Transcript Blood - Studyclix

Blood
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Contents
Composition of Blood
- Plasma
- Dissolved substances
- Blood Cells
- Red Blood Cells
- White Blood Cells
- Platelets
Functions of Blood
- Transport
- Protection
- Regulation
Blood Groups
Blood Transfusions
Rhesus Factor
Defence System in
Humans
General Defence System
Specific Defence System
Immunity
Vaccination
Lymphocytes
Lymphocytes and AIDS
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Composition of Blood
• Plasma
55% - liquid part of blood
• Blood ‘cells’
45% - suspended in liquid
• Blood pH = 7.4
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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
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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
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Blood ‘cells’
Three types
• Red blood cells or corpuscles
• White blood cells
• Platelets = cell fragments
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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]
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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
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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
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Red blood cells
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Human blood film showing
distribution of cells
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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
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Different types of white blood cells
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Types of white blood cell
Two types are:
• Lymphocytes and
• Monocytes
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Types of white blood cells
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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
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Monocytes
Made in the bone marrow
Largest of the white blood cells
Engulf bacteria and dead cells
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Platelets
Fragments of larger cells made in bone marrow
No nucleus
Important in blood clotting
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Platelets
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Summary of blood cells
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Functions of the blood
Three main functions
1. Transport of materials
2. Protection
3. Regulation
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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
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2. Protection
produce antibodies - lymphocytes
destroy bacteria - monocytes
clotting of wounds - platelets
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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
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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’
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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.
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Blood Groups
Group
Antigens on red
blood cells
A
A
B
B
AB
A and B
O
None
It is essential to know a persons blood
group for safe blood transfusions
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Red blood cells showing blood group antigens
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Blood Transfusions – not
examinable – for info only
A
Universal
Donor
Universal
AB
O
Recipient
B
Can be donated to
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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 RhWhen 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
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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
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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
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Defence System in Humans
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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
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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.
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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.
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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
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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.
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The effect of a phagocytic white
blood cell on a bacterium
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The barriers to invasion by a
microbe in a human
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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
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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.
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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
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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
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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
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The response of the immune system
when exposed to an antigen
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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)
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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
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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.
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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
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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.
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T Lymphocytes
(2/2)
Suppressor T cells – can suppress the immune
response of other cells
– prevents the immune system from overreacting
– 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
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The role of T cells in the defence
system
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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
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Infections by bacteria
not examinable
for information only
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Sinusitis
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END
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