The senses

17 important questions on The senses

What is the difference between cones and rods?

Rods are the most sensitive but very restricted to contrast. Cones are not so sensitive but they can discriminate different wavelengths, colors.

If there is no light, are photoreceptors depolarized and secreting neurotransmitter or hyperpolarized and not secreting neurotransmitter?

Depolarized and secreting glutamate

What happens to the photoreceptors if there is light?

The level of cGMP is reduced and the sodium/calcium channel closes. There will be less influx of sodium but potassium will keep flowing out and this causes hyperpolarization. This will stop the secretion of glutamate.
  • Higher grades + faster learning
  • Never study anything twice
  • 100% sure, 100% understanding
Discover Study Smart

How can photons cause a drop in cGMP?

This works through a G-protein couples receptor. There is an 11-cis-retinal transmembrane protein that changes its conformation upon binding of a photon. Transducin is activated and hydrolyzes the cGMP. cGMP becomes inactive (GMP) and this causes the sodium/calcium channels to close.

Where do you find rods and where do you find cones?

Rods: basically everywhere (but low concentration in the fovea)
Cones: mainly in fovea.

Rods and cones relay their information to bipolar cells. How many rods are connected to one bipolar cells? And how about cones?

Rods: many rods together to 1 bipolar cell (low precision, high sensitivity)
Cones: 1 cone to 1 bipolar cell (high precision, low sensitivity)

What is the difference between ON and OFF bipolar cells?

The ON cells are hyperpolarized when there is no light (high glutamate), this means no activation of the ON ganglion cell and therefore no suppression. When there is light there is less glutamate, this causes depolarization and activation of the ON ganglian cell which leads to suppression of activity.
The OFF cells are depolarized when there is no light and action potentials are generated to the OFF ganglion cell. When there is light, there is less glutamate, the OFF cell hyperpolarizes and there are less action potentials.

What is the function of horizontal cells?

These cells integrate signals via surround suppression.

What part of the ear translates vibration into mechanical movement?

The middle ear

What causes an action potential in the ear?

The difference between the basal membrane and tectorial membrane.

How is it possible that K causes depolarization in the ear, because usually K causes hyperpolarization?

In the ear the concentration on the outside is high and on the inside is low. This causes an influx of K, and depolarization. Normally K flows out (because high concentration on the inside) so then it causes hyperpolarization.

Where do the left and right cochlea project to?

The MSO, medial superior olive.

What is special about smell?

Smell is the only sense that does not require the thalamus as relay station.

Why does the olfactory epithelium need continuous regeneration?

Because it is directly accessible for pathogens.

How do you taste salt and acid?

Salt (Na+) and acid (H+) can go through channels which can release neurotransmitters.

How do you taste sweet, umani, and bitter?

Via activation of the TRPM5 channel. This causes Ca to move into the cell and trigger neurotransmitter release.

Which neurotransmitter is associated with taste?

Serotonin

The question on the page originate from the summary of the following study material:

  • A unique study and practice tool
  • Never study anything twice again
  • Get the grades you hope for
  • 100% sure, 100% understanding
Remember faster, study better. Scientifically proven.
Trustpilot Logo