3.1 - B - Exchange Surfaces & Breathing Flashcards
What are the 3 main factors that affect the need for an exchange system?
Size
SA:V
Level of activity
How do single-called organisms take up and remove products?
Diffusion
Give 4 examples of specialised exchange surfaces in larger organisms
Alveoli
Villi
Gills
Root hair cells
Give 5 features that good exchange surfaces have
Large surface area Thing walls (one cell thick) Permeable for substances Steep concentration (diffusion) gradient Good blood supply
What is the equation for surface area of a cube?
Length x Width x # sides
What is the equation for the surface area of a sphere?
4 x pi x radius^2
What is the equation for the volume of a cube?
Length x Width x Height
What is the equation for the volume of a sphere?
(4/3) x pi x radius^3
The bigger the organism… (SA, V, SA:V)
The bigger the SA and V but the smaller the SA:V
What is alveoli?
Tiny folds of the lung epithelium to increase the surface area
What are bronchi/bronchioles?
Smaller airways leading into the lungs
What is a diaphragm?
A layer of muscle beneath the lungs
What are intercostal muscles?
Muscles between the ribs. Contraction of the external intercostal muscles raises the rib cage
What is a trachea?
The main airways leading from the back of the mouth to the lungs
Define Gaseous Exchange and give an example
The movement of gases by diffusion between an organism and its environment across a barrier
Alveoli
Define ventilation
The refreshing of the the air in the lungs, so that there is a higher oxygen concentration than in the blood, and a lower carbon dioxide concentration
Give the 5 key points that describe inspiration
Diaphragm contracts, flattens and moves downwards
Intercostal muscles contract and move the ribs up and out
This increases the volume inside the thorax and the lungs
It also reduces the pressure inside the thorax and lungs
Air moves into the lungs down a pressure gradient
(Opposite for expiration)
What 2 things maintain a concentration gradient?
Good blood supply
Ventilation
What does ventilation ensure?
There is always a higher concentration of oxygen in the alveolus than in the blood.
There is always a lower concentration of carbon dioxide in the alveolus than in the blood.
Define Surfactant
A compound produced by the lungs and lines the inner wall of the alveoli that reduces cohesion between water molecules so alveoli don’t break down
Define cartilage
A form of connective tissue