Sensory System - The Nose

Question 1

How do animals detect a presence of substances in the air?

Answer 1

by reacting to the molecules that make up those substances

Question 2

What is the sense of smell more formally known by?

Answer 2

the olfactory system

Question 3

What is the nose made up of?

Answer 3

nasal chambers
turbinates
olfactory nerve
olfactory bulb

Question 4

What are the nasal chambers?

Answer 4

refers to the spaces leading from the nostrils all the way to the top of the throat

each nostril leads to it’s own chamber, separated from the other by the septum until the two chambers merge and join with the top of the throat

Question 5

What are the turbinates?

Answer 5

contained within the nasal chambers

networks of bone, tissue and blood vessels, shaped like shells that air passes through during breathing

warms and regulates the moisture content of air that is breathed in

Question 6

How can the turbinates warm and regulate the moisture content of air that is breathed in?

Answer 6

because blood vessels in the turbinates are very close to the surface

Question 7

What is the olfactory nerve?

Answer 7

located at the back of the nose

made up of receptor cells which are stimulated by molecules that pass through in air that is breathed in

receptor cells pass electrical signals through bundles of nerve fibres called fila which pass through a sieve-like bone that separates the nasal cavity from the brain

the receptors and fila are collectively known as the olfactory nerve

does not connect to the brainstem but instead connects to the olfactory bulb

Question 8

What is the olfactory bulb?

Answer 8

made up of a range of cells that process the signals sent by the olfactory nerve

is able to organise and categorise different smells but sends on the information to the cerebral cortex in the brain for further processing

this is so the brain can determine higher-level responses that might be required

Question 9

Why do animals use their sense of smell?

Answer 9

to detect the presence of food

to sense if something is potentially toxic or dangerous

allows animals to communicate with each other by producing chemicals that are used to signal information about territories, social hierarchies, mating behaviour or the presence of food