TRANSPORT IN HUMANS Flashcards
What does the plasma contain?
Contains soluble proteins like fibrinogen, prothrombin and antibodies
Dissolved mineral salts e.g HCO3, Cl, Ca
Excretory substances
Hormones
What are the adaptations of the red blood cell?
- Contains haemoglobin which contains combines reversibly with oxygen allowing it to transport oxygen.
- Circular, flattened biconcave disc, increases the cell SA:V ratio for a faster rate of absorption.
- Does not possess a nucleus, enabling it to carry more haemoglobin and thus more oxygen.
- It is elastic and can turn bell-shaped to squeeze through blood vessels.
What are the four blood groups?
A
B
AB (universal acceptor)
O (donor)
What are the protective functions of blood?
When blood vessels are damaged, damaged tissues and blood platelets release thrombokinase. Thrombokinase converts the protein thrombin found in blood plasma into thrombin. Ca ions must first be present. Thrombin is also an enzyme, catalysing the conversion of soluble fibrinogen to insoluble fibrin threads. Fibrin threads entangle red blood cells and the whole mass forms a clot, sealing the wounds, and preventing microorganism entry.
What are the adaptations of the arteries?
Arteries have thick, muscular and elastic walls to withstand the immense pressure of the blood forced from the heart.
This allows the artery walls to stretch and recoil.
What are the features of veins?
The blood flow is much slower in veins. Blood flows slowly and smoothly.
Vein walls do not need to be as thick or as muscular as the artery.
Most veins have valves to prevent the backflow of blood.
Why do animals have a double circulation?
Blood entering the lungs is at a lower pressure compared to blood leaving the heart, allowing sufficient time for blood to be well oxygenated before it is returned to the heart.
The heart pumps oxygenated blood at a high pressure to the rest of the body so oxygenated blood is distributed to the body tissues more quickly.
