Flashcards · Biology · Blood, Blood Vessels and the Heart
The Structure and Functions of Blood
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What are the four components of blood?
Plasma, red blood cells, white blood cells and platelets.
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What is plasma mostly made of?
Water.
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Name four things that plasma carries.
Any four of: carbon dioxide, glucose, amino acids, urea, hormones, mineral ions, heat.
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What is the job of a red blood cell?
To carry oxygen from the lungs to the cells.
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What is haemoglobin?
A red protein containing iron that combines with oxygen.
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What does haemoglobin form in the lungs?
Oxyhaemoglobin, by combining with oxygen.
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Why does a red blood cell have no nucleus?
To make more room for haemoglobin, so it can carry more oxygen.
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Why is a red blood cell a biconcave disc?
It has a large surface area for its volume, so oxygen diffuses in and out quickly.
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Why can red blood cells squeeze through capillaries?
They are small and flexible.
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Does a white blood cell have a nucleus?
Yes.
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What do phagocytes do?
They engulf and digest pathogens, which is called phagocytosis.
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Why can a phagocyte surround a pathogen?
It can change shape.
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What do lymphocytes make?
Antibodies.
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What are platelets?
Small fragments of cells with no nucleus.
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What is the job of platelets?
To help the blood to clot at a wound.
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Why is a clot useful?
It stops blood loss and keeps pathogens out of the wound.
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Which is more numerous, red or white blood cells?
Red blood cells, about 5 million per cubic millimetre against about 7000.
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What is the formula for magnification?
\(\text{magnification} = \text{image size} \div \text{actual size}\).
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Which mineral ion is needed to make haemoglobin?
Iron.
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What is the common mistake about red blood cells?
Saying they have a nucleus, or that they carry carbon dioxide. They have no nucleus and mainly carry oxygen.
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Name each type of blood cell in this diagram and say what each does. 
The red cells carry oxygen using haemoglobin. The cell with the lobed nucleus is a phagocyte, which engulfs pathogens. The cell with the large round nucleus is a lymphocyte, which makes antibodies. The small fragments are platelets, which help the blood to clot.
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What percentage of the blood is plasma, and what makes up the rest? About 55 percent is plasma. About 44 percent is red blood cells, and less than 1 percent is white blood cells and platelets.