Blood And Blood Groups

Question 1

Name the three types of blood cells

Answer 1

RBCs/erythrocytes
WBCs/leucocytes
Thrombocytes/platelets

Question 2

Briefly outline the characteristics of RBCs

Answer 2

Erythrocytes
Biconcave discs (higher SA to carry more oxygen)
Carry Hb to deliver dissolved oxygen to tissues
Flexible membrane of lipids and proteins (antigens)
Develops in bone marrow by erythropoiesis
No nucleus
45% blood composition

Question 3

Briefly outline the characteristics of WBCs. What are their divisions?

Answer 3

Leucocytes
Nucleus- allows for reproduction
Main function= part of the immune response to allow the body to fight infection and disease
Vast majority (60-70%) is made in bone marrow
Lymphocytes- T and B cells, NK cells
Granulocytes- neutrophils, basophils and eosinophils
Less than 1% blood composition

Question 4

Briefly outline the characteristics of thrombocytes

Answer 4

Platelets
Clotting and haemostasis
Viscosity- thickness of blood
Smallest blood cells
Cytoplasmic fragments from megakaryocytes in bone marrow
Lipid bilayer on membrane
Compact sphere with long dendritic extensions
Less than 1% of blood composition

Question 5

Define haematology

Answer 5

The branch of medicine concerned with blood
Cause, prognosis, treatment and prevention of diseases related to blood

Question 6

What two extremes are do blood disorders take the form of?

Answer 6

Inability to clot - haemophilia
Clot too much - thrombophilia

Question 7

What are the causes of blood disorders?

Answer 7

Genetic
Result of other diseases
Medications
Lack of nutrients in the diet

Question 8

Describe the prognosis of blood disorders

Answer 8

Some resolve completely with therapy, don’t cause symptoms and are benign
Some are chronic and lifelong but do not affect life expectancy
Some are fatal and do affect life expectancy (e.g. sickle cell disease and blood cancers)

Question 9

How to oestrogen and progesterone play a role in blood disorders?

Answer 9

The two hormones oestrogen and progesterone are released from the ovaries
They both increase the likelihood of clotting
This is why caution has to be taken when going on the contraceptive pill and during pregnancy

Question 10

List some common blood disorders

Answer 10

Anaemia- iron deficiency due to lack of healthy RBCs
Haemophilia- blood isn’t able to clot efficiently, leads to excessive bleeding
Leucocytosis- high count of WBCs, frequently sign of inflammatory response
Polycythaemia Vera- type of blood cancer, causes marrow to produce too many RBCs
Sickle cell disease- group of inherited blood conditions that affect the RBCs
Thalassemia- group of diseases that cause faulty Hb synthesis
Von Willebrand disease- bleed more easy than normal due to lack of clotting proteins

Question 11

Outline the blood disorder ‘anaemia’

Answer 11

Patients will be referred to as ‘anaemic’
Occurs when there are not enough healthy RBCs to carry oxygen to the body’s organs
Symptoms- cold, tiredness, fatigue
Many different types of anaemia (sickle cell anaemia, iron-deficiency anaemia, aplastic anaemia, Thalassemia, vitamin deficiency anaemia)
Some causes- lack of nutrients, genetics, pregnancy, excess bleeding

Question 12

What is the main characteristic of haemophilia?

Answer 12

Where the blood doesn’t clot
E.g. if a normal person has a haemorrhage then their blood will clot and the bleeding will stop. If a haemophiliac has a haemorrhage then their blood will not clot and they will continue to bleed out!

Question 13

Why is haemophilia relevant to inheritance and the family tree?

Answer 13

It is a sex-linked genetic disorder
Only male family members will get haemophilia (be a haemophiliac)
Females can be carriers, but will not suffer with the disorder
The disease is carried on the sex chromosome ‘Y’, not on one of the autosomes

Question 14

Describe the characteristics of haemophilia as a blood disorder, describe the two types of haemophilia

Answer 14

An inherited bleeding disorder
Occurs when blood clotting factors are faulty or missing
It almost always affects males
Bleeding can happen internally and externally

Two main types of inherited haemophilia:
-TYPE A
Classic haemophilia, most common type, caused by deficiency in factor VIII- one of the proteins that helps to form blood clots
-TYPE B
Christmas disease, caused by deficiency in factor IX

Question 15

Genetically, what causes haemophilia?

Answer 15

Faults in the genes that regulate the production of factors VIII and IX
These genes are only found on the X chromosome (sex chromosome)
Haemophilia is caused by mutations in either the factor VIII or factor IX genes on the X chromosome

Question 16

Discuss the 6 main symptoms of haemophilia

Answer 16

The location of a bleed depends on the requirement for a clotting factor or not

Soft tissue bleeds and bruising
Iliopsoas bleeds
Thigh/calf bleeds
Deltoid/fore arm bleeding and bruising
Buttock bleeds
Neck swelling (EMERGENCY as airway may be compromised)

Question 17

How do heamostasis and thrombosis differ?

