Overview of Gas Exchange

Learning Check-List

Vocabulary

Can you distinguish between cellular respiration, gas exchange, and ventilation?

Can you describe the role of diffusion in gas exchange?

Tasks - milestone #1

Please note there is more to cover for milestone #2 on the next tab (linked here): Characteristics of an efficient gas exchange system.

Engage with the videos and notes below. In your portfolio of learning complete the following tasks. It is important to paraphrase in your own words, and include the URL's and any other resources you used in your reference list. So that they are there ready for your final assessment.

1. Complete sciPAD pgs: 48-49

2. Describe what it means to "breathe"?

3. Why do animals need to breathe?

4. Describe the difference between "BREATHING" and "CELLULAR RESPIRATION."

5. How does oxygen get from the air or water to the gas exchange surface to the cells?

Breathing / ventilation: Movement of air/water in and out of the gas exchange system.
Cellular respiration: The process by which cells break down glucose using oxygen to produce energy, and water and carbon dioxide as by-products.
Locust: Example of an insect with a tracheal system for gas exchange.
Diffusion: Movement of molecules from an area of higher concentration to an area of lower concentration.
Gas exchange: The process of obtaining oxygen from the environment and releasing carbon dioxide
Human: Example of a mammal with a lung system for gas exchange.
Oxygen: Molecule needed for aerobic cellular respiration
Snapper: Example of a fish with a gill system for gas exchange,

Summarising Gas Exchange - Videos

It's all about OXYGEN!

Most living things (plants & animals) require oxygen in order to turn the glucose (from food, or photosynthesis), into useable energy for cell processes, and in order to survive - for animals this involves looking for food, reproducing, migrating or escaping predators.

Cells cannot use glucose, so it is turned into ATP (adenosine triphosphate), which is the energy currency for cells.

For example, muscle cells need a large amount of energy to be able to contract and relax, which gives animals the ability to escape predators. The large amount of energy (ATP) needed is produced inside animal cells within the mitochondria through a process called aerobic CELLULAR RESPIRATION. Without aerobic cellular respiration, animals would not be able to survive in their niche.

Aerobic cellular respiration requires OXYGEN. Without oxygen, aerobic cellular respiration cannot happen, which means the animal would not get the energy it needs to survive in its niche. So, animals absolutely need oxygen for aerobic cellular respiration to make energy.

HUMANS, like all mammals, and LOCUSTS, like many other insects, are terrestrial animals, meaning they live on land and get their oxygen from the oxygen available in air. Whereas snapper, like all fish, are aquatic animals, meaning they live in bodies of water, and get their oxygen from the dissolved oxygen available in water. Dissolved oxygen is oxygen that has dissolved from the atmosphere, into the ocean.

WHERE DO ANIMALS GET OXYGEN FROM?

An animal's source of OXYGEN depends on their ecological niche. (Remember that ecological niche is the "functional position of an organism in its environment" - the environment being the habitat, and the resources available in this habitat). So the source of oxygen depends on where the animal lives (land or sea) and what oxygen resources are available in this habitat (oxygen in air or dissolved oxygen in water).

How do Animals get oxygen to their cells for cellular respiration?

Gas Exchange

The act of OXYGEN being absorbed from air or water, and then the release of CARBON DIOXIDE (waste product) back into air or water is through a process called GAS EXCHANGE. Gas exchange is the process where different gases (oxygen and carbon dioxide) get exchanged/transferred/swapped in opposite directions.

Oxygen goes from the outside of the body/cell to the inside of the body/cell.
Carbon dioxide from the organism, as carbon dioxide goes from the inside of the body/cell to the outside of the body/cell.
Oxygen and carbon dioxide move from areas of high to low concentration via a process called diffusion

Picture showing a single alveoli (human lung) surrounded by a blood vessel. O2 comes into the alveoli via the nose and trachea (wind pipe). It then diffuses across the thin alveoli membrane into the blood stream to be carried to the cells in the body for cellular respiration. CO2 diffuses from the blood stream into the alvoli to be exhaled up through the trachea and nose.

Diffusion

Diffusion is the passive movement of molecules from an area of high concentration to low concentration.

For diffusion to occur, there must be a SPECIALISED RESPIRATORY SURFACE that is semipermeable. There must also be a concentration gradient across this specialised respiratory surface to drive the process of diffusion. In other words, the concentration of oxygen must be higher on one side of the membrane, and lower on the other side of the membrane.

Oxygen moves across the semipermeable membrane from an area of high concentration outside of the body, to an area of low concentration inside of the body.
Carbon dioxide moves across the semipermeable membrane from an area of high concentration inside of the body, to an area of low concentration outside of the body.

How does oxygen get into the system and carbon dioxide out?

Ventilation

Before GAS EXCHANGE and DIFFUSION can happen, air/water first needs to get from the outside of the body, to the SPECIALISED RESPIRATORY SURFACE which is located inside of the body for most animals. So animals must first take in the air/water from their surroundings, through a process called VENTILATION. Ventilation is the flow of air or water in and out of the gas exchange system, to increase the rate of gas exchange.

Animals have mechanisms that help them to ventilate (move air/water) into and out of their bodies. You will need to detail how this is different in mammals, insects and fish for this assessment.

Humans and other mammals use their diaphragm, a structure under the ribs along with the intercoastal muscles between ribs to create a pressure change which allows the lungs to fill with air, and then deflate again pushing carbon dioxide out.

Fish gulp the water they are swimming in, this then travels through they buccal cavity and over the gills, where oxygen is extracted, carbon dioxide is removed as the same water passes out under the gill covers (operculum)

Insects have a series of small holes (spiracles) running along either side of their abdomens, when they contract their abdomens air is forced into and out of the spiracles.

Information on this website has been sourced from a range of online sources for the purpose of education.

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