5. CARDIOVASCULAR SYSTEM I Flashcards
Components of the blood and the specific functions of blood in the human body. Signs, symptoms, investigation procedures and some orthodox treatments of common blood pathologies.
Which two types of circulation are there in the body?
- Systemic circulation: Blood from the heart is distributed around the body before returning to the heart
- Pulmonary circulation: Blood from the heart flows to the lungs and back
Name three types of blood vessels and their functions.
Arteries: Carries oxygenated blood away from the heart (with exception of pulmonary and umbilical arteries) under high pressure. Smaller arteries are called arterioles.
Veins: Carries deoxygenated blood towards the heart (exceptions - pulmonary and umbilical veins) under low pressure. Small veins are called venules. They contain valves to aid in blood flow.
Capillaries: Smallest blood vessels that connect arterioles and venules. They specialise in the exchange of substances between the blood and cells/tissues.
Name three components (not water) of blood plasma.
Proteins Nutrients Enzymes Hormones Mineral salts Organic waste materials Gases
Where are most blood plasma proteins synthesised in the body?
In the liver by hepatocytes
List two functions of albumin
- Carrier of substances (lipids, steroid hormones)
2. Maintains osmotic pressure
List two functions of globulins
- Immunity (immunoglobulins secreted by B-cells)
2. Transports iron, lipids and vitamins
What is another name for ‘clotting factor 1’?
Fibrinogen
Name two cations (+)
Calcium, Magnesium, Sodium, Potassium
Name two anions (-)
Chlorine, Bicarbonate, Phosphate, Sulphate
Which four nutritional products of digestion pass into the blood for distribution?
Carbohydrates
Amino Acids
Lipids
Vitamins
Define haematopoiesis
The production of all blood cells in red bone marrow from pluripotent stem cells.
During the first two months of gestation the embryonic yolk sac performs this function. From months 2-9, the liver and spleen of the foetus takes over this role.
Name two other locations in the body where haematopoiesis takes place
In the red bone marrow inside vertebrae, ribs, sternum, skull, sacrum, pelvis and proximal long bones (mostly femur)
Describe how the structure of RBCs support oxygen transport.
Erythrocytes are bi-concave and have no nucleus, giving the cells a larger surface area to transport oxygen.
Describe the structure of haemoglobin (Hb)
Each erythrocyte has 280million Hb molecules. One haemoglobin molecule consists of four polypeptide chains (globin) and each chain is bound to a pigment called ‘haem’ which contains iron. Each haem group can carry an oxygen molecule, which means each haemoglobin can carry four oxygen molecules.
What is ‘haematocrit’ and why is this value smaller in females?
It is the percentage of blood volume occupied by erythrocytes and in females it is roughly 42% while in males it is roughly 47%. The reason for this is menstrual blood loss in women and the fact that androgens, of which men have more, stimulate RBC production
What is the main difference between adult and foetal haemoglobin?
Adult haemoglobin molecules are composed of two alpha and two beta sub-units.
Foetal haemoglobin is composed of two alpha and two gamma sub-units.
Why is the colour of blood red?
The chemical bond between iron and oxygen reflects red light.
What nutrients are required for erythropoiesis?
Vitamin B12
Folate (B9)
Iron
List two triggers of erythropoiesis
Hypoxia (stimulates kidneys to produce erythropoietin which stimulates erythropoiesis in bone marrow)
High altitude
Blood loss
Pregnancy
What is erythropoietin?
Hormone secreted by the kidneys (in adults and children) which stimulates the formation of erythrocytes in red bone marrow.
Why do premature newborns often exhibit anaemia?
Partly due to inadequate EPO (erythropoietin) and during the first weeks of life, the liver produces EPO, but is less sensitive to hypoxia than the kidneys
Explain what is meant by:
a. Rhesus positive
b. Rhesus negative
a. Erythrocytes have Rhesus antigens on surface
b. Erythrocytes do not have Rhesus antigens on surface
Inheritance of the Rhesus factor is via a rhesus _________ gene. Anti-rhesus antibodies are produced in rhesus ________ individuals only if they come into contact with the rhesus ________. They could come into contact in ________ or incompatible blood infusion.
recessive
negative
antigen
pregnancy
List two key functions of leukocytes
Defends the body from microbes and foreign particles. Plays an important role in immunity
Describe the difference between granulocytes and agranulocytes
Granulocytes have secretory granules in their cytoplasm and agranulocytes do not.