Answer 17

Heamostasis- the normal response of a vessel to injury by forming a clot that serves to limit haemorrhage
Thrombosis- pathological clot formation that results when haemostats is excessively activated in the absence of bleeding (heamostasis in the wrong place)

E.g.
if you get a cut and bleed… heamostasis comes into place to stop the bleeding
Thrombosis… occurs when there isn’t any bleeding in the first place

Question 18

Describe the three steps involved in haemostasis

Answer 18

1- Primary Haemostasis (platelet clotting)
So that blood flow is minimised and the body doesn’t excessively bleed
Temporary plug to seal an injury
Platelets circulating stick to the damaged tissue and activate
The activation means they recruit more platelets to form the plug to stop blood loss
Bottle stopper- keeps blood in, and germs and debris out

2- Secondary haemostasis (coagulation cascade)
Platelet plug isn’t stable enough to stay in place without help
Molecules in blood called ‘coagulation factors’ activate in sequence
This sequence is called the ‘coagulation cascade’ which amplifies clotting effects as the sequence continues
Fibrin is formed
Solid stable clot is formed with the platelet plug

3- Fibrin Clot Remodelling
Body remodels the existing clot into a fibrin clot
This is done because the blood clots are a temporary latch not a permanent solution
The removal involved a process called fibrinolysis
Fibrinolysis- body remodels the clot into the same kind of tissue that was there before the clot

Question 19

What is the name of the triad used to outline the contributing factors in causing thrombosis?

Answer 19

Virchow’s Triad

Question 20

What are the three elements of Virchow’s Triad? How might we reduce the chances of thrombosis for out patients in hospital?

Answer 20

1- Hypercoagulability- increased tendency to develop blood clots
2- Hemodynamic Changes (stasis, turbulence)- mechanics of blood circulation
3- Endothelial injury/dysfunction- type of coronary artery disease or damage

All of these factors combined increase a persons chances of developing thrombosis

In hospital, we do these two things to reduce patients chances of developing thrombosis:
- Subcutaneous injections at about tea time. Stops clots that may be caused due to lots of lying down that is done in pregnancy
- Stockings and compression socks. Helps with vasoconstriction

Question 21

Why is warfarin important in blood disorders?

Answer 21

It is the most commonly used anti-clotting drug in practise to help prevent instances of thrombosis
It does however have its downsides…
-It tends to cause excessive bleeding and bruising. This is something that we need to be aware of as it may impact any other disorders that the patient is experiencing. Patients on warfarin also cannot eat certain foods and vegetables
… nurses therefore need to be given the right education to give warfarin and patients need to be given the correct education and lifestyle advice to reduce negative effects

Question 22

Describe ‘hyper-coagulable state’ in thrombosis

Answer 22

=disorder that makes the blood clot too easily
-malignancy (condition that becomes progressively worse)
-pregnancy and peripartum period (short period just before, during and after birth)
-oestrogen therapy (e.g. contraceptive pill)
-trauma or surgery of lower extremities, hips, abdomen or pelvis)
-inflammatory bowel disease
-nephrotic syndrome (kidney disorder- too much protein in urine)
-sepsis (blood vessels dilate increasing clotting risk)
-thrombophilia

Question 23

Describe ‘vascular wall injury’ in thrombosis

Answer 23

=blood vessel is torn, punctured or severed
-trauma or injury
-venepuncture (gaining intravenous access, normally for blood sampling reasons)
-chemical irritation
-heart valve disease or replacement
-inflammatory bowel disease
-atherosclerosis (fat and cholesterol build up in the artery walls)
-indwelling venous catheter (like a cannula in the neck that increases clotting risk)

Question 24

Describe ‘circulatory stasis’ in thrombosis

Answer 24

=blood not able to flow properly through the tissues
-atrial fibrillation (top chamber twitches, heart doesn’t fill, leads to clots)
-left ventricular dysfunction
-immobility or paralysis
-venous insufficiency or varicose veins (when standing the blood pools and stagnates so unable to pump and push blood back up the leg)
-venous obstruction from tumour, obesity or pregnancy

Question 25

How is haemostasis related to thrombosis?

Answer 25

Thrombosis is the primary cause of heart attacks and strokes

Thrombosis= the formation of a blood clot inside a blood vessel
Haemostasis= the process to prevent and stop bleeding

Embolus (Greek meaning of ‘wedge’)= is an unattached mass that travels through the blood stream and is capable of creating blockages
When an embolus occludes a blood vessel is is called an EMBOLISM

DVT+PE=VTE
DVT and PE are collectively referred to as VTE- Venous Thromboembolism

Question 26

Where can clots form?

Answer 26

Anywhere!

But, when a clot forms in a vein that is located deep within the body is is called ‘deep vein thrombosis’. Typically in the lower leg or thigh (but… can be wherever)

Question 27

What are the three main nursing considerations to be made in treating blood disorders?

