Receptors

Question 1

Response to Stimuli in Mammals

Answer 1

uses Nervous System, Hormonal System (nervous and hormonal systems coordinate response to stimuli)

Question 2

The job of Nervous System

Answer 2

coordinate response to certain stimuli – response is fast, short-acting, localised.

Question 3

Pathway of Nervous System

Answer 3

Stimuli to the receptor to sensory neuron to the spinal cord to the brain to the spinal cord to motor neuron to effector for response.

Question 4

What does a Receptor do?

Answer 4

Detects stimuli
and converts stimuli energy into a nerve impulse
(acts as a transducer – converts one type of energy into another)

Each type of stimulus has a specific receptor

Uses stimuli energy to send Na+ ions into the start of the sensory neuron

2 examples of receptors: Pacinian Corpuscle, Retina of the Eye

Question 5

What does a Pacinian Corpuscle do?

Answer 5

Touch receptor
Found in the skin, fingers, and toes
Responds to pressure/touch

structure = corpuscle (several layers of tissue) wrapped around the start of a sensory neuron

Process = pressure applied, corpuscle compressed, stretch-mediated Na+ channels opened, Na+ ions move into the start of the sensory neuron

Question 6

How does the Retina of the Eye work?

Answer 6

Detects light so the brain can generate an image

Detected by the retina (located at the back of the eye)

Made of Cone and Rod cells

Cone Cells detect high light intensity only, and produces colour image, with high visual acuity

Rod Cells can detect low light intensity, produces a black and white image, with low visual acuity

Cone Cells located in centre of the retina (fovea) – site of high light intensity

Rod Cells located in the periphery of the retina

Question 7

Properties of Cone Cells

Answer 7

Made of Iodopsin Pigment which is only broken down at high light intensity

One cone cell connects to one bipolar neurone which connects to one sensory neurone (therefore no summation of light can take place so only detects high light intensity)

But because one cone cell connects to one bipolar neurone which connects to one sensory neurone, each stimulus can be distinguished = by high visual acuity

Question 8

Properties of Rod Cells

Answer 8

Made of Rhodopsin Pigment which can be broken down at low light intensity

A few rod cells connect to one bipolar neurone which connects to one sensory neurone (therefore summation of light can take place so can detect low light intensity)

But because a few rod cells connect to one bipolar neurone which connects to one sensory neurone, the stimuli will be merged together = low visual acuity