Chapter 29, Problem 1CC

Summary Introduction

To label: The sensory receptor that receives stimuli from the environment and also list the responses they show in respect to stimuli.

Concept introduction:

Sensory receptors are the structures that send stimuli to brain after receiving it in response to changes in the environment. They convey the signal to neurons from the external or internal body. Sensory receptors are present on sensory organs, namely, eyes, skin, and ear.

Explanation of Solution

Pictorial representation:

Fig.1 shows the types of sensory receptors present in humans and responses they generate.

Fig.1: Shows the type of sensory receptors and their responses.

(a)

Correct answer: Mechanoreceptor.

Plasma membrane contains a mechanogated ion channel that opens or closes in response to the stimuli. When there is a pressure applied on the membrane by stretching or twisting, the channels get activated. For example, the tympanic wall present in the ear has a mechanogated ion channel, and it helps in hearing by transmission of sound vibration. Hence, the correct answer is mechanoreceptors.

(b)

Correct answer: Chemoreceptor.

Chemoreceptors have an autonomic control, and they get stimulated by the change in the chemical concentration in the environment. Generally, they are found in the nose and mouth. Hence, the correct answer is chemoreceptors.

(c)

Correct answer: Light.

Electromagnetic receptors involve photoreceptor and thermoreceptor. Photoreceptors covert light into an electromagnetic stimulus and send it to the brain for phototransduction. Hence, the correct answer is light.

(d)

Correct answer: Electricity.

Some organisms have the ability to detect electrical energy; their electroreceptors receive the stimulus and send it to the brain for detection. For example, sharks can detect electricity that is generated by any muscular activity. Hence, the correct answer is electricity.

(e)

Correct answer: Magnetism.

Electromagnetic receptors sense the magnetic field in the environment. Birds use the magnetic field of the Earth in navigation when they migrate. Hence, the correct answer is magnetism.

(f)

Correct answer: Hair cells.

Hair cells have mechanoreceptors that generate an electrical stimulus upon stretching or when the cell feels any pressure; for example, hair cells present in the ear have receptors that detect head movement and sound. Hence, the correct answer is hair cells.

(g)

Correct answer: Photoreceptor.

Photoreceptors are present in the retina of the eye and receive the stimulus from light. Photoreceptors convert light into electric signal and send it to the brain for visual transduction. Hence, the correct answer is photoreceptor.