Flashcards in Haematology Deck (74):
What is blood?
A connective tissue
What are the 3 functions and their sub-functions of blood?
- Oxygen from the lungs to the tissues & CO2 from the tissues to the lungs, for excretion
- Nutrients from digestive tract tissues & cell wastes from the tissues to excretory organs (kidneys)
- Hormones secreted from the endocrine glands to their target cells/tissues
- Heat from active tissues to less active tissues
- Antibodies: migrate to areas for infection (inflammation)
- Clotting factors: coagulate in order to prevent the loss of blood from a ruptured blood vessel
- Fluid/electrolyte balance
- pH of the blood plasma
What proportion of the body does blood make up (%)?
Man = 7%
Women = less than 7%
Children = more than %
What are the 2 components of blood and their %'s?
1) Plasma (matrix) = 55%
2) Cellular components = 45%
What are the 7 components of blood plasma?
1) Mainly water (90-92%)
2) Plasma proteins (7%)
3) Mineral, inorganic salts
4) Organic waste products
3 Properties of the plasma proteins:
1) They remain within the blood vessels as they are too large to pass through the capillary pores within the capillary bed.
2) Responsible for: maintaining the OSMOTIC PRESSURE (normal: 25 mmHg) in order to keep the water component of the blood plasma within the blood vessel.
If the plasma proteins where not produced/moved out of the blood vessels, the water would follow are OEDEMA would occur!
3) Responsible for: maintaining the VISCOSITY of the blood. The viscosity of the blood can be used as a measure of how well the body's response is to particular diseases.
What is Oedema?
When the plasma proteins are not produced/move out of the blood vessels so water follows.
Osmotic pressure is lower than 25mmHg.
What are the different plasma proteins:
1) Albumin: (most abundant plasma protein)
Produced: in the liver.
Responsible for: Maintaining the normal osmotic pressure of blood & transports lipids and steroid hormones within the blood.
Produced: Mainly liver & the rest in lymphoid tissue.
Responsible for: Immunoglobulins (antibodies) that will bind to specific antigens --> important in immunity, transport certain hormones and mineral salts & inhibit some protease enzymes.
3) Clotting factors (e.g. Fibrinogen)
Responsible for: Coagulation of the blood
What is blood called if it doesn't contain clotting factors?
Inorganic (mineral) salts:
Responsible for: Maintaining a balance of acids and alkalis (in order to maintain the normal pH of the blood).
Also involved in:
1) Cell formation
2) Secretion formation
3) Nerve impulse transmission
4) Muscle contraction
Normal pH of blood:
Slightly alkaline (7.35 - 7.45)
Absorbed from the digestive tract into the blood.
They are required by cells for:
3) Cell repair and replacement
4) Cell secretion production
5) Production of other blood components
Organic waste products:
1) Products of protein metabolism (urea, creatinine & uric acid) which are produced in the liver and transported to the kidney for excretion
2) CO2 which is produced by all tissues and transported to the lungs for excretion
Produced by endocrine glands and transported via the blood to target tissues/glands. Responsible for influencing cellular activity
O2, CO2 & N+ (atmospheric nitrogen)
O2 and CO2 can be transported in the blood in haemoglobin (in RBC's).
CO2 dissolved in plasma = BICARBONATE IONS.
Ways of obtaining a blood sample:
2) Thumb/heel prick (mainly in babies)
What are the 3 types of blood cells that make up the cellular component of blood?
1) Erythrocytes = Red blood cells
2) Leukocytes = White blood cells
3) Thrombocytes = Platelets
Development of blood cells/bone marrow
1) All blood cells originate from pluripotent stem cells
2) Before they can enter the blood they must undergo HAEMOPOIESIS (which occurs in red bone marrow)
Red marrow = takes up the capacity of bones (in the 1st few years of life)
Yellow fatty marrow = replaces the red bone marrow (over the next 20 yrs of life)
Haemocrit (aka PCV = packed cell volume)
The total volume (%) of erythrocytes in 1L of blood.
How to discover the haemocrit?
Using a centrifuge which separates the components of the blood (plasma from the cellular component).
Order of separation (bottom to top) = erythrocytes - leukocytes - plasma
Haemocrit levels in men and women:
Men: 40 - 54%
Women: 37 - 47 %
Developmental process (erythropoiesis) and lifespan of erythrocytes:
Development: (formed in red bone marrow)
1) Stimulus: Hypoxia (low levels of oxygen reaching cells -detected by the kidneys)
2) Stimulates kidneys and liver to release erythropoietin (hormone)
3) Erythropoietin stimulates proerythroblasts to be developed from pluripotent stem cells.
4) Erytrhopoiesis: Maturation of proerythroblasts and the formation of haemoglobin.
(takes 7 DAYS)
4) Once the erythrocytes are released into circulation = last for 120 DAYS.
What is erythropoiesis and what are its 2 stages?
The development of erythrocytes from pluripotent stem cells (lasts 7 days).
Stages: 1) Maturation of the cell of proerytroblast 2) Formation of haemoglobin
First stage of erytropoiesis: 1) Maturation of the proerythroblast:
Cell decreases and nucleus is removed.
