Sensory Flashcards
What do Photoreceptors do
- detect light (hyperpolarize)
- transmit to horizontal & bipolar cells
What do Horizontal Cells do
- integrate signal from photoreceptors horizontally &
transmit to bipolar cells - hyperpolarize
- Mediate interactions over a wide area
- Inhibitory (lateral inhibition)
What do bipolar cells do
- transmit signals vertically from photoreceptors &
horizontal cells to ganglion cells & amacrine cells - Hyperpolarize (OFF) or depolarize (ON)
what do Amacrine cells do
- 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,…)
How do we perceive colours?
We compare the ratio of responses between cones of different types
Once a stimulus passes the threshold of activation of a receptor, what does its potential represents
The intensity of the stimulus.
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
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).
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
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
What is the function of Afferent neurons
Sensory neurons provide environmental information to the CNS
What is the function of Interneurons
They integrate information and formulate a response
What us the function of Efferent neurons
Carry instructions from the CNS to the effector organs
What do photoreceptors responds to
Photons via opsins
What do Osmoreceptors detect
changes in the solute concentration of body fluids
What are Nociceptors
Pain receptors
What do Ganglion cells do
- 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
