Nervous System Flashcards
Merkels Disk
Organ for sensing gentle touch and is essential for sophisticated sensory tasks, including social interaction, environmental exploration, and tactile discrimination.
Hair Follicle Receptor
Each hair plexus forms a network around a hair follicle and is a receptor, which means it sends and receives nerve impulses to and from the brain when the hair moves. Endings of sensory nerve fibers which form a plexus around a hair follicle in hairy skin
Ruffins Corpsucle
found in the superficial dermis of both hairy and glaborous skin where they record low-frequency vibration or pressure
Pacinian Corpsuckle
espond only to mechanical deformation. A Pacinian corpuscle is an onion-shaped structure of nonneural (connective) tissue built up around the nerve ending that reduces the mechanical sensitivity of the nerve terminal itself.
Free Nerve Ending
Free nerve endings are the most common nerve endings in skin, and they extend into the middle of the epidermis. Free nerve endings are sensitive to painful stimuli, to hot and cold, and to light touch. They are slow to adjust to a stimulus and so are less sensitive to abrupt changes in stimulation.
malleus (hammer)
Incus (anvil)
Stapes (stirrup)
transmits vibrations caused by sound waves from the eardrum membrane to the liquid of the inner ear
Cochlea
The function of the cochlea is to transform the vibrations of the cochlear liquids and associated structures into a neural signal.
Cornea
The cornea acts as the eye’s outermost lens. It functions like a window that controls and focuses the entry of light into the eye. The cornea contributes between 65-75 percent of the eye’s total focusing power.
Pupil
The function of the pupil is clearly that of controlling the amount of light entering the eye, and hence the light reflex.
Iris`
The iris controls the amount of light that enters the eye by opening and closing the pupil.
Retina
The retina is an essential part of the eye that enables vision. It’s a thin layer of tissue that covers approximately 65 percent of the back of the eye, near the optic nerve. Its job is to receive light from the lens, convert it to neural signals and transmit them to the brain for visual recognition.
Lens
Behind the iris sits the lens. By changing its shape, the lens focuses light onto the retina. Through the action of small muscles (called the ciliary muscles), the lens becomes thicker to focus on nearby objects and thinner to focus on distant objects.
Farsighted
unable to see things clearly, especially if they are relatively close to the eyes, owing to the focusing of rays of light by the eye at a point behind the retina; hyperopic.
Nearsighted
unable to see things clearly unless they are relatively close to the eyes, owing to the focusing of rays of light by the eye at a point in front of the retina; myopic.