Requires: Vitamin B12 and Folic Acid
Absorbed from diet and stored in the liver.
Vitamin B12 required glycoprotein for:
1) it's absorption and
2) (when binds to glycoprotein) protection from enzyme digestion
When will the effects be seen of low levels of vitamin b12 and folic acid?
Vitamin B12 = effects won't be seen for year due to the high stores in the liver.
Folic acid = effects will be seen within a few months
Second stage of erythropoiesis: 2) Formation of haemoglobin:
Haemoglobin is produced inside the developing erythrocyte during erythropoiesis.
Contains globin and 4 haem groups. Each haem group can carry one O2 molecule.(oxyhaemoglobin)
Fully saturated haemoglobin = 4 molecules of O2.
Can help to carry CO2 to the lungs for excretion.
What gives blood its red colour?
Control of erythropoiesis:
Negative feedback mechanism.
Hypoxia is the stimulus for erythropoietin to be released from kidneys and liver, in order for the stimulation of erythropoiesis to take place.
Once there is enough oxygen supplying the cells, then erythropoietin is no longer excreted.
Definition and causes of hypoxia:
Def: Deficiency of oxygen supplying the body cells
1) Heaemorrhage = loss of erythrocytes, so loss of haemoglobin.
2) Haemolysis = breakdown of erythrocytes, breakdown of haemoglobin
3) High altitude = less O2 in the air
When there isn't enough erythrocytes OR isn't enough haemoglobin - to transport a sufficient amount of oxygen in the blood to the body cells.
Causes of anaemia:
(even in hypoxia) When there isn't enough erythropoietin produced, so erythropoiesis isn't stimulated to take place, so erythrocytes won't be produced.
Less erythrocytes = less oxygen transported in the blood = less O2 supplied to tissues
Recycling of erythrocytes:
After 120 days, the erythrocytes cell membrane becomes more susceptible to haemolysis.
Haemolysis of erythrocytes is carried out by Phagocytic reticuloendothelial cells.
Erythrocytes are broken down to:
Cellular parts and heamoglobin.
Cellular parts = phagocytosed
Heamoglobin = heam (bile then feaces and iron is either: reused, stored in liver or lost through loss of blood) and globin (hydrolyses to free amino acids)
Main tissues where haemolysis of erythrocytes takes place:
3) Bone marrow
Heamoglobin decrease but the erythrocytes remain at normal volume (heamocrit)
Cause: acute heamorrhage
Hypoplastic and Apoplasitc
Hypoplastic: Bone marrow function is reduced.
Apoplastic: Bone marrow function is absent.
Erythrocytes are smaller than normal.
Cause: Iron deficency
Erythrocytes are larger than normal.
Cause: Vitamin B12 and Folic acid deficiency - which are needed in the 1st stage of erythropoiesis when the cell reduces in size and looses its nucleus
Erythrocytes are paler than normal
Cause: Iron deficiency as iron causes the red colour of erythrocytes
When the rate of cell destruction is increased.
1) Autoimmune response
2) Sickle cell disease
Sickle cell disease
The shape of the erythrocytes change and can no longer hold oxygen and can also block blood vessels
What determines an individual's blood group?
On the surface of erythrocytes are antigens. These antigens will be genetically determined.
A person makes antibodies that compliment erythrocyte surface-antigens (apart from antibodies that would make a complex with their own antigens).
4 symptoms that occur if a person makes antibodies that compliment their own erythrocyte surface-antigens:
1) Clumping of erythrocytes
3) Kidney failure (as the haemoglobin from the broken down cells can block kidney tubules)
The ABO blood system:
A (A antigens) (anti-B antibodies)
B (B antigens) (anti-A antibodies)
AB (A and B antigens) (no antibodies)
O (no antigens) (anti-A and anti-B antibodies)
AB blood group (as no antibodies are produced)
O blood group (no antigens on its surface)
Rhesus (Rh) antigen:
Erythrocytes will have the Rhesus surface antigens. Individual will NOT make the anti-rhesus antibodies.
Erythrocytes will not have the Rhesus surface antigens. Individual can make the anti-rhesus antibodies in certain circumstances: 1) Pregnancy 2) If given incompatible blood transfusion
What is Haemolytic disease of the newborn?
Whereby the mother produces antibodies that can make a complex with the babies erythrocyte surface-antigens. This cause heamolysis of the babie's erythrocytes.
How does haemolytic disease of the newborn occur?
1) Rh negative mother makes a child with a Rh positive father.
2) The child inherits the father's Rh antigen (blood group = Rh positive)
3) The child is protected from the mother's immune system due to the placenta.
4) On delivery of the child, some of the child's erythrocytes can enter the mother's circulation.
5) The Rh-antigens on the child's erythrocytes will stimulate the mother to produce anti-Rh antibodies.
6) 2nd child inherits the father's Rh-antigen (blood group = Rh positive)
7) The 2nd child is not protected from the mother's immune system due to the placenta.
