3.1 exchange surfaces Flashcards
What is an organ?
A group of different tissues that work together to perform a certain function.
What is a tissue?
A group of cells that act together to perform a specific function.
What happens during inhalation?
You breath in. Then the external intercostal muscles contract so ribs move upwards and outwards. The diaphragm contracts and flattens is the thoracic cavity volume increases. The lungs expand so air pressure in the lungs decreases. Finally, the difference in air pressure caused air to rush into the lungs.
What happens during exhalation?
You breath out. The diaphragm expands and relaxes. Volume in the thoracic cavity decreases. The lungs compress so air pressure in the lungs increased. Finally, the difference in air pressure caused air to rush out of the lungs.
What is an exchange surface?
A specialised area that is adapted to make it easier for molecules to cross from one side of the surface to another.
Why can small organisms rely on simple diffusion?
They have a large surface area to volume ratio.
What is the purpose of a nasal cavity?
To keep air warm and control moisture levels. Nasal hairs trap dust and microorganisms.
To keep air warm and control moisture levels. Nasal hairs trap dust and microorganisms.
Give an example of a specialised exchange surface with s large surface area.
Root hair cells. The cells on plant roots grow into long hairs which stick out. Each branch of root will be covered in millions of these microscopic hairs which increase surface area. This increases rate of absorption of water.
Give an example of a specialised exchange surface that is thin.
Alveoli. Each alveolus is made from a single layer of thin, flat cells called alveolar epithelium. O2 diffuses out of the alveolar space into the blood and CO2 diffuses out of the alveoli in the opposite direction. This helps to decrease the diffusion distance to increase rate of diffusion.
Give an example of a specialised exchange surface that has a good supply.
Fish Gills. In the gills, CO2 and O2 are exchanged between the fish’s blood and the surrounding water. They contain a large network of capillaries which keeps them supplied with blood. They are also well ventilated as fresh water constantly passes over them.
Describe the structure of a mammalian gaseous exchange system.
As you breathe in, air enters your trachea. The trachea splits into 2 bronchi. Each bronchus branches into small tubes called bronchioles which end in smaller air sacs called alveoli.
What is the function of elastic fibres in the gaseous exchange system.
They are in the walls of the trachea, bronchi and bronchioles and alveoli. They help the process of breathing out. On breathing in, the lungs inflate and the elastic fibres are stretched. Then the fibres recoil to help push air out.
What is the function of smooth muscle in the gaseous exchange system
They’re in the walls of the trachea, bronchi and bronchioles. Allows their diameter to be controlled. During exercise the smooth muscle relaxes, making the tubes wider. This means there’s less resistance to air flow and air can move in and out of the lungs more easily.
What is the function of the rings of cartilage in the gaseous exchange system
They’re in the walls of the trachea and bronchi. They provide support as its strong but flexible. It stops the trachea and bronchi collapsing when you breath in and pressure drops.
What kind of circulatory system do fish have?
A single circulatory system. The heart pumps blood to the gills to pick up oxygen and then on through the rest of the body in a single circuit.
