Sensory receptors and eyes Flashcards
What are the 5 major types of sensory receptors?
- mechanoreceptors
- thermoreceptors
- pain receptors
- chemoreceptors
- photoreceptors
What are sensory receptors?
Dendrites that react to a certain external or internal stimulus
Which sensory receptor is responsible for touch?
Mechanoreceptor
Which sensory receptor is responsible for temperature?
Thermoreceptors
Which sensory receptor is responsible for pain?
Pain receptors (noriceptors)
Which sensory receptor is responsible for chemicals?
Chemoreceptors
Which sensory receptor is responsible for light?
Photoreceptors
What are the impulses produced in the skin called?
Cutaneous sensations
What do cutaneous sensations include?
- touch
- heat
- cold
- pressure
- pain
Free nerve endings
- pain
- temperature
- touch
- pressure
Meissner’s corpuscles
Encapsulated nerve endings found in hairless skin that detect light touch
Merkel’s disks
Detect light touch and pressure within the epidermis
Hair follicle receptors
Detect movement of hair
Ruffini’s corpuscles
Detect deep pressure and stretching of the skin
Pacinian corpuscles
Encapsulated nerve endings that detect deep pressure and vibrations
Why is touch considered a general sense?
It includes many types of receptors found all over the body
Special senses are what and what are they?
Their receptors are clustered in specialized organs or in a small area
- sight
- hearing
- smell
- taste
- balance
What covers the surface of the eyeball and is the inner layer of the eyelid?
Conjuctiva. It secretes mucus to lubricate the eye
What are the corners of the eye called?
Medial commissure and the lateral commissure
Besides the conjuctiva, what else lubricates the eye?
Lacrimal apparatus
What do lacrimal glands release and why?
Tears to cleanse and moisten the eye
What do tears contain?
- mucus
- antibodies
- lysozyme (antibacterial enzyme)
What is the path that tears take when they drain?
- lacrimal canaliculi
- lacrimal sac
- nasolacrimal duct
What are the 3 tissues that the eye is comprised of?
- sclera
- choroid
- retina
Sclera
- white of the eye
- fibrous connective tissue
- protects and shapes the eye
Choroid
- pigmented
- vascular membrane that includes iris and pupil
Retina
Contains photoreceptors that turn light energy into nerve impulses
What allows light into the eye?
Cornea
Iris
- colored part of the eye
- located behind the cornea
- works with the pupil to regulate light coming into the eye
Pupil
The opening in the center of the iris through which light enters
Lens
A semi-solid disc that directs light waves towards the retina
What is the lens controlled by?
Ciliary muscles and suspensory ligaments
What happens to the lens with age?
It becomes less elastic
Aqueous humor
Fluid in front of the lens which nourishes the cornea
Vitreous humor
A thick, jelly-like fluid that refracts light and fills the space between the lens and retina
What does the retina contain?
Thousands of photoreceptors
What are the two types of photoreceptors?
- rods
- cones
Rods
- distributed all over the retina
- responsible for vision in low-light
- extremely sensitive
Cones
- concentrated in the center of the retina
- responsible for the detection of colors
- less sensitive
In order to see an image, light passes through the eye and hits what?
Retinal pigment epithelium (RPE) on the back of the eye
What point of the eye contains only cones and provides the sharpest image?
Fovea centralis
What is a blind spot?
No photoreceptors where the optic nerve meets the eye, but the brain makes up for it
Myopia
Near-sightedness
Hyperopia
Far-sightedness
How do corrective lenses help the eyes?
They refract the light so it accurately converges on the retina
