These questions are to help you quiz yourself. Try to answer these yourself before you check my answers or you miss out on the main purpose of these quizzes - to involve you more in the material.  To see my answers, select the area underneath the question using your mouse. (click and drag)  Don't print this out, or the answers will be visible as well!

How do we form perceptions?
A perception or sensation does not occur until the information reaches the cerebral cortex. This is when we become "aware" of what is happening.

In general, how do all sensory receptors work?
All sensory receptors are stimulated by one main form of stimulus - light,  pressure, etc., but will respond to some others. The receptor receives a stimulus, and if that stimulus is of sufficient strength, it passes the information on to a neuron that carries the message to the brain, or carries the information if the receptor is neuron.

What sense organs help us feel touch and pressure? What are their receptor cells?
Free nerve endings, Meissner's corpuscles and Pacinian corpuscles. For the last two, the receptors are connective tissue cells.

When a muscle spindle is activated, the muscle it is located in ... contractsto keep you from falling over .

When a Golgi tendon organ is stimulated, its corresponding muscle ....  relaxes to prevent the tendon from being torn off the bone.

You lost your arm in a farming accident years ago, but sometimes your "hand" hurts.
 This is called ... phantom pain.

What type of receptor is responsible for both our sense of taste and our sense of smell?
Chemoreceptors

What part of your brain is responsible for the strong memories that are associated with certain smells?
The limbic system

Where do we see neurons being constantly replaced?
The bipolar neurons in our olfactory organs in our nasal cavity.

What role does mucus play in the sense of smell?
For the chemoreceptors of our senses of smell and taste to react, a substance must be dissolved - in watery saliva or in mucus.

Why is it sometimes difficult to get older people to eat?
They have lost many of their olfactory receptors. Without our sense of smell, food doesn't "taste" good.

Recent research has indicated we may also have taste receptors for what common substance?
Water !

Of the four types of tissues, which type of cells form the receptors for the sense of taste?
Epithelial cells.

Where would you find ceruminous glands?
In the external auditory meatus or auditory canal of the outer ear. These glands make earwax.

You are driving up a mountain, and your ears start to hurt and you don't hear as well. What should you do?
Yawn, or swallow to open up your eustachion tube and equalize the pressure on both sides of your tympanic membrane.

What is the tympanic reflex?
In the case of a prolonged loud noise, the tensor tympani muscle and the stapedius muscle pull the ossicles in the middle ear together, dampening the sound vibrations that reach the inner ear.

Your little nephew loves to spin around. When he stops, you notice his eyes travel to the side and then flick back, repeatedly. What's going on?
The endolymph in his semicircular canals is still moving, even though he has stopped. This movement is stimulating the crista ampularis to fire, and tell nuclei in his medulla oblongata that his head is moving. This nucleus  (group of neurons) is sending messages to his external eye muscles, so his eyes can follow where his head is (supposedly) going. This is called nystagmus.

Your little sister says that you have "rocks" in your head. You tell her she is right because...
Your vestibule contains otoliths - calcium carbonate granules that aid with your sense of static equilibrium. Otolith means "ear rock".

Why does your nose run when you cry?
Excess tears leave through the lacrimal puncta, drain into canaliculi, into the lacrimal sac and down the lacrimal duct into your nasal cavity.

Why should you not try to match socks in dim light?
Cones don't function low levels of light, so you are using your rods. Rods don't see in color, so a dark green sock looks just like a dark blue sock.

Light focuses in front of your retina. Where can you see clearly, and can you fix it without glasses?
You are myopic, or nearsighted, and see better up close than far away. You can't fix it, but if you were hyperopic, you could accommodate to see clearly at distance.

How are your eyes "backward" ?
The photoreceptors are closest to the inner layers of your eye, and not where the light comes in. Your photoreceptors are giving off neurotransmitters when they are in the dark. Light focuses upside down and backward on your retina.

You have a friend who is color blind. Statistically speaking, is your friend a girl or a boy? Why?
Chances are twice as good your friend is a boy. The gene for color vision is carried on the X chromosome (sex-linked)  and guys only have one X chromosome. If that one gene is bad, they are color blind!

and fall over. Not a good idea.