Life Book (11th Edition) Chapter 45 - Sensory Systems

Question 1

What is meant by sensory adaptation?

Answer 1

Sensory adaptation is when sensory receptor cells (afferent neutrons) are able to ignore maintained or repeated stimuli.

Question 2

State some sensory receptor cells that demonstrate little sensory adaptation.

Answer 2

Pain receptors and the mechanoreceptors that control balance.

Question 3

Think of a benefit of sensory adaptation

Answer 3

Allows your body to ignore unchanging stimuli (like clothes) that is usually unimportant and helps you react to new stimuli such as someone punching your arm.

Question 4

Why should pain receptors not show large sensory adaptation?

Answer 4

Because pain receptors let you know what is wrong with something in your body. Such as that punch to the arm.

Question 5

Action potentials arriving at the visual cortex of the brain will be interpreted as ______________

Answer 5

Light

Question 6

Action potentials that arrive at the olfactory bulb will be interpreted as ________________

Answer 6

Smells

Question 7

What is a sensory system

Answer 7

A set of organs and tissues for detecting a stimulus

Question 8

What is a sensory organ?

Answer 8

A sensory organ is one that converts a stimulus into an electrical signal

Question 9

Name some common examples of sensory organs.

Answer 9

Ears 👂🏻, eyes 👀, nose 👃🏻

Question 10

What is sensory transduction?

Answer 10

The transformation of environmental stimuli or information into neural signals

Question 11

What are receptor proteins?

Answer 11

A protein that has the ability to open or close an ion channel in response to a particulate type of stimulus.

Question 12

A change in membrane potential of a sensory receptor cell due to a particular stimulus is known as a ________ ________

Answer 12

Receptor potential

Question 13

Name all the types of sensory cell membrane receptor proteins. Hint: I MET Mr Cameron Pollock

Answer 13

Mechanoreceptor 🔧, electroreceptor⚡️, thermoreceptor🔥, chemoreceptor💊, photoreceptor ☀️.

Question 14

Receptor potentials are graded membrane potentials or action potentials?

Answer 14

Graded membrane potentials

Question 15

State one difference between action potentials (AP) and graded membrane potentials (GMP).

Answer 15

APs can travel long distances whereas GMPs travel short distances.

Question 16

State two ways in which receptor potentials (graded membrane potentials) can generate action potentials.

Answer 16

1. The receptor potential triggers action potentials in sensory receptor cell itself. 2. Receptor potential can cause pre-synaptic neutron to release neurotransmitters that cause post-synaptic neurone to generate action potentials.

Question 17

Which sensory receptors are iononotropic and which are metabotropic? Hint: I MET Mr Cameron Pollock

Answer 17

Ionotropic: mechanoreceptor, thermoreceptor and electroreceptor. Metabotropic: chemoreceptor and photoreceptor

Question 18

Photo and chemoreceptors activate what in response to its stimulus?

Answer 18

Photo and chemoreceptors activate a G-protein signalling cascade that opens ion channels on the receptor cell.

Question 19

What is an odorant?

Answer 19

A molecule in the environment that binds to and activates an olfactory receptor protein on the cilia of olfactory receptor neutrons (ORN)

Question 20

Why is it hard to smell when you have a cold? 🤧

Answer 20

You get a runny nose when you get a cold and that extra mucous creates a thicker layer of mucous around the Olfactory receptor neurons (ORN). Odorant molecules will find it harder to diffuse through the thicker layer of mucous and so few odorant molecules will bind to the receptor proteins (chemoreceptors) on the ORN.

Question 21

What is the function of the mucous film part of the olfactory epithelium.

Answer 21

It’s gives protection to the epithelial tissue lining the nasal cavity

Question 22

Can ORNs regenerate themselves and if so why?

Answer 22

Yes - the epithelial lining is constantly shed so ORNs have to regenerate.

Question 23

Explain how an action potential is generated in ORNs

Answer 23

1. Odorant molecules diffuse across mucous film and binds with receptor proteins on ORNs activating a G-protein. 2. The G-protein then activates an enzyme that increases the number of a second messengar (cAMP in vertebrates) in the receptor cell’s cytoplasm. 3. cAMP then opens a ion channel allowing Na+ into the cell causing depolarisation of that part of the cell, generating the action potential. In short: Odorant molecule - receptor protein - G-protein - enzyme - second messenger - Influx of Na+ causing depolarisation - Action potential generated in ORN.

Question 24

Each ORN expresses how many receptor protein types?

Answer 24

Just one type

Question 25

State the trend in odorant molecules and perceived smell.

Answer 25

The greater the concentration of odarent molecules the greater the frequency of action potentials and this the greater the intensity of the smell.

Question 26

What is a pheromone?

Answer 26

A type of chemical signal molecule that is used to communicate with individuals of the same species.

Question 27

Tastebuds are ____________

Answer 27

Chemoreceptors

Question 28

The sense of taste is called _________

Answer 28

Gustation

Question 29

State the name of each type of sensory receptor cell membrane protein below: