Blood 1

Contents Composition of Blood -PlasmaPlasma -Dissolved substancesDissolved substances -Blood CellsBlood Cells -Red Blood CellsRed Blood Cells -White Blood CellsWhite Blood Cells -PlateletsPlatelets Functions of Blood -TransportTransport -ProtectionProtection -RegulationRegulation Blood Groups Blood Transfusions Rhesus Factor Defence System in Humans General Defence System Specific Defence System Immunity Vaccination Lymphocytes Lymphocytes and AIDS 2

Composition of Blood Plasma55% - liquid part of blood Blood ‘cells’45% - suspended in liquid Blood pH = 7.4 3

Plasma Composed of 90% water in which the ‘cells’ are suspended together with a number of dissolved substances The water acts as a transport medium for the cells and dissolved substances 4

Dissolved substances include products of digestion - glucose, amino acids, glycerol, fatty acids, minerals, vitamins. waste products - carbon dioxide, urea, uric acid hormones - e.g. insulin, thyroxine, testosterone plasma proteins - albumen, fibrinogen, prothrombin. antibodies - proteins which destroy pathogens. enzymes - thrombin salts - e.g. NaCl, sodium bicarbonate 5

Blood ‘ cells ’ Three types Red blood cells or corpuscles White blood cells Platelets = cell fragments 6

Red Blood Cells Bi-concave discs – large surface area Have no nucleus or mitochondria Have flexible membranes – to facilitate exit from capillaries Made in marrow of long bones – ribs & sternum Contain the pigment haemoglobin [iron (Fe) necessary for its formation] 7

Function of Red Blood Cells Joins with oxygen to form oxyhaemoglobin Transports oxygen to all cells of the body Effete corpuscles broken down in liver and spleen Haem (iron) retained and stored Rest forms part of bile 8

Lack of iron Lack in the diet causes anaemia Iron-rich food in diet important e.g. red meats, liver, kidneys, eggs, nuts, green vegetables, etc 9

Red blood cells 10

Human blood film showing distribution of cells 11

White Blood Cells Have a nucleus but no definite shape Larger than red blood cells No haemoglobin Formed in the bone marrow and mature in the lymph system Protect the body against disease Less numerous than red blood cells There are different types each with different functions 12

Different types of white blood cells 13

Types of white blood cell Two types are: Lymphocytes and Monocytes 14

Types of white blood cells 15

Lymphocytes Made in bone marrow and mature in lymph system Have large nucleus Produce antibodies, in response to presence of bacteria or viruses, that kill the bacteria or viruses 16

Monocytes Made in the bone marrow Largest of the white blood cells Engulf bacteria and dead cells 17

Platelets Fragments of larger cells made in bone marrow No nucleus Important in blood clotting 18

Platelets 19

Summary of blood cells 20

Functions of the blood Three main functions 1.Transport of materials 2.Protection 3.Regulation 21

1. Transport of materials products of digestion - glucose, amino acids, glycerol, fatty acids, minerals, vitamins. waste products - carbon dioxide, urea, uric acid hormones - e.g. insulin, thyroxine, testosterone plasma proteins - albumen, fibrinogen, prothrombin. antibodies - proteins which destroy pathogens. enzymes - thrombin salts - e.g. NaCl, sodium bicarbonate 22

2. Protection produce antibodies - lymphocytes destroy bacteria - monocytes clotting of wounds - platelets 23

3. Regulation Maintains the level of water and salts in the cells Temperature regulation - blood flowing through organs with a high rate of respiration (liver and muscles) is warmed and the heat carried all over the body. Blood also carries water to sweat glands to cool the body 24

Blood Groups Four groups - based on glycoprotein molecules present or absent on surface of red blood cells Glycoprotein = carbohydrate + protein –acts as an antigens Antigen = a substance (e.g. a micro-organism or its waste products) that the immune system of the body recognises as ‘foreign’ 25

Antigen (cont ’ d) and as a result will produce antibodies that will react with the antigen and neutralise or destroy it. e.g. antigens found in bacterial cell walls, virus coats, foreign cells and produced in cancerous cells. 26

Blood Groups Group Antigens on red blood cells 27 It is essential to know a persons blood group for safe blood transfusions A B AB O A B A and B None

Red blood cells showing blood group antigens 28

Blood Transfusions – not examinable – for info only 29 A O AB B Universal Donor Universal Recipient Can be donated to

Rhesus Factor Another blood grouping system Involvs antigen called factor D If you have factor D you are Rhesus positive or Rh+ If you haven’t you are Rhesus negative or Rh- When classifing blood both systems are used e.g. you may be O+ i.e. you have neither A nor B antigens but do have factor D 30

Rhesus Factor Significance (1/2) In pregnant women If a Rh- woman is carrying a Rh+ baby Some of baby’s factor D may cross into the mother’s bloodstream Mother’s defence system will recognise these as foreign antigens Will make antibodies against them 31

