Sensory Receptors
input to the nervous system is in the form of our five senses: touch, taste, smell, sight and sound
sight, taste, smell and sound are known as the _______________________
______________________________________________________________ ______________________________________________________________ touch (pain, temperature, pressure) is known as the ___________________ ______________________________________________________________ ______________________________________________________________ 1. Touch
the skin contains receptors for ___________, ____________, ________ and ____________.
(http://www3.open.uoguelph.ca/de/ideaExchange/zoo1500/images/cwork/unit3/skin.gif)
- Pressure receptors are not evenly distributed in the skin, nor are they equally sensitive
- The fingertips, mouth and tongue are the ________ sensitive to pressure and the back, chest and abdomen are the _________ sensitive
- The body contains many more __________ receptors than heat
receptors
- Different body parts have different sensitivities to temperature (eg. the mouth can withstand more than the skin)
2. Taste
- the tongue contains taste buds -a type of ____________________.
- small bumps on the tongue called __________________ contain the taste buds.
- there are five types of specialized taste receptors: _______________ _______________________________. These are found in each of our taste buds.
- ________________ are actually buried in the tissue, and a small pore lets solutions in to stimulate the receptors in the taste bud
- these receptors are attached to nerves which lead to the _____________ lobe of the brain
- we need saliva in order to taste because...
3. Smell
- in the upper part of the nasal cavity there are ________________ cells which respond to smell
- olfactory cells are columnar cells with _________ which act as sensors
- the cilia are attached to nerves which lead to the _____________ in the ________________________ located in the ________________.
4. Sight
- the human eye:
- parts of the eye: sclera –
cornea –
choroid layer –
pupil –
retina –
rod –
cone –
fovea –
lens –
aqueous humor (anterior chamber) –
vitreous humor (vitreous chamber) –
optic disk –
optic nerve –
-- the human eye can detect light in the 400-700nm range, which really is only a small portion of the electromagnetic spectrum:
(http://www.yorku.ca/eye/spectrum.gif)
- what makes a colour a colour is because that wavelength is what is being ______________ and every other colour is being __________.
- white light =
- This explains why you get hot when you wear dark clothes.
- light enters the pupil and passes through the _________ onto the ____________ at the back of the eye. See Figure B-30
- the ciliary muscles stretch or relax to accommodate and focus the lens on the object
- there are rods and cones (photoreceptors) in the retina that detect the image
- rods are used to detect light _____________________
- cones are used to see ____________ and fine detail
- there are three types of cones, each sensitive to a different color of light: red, green and blue. (Primary colours of light. If mixed, we get white light. Not like mixing paint…we would get brown paint).
- rods are more common in a circular zone, near the edge of the eye
- cones are found in the centre of the retina in an area called the _______________________. Our most detailed vision occurs here!
- at the point at which your optic nerve comes into contact with the retina there are no rods or cones – this is called your ___________!
- light reaching the rods causes a breakdown of the light sensitive pigment, ___________________, into two parts: _____________ & _____________. This breakdown of the pigment causes a series of action potentials in neurons which are sent to the brain via the ___________ nerve.
- Cones contain a similar pigment to rods, but are less sensitive to light intensity. Like rhodopsin, this pigment contains an __________ & ____________ component.
- This message travels to the ___________ lobe of the brain!
- Eye disorders:
astigmatism –
myopia (near-sightedness) –
glaucoma –
cataracts –
conjunctivitis –
colour blindness –
diabetic retinopathy –
retinal detachment –
macular degeneration –
strabismus –
- Technologies to correct vision:
corrective lenses –
radial keratotomy –
5. Sound
- in addition to hearing, the ear has a function in balance
- parts of the ear:
The Outer Ear
- made of skin and cartilage
- the ear flap is called the ______________
- the auditory canal leads into the head, it is lined with wax secreting cells (for protection)
- the canal ends when it reaches the tympanic membrane (___________________)
- the outer ears function is to gather sound, causing the eardrum to vibrate
The Middle Ear
- the eardrum is connected to the three smallest bones in the human body: the ___________ (hammer),
__________ (anvil) and ___________ (stirrup)
- these three bones together are known as the ________________
- the bones are attached to each other by ligaments that allow them to move back and forth
- the last ossicle, the stirrup, is attached to the oval window
- the _______________ tube is located just after the eardrum, in the middle ear
- the Eustachian tube connects to the throat and allows for pressure equalization on both side of the tympanic
membrane
- pressure can be equalized by yawning or swallowing
The Inner Ear
- the inner ear converts the sound vibrations from the middle ear into nerve impulses
- the inner ear also helps with balance
- the__________ is the organ that is responsible for hearing (this is the place where nerves attach)
- the cochlea is coiled, like a snail shell
- the cochlea is divided into scala vestibule and scala tympani by the cochlear duct
(http://galileo.phys.virginia.edu/classes/304/cochlea2.gif)
- the cochlear duct contains the ____________________, where sound receptors (four rows of hair cells) are found
- a fluid called ________________ surrounds the Organ of Corti
- both the scala vestibuli and the scala tympani contain another fluid called ___________________
- the utricle, saccule and semicircular canals are responsible for _____________ and body position
- the mechanics of hearing:
Longitudinal sound waves travel down the _____________.
_____________ vibrates.
_____________ (malleus, incus, & stapes) move.
Stapes is connected to the ___________________. When the
stapes moves, it causes this window to bulge.
The oval window bulging causes the fluid in the outer two parts of the cochlea to move.
This puts pressure on the ________________ duct.
The pressure waves cause the ______________ membrane to
move which causes the hairs in the organ of Corti to bend against the tectorial membrane.
As the hairs bend, the small nerves that are connected to the base of the hairs are stimulated.
These nerve impulses are carried to the brain along the auditory nerve.
the temporal lobe of the cerebral cortex interprets the impulses as sound.
- the mechanics of balance:
the ________, __________ and ___________________ are
important structures for balance & are filled with fluid and contain sensory hairs.
the utricle & saccule contain small calcium carbonate particles called ________________(ear stones).
movement of the head ( along one plane – horizontal/vertical), causes the otoliths to move in response to gravity. These particles cause sensory hairs to bend, triggering impulses which alert the brain as to the position of the head.
the saccule contains sensory hairs as well
the semicircular canals contain sensory hairs which are bent by movement in the fluid surrounding them. One canal detects bending forward and backward, another detects bending left or right, and a third detects a turning motion.
the brain then signals the appropriate muscles to maintain balance.
- Hearing disorders are often grouped in one of two categories:
conduction deafness –
