Chapter 50 - Sensory and Motor Functions

Flashcards covering sensory pathways, receptor types, hearing, equilibrium, vision, gustation, olfaction, and skeletal muscle function based on the Chapter 50 lecture notes.

Sensation

The process involving the ability to convert stimuli (energy) into an action potential of sensory receptors.

Reception

The stage of sensory pathways involving the detection of stimuli via sensory receptors.

Transduction

The conversion of stimulus energy into a change in membrane potential, known as a receptor potential.

Receptor potential

Graded potentials in sensory receptors where the magnitude is based on the strength of the stimuli.

Transmission

The process where sensory cells generate action potentials to the CNS, either through specialized neurons or cells that release neurotransmitters to regulate neurons.

Perception

The brain’s construction or interpretation of stimuli; how the brain understands the stimuli.

Integration

The summation of action potentials within the nervous system.

Amplification

The strengthening of a stimulus by cells in sensory pathways, which can occur in accessory structures or during transduction.

Sensory adaptation

A decrease in responsiveness to continued stimulation, resulting in selective information being sent to the CNS.

Exoreceptors

Sensory receptors that monitor external environmental conditions.

Interreceptors

Sensory receptors that monitor internal bodily conditions.

Mechanoreceptors

Receptors that sense physical deformation such as pressure, stretch, motion, and sound by increasing permeability to $Na^+$ and $K^+$.

Chemoreceptors

Sensory receptors that respond to chemical stimuli such as solutes, odorants, glucose, oxygen, or carbon dioxide.

Osmoreceptors

Mammalian chemoreceptors that detect changes in the total solute concentration of the blood and stimulate thirst when osmolarity increases.

Electromagnetic receptors

Receptors that detect electromagnetic energy including light, electricity, and magnetism.

Thermoreceptors

Sensory receptors that detect heat and cold to regulate body temperature.

Nociceptors

Commonly known as pain receptors, these detect stimuli that reflect extreme harmful conditions and trigger defensive reactions.

Prostaglandins

Chemicals produced by damaged tissue that increase pain by lowering the thresholds of nociceptors; their production is inhibited by aspirin and ibuprofen.

Statocysts

Mechanoreceptors in most invertebrates responsible for the sense of gravity and balance.

Statoliths

Grains of sand or dense material in a statocyst that resettle when an animal moves, stimulating mechanoreceptors to provide orientation info.

Pinna

The part of the outer ear that gathers and funnels sound waves into the external auditory canal.

Tympanic membrane

Also known as the eardrum, this membrane vibrates upon receiving sound waves, causing the bones of the middle ear to move.

Eustachian tubes

Passageways between the middle ear and nasal cavity that maintain equal pressure between the middle ear and the atmosphere.

Malleus, incus, and stapes

Three bones in the middle ear that amplify vibrations and transmit them to the inner ear via the oval window.

Oval window

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

Cochlea

The inner ear structure that converts sound waves into pressure waves in fluid and eventually into neural signals.

Organ of Corti

The part of the cochlea that contains hair cells, which act as the sensory receptors for hearing.

Basilar membrane

The membrane within the Organ of Corti that vibrates in response to pressure waves, moving attached hair cells up and down.

Stereocilia

Hairs projecting from the top of hair cells that bend against the tectorial membrane, leading to depolarization or hyperpolarization.

Round window

The structure that relieves pressure created by the oval window and prevents the reverberation of pressure waves within the ear.

Utricle and saccule

Chambers behind the oval window that perceive position with respect to gravity and linear movements.

Otoliths

Ear stones made of calcium carbonate that shift when the head tilts, altering neurotransmitter output from hair cells.

Semicircular canals

Three canals connected to the utricle that detect angular motion and rotation of the head in three spatial planes.

Ocelli

Eyespots found in planarians that receive light through an opening to help the organism move away from light sources.

Compound eyes

Eyes consisting of several thousand light detectors called ommatidia, effective at detecting movement.

Ommatidia

The individual light-detecting facets of a compound eye, each having its own light-focusing lens.

Single-lens eyes

Camera-like eyes found in jellies, spiders, and vertebrates where light enters through a pupil directed by a single lens.

Iris

The adjustable aperture of the eye that contracts or expands to change the diameter of the pupil.

Sclera

The connective tissue that forms the white of the eye and the cornea.

Cornea

The part of the sclera that functions in letting light into the eye.

Retina

The innermost layer of the eyeball containing neurons and photoreceptors.

Aqueous humor

A clear watery substance in front of the lens that provides nutrients to the eye.

Vitreous humor

A jelly-like substance behind the lens that helps the eye hold its shape.

Rods

Photoreceptors that are more sensitive to light than cones and are used for night vision in black and white.

Cones

Photoreceptors responsible for color vision, categorized into three types: red, green, and blue.

Rhodopsin

The visual pigment specifically found in rods.

Optic disc

A blind spot in the retina that lacks photoreceptors and is the site where the optic nerve exits.

Horizontal cell

A retinal neuron that integrates information across the retina and facilitates lateral inhibition.

Lateral inhibition

A process that enhances contrast and sharpens edges by inhibiting distant photoreceptors and bipolar cells that are not illuminated.

Optic chiasm

The site where the two optic nerves meet, resulting in information from the right eye being transmitted to the left brain and vice versa.

Photopsins

The visual pigments of the colored cones, which include distinct opsin proteins for different wavelengths.

Gustation

The sense of taste, involving the detection of chemicals called tastants in solution.

Olfaction

The sense of smell, involving the detection of airborne odorants.

Papillae

Tiny nipple-shaped projections on the tongue where taste buds are located.

Sarcomeres

The basic contractile units of skeletal muscle, responsible for the striations seen in muscle tissue.

Myofibrils

Bundles of repeating sarcomere units that make up a muscle fiber.

Tropomyosin and troponin complex

Proteins that bind to actin to block myosin-binding sites; they are dislodged when calcium ions bind to the troponin complex.

Motor unit

A functional unit consisting of a single motor neuron and all the muscle fibers it controls.