L28 Active learning

Question 1

What does convergence in the glomerulus enable?
i) increased likelihood of sensing low concentrations of odorants
ii) lower threshold for sensation of odorants by olfactory receptor neurons
iii) continued sensation of odorants when olfactory receptor neurons are being replaced
iv) an increase in the number of odorants that a single second order neuron receives input about.

Answer 1

i.) and iii.)

Question 2

Why do things look blurry underwater?

Answer 2

There is very little difference in the refractive index between the water and cornea which drastically reduces the refractive power of the cornea.

Question 3

Light that passes all the way through the retina is absorbed by the pigmented epithelium – what does this achieve?
1. Increased ability for adaptation
2. Increased differentiation of colour
3. Increased sensitivity
4. Increased visual acuity

Answer 3

Increased visual acuity as it prevents photons being refelected back onto photoreceptors, so image formation is not distorted. It means we sacrifice some sesnitivity compared to aniamls with a reflective tapedum lucidum.

Question 4

What would we need to place in the photoreceptor membrane to maintain the process of phototransduction?

Answer 4

To maintain the chemical gradients for Na+ and K+ and Na+-K+-ATPase must remove Na+ from the intracellular solution and move K+ back into the intracellular solution.

Question 5

Choose from the terms: graded receptor potential (GP), excitatory post-synaptic potential (EPSP) and action potential (AP), which type of potential is occuring in the different cells of the retina.

Question 6

If you step from the light to the dark, what will happen in your ON bipolar cells?

Answer 6

Hyperpolarise - Moving into the dark would depolarise photoreceptors and would cause glutaamte to move i causing bipolar cells to hyperpolarise.

Question 7

What is special about endolymph compared to most fluids within the body?

Answer 7

High K+ content.