.

The cochlear duct is filled with a fluid called endolymph, which is high in potassium ions. This fluid is crucial for the transmission of sound signals.

When the hair cells bend, they open channels that allow potassium ions (K+) to flow into the cells. This influx of potassium causes depolarization, which triggers the release of neurotransmitters and ultimately generates a nerve impulse.

The hair cells are specialized sensory receptors that detect mechanical stimuli, such as sound waves or changes in head position.

Endolymph is a unique fluid found in the inner ear. It is characterized by a high concentration of potassium ions.

The basilar membrane, a flexible structure within the cochlea, responds to different frequencies of sound by vibrating at different locations. This location-specific vibration provides the brain with information about the frequency of sound.

The semicircular canals are responsible for detecting angular head movements, such as rotation or spinning.