Compare the mode of action of neutrophils with basophils and eosinophils
Neutrophils are phagocytic and they secrete lysosomes to digest microbes. They are normally first on the site of infection.
Basophils play a key role in inflammation by releasing histamine and heparin from their granules. Histamine also dilates blood vessels.
Eosinophils are phagocytic and eliminate parasites. They migrate to allergic sites and promote inflammation (allergic reactions).
Name the types of agranulocytes
Monocytes (Macrophages in tissues)
Lymphocytes
Describe two functions of macrophages
- Phagocytosis: ingest & destroy cellular debris/pathogens
- Antigen presentation: Activate other immune cells by showing what it has ingested
Describe the mode of action of B-lymphocytes
B-lymphocytes activate immune response via antibody formation
Describe the mode of action of T-lymphocytes
T-lymphocytes and Natural Killer cells kill invading pathogens (NK do this non-specifically)
What is the role of thrombocytes and what is their lifespan?
Thrombocytes are involved in blood clotting and prevent the loss of blood from damaged blood vessels by forming a platelet plug
Name one factor that influences the production of thrombocytes
Thrombocytes are produced under the influence of thrombopoetin, which is produced in the liver.
Describe in detail the four stages of blood clotting
- Vasoconstriction:
When arterioles are damaged and collagen is exposed in vascular endothelium, thromboxane is released, which causes vascular spasm and attracts platelets. - Platelet plug formation:
Platelets stick to the damaged wall, are activated and release binding proteins. Platelet aggregation cause them to become sticky. - Coagulation:
Clotting factors form a clot, reinforcing the plug. The enzyme ‘thrombin’ is produced, which converts fibrinogen to fibrin. Fibrin forms a mesh of long sticky threads and erythrocytes become trapped. - Fibrinolysis:
The enzyme plasmin dissolves the clot by digesting fibrin threads and inactivating fibrinogen and thrombin.
Explain the main role of vitamin K in the body
Vitamin K is a fat soluble vitamin responsible for making four clotting factors (II;VII;IX;X)
List one example of each type of coagulant:
a. Natural
b. Medicine
c. Herb
d. Nutrient
a. Heparin
b. Warfarin
c. Gingko Biloba, garlic, ginger, turmeric
d. Vitamin E, Essential fatty Acids
List three generalised symptoms of anaemia
Fatigue, shortness of breath on exertion, palpitations, irritability, fainting
List three generalised signs of anaemia
Pallor (skin/conjunctiva)
Tachycardia
Thin, thready pulse
Name two causes (not dietary deficiency) of iron deficiency anaemia
- Malabsorption (i.e. low stomach acid, coeliac disease)
- Excessive blood loss (menses, GIT bleed)
- Excessive requirements (pregnancy, rapid growth)
What are the characteristic appearance of erythrocytes in a patient with iron deficiency anaemia?
Reduced concentration of haemoglobin results in the cells appearing paler and smaller than normal (hypochromic microcytic anaemia)
List two signs / symptoms specific to iron deficiency anaemia
Spoon-shaped nails (koilonychia) Angular stomatitis (cracked mouth corners) Glossitis (swollen tongue) Brittle hair Tachycardia
Name one blood test for diagnosis of iron deficiency anaemia
Low RBCs, haemoglobin and ferritin
Describe the pathophysiology of megaloblastic anaemia
Because of a shortage of Vitamin B12 and B9 (Folate), DNA replication slows down and cell growth continues without division and maturation, resulting in large erythrocytes. [Blood test shows MCV > 97 fL]
List two causes of megaloblastic anaemia (not dietary)
- Lack of intrinsic factor (required for the absorption of B12) due to autoimmune disease (pernicious anaemia), coeliac, chronic gastritis, stomach cancer, gastrectomy
- Malabsorption (Crohn’s disease, surgical excision)
- Drugs (Methotrexate is a folate antagonist)
Describe the difference between megaloblastic anaemia due to folate deficiency and megaloblastic anaemia due to Vitamin B12 deficiency
When it is due to a vitamin B12 deficiency, anaemia will also present with neurological symptoms such as tingling, numbness, weakness, loss of coordination, burning sensations, tinnitus, depression.
