Sensory

Question 1

What do Photoreceptors do

Answer 1

• detect light (hyperpolarize)
• transmit to horizontal & bipolar cells

Question 2

What do Horizontal Cells do

Answer 2

• integrate signal from photoreceptors horizontally &
  transmit to bipolar cells
• hyperpolarize
• Mediate interactions over a wide area
• Inhibitory (lateral inhibition)

Question 3

What do bipolar cells do

Answer 3

• transmit signals vertically from photoreceptors &
  horizontal cells to ganglion cells & amacrine cells
• Hyperpolarize (OFF) or depolarize (ON)

Question 4

what do Amacrine cells do

Answer 4

• Transmit signals in two directions
• bipolar à ganglion
• amacrine à ganglion (or other amacrine cells)
• There are more than 30 subtypes
• Integrates information horizontally
• GABA (wide), glycine (narrow)
• Many functions (DS, ON, OFF,…)

Question 5

How do we perceive colours?

Answer 5

We compare the ratio of responses between cones of different types

Question 6

Once a stimulus passes the threshold of activation of a receptor, what does its potential represents

Answer 6

The intensity of the stimulus.

Question 7

Describe the actions leading to the membrane potential of a vestibular or auditory hair cell as it is
stimulated and how the intensity of the signal is transmitted

Answer 7

Mechanical deformation of the hair bundle toward the largest stereovilli/cilium (1 mark) opens mechanically
gated cation channels (1 mark) this allows K+ influx (1 mark) and depolarizes the cell (1 mark) The stronger
the bending, the stronger the signal (1 mark).

Question 8

How does the vestibular system differentiate between tilt and acceleration? Explain how this is achieved
during a sustained head tilt forward, with no linear acceleration

Answer 8

Sensory inputs from the otolith organs (1) and the semi-circular canals (1) are integrated to differentiate
between head tilt and acceleration (1). A forward head tilt will stimulate the semi-circular canals and
the otolith organs (1) allowing it to be discriminated from backward acceleration

Question 9

What is the function of Afferent neurons

Answer 9

Sensory neurons provide environmental information to the CNS

Question 10

What is the function of Interneurons

Answer 10

They integrate information and formulate a response

Question 11

What us the function of Efferent neurons

Answer 11

Carry instructions from the CNS to the effector organs

Question 12

What do photoreceptors responds to

Answer 12

Photons via opsins

Question 13

What do Osmoreceptors detect

Answer 13

changes in the solute concentration of body fluids

Question 14

What are Nociceptors

Answer 14

Pain receptors

Question 15

What do Ganglion cells do

Answer 15

• Transmit signal from retina to brain via optic nerve
• Are the sole output of the retina (AP)
• Receive input from 1 to 100 photoreceptors
• Many subtypes
• They have either ON- or OFF-centre response

Question 15

What are thermoreceptors sensitive to

Answer 15

heat and cold