Introduction to the structure and function of blood Flashcards

1
Q

What are the four components of blood?

A
  1. Plasma (fluid)
  2. Red blood cells
  3. White blood cells
  4. Platelets
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2
Q

What are the three layers formed when you centrifuge blood? Name them from top to bottom.

A

1) Plasma
2) A layer of white blood cells called buffy coat (buffy is a pale yellow-brown colour)
3) Red cells at the bottom as they are denser than white blood cells

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3
Q

What is the importance of the shape RBCs / erythocytes have to their function?

A

1) The biconcave shape gives them a bigger surface area for the exchange of oxygen.
2) It allows for flexibility when they travel through narrow capillaries so that they dont rupture or cause blood clots
3) they do not have a nucleus, DNA, RNA or mitochondria (only very immature RBCs have RNA in the first 24 hours)

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4
Q

What is the diameter of a RBC? Extra points for knowing the centre and outer thickness

A

It is approximately 8um. But it can be anywhere between 6-8um in humans.

The central thickness is approx. 1um and the outer is approx. 2.4um.

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5
Q

What are granulocytes?

A

Granulocytes are a category of white blood cells characterised by the presence of granules in their cytoplasm.

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6
Q

What are the three different types of granulocytes?

A
  1. Neutrophils - they have weakly staining granules
  2. Eosinophils - they have a much more prominent pinkish-reddish granules
  3. Basophils - they have big purple granules in the cytoplasm (often you can’t see the nucleus because of the granules)
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7
Q

What do the granules in granulocytes contain?

A

The granules contain substances that are going to be released from the cells like antibacterial agents, inflammatory agents, etc.

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8
Q

What are mononuclear cells? What are the two types?

A
  • Mononuclear cells have a single nucleus (rather than the multi-lobe nucleus of granulocytes).
  • They have a large, regular sized nucleus.

The two types are:-

1) Monocytes:- they are the largest type of WBCs. They have a round or kidney shaped nucleus.
2) Lymphocytes:- they have a nucleus the same size as a RBC.

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9
Q

What is the function of platelets / thrombocytes.

A

They are clotting cells whose function is to react to bleeding from blood vessel injury by clumping, thereby initiating a blood clot.

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10
Q

Describe the structure of platelets / thrombocytes.

A
  • They are a fragment of cytoplasm that don’t have a nucleus.
  • They are membrane bound (they have a cell membrane around them like a nucleus).
  • They have granules that are waiting to be secreted and contain substances that are involved in clotting and inflammation.
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11
Q

Where do blood cells come from?

A
  • Mature blood cells are produced from stem cells in the bone marrow.
  • The bone marrow contains many immature cells.
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12
Q

What is blood plasma?

A

• It is a fluid containing:-
◦ Water
◦ Salts
◦ Proteins
◦ Organic molecules
‣ E.g. metabolites, carbohydrates, lipids

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13
Q

What are the ionic constituents of blood plasma?

A

Ionic constituents are:-
• Positive ions (cations) such as -
◦ Sodium, potassium, calcium, magnesium and hydrogen ions
• Negative ions (anions) such as -
◦ Chloride, bicarbonate, phosphate, sulphate and organic anions.

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14
Q

What is the difference between plasma and serum?

A
  • Plasma contains fibrinogen (an important blood clotting factor). This is not present in serum.
  • Plasma is the fluid component of the whole blood, whereas serum is the fluid left after blood clotting factors have been removed from the plasma.
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15
Q

What is used to prevent blood from clotting?

A

Anticoagulants - they work by interfering with the chemicals needed to make clots or clotting factors.

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16
Q

What percentage of the plasma is protein? What is the most prevalent protein and what percentage is it?

A
  • Usually about 7-9% of the plasma is protein.
  • Its complex as there are thousands of different proteins.
  • But more than 90% is a single protein called albumin.
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17
Q

What are the three main functions of the blood?

A
  1. Transport
  2. Immunity
  3. Homeostasis
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18
Q

What is the role of blood in transport?

A
  1. The blood carries oxygen / nutrients to tissues
  2. It removes CO2 / other waste products from tissues
  3. It also transports other substances (e.g. hormones) from sites of production to the sites of action.
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19
Q

Explain the role of erythrocytes in transport in blood

A

• Erythrocytes transport oxygen from the lungs to the body tissues
• They also help in the removal of CO2 from body tissues to the lungs.
◦ Most of this CO2 is carried as bicarbonate ion (HCO3-) in the plasma.
◦ The red cell enzyme carbonic anhydrase helps CO2 in two ways:-
‣ It helps it (CO2) to dissolve in plasma in the tissues.
‣ It helps the CO2 to come out of solution in the lungs.