Using definitions, compare aplastic anaemia with iron deficiency anaemia.
Aplastic anaemia is the rare, potentially life-threatening failure of haematopoiesis which results in pancytopenia and hypocellular bone marrow. Iron deficiency anaemia is the reversible low concentration of erythrocytes due to a lack of iron.
List two causes of aplastic anaemia
Congenital (Fanconi’s Anaemia)
Idiopathic
Secondary (Iatrogenic, radiation, cancer, EBV)
List two symptoms more suggestive of aplastic anaemia
Multiple infections (low erythrocyte count) Easy bleeding and bruising (low thrombocytes)
Define haemolytic anaemia
Anaemia resulting from the excessive breakdown of erythrocytes, when bone marrow activity cannot compensate for the loss of RBCs. [Erythrocyte lifespan can become as low as 5 days]
List two causes of haemolytic anaemia
Genetic (Sickle cell, Thalassaemia) Rhesus incompatability Malaria Drugs, radiation and chemicals Autoimmune
List two signs / symptoms more suggestive of haemolytic anaemia
Jaundice
Splenomegaly
Using definitions, compare sickle cell anaemia to thalassaemia
Both are genetic conditions, but in sickle cell anaemia the RBCs sickle up because of a deficiency of the 2-alpha 2-beta formation of haemoglobin.
In thalassaemia, there is a defect in the synthesis of either the alpha of beta Hb chains (A- or B-Thalassaemia)
Describe the pathophysiology of haemolytic anaemia of newborns
Excessive haemolysis occurs in the newborn due to Rhesus factor inncompatability
Define polycythaemia
Excessive production of RBCs resulting in increased blood viscosity, lower blood flow and risk of thrombosis.
Using definitions, compare granulocytopenia and leukocytosis
granulocytopenia is the marked reduction of granulocyte leukocytes resulting in severe illness and leukocytosis is a marked increase in the number of all leukocytes.
Define leukaemia
Leukaemia describes a group of bone marrow cancers, characterised by an overproduction of leukocytes
List two signs /symptoms of leukaemia
Anaemia
Malaise
Easy bleeding/bruising
Splenomegaly
Describe the difference between acute and chronic leukaemia
Acute leukaemia is a sudden onset condition that can affect all ages. The leukaemic cells are immature and anaemia and thrombocytopenia is prominent but lymph node and spleen enlargement is mild. The leukocyte count can be variable.
Chronic leukaemia is insidiuous in onset and usually affects adults. The leukaemic cells are mature and anaemia and thrombocytopenia is mild, but lymph node and spleen enlargement is prominent. An increased leukocyte count is prominent.
List one diagnostic procedure to diagnose leukaemia
Bone marrow biopsy
FBC
Blood film (viewing sample of blood)
List two signs / symptoms of thrombocytopenia
Excessive bleeding and bruising (with prolonged bleeding times)
Petechiae (micro-haemhorrhages in the skin)
Haematuria
Vomiting blood
Bleeding gums
List two viral causes of thrombocytopenia
EBV
MMR
Hepatitis
Describe the difference between Haemophilia A and Haemophilia B
Haemophilia A is the deficiency of clotting factor 8 and Haemophilia B is the deficiency of clotting factor 9
List one cause of haemophilia
It is genetically acquired through an x-linked recessive gene (usually affects males, females are carriers)
List two signs / symptoms of haemophilia
Excessive, easy bleeding
GIT / mucosal haemorrhage
haematuria
haemarthrosis
