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Biology
Human biology
Physical education
Science
If you cut yourself you bleed. Your blood looks red but it is really a yellow liquid with lots of red cells floating in it! Your blood is the transport medium for the cardiovascular system.
Plasma is a yellow liquid which transports all of the blood cells around your body. It carries waste carbon dioxide from the cells of the body to the lungs to be removed. It takes urea from the liver where it is made to the kidneys to be excreted in the urine. It carries the small dissolved food molecules from the gut to the cells where they are needed.
Red blood cellsred blood cells
Carry oxygen in the blood. They are also known as erythrocytes.
are small biconcave discs. They contain the red pigment haemoglobinhaemoglobin
The protein that carries oxygen within red blood cells.
which picks up oxygen in your lungs and carries it to the body cells where it is needed. Mature red blood cells don't have a nucleus so they can pack in more haemoglobin and carry more oxygen.
Oxygen is taken up in the lungs where it is at a relatively high concentrationconcentration
The amount of a substance (solute) in a solution.
, and released into cells where it is at a relatively low concentration.
This curve illustrates how the association between oxygen and haemoglobin changes as haemoglobin leaves the lungs and heads to the tissues through the arteries. At the lung, precisely in the alveolialveoli
The tiny air sacs which make up the structure of the lungs. The site of gaseous exchange.
, oxygen binds to haemoglobin and both saturation of haemoglobin and partial pressure of oxygen in arterial blood is high. As the oxygenated bloodoxygenated blood
Blood which is carrying oxygen in the form of oxyhaemoglobin.
leaves the lungs, and provides tissues with oxygen, both the partial pressure of oxygen in arterial blood and haemoglobin oxygen saturation goes down, as oxygen dissociates from blood to go into tissue cells. Eventually, no oxygen is left, and this blood returns to the heart through the veins. At this point oxygen pressure and saturation are very low.
White blood cellswhite blood cells
Cells specialised in defending the body against disease.
are bigger than red blood cellsred blood cells
Carry oxygen in the blood. They are also known as erythrocytes.
but there are fewer of them. They are an important part of the way your body defends itself against disease. There are lots of different types of white blood cells. Some of them make antibodies against disease-causing organisms. Some of them engulf bacteriabacteria
Single-celled organism. Has a cell wall, cell membrane, cytoplasm. Its DNA is loosely-coiled in the cytoplasm and there is no distinct nucleus.
and digest them. They all have a nucleus. The diagram below shows different types of white blood cells.
Plateletsplatelets
Fragments of cells that circulate in the blood and play a role in the formation of blood clots.
are small fragments of cells that have no nucleus. They are very important in the successful clotting of your blood. If you cut yourself, it is very important that the blood forms a solid clot as fast as possible to prevent you from bleeding to death. The clotting of your blood involves a series of enzyme-controlled reactions which produce a net of fibres made of a protein called fibrin. These fibres then trap lots of red blood cells and platelets and form a jelly like clot which dries to form a scab. The skin heals under the scab.
Neutrophils: they make up 40-70% of all white blood cellswhite blood cells
Cells specialised in defending the body against disease.
(WBCs) in human. They are an essential part of the innate immune systemimmune system
The body's natural defence mechanism against infectious diseases.
.
Eosinophils: they form 2-3% of WBCs. They are responsible for fighting multicellularmulticellular
Made up of more than one, usually many cells.
parasiteparasite
Organism that feeds off another living host and causes it some damage. An example of a parasite is a tapeworm that lives in the digestive system of a host organism.
s amongst other infections. They also control mechanisms related to allergy and asthma.
Basophils: 0.5-1% of WBCs. They are responsible for inflammatory reactions during immune response.
Lymphocytes: 18-42% of WBCs. Lymphocytes include three different types of cells:
Monocytes: largest WBC in blood in size. Monocytes play a role in adaptive immune response and perform tissue repair functions.
Macrophages: these cells engulf and digest pathogens such as cancer cells, microbesmicrobes
Group of organisms of microscopic size that can be found in a single cell form or forming multicellular colonies. Most microbes are found in the domains of archaea and bacteria, but there are also some eukaryotes.
, cellular debris, and exogenous substances that are recognised as foreigner and nor coming from our body. This process is called phagocytosisphagocytosis
Energy-requiring process by which a cell takes large particles into membrane-bound vesicles.
.