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20
Q

Describe the structure and function of haemoglobin.

A

• Hb binds to oxygen and carries it from the lungs to the tissues
• It is a protein tetramer made up of 4 polypeptide chains:-
◦ 2 alpha globin chains
◦ 2 beta globin chains
• Each globin chain carries a haem molecule.
• The haem holds a ferrous (Fe++) iron atom.
• Oxygen binds reversibly to the iron atom by coordination bond (dative covalent bond). This process is called oxygenation, not oxidation (as the Fe++ is not oxidised to Fe+++).

There are about 300,000,000 Hb molecules in each RBC, which takes up almost 50% of the space in each RBC.

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21
Q

What is the difference between oxygenation and oxidation?

A
  • Oxygenation is a physical property that refers to the amount of dissolved oxygen in a system; or the process of increasing it.
  • Oxidation is a chemical concept that originally referred to the addition of oxygen to an element or compound, but now is usually taken to mean the loss of electrons or an increase in oxidation state.
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22
Q

What are the two forms of haemoglobin (Hb)?

A

The two forms are:-

  1. Oxyhaemoglobin - When Hb is fully saturated with O2, making it bright red.
  2. Deoxyhaemoglobin - When Hb has lost all of its O2, making it dark red.
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23
Q

Differentiate between haemoglobin and deoxyhaemoglobin

A
24
Q

How does a pulsometer work? What is this monitoring of a persons oxygen saturation called?

A
  • A pulsometer shines a light through the finger and measure the colour of the haemoglobin (so it measures the saturation of the blood).
  • It is called pulse oximetry.
25
Q

What is hypoxia (a medical condition)?

A

It is a condition in which the body or a region of the body is deprived of adequate oxygen supply at the tissue level.

26
Q

What is the difference in what the plasma carries and what the plasma proteins carry?

A

• Plasma carries soluble metabolites in solution.
• Plasma proteins carry substances which are poorly soluble in water. E.g. :-
◦ Lipids are carried mostly in complexes called lipoproteins (high density lipoproteins and low density lipoproteins). There are also cylomicrons that carry fats from the digestive system to the liver.
◦ Lipid soluble hormones and vitamins (like vitamin D) dissolves poorly in water and needs to be carried by proteins
• Plasma proteins also carry metal ions. E.g. :-
◦ Ca++
◦ Fe++ (bacteria need ferrous iron. If your blood gets infected with bacteria (septicaemia) it needs iron to grow. If the body keeps the iron tightly linked to a protein, it makes it might harder for the bacteria to get hold of the iron and for the bacterium to grow).
◦ Cu++

27
Q

Why do plasma proteins need to carry ions?

A

They need to carry metal ions in the blood because:-

  1. The metal ions can be toxic and can generate oxygen free radicals (reactive chemical species containing oxygen).
  2. Bacteria need ions to grow (especially Fe++). If your blood gets infected with bacteria (septicaemia) it needs ion to grow. If the body keeps the ion tightly linked to a protein, it makes it much harder for the bacteria to get hold of the ion and for the bacterium to grow.
28
Q

Describe the structure of neutrophils

A

They have a nucleus which is multilobed (3 - 5 lobes) with small numerous granules

29
Q

Describe the structure of eosinophils

A

They are bi-lobed (2-3 lobes) and have large granules that stain pink-orange.

30
Q

Describe the structure of a basophil

A

They are bi-lobed or tri-lobed and have large granules that stain blue. The nucleus is barely visible.

31
Q

Describe the structure of lymphocytes

A

A normal lymphocyte has a large, dark-staining nucleus.

32
Q

Describe the structure of a monocyte

A

It has a kidney shaped nucleus and a granulated cytoplasm.

33
Q

What are the functions of neutrophils?

A
  1. To phagocytose and kill bacteria and fungi
  2. They are the main mediators of innate immunity (defence mechanism you are born with)
34
Q

What are the functions of lymphocytes?

A
  1. They are the main mediators of adaptive / acquired immunity (immunity you get after you have been exposed to a disease. Most of the time you only get it once).
  2. Produce antibodies
  3. Kill virus infected cells
35
Q

What are the functions of eosinophils?

A
  1. Kill parasites
  2. Involved in allergic responses
36
Q

What are the functions of basophils?

