3.1 - Exchange And Transport Flashcards
Why do organisms have exchange surfaces?
- Cells need to take in oxygen and glucose for aerobic respiration and other metabolic processes
- To excrete waste products like carbon dioxide
How do you work out surface area:volume ratio?
Surface area - length x width
Volume ratio - length x height x width
Why do single celled organisms not need a specialised exchange surface?
Substances are able to diffuse directly due to:
- Small surface area:volume ratio
- Short diffusion distance so quicker rate
- Lower metabolic rate (most of the time)
Why do large multi celled organisms need a specialised exchange system?
Diffusion across the membrane is too slow because:
- Too big of a distance between the environment and the cells deep in the body
- Low surface area:volume ratio so it is difficult to exchange an efficient amount of substances needed
- High metabolic rate so the use of glucose and oxygen is faster
What are 4 features of an efficient specialised exchange surface?
- Large surface area
- Short diffusion distance/thin layer
- Good blood supply
- Sufficient gas exchange
What is example of a specialised exchange surface with a large surface area and the benefits?
A root hair cell:
- Long hair like structures to increase surface area
- Leads to an increase in the rate of absorption (eg. Water and mineral ions)
What is an example of a specialised exchange surface with a thin surface and the benefits?
Alveoli:
- Single celled walls of endothelium
- Allows for increased rate of diffusion due to the short diffusion distance (eg. Oxygen and carbon dioxide)
What is an example of a specialised exchange surface that has a good blood supply and the benefit?
Alveoli:
- Surrounded by a large capillary network so blood is constantly bringing oxygen and removing carbon dioxide
- To maintain concentration gradients increasing rate of diffusion due
- Well ventilated so air is constantly replaced
What is an example of a specialised exchange surface with good ventilation and blood supply and the benefits?
Alveoli:
- Surrounded by a large capillary network so blood is constantly bringing oxygen and removing carbon dioxide
- To maintain concentration gradients increasing rate of diffusion
- Well ventilated so air is constantly replaced
What structures are involved in a mammals gaseous exchange system and in what order?
- Air enters through the trachea
- Trachea splits into bronchi leading to the lungs
- Each bronchus branches into bronchioles
- The bronchioles lead into alveoli where gas is exchanged
- The ribcage, intercostal muscles and diaphragm to move the air out of the
What are the specialised structures in a gaseous exchange system?
- Goblet cells
- Cilia
- Elastic fibres
- Smooth muscles
- Rings of cartilage
What is the function of a goblet cell?
They secrete mucus to trap microorganisms and dust particles inhaled to stop them from reaching alveoli
What is the function of cilia?
They beat the mucus to move it upwards away from the alveoli to prevent lung infections, by it being swallowed instead
What is the function of elastic fibres?
Located in the trachea, bronchi, bronchioles and alveoli. This helps with breathing out, the fibres stretch and recoil when inhaling and exhaling
What is the function of smooth muscle?
Allows the control of diameter, when exercising the smooth muscles relaxes to make the tube wider so there is less resistance to airflow
What is the function of rings of cartilage?
In the trachea and bronchi to provide support. This prevents them collapsing when you breathe in and the pressure drops
What specialised structures are found in the trachea?
- C-shaped cartilage
- Smooth muscle
- Elastic fibres
- Goblet cells
- Ciliated endothelium
What specialised structures are in the bronchi?
- Small pieces of cartilage
- Smooth muscle
- Elastic fibres
- Goblet cells
- Ciliated endothelium
What specialised structures are found in bronchioles?
- Smooth muscle, but not in the smallest
- Elastic fibres
- Goblet cells, but only in large ones
- Ciliated endothelium, but non ciliated in the smallest
What specialised structures are in the alveoli?
- Elastic fibres
- Non-Ciliated endothelium
