Why do cells need to take in oxygen?
Name 2 waste products of cells
What does the ease of exchanging substances depend on?
-Surface area to volume ratio
Smaller animal have h***** SA:V ratio
How do you calculate SA:V ratio?
-Divide surface area by volume
What sort of SA:V ratio do large organisms have in comparison to small organisms?
What do large organisms need, due to their small SA:V ratio?
Give examples of substances that must be supplied to cells for respiration
Why do waste products need to be removed from a cell?
-Stop it damaging itself
In single-celled organisms, substances can ******* directly into or out of the cell across the cell surface membrane
The diffusion rate is q**** for single-celled organisms
Why is the diffusion rate for single-celled organisms quick?
-Substances have to travel small distances only
In what sorts of organisms/animals is the diffusion rate slow? Why?
-Some cells are deep within the body – there’s a big distance between them and the outside environment
-Larger animals have a low surface area to volume ratio – it’s difficult to exchange enough substances to supply a large volume of animal through a relatively small outer surface
Give an example of a specialised exchange organ?
Describe the route of air in the lungs?
-2-Air splits into two bronchi – one bronchus leading to each lung
-3-Bronchus branches off into smaller tubes called bronchioles
-4-Bronchioles end in small ‘air sacs’ called alveoli, where gases are exchanged
-5-Ribcage, intercostal muscles and diaphragm work together to move air in and out
Where does gas exchange happen?
What is an alveolus made of?
-Single layer of thin, flat cells called the alveolar epithelium
Describe the alveoli
-Arranged in bunches at the end of bronchioles
-Surrounded by a network of capillaries, giving each alveolus its own blood supply
Is it epithelial tissue common in the body? Where is it found?
What is the name of the tissue that makes the capillary?
Briefly describe deoxygenate blood being oxygenated at the capillary
-O2 diffuses out of the alveoli, across the alveolar epithelium and the capillary endothelium, and into haemoglobin in the blood
-CO2 diffuses into the alveoli from the blood, crossing the capillary endothelium then the alveolar epithelium. After entering the alveolar space, it’s breathed out
Name 2 things most gas exchange surfaces have in common
-Large surface area, which increases the rate of diffusion
-Thin (often just 1 layer of epithelial cells) – provides a short diffusion pathway across the gas exchange surface, which increases the rate of diffusion
Outline how large surface area and thin wall are shown in the lungs
-Alveoli (large surface area)
-Thin wall (alveolar epithelium and capillary endothelium) one cell thick giving…