A
  1. Kill parasites
  2. Involved in allergic responses
  3. Involved in inflammation
37
Q

What is the function of monocytes (macrophages)?

A
  1. Phagocytosis of dead cells and pathogens.
38
Q

What are the two types of plasma proteins in immunity defence and what are their functions?

A

The two types are :-

  1. Immunoglobins (Ig)
    * They are proteins made by B-lymphocytes that act as antibodies against pathogens.
  2. Complement proteins
  • They kill bacteria and other pathogens - one way they do this is by binding to bacterial cell membrane and blowing holes into it
  • they co-operate with Ig and WBCs
39
Q

What is the difference between ferrous and ferric iron?

A
40
Q

What is haemostasis? What are the three major steps of haemostasis?

A
  • Haemostasis is a process which causes bleeding to stop, meaning to keep blood within a damaged blood vessel. It is the first stage of wound healing.
  • Hemostasis has three major steps:-

1) vasoconstriction,
2) temporary blockage of a break by a platelet plug, and
3) blood coagulation, or formation of a fibrin clot.

These processes seal the hole until tissues are repaired.

41
Q

What is the role of platelets in haemostasis?

A
  1. They recognise the damage at blood vessel walls and form a platelet plug.
  2. This prevents / stops bleeding.
  3. But this platlet plug is insecure and temporary.
42
Q

What is the role of plasma in haemostasis?

A
  1. Fibrinogen is a major plasma protein that is converted to fibrin that forms the blood clot.
  2. The clotting factors control the process.
  3. The fibrin clot reinforces the primary platelet plug.
43
Q

What is homeostasis?

A

Homeostasis is the regulation of a constant internal environment in the body.

This includes:-

  • Maintaining pH at 7.4
  • Controlling distribution of water and solutes
  • Distributing heat
44
Q

What is the U and E test for?

A
  • A U+E test refers to a blood test that checks Urea and Electrolytes.
  • The test involves checking the blood levels of sodium, potassium, bicarbonate, urea, creatinine and often glucose.
  • It is used to screen for kidney failure and dehydration.
45
Q

What is a LFTs (liver function test)?

A
  • Liver function tests, also referred to as a hepatic panel, are groups of blood tests that provide information about the state of a patient’s liver.
  • One thing you test for is the things made by the liver such as serum albumin and clotting factors.
  • These tests can be used to detect the presence of liver disease, distinguish among different types of liver disorders, gauge the extent of known liver damage, and monitor the response to treatment.
46
Q

What is the total volume of blood in a 70kg male?

A

It is approximately 5 litres.

47
Q

What is the plasma volume in a normal adult?

A

It is about 2.5-3 litres.

48
Q

What is the haematocrit?

A
  • The haematocrit is the volume percentage (vol%) of red blood cells in blood.
  • It is normally 47% (±5%) for men and 42% (±5%) for women.
49
Q

What does a low haematocrit value indicate?

A

An abnormally low hematocrit may suggest anaemia, a decrease in the total amount of red blood cells.

50
Q

What does a high haematocrit value indicate?

A
  • An abnormally high hematocrit is called polycythemia.
  • Polycythemia is a disease state in which the hematocrit (the volume percentage of red blood cells in the blood) is elevated.
  • It can be due to an increase in the number of red blood cells or due to a decrease in the volume of plasma.
51
Q

What is the average life span of a RBC?

A

It is around 120 days.

52
Q

What does full blood count (FBC) include?

A
  • It gives information about the cells in a patient’s blood, such as the cell count for each blood cell type and the concentrations of hemoglobin (in g/l).
  • It can be used to diagnose anaemia.
53
Q

What is the mean (red) cell volume (MCV)?

A
  • It is a measure of the average volume of a red blood corpuscle (or red blood cell).
  • The measure is attained by multiplying a volume of blood by the proportion of blood that is cellular (the hematocrit), and dividing that product by the number of erythrocytes (red blood cells) in that volume.
54
Q

What is the mean (red) cell haemoglobin content (MCHC)?

A
  • The Mean corpuscular hemoglobin concentration is a measure of the concentration of haemoglobin in a given volume of packed blood.
  • It is calculated by dividing the haemoglobin by the haematocrit.
55
Q

What is albumin?

A

It is a simple form of protein that is soluble in water and coagulable by heat, such as that found in egg white, milk, and (in particular) blood serum.

56
Q

Which two types of WBCs perform phagocytosis?

A

Monocytes and neutrophils