They translate stimuli like light waves or food molecules into electrical signals through transduction.
They convert physical movement into electrochemical signals when their stereocilia bend against the tectorial membrane.
Agonists promote movement while antagonists oppose or inhibit it.
Rods and cones.
The central nervous system (brain and spinal cord) and the peripheral nervous system (nerves and ganglia).
Flexors bend a joint, bringing bones closer together, while extensors straighten a joint, increasing the angle between bones.
They detect how much force or tension is applied to a muscle during ongoing movement, increasing precision.
The simultaneous contraction of agonists and antagonists to stabilize or control a movement.
Individuals can lose their ability to move.
A small area in the center of the retina where cones are most densely packed, allowing for sharp vision.
Special sensory fibers that respond to stimuli that can cause tissue damage.
A condition where even soft touch can produce pain, often due to heightened sensitivity.
Strabismus.
It acts as the brain's relay station for incoming sensory information before sending it to the auditory cortex.
A motor unit consists of an alpha motor neuron and all the muscle fibers it controls.
They pick up fine detail and color, enabling high visual acuity.
The minimum distance between two points on the skin that can be identified as distinct stimuli.
Skeletal muscles.
Neuronal circuits in the spinal cord and brainstem that produce rhythmic patterns for locomotion.
About 30 percent.
They are extremely sensitive and allow vision in dim light.
Signals travel along sensory nerve fibers to neurons in the spinal cord, then to the thalamus and somatosensory cortex.
When a bare foot encounters a sharp object, pain receptors send a message to the spinal cord, activating alpha motor neurons to lift the leg.
Light passes through the cornea, pupil, and lens, then travels through ganglion cells and interneurons before reaching photoreceptors.
Through small A-delta fibers and C fibers to the spinal cord, then to the brainstem and thalamus.
Reflexes are automatic muscle responses to stimuli that occur without conscious control.
To process and interpret complex messages in the form of speech sounds.
The membrane moves, vibrating to higher-pitched sounds near the oval window and to lower-pitched sounds in the center.
Each hair cell responds most strongly to a narrow range of sound frequencies based on its location along the cochlea.
It is the process where the activation of motor neurons controlling one muscle (extensor) also inhibits the motor neurons controlling the antagonist muscle (flexor).
It integrates sensory information to ensure proper timing and coordination of muscle action.
They mix in the brain to create the perception of flavor, enhancing taste experiences.
Specialized receptors located where muscle fibers connect to tendons, providing feedback about muscle tension.
In the occipital lobe at the back of the brain.
Pain perception can vary based on emotional state and the context of the injury.
The motor cortex.
Dopamine.
Humans have between 5,000 and 10,000 taste buds, but start to lose them around age 50.
A condition that leads to blindness due to the death or degeneration of photoreceptors in the macula.
Center-surround antagonism.
Seeing with two eyes, allowing perception of depth.
It decreases, likely due to damaged receptors and sensory neurons not being replaced.
They help navigate the chemical world and detect hazardous substances.
A stretch reflex that occurs when a physician taps the tendon below the knee, causing the lower leg to swing forward.
They tile the retina and create a two-dimensional representation of the visual scene.
A crossover junction where nerve fibers from both eyes converge.
It is the activation of extensors in the opposite leg to maintain balance when one leg is lifted due to a painful stimulus.
Meditation, hypnosis, massages, cognitive behavioral therapy, and controlled use of cannabis.
They facilitate desired motor programs and suppress unwanted actions.
Touch sensations including light touch, pressure, vibration, temperature, texture, itch, and pain.
It sends messages from the brain to control muscles and internal organs.
It refines and sharpens motor programs for tasks like walking, speaking, or playing an instrument.
They are sensitive to different ranges of colors (red, green, blue) and their overlapping sensitivities allow for the perception of the full color spectrum.
It converts mechanical vibrations into pressure waves and then into electrical signals.
A person can hear speech but may not understand what is being said.
Through alpha motor neurons that originate in the spinal cord or brain.
Comparing the amounts of light hitting small, adjacent areas on the retina.
It processes smell information and sends it directly to the cerebral cortex.
It is tuned to different frequencies along its length.
Stem cells may give rise to neurons that mediate smell or taste, potentially leading to therapies for restoring these senses.
They connect within the spinal cord to inhibit motor neurons supplying the flexor muscle during reflex actions.
Poor coordination, balance disorders, and difficulties in speech.
Thermal, mechanical, and chemical stimuli.
The dorsal stream (where) and the ventral stream (what).
Vision can be restored if treated before the age of 8.
Tremor, rigidity, and akinesia (inability to move).
Olfactory neurons are continually replaced throughout our lives.
The portion of visual space providing input to a single ganglion cell.
They keep the muscle spindles taut, allowing for better detection of muscle stretch.
Transducing pressure waves into electrical signals.
They provide information about changes in muscle length or stretch to the brain.
They act as natural analgesics, helping to regulate and reduce pain.
Through vibrations of the eardrum transmitted by three tiny bones in the middle ear.