8) The mother's anti-Rh antibodies can enter the 2nd child's circulation.
9) Anti-Rh antibodies make a complex with the child's Rh-antigens on the surface of its erythrocytes.
10) Haemolysis of erythrocytes.
Consequences of heamolytic disease of the newborn?
1) Can die if the baby has severe anaemia.
2) Or is delivered with minor anaemia and can be treated with the correct blood transfusion.
How to prevent haemolytic disease from occuring before it happens in the 2nd child?
Injecting the Rh negative mother with anti-Rh antibodies within 72 hours of delivering the 1st baby (Rh positive). This way, the mother has not had time to produce her own anti-Rh antibodies.
The injected anti-rh antibodies will bind to the antigens on the erythrocytes and destroy them.
The mother's immune system will no longer need to produce any anti-rh antibodies.
Properties of leukocytes?
Responsible for defending the body against microbes and other foreign materials.
Largest blood cells
Contain a nucleus
1% of the blood
2 main types of leukocytes and their subtypes:
1) Granulocytes (contain granules):
2) Agranulocytes (don't contain granules BUT contain large nucleus):
Function of neutrophils:
Neutrophils contain lysosomes in their cytoplasm (granules).
Main role: Phagocytosis.
They protect the body from foreign material and remove cell wastes by undertaking phagocytosis:
1) Neutrophils are attracted to an area of inection, as the damaged cell will release chemotaxins.
2) Neutrophils will move out of the capillaries and to the site of infection.
3) Engulf the pathogen and lysosomes will digest the pathogen/cell wastes.
Function of Eosinophils:
1) Capable of carrying out phagocytosis - but do not have as much of an active role as the neutrophils do.
2) Main role: To break down parasites that are too big to be phagocytosed. Their granules contain toxic chemicals that are released when the eosinophils attach to the parasites.
3) Also, have a role in allergic reactions:
- Can promote inflammation = by releasing toxic chemicals from their granules and by relesing enzymes (e.g. histamines) from their granules
Function of Basophils:
Main role: Involvement in allergic reactions.
1) If allergens are introduced into the body, the allergens will bind to receptors on the basophils membrane.
2) This stimulates the basophils to release the contents of their granules:
Heparin = anti-coagulant
Histamine = inflammatory agent
and other substances which promote inflammation.
Similar function to basophils - allergens will bind to the receptors on mast cell's membrane.
Different because they are found in tissues rather than within the blood.
1) Circulate in blood where they are actively motile and actiely phagocytic.
2) Migrate into the tissues where there develop into MACROPHAGES - either actively motile or fixed and are actively phagocytic.
Both play a role in immunity and inflammation as:
1) Both produce INTERLEUKIN 1.
2) At the site of infection- they will multiply and form a barrier around the site of infection.
3 functions of Interleukin 1:
1) Act on the hypothalamus: to increase the body temperature
2) Act on the liver: to stimulate the production of globulin
3) Increase the production of activated T-lymphocytes
Monocytes which have migrated to the tissues and developed into macrophages. Same function as monocytes. Different as they can be actively motile or fixed.
Function of Lymphocytes:
Found either in:
1) Circulating in the blood
2) In lymphatic tissue - where they are activated and can respond to antigens by developing into either:
B - lymphocytes or T- Lymphocytes
Properties of thombocytes (platelets):
- Small Fragments
- Do NOT contain a nucleus
- Contain substances which promote blood clotting
Lifespan of thrombocytes
8 to 11 days
If thrombocytes are not used in the blood clotting process...
They are destroyed by macrophages
What hormone stimulates the production of thrombocytes (platelets)?
Balancing the: prevention of blood loss with the function of blood clotting
The 4 stages of haemostasis:
1) Vasoconstriction (immediately)
2) Platelet plug formation (platelet adhesion - seconds and platelet aggregation - minutes)
3) Coaggulation (minutes)
4) Fibrinolysis (hours)
Occurs immediately after the vessel is damaged.
During platelet adhesion, the platelets will release vasoconstrictors (e.g. serotonin) in order to restrict the amount of blood passing through the blood vessels.
2) Platelet plug formation:
Platelet adhesion (seconds):
1) Platelets adhere to the damaged vessel wall.
2) Their surfaces become sticky.
Platelet aggregation (minutes):
1) Release ADP to attract other platelets.
2) Other placelets will adhere and release ADP too.
(Positive feedback mechanism)
3) Platelets form the primary platelet plug (UNSTABLE)
Clotting factors (plasma proteins) are activated with the help of tissue factors that are released into the circulation from the damaged blood vessel.
Fibrin clot formation (minutes)
1) Prothrombin activator activates prothrombin.
2) Prothrombin turns into thrombin.
3) Thrombin activates fibrinogen.
4) Fibrinogen turns into fibrin.
Fibrin clot (thread - like) is formed. (STABLE)
What substance is required for the synthesis of some clotthing factors?
Plasminogen (inactive) (contained within the primary platelet plug) is activated by the tissue factors released from the damaged vessel wall and turns into plasmin (active).
Plasmin breaks down the fibrin clot into soluble substances.