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
What are elastic fibres?
Protein fibres that can deform and then recoil to their original size
What is smooth muscle?
Involuntary muscle that contracts without the need for conscious thought
What is a ciliated epithelium?
A layer of cells that have many hair-like extensions called cilia
What’s the difference between epithelial and endothelial?
Epithelial - attached to the outside
Endothelial - attached to inside
What is the use of the elastic fibres?
Found in the alveolus walls (squamous epithelium), they stretch during inspiration to expand the lungs then recoil to force out the air.
List all the parts of the respiratory system
Trachea (and rings of cartilage) Bronchi Bronchioles Alveoli Lungs Ribs Diaphragm Intercostal muscles Elastic fibres Squamous epithelium (wall of alveoli)
What is a squamous epithelium
Alveoli walls one cell thick to provide a short diffusion distance for gaseous exchange
What do goblet cells do?
Secrete mucus which captures pathogens. Ciliated epithelial cells then waft the mucus to the mouth where it is swallowed.
What do the smooth muscle and the elastic fibres do in the airways?
The smooth muscle contracts, reducing the lumen. This can be due to an allergic reaction or something dangerous in the air. The elastic fibres then return the muscle to its original shape, opening the lumen wider again.
Define breathing rate
The number of breaths per minute
Define oxygen uptake
The volume of oxygen absorbed by the lungs in one minute
What is a spirometer?
A device that can measure the movement of air into and out of the lungs
Define tidal volume
The volume of air inhaled or exhaled in one breath, usually measured at rest
Define Vital Capacity
The maximum volume of air that can be moved in the lungs in one breath
List 5 precautions that must be taken when using a spirometer
The subject should be healthy and not asthmatic
The soda lime should be fresh and functioning
There should be no air leaks in the apparatus
The mouthpiece should be sterilised
The water chamber must not be overfilled as this can enter the air tubes
Define residual volume and what is its average?
The volume of air that is permanently in the lungs
1.5dm^3
Define tidal volume and what is its average?
The volume of air moved in and out in a normal rest breath
0.5dm^3
How do you work out the total lung capacity?
Vital capacity + residual volume
How do you calculate oxygen uptake from a spirometer trace?
Difference in volume (dm^3) / time taken (s)
What is the purpose of soda lime in a spirometer?
To absorb the carbon dioxide
What is a fish’s mouth called?
Buccal cavity
Define countercurrent flow
Where 2 fluids flow in opposite directions
What are the gill plates called and where are they found?
Gill lamella found in the gill filaments (primary lamellae) which are attached to the gill arches
What does countercurrent flow allow?
A gradient to allow diffusion of oxygen
What are filaments?
Slender branches of tissue that make up the gills. They’re are often called primary lamellae.
What is an operculum?
A bony flap that covers and protects the gills
What is the name of the system that insects have?
Tracheal system
What is a spiracle?
An external opening or pore that allows air in or out of the tracheae
What is tracheal fluid?
The fluid found at the ends of the tracheoles in the tracheal system
What is a tracheal system?
A system of air-filled tubes in insects
How does air enter the body of an insect and reach the site of gaseous exchange?
The spiracle (pore) is connected to a tracheae which divides into tracheoles. The ends of these are open and filled with tracheal fluid.
What type of cells are endothelium tissues made from?
Squamous epithelial cells
Define oncoming pressure
The pressure created by the osmotic effects of the solutes
