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Flashcards in Optics Deck (25):
1

What are the most basic sensors

Free nerve endings

2

What are coated receptors used to detect

Chemical changes and are often called chemoreceptors

3

The most advanced sensors are called

Specialised sensors

4

The four classes of receptors are

Chemoreceptors
Mechanoreceptors
Photoreceptors
Thermoreceptors

5

What is transduction

Turning the stimulus into something the body can use/manage

6

Why do sensory neurons use sensory fields. Give three examples

Because if a sensor was used to monitor ever cell in the body:
We would be way to sensitive
Use up too much energy
There just isn't room

7

What are receptive fields

Where sensory areas overlap

8

What is a perceptual threshold

When a sensor fires an AP but it's not enough to warrant a response from the sensory neuron so it isn't passed on

9

What is resolution

Depth of information. High resolution is a high amount of info. Very detailed
Low resolution is a low amount of info. Not very detailed

10

Where do sensors relay their message to? Except the sense of smell. Where do those messages go

The thalamus
Smell to olfactory bulb and onto the olfactory cortex

11

What is population coding

Low threshold receptors firing first which are easily excitable so the body doesn't care. As intensity increases more sensors fire

12

Frequency coding is

AP frequency is directly proportional to the intensity of the stimulus

13

What is the retina

A layer of cells at the back of the eye that contain photoreceptors

14

What is the fovea

The area in the centre of the back of the eye with the sharpest vision

15

Why is the focused image in the fovea so clear

Because there are lots of cones with a 1:1 relationship with sensory neurons with all the neurons pushed to the side to allow the most amount of light in

16

What does the corpus colosseum do

Connects both sides of the brain

17

Why can we see in colour

Because the different wavelengths activate different proteins which correspond to the colours we see

18

Describe the passage of light

Light is picked up by rods and cones on the back of the eyeball
They relay message to bipolar nerve cells which then send the message to ganglion nerve cells which sends it to the optic nerve

19

Why are rods and cones and the pigmented epithelial cells that absorb pigment are located at the back of the eyeball

Imagine if they weren't. Not all light would get in. And if they didn't absorb light and reflected it well it would be like mirrors bouncing around everywhere

20

Why can we see better in the dark from the sides of our eyes

Because more rods are located there

21

Give three points about rods

Detect black and white
Transfuse light into signals the brain can work with
Much more numerous than cones

22

Give two facts about cones

Detect colour (red blue green) due to pigments
Also transduce light that the body can work with

23

Rods and cones have disks embedded in their heads which house proteins called

Opsins

24

What chemical found in opsin responds to different wavelengths of light

Retinal

25

What happens when light hits a rod

It closes Na+ channels hyper polarising the membrane causing the cell to stop releasing neurotransmitter (glutamate) preventing APs from being fired