1B Mammalian Transport Flashcards
What is a mass transport system?
arrangement of structures by which substances are transported with a fluid and a mechanism (e.g. pump) for moving it around the body
Why is a mass transport system needed in larger organisms?
The surface area : volume ratio is too small to maintain effective diffusion.
Describe a single circulatory system
The heart pumps blood to the organs of gas exchange (e.g. gills in fish) and then the blood travels to the rest of the body before returning to the heart
Describe a double circulatory system
Circulation involves two separate circuits, one for deoxygenated blood moving from the heart to the gas exchange organs and one for oxygenated blood flowing around the body before returning to the heart.
What are the 4 components of blood?
Red blood cells (erythrocytes), white blood cells (leucocytes), plasma and platelets
What is the function of the red blood cells?
To transport oxygen from the lungs to the respiring cells.
How are red blood cells adapted to their function?
No nucleus - more space for haemoglobin means more oxygen can be carried
Biconcave shape - large surface area : volume ratio for rapid diffusion of oxygen
What is the function of plasma?
It transports blood cells and other dissolved substances, including waste products (e.g. glucose, urea, hormones, carbon dioxide).
It also helps to maintain steady body temperature and acts as a buffer to regulate pH changes.
What is the function of the white blood cells?
To defend the body against infection
How are white blood cells adapted to their function?
Can change their shape - they squeeze through the blood vessel walls to get to pathogens and the can engulf pathogens
What is the function of the platelets?
Blood clotting - prevent blood loss and minimise risk of pathogens entering the body
How is oxygen transport in the blood?
As oxyhaemoglobin, combined with haemoglobin in the red blood cells
Describe and explain the shape of the oxygen dissociation curve for haemoglobin.
S-shaped curve. As partial pressure of oxygen increases, haemoglobin saturation increases. Each haemoglobin molecule can bind to 4 oxygen molecules - the first is relatively easy to bind, this changes the shape of the haemoglobin, making it easier for molecules 2 and 3 to bind, then molecule 4 is harder because the haemoglobin is “full”
What are the 3 ways carbon dioxide can be transported in the blood?
Carried dissolved in the blood plasma, combined with haemoglobin as carbaminohaemoglobin and in the cytoplasm of red blood cells as hydrogencarbonate ions.
What does the Bohr Effect relate to?
The that carbon dioxide concentration affects the affinity of haemoglobin for oxygen.
Describe the Bohr Effect.
As the concentration of carbon dioxide rises (e.g. in respiring tissues), the affinity of haemoglobin for oxygen is reduced. This makes it easier for the haemoglobin to release oxygen, allowing it to move to the respiring tissues where it is needed.
Outline the blood clotting process.
Damage to the blood vessel wall exposes the collagen. This stimulates the release of thromboplastin. Thromboplastin, with calcium ions, catalyses the conversion of prothrombin into thrombin. Thrombin stimulates the conversion of fibrinogen into fibrin. Fibrin creates a mesh that covers the wound, trapping other blood cells to strengthen the layer.
Describe the structure of arteries.
Small lumen, smooth endothelium, thick wall with elastic fibres and muscle tissue.
How is the structure of an artery related to its function?
Smooth endothelium for easy blood flow, thick elastic layer for stretch and recoil, muscle tissue contracts and relaxes to change the size of the lumen - the smaller the lumen, the higher the pressure.
Describe the structure of a vein
Veins have valves, relatively large lumen, smooth endothelium lining, outer layer of collagen, thin layer of muscle and some elastic fibres.
How is the structure of a vein related to its function?
Smooth endothelium lining for easy blood flow, the large lumen means blood is under low pressure, so valves prevent backflow of blood. Low pressure means less need for muscular and elastic layer.
Describe the structure of a capillary
Very small lumen (just bigger than a red blood cell), very thin walls - just one epithelial cell thick.
How is the structure of a capillary related to its function?
The thin walls allow for rapid diffusion of substances between the blood and cells. The small lumen means blood travels slowly for maximum diffusion opportunities and means they can fit between individual cells to provide substances all over the body.
Which blood vessels supply the heart muscle with blood and oxygen?
The coronary arteries