Answer 27

-Risk Assessment
This is done using the Wells score (criteria to calculate risk of DVT using clinical indicators)
-Inter-Professional Teamwork
E.g. physios, Occupational therapists, dieticians,
-DVT Prophylaxis
Pharmacological and non-pharmacological measures to diminish the risk of a DVT

Question 28

What score is used to conduct risk assessment in blood disorders?

Answer 28

Wells score
Combines risk factor and clinical findings to calculate a patients probability of developing a blood disorder, specifically DVT
Points based system with maximum of 8 points
3+ points indicates a high clinical possibility of DVT

Question 29

What is DVT prophylaxis? Describe the two methods of thrombopropylaxis

Answer 29

=pharmacological and non-pharmacological measures to assess the risk of a DVT
1- Mechanical
Anti-embolism stockings
Provide graduated compression
Calf pressure of 14-15 mmHg
Intermittent pneumatic compression
2- Pharmacological
LMWH (low-molecular weight heparins). These are a class of anticoagulants
E.g. clexanine, deltaparin

Question 30

Describe the main characteristics of Sickle Cell Disease (SCD)

Answer 30

Usually inherited
Group of multiple types of conditions that affect the sickle cells, most common is sickle cell anaemia
Results in abnormality in the haemoglobin (Hb) found in the RBCs
Leads to a rigid sickle-like shaped RBC
Occurs when a person inherits two abnormal copies of the B-Globin gene, this is the gene that makes haemoglobin

Question 31

Describe the RBCs and vessels of someone with SCD

Answer 31

RBCs are rigid, pointed and hooked
They are long and shaped a bit like a banana, normal cells are oval shaped
This shape increases their likelihood of getting stuck and causing a blockage

Question 32

Outline and explain what is meant by sickle cell crisis

Answer 32

=episodes of pain experienced by someone with SCD
One of the most common symptoms of SCD
Causes agony and pain all over the body, it can be quite distressing to see
Occurs when the blood vessels in the body become blocked
Sever pain lasts up to 7 days on average
Often affects particular parts of the body, most common: hands or feet (esp in young children), ribs and breastbone, spine, pelvis, tummy, legs and arms
It makes the individual get sick quite regularly as it effects the whole body
It is a medical emergency!

Question 33

What is an intrinsic pathway?

Answer 33

The process of haemostasis occurs via two pathways which unite downstream to form the common pathway
One of these is the INTRINSIC PATHWAY
The intrinsic pathway is triggered by internal damage to the vessel wall

The longer and more intricate pathway
Factor XII is activated when it contacts the negatively charged collagen on the damaged endothelium
Triggers the cascade
Clotting factors and platelets form cellular plug at the site of injury
Platelets release further mediators to assist clotting (including factor VIII)
Factor XI combines with factor VIII to form an enzyme complex that stimulates thrombin production

Question 34

What is an extrinsic pathway?

Answer 34

The process of haemostasis occurs via two pathways which unite downstream to form the common pathway
One of these is the EXTRINSIC PATHWAY
The extrinsic pathway is triggered by external trauma which causes blood to escape the circulation

Damage to blood vessel means that factor VII exits circulation into surrounding tissues
Tissue factor (factor III) is released by damaged cells outside of circulation
Factor VII and factor III form a complex
This complex is called ‘TF-Vlla’ complex
Factor X then triggered to take its active form- factor Xa
In conjunction with factor Va, the formulation of thrombin is triggered

Question 35

Outline the role of calcium in haemostasis

Answer 35

Calcium ions Ca2+
Major role in the tight regulation of the coagulation cascade
They’re responsible for complete activation of several of the coagulation factors (VIII, VII, III, IX)
Binds to phospholipids that are secondary to the platelet activation and provides a surface for the assembly of multiple coagulation factors

Question 36

Outline the role of vitamin K in haemostasis

Answer 36

= A blood clotting vitamin!
It is a fat-solvable vitamin essential for the post-translational processing of the prothrombin group of coagulation factors
Vitamin K acts as a cofactor for a group of proteins called the vitamin K-dependent clotting factors (II, IX, VII and X)
These factors are responsible for activation of blood clotting proteins

Question 37

Outline the role of fibrin in haemostasis

Answer 37

Essential for blot clot contraction (or retraction)
Pathological inhibitor
This is spontaneous shrinkage if the clot, playing a major role in heamostasis
Fibrinogen is a complex glycoprotein, makes high content of plasma. Fibrinogen is then converted to fibrin which stabilises blood clots and promotes heamostasis

Question 38

Outline the role of prothrombin activator in haemostasis

Answer 38

A protein released by the liver that helps the blood to clot
Is a complex of a dozen coagulation factors that functions in catalysing prothrombin into thrombin
It is released into the body in a cascade of chemical reactions in response to blood vessel damage