Assignment for lecture 1 (special senses)
Please fill in the blanks. In some cases I have given you two options, one of which is the correct
answer. Delete the one that does not apply or circle the one that does apply.
The eye can be seen as analogous to a camera, with the camera’s lens corresponding to the ________
and the _________ in the eye; of the two, the _______ has the greater refracting power. The refracting
power of the eye must be matched well to its length: if the eye is too long, the individual will suffer
from (myopia/hyperopia), which can be corrected by adding a (convex/concave) lens to decrease the
total refracting power of the eye; of it is too short, the individual will suffer from (myopia/hyperopia),
which can be corrected by adding a (convex/concave) lens to increase the total refracting power of the
eye.
As we become older, it becomes more difficult to focus on near objects. Focusing on near objects
depends on (increasing/decreasing) the refracting power of the eye, by changing the shape of the
(lens/cornea): to focus close up, it must become (flatter/more rounded). The process of changing
refractive power to focus on near objects is known as _________, and the deterioration on ageing is
because __________________.
The cells that detect light are found in the ________, the part of the eye that corresponds to the film of
the camera. These cells are known as _________________, and are of two types: ________ and
__________. The ________ are mainly active in (dim/bright) light, are not involved in colour vision
and are found mainly in the (foveal/peripheral) area of the retina. The ________ are mainly active in
(dim/bright) light, are involved in colour vision and are found mainly in the (foveal/peripheral) area of
the retina.
The ear can be divided into three sections: outer, middle and inner. The middle ear contains three tiny
bones known as the ________, the ________ and the ________. Their function is to
____________________________, and this is achieved by increasing the pressure. The bones connect
the ___________, whose area is about 55 mm2, with the _______________, whose area is about
3.2 mm2, and this reduction in surface area is the major mechanism underlying the pressure increase.
The part of the inner ear that is involved in hearing is known as the _________. The cells that convert
sound-induced vibration into electrical signals are known as ______________ and are of two types:
inner and outer. The (inner/outer) are the main sensory cells. They form part of the organ of _______,
which sits on the __________ membrane. Sound causes vibration of this membrane at specific points:
near the oval window at (high/low) frequencies, and far from the oval window at (high/low)
frequencies.
The vestibular system maintains balance by allowing us to detect head position and movement. The
linear acceleration stimulus that we experience at all times results from the force of _________, which
stimulates the ________ organs. These organs are so named because they contain small crystals of
calcium carbonate, called “otoconia”. Head tilt thus stimulates these organs in the same way as
acceleration, with forward acceleration (e.g. being in a car starting from rest) being equivalent to
(forward/backward) head tilt.
We can also detect angular acceleration, with the _________________________ (of which we have 3
on each side, at right angles to each other). These detect head turning, and are stimulated by turning in
one direction, while being inhibited by turning in the other direction.