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Nervous systems

Nervous systems

Systems in animals that consist of circuits of neurons and supporting cells.

Neurons

Cells in the nervous system that transmit electrical signals.

Supporting cells

Cells in the nervous system that provide support and nourishment to neurons.

Nerve net

Interconnected nerve cells in cnidarians that control contraction and expansion of the gastrovascular cavity.

Nerves

Bundles of axons of multiple nerve cells that channel and organize information flow through the nervous system.

Ganglia

Segmentally arranged clusters of neurons found in annelids and arthropods.

Glia

Cells in the nervous system that nourish, support, and regulate neurons.

Central Nervous System (CNS)

The brain and spinal cord.

Peripheral Nervous System (PNS)

Nerves and ganglia outside of the CNS.

Motor system

Component of the PNS that carries signals to skeletal muscles.

Autonomic nervous system

Component of the PNS that regulates smooth and cardiac muscles.

Sensory receptors

Structures that detect stimuli and transmit signals to the CNS.

Sensory transduction

Conversion of stimulus energy into a change in the membrane potential of a sensory receptor.

Receptor potential

Change in membrane potential of a sensory receptor in response to a stimulus.

Perception

Brain's construction of stimuli based on action potentials from sensory receptors.

Amplification

Strengthening of a sensory signal during transduction.

Adaptation

Decrease in responsiveness to continued stimulation.

Mechanoreceptors

Sensory receptors that sense physical deformation caused by pressure, touch, stretch, motion, and sound.

Electromagnetic receptors

Sensory receptors that detect electromagnetic energy such as light, electricity, and magnetism.

Thermoreceptors

Sensory receptors that detect heat and cold.

Pain receptors

Sensory receptors that detect stimuli that reflect conditions that could damage animal tissues.

Chemoreceptors

Sensory receptors that transmit information about solute concentration or respond to specific molecules.

Olfaction

Detection of odorants carried in the air.

Gustation

Detection of tastants present in a solution.

Hearing

Detection of sound waves by mechanoreceptors.

Equilibrium

Perception of body balance and orientation.

Statocysts

Organs in invertebrates that sense gravity and maintain equilibrium.

Taste buds

Structures in the tongue that contain taste receptors.

Papillae

Projections on the tongue where taste buds are mostly found.

Umami

One of the five types of taste recognized by humans, associated with savory or meaty flavors.

Hearing

Vibrating objects create pressure waves in the air, which are transduced by the ear into nerve impulses, perceived as sound in the brain.

Tympanic membrane

The membrane in the ear that vibrates in response to vibrations in the air.

Middle ear

The part of the ear that contains three bones that transmit vibrations of moving air to the cochlea.

Oval window

A membrane on the cochlea's surface that receives the vibrations from the middle ear.

Cochlea

A part of the inner ear that contains fluid and hair cells responsible for detecting sound.

Basilar membrane

A membrane in the cochlea that vibrates in response to pressure waves in the fluid.

Hair cells

Cells in the cochlea that bend in response to vibrations, causing ion channels to open or close and resulting in a change in auditory nerve sensations.

Round window

The window at the end of the vestibular canal where fluid waves dissipate.

Scala vestibuli

The vestibular canal in the cochlea.

Scala tympani

The tympanic canal in the cochlea.

Volume

The amplitude of the sound wave, which the ear can capture information about.

Pitch

The frequency of the sound wave, which the ear can distinguish due to the non-uniformity of the basilar membrane.

Equilibrium

The detection of body movement, position, and balance by several organs in the inner ear.

Utricle and saccule

Organs in the inner ear that contain granules called otoliths, allowing perception of position relative to gravity or linear movement.

Semicircular canals

Three canals in the inner ear that contain fluid and detect angular movement in any direction.

Visual receptors

Cells or organs that detect light in animals.

Photoreceptors

Cells that contain light-absorbing pigment molecules.

Light-detecting organ

An organ in animals that detects light.

Compound eyes

Eyes found in insects, crustaceans, and some worms, consisting of multiple light detectors called ommatidia.

Single-lens eyes

Eyes found in some jellies, worms, mammals, spiders, and molluscs, working on a camera-like principle.

Vertebrate visual system

The visual system in vertebrates, where light enters the eye and strikes the rods and cones, and the brain processes the visual information.

Retina

The part of the eye where rods and cones are located and where visual information processing begins.

Rods and cones

Photoreceptor cells in the retina that release the neurotransmitter glutamate in response to light.

Bipolar cells

Neurons in the retina that receive glutamate from rods and cones and are either hyperpolarized or depolarized in response.

Glutamate

A neurotransmitter released by rods and cones in the retina.

Optic nerves

Nerves that carry visual information from the retina to the brain.

Optic chiasm

The point where the optic nerves meet near the cerebral cortex.

Color vision

The ability to perceive different colors.

Cones

Photoreceptor cells in the retina responsible for color vision, with different types containing visual pigments for red, green, or blue.