Gas Exchange Flashcards Preview

Biology AS > Gas Exchange > Flashcards

Flashcards in Gas Exchange Deck (32):

What kind of gases do organisms need to diffuse across gas exchange surfaces as quickly as possible

Oxygen and carbon dioxide


What do most gas exchange surfaces have in common that increase the rate of gas exchange

- they have a large surface area
- they are thin (often one layer of epithelial cells)


Why are gas exchange surfaces thin?

It provides a short diffusion pathway across the gas exchange surface


How do single called organisms absorb and release gases into/from their body

By diffusion through their cell-surface membrane


What is a gas exchange surface

A boundary between the outside environment and the internal environment of an organism


Why is there no need for a specialised gas exchange system in single- called organism

Because they have a relatively large surface area, a thin surface and short diffusion pathway


Is there a higher or lower concentration of oxygen in water than in air



In a fish, what is the gas exchange surface

The gills


Each Gill is made out of lots of think plates called what?

Gill filaments


What do the Gill filaments do for the gas exchange

Give a large surface area for exchange of gases (increasing rate of diffusion)


What tiny structures are the Gill filaments covered in



What do the Lamellae do to the rate of diffusion

Increase it, as they increase the surface area


What makes the Lamellae speed up diffusion between the water and the blood

-they have lots of blood capillaries
-thin surface layer of cells


What is the counter current system in fish

In the gills, blood flows through the Lamellae in one direction and water flows over them in the opposite direction


What does the counter current system mean in relation to the water with a high oxygen concentration always flowing next to blood with a lower concentration of oxygen

A steep concentration gradient is maintained between the water and the blood. Meaning as much oxygen as possible diffuses from the water into the blood


What is the main gas exchange surface for dicotyledonous plant?

Surface of the mesophyll cells in the lead


Where do gases move in and out of a leaf?

The stomata in the epidermis


Describe how carbon dioxide moves out of an insects cells into the atmosphere

-down its concentration gradient
- through the tracheoles
- towards the spiricles
- to be released to the atmosphere


What's a xerophyte?

A plant specially adapted for life in a warm, dry or windy habitat


Give 3 adaptions that a xerophytic plant has to reduce water loss

Stomata sunk in pits
Reduced number of stomata
Curled leaves with stomata inside


Describe what happens to make the volume of the thorax increase during inspiration

The external intercostal and diaphragm muscles contract, which causes rib age to move upwards and outwards and the diaphragm to flatten


What is inspiration

Breathing in


What is expiration

Breathing out


What is normal expiration

It's a passive process that doesn't require energy


Describe what happens during forced expiration

The external intercostal muscles relax and the internal intercostal muscles contract, pulling the rib cage further down and in


What are the microscopic air sacs where gas exchange occurs in the lungs called



What are the alveoli surrounded by

A network of cappileries


Describe how oxygen gets from the lungs into the blood

oxygen diffuses out of the alveoli, across the alveolar epithelium and the capillary endothelium and into the haemoglobin in the blood


What is forced vital capacity? (FVC)

The maximum volume of air it is possible to breathe forcefully out of the lungs after a really deep breath in


A person with fibrosis scar tissue has a reduced tidal volume. Explain why.

Scar tissue is thicker and less elastic than normal lung tissue. This means that the lungs are less able to expand and so can't hold as much air as normal, so the tidal volume is reduced.


Explain why the rate of gaseous exchange in someone with fibrosis is slower than in a healthy person

Scar tissue is thicker than normal lung tissue, so diffusion of gases is slower (increases diffusion pathway)


What happens to the forced expiratory volume during an asthma attack

Reduced air flow means that FEV is severely reduced