Rhesus Factor Significance (2/2) No danger during a first pregnancy – time taken to develop antibodies Problem with second Rh+ baby Antibodies previously formed will attack red blood cells of baby – kill baby Prevented by injecting mother with antibodies against factor D when baby is born These destroy the anti-D antibodies in the mother 32

Defence System in Humans 33

Defence Systems The human body has two systems to protect itself from foreign bodies and cells. These are the: - General Defence System and the Specific Defence System 34

General Defence System (1/5) Prevents the entry of microbes (by acting as a barrier) and destroys microbes once they get inside the body e.g. The Skin: A continuous unbroken waterproof barrier - sweat contains a bactericidal agent. Blood Clotting: seals wounds and prevents micro-organisms from entering the body. 35

General Defence System (2/5) Respiratory System: Is lined with mucus membranes and cilia, which trap dust and microbes and carry them to the throat where they are swallowed. Digestive System: Produces hydrochloric acid and digestive juices - kill micro-organisms that have been swallowed. 36

General Defence System (3/5) Body Fluids: e.g. tears, urine, saliva; contain enzyme lysozyme which puts holes in bacterial cell walls and allows water in. Cells in wall of vagina secrete carbohydrate – used by beneficial bacteria – converted to lactic acid – inhibits growth of pathogens 37

General Defence System (4/5) Phagocytes: = white blood cells - amoeboid - ingest and destroy bacteria - can travel in ECF (extra cellular fluid) to site of infection - pus. Others secrete chemicals that stimulate the general defence system and cause fever to destroy microbes at high temperatures. 38

The effect of a phagocytic white blood cell on a bacterium 39

The barriers to invasion by a microbe in a human 40

General Defence System (5/5) Blood system also produces proteins (complement) – put holes in bacterial walls – fill with fluid – burst Cells infected by viruses produce protein (interferon) – makes surrounding cells resistant to the virus – limits the spread of the virus 41

Specific Defence System (1/2) Produces an individual response to each foreign body (antigen) that enters the body. This system also called the immune system. The response is called an immune response. White blood cells found in spleen, thymus, lymph system and blood produce antibodies in response to the presence of antigens. 42

Specific Defence System (2/2) Antibodies are specific to the antigens (similar to enzymes and substrate) one antibody destroys one antigen. Born with millions of these white blood cells – each capable of producing a different antibody 43

How do they work? Microbe enters the body e.g. chicken pox virus White blood cells try to attach their antibodies to it Correct match eventually found This white blood cell reproduces rapidly More and more antibodies released and microbes are destroyed The body may show external signs of having chicken pox until the virus is destroyed 44

e.g. of Induced immunity Some of these white blood cells remain in the blood If the same microbe tries to re-infect the body an immediate response occurs and the microbe is eliminated The body will never show external signs of having been attacked by the chichen pox virus again 45

The response of the immune system when exposed to an antigen 46

Immunity = the ability of the body to resist infection Two types: – Natural immunity – using the general defence system and – Induced or Acquired immunity (two ways) - Active - suffering disease or vaccination (long term protection) - Passive – injected with antibodies – not produced by body’s cells (short term) 47

Vaccination is a non-disease-causing dose of a pathogen or its toxin is injected into a healthy individual. This causes antibodies to be produced which remain in the blood and induces long term immunity to that pathogen e.g. 3 in 1 (Diphtheria, Whooping cough and Tetanus - bacteria); MMR (measles, Mumps and Rubella - viruses); Polio - virus. BCG & Hib 48

Lymphocytes Two types: - B cells – produce antibodies and inactivate antigens by surface recognition. Each B cell produces just one type of antibody. T cells – do not produce antibodies but act in one of four processes as helper T cells, killer T cells, suppressor T cells or memory T cells. 49

B Lymphocytes Produced in the bone marrow Migrate to and mature in the lymph nodes On contact with an antigen reproduce rapidly Provide large quantities of antibodies Destroys antigen Some of the cells produced remain in lymph nodes as memory cells These provide a rapid response for successive exposures to the antigen – active immunity 50

T Lymphocytes (1/2) Helper T cells – stimulate other T lymphocytes (killer & suppressor) to work and enhance their effectiveness – cause the B cells to reproduce Killer T cells – attack large pathogens e.g. unicellular parasites – destroy cancer cells & cells containing viruses – work by puncturing cell membranes. 51

T Lymphocytes (2/2) Suppressor T cells – can suppress the immune response of other cells – prevents the immune system from over- reacting – regulates the immune system Memory T cells – long lived in circulatory system – produced when T lymphocytes are stimulated – provide a rapid response for successive exposures to an antigen 52

The role of T cells in the defence system 53

T Lymphocytes and AIDS Helper T cells infected by HIV When a person develops AIDS Susceptible to other infections as Immune system is compromised i.e. it’s ability to function is greatly reduced 54

Infections by bacteria not examinable for information only 55

Sinusitis 56

END 57