Introduction to Blood Flashcards
What is average circulating volume of blood in a typical adult male ( 70 kg) and how is it distributed?
5 litres of blood
1L in lungs
3L in systemic venous circulation
1L in heart and arterial circulation
What are the functions of blood?
Carriage of physiologically active compounds (plasma)
Clotting (platelets)
Defence (white blood cells)
Carriage of gas (red blood cells)
Thermoregulation
Maintenance of ECF pH (7.4)
Platelets role in blood clotting?
-clotting factors need platelets to be present (platelets themselves do not participate in clotting cascade)
What is in blood?
Plasma, red blood cells, white blood cells and platelets.
What is percentage of body weight is plasma and percentage of blood?
4% of body weight is plasma and accounts for half of blood weight.
Composition of plasma?
95 % water
What isn’t water- made up of ions , hormones, enzymes , plasma proteins.
Role of plasma?
Circulates biologically active molecules & compounds
Composition normally kept within strict limits.
What are the three categories of plasma proteins?
Albumin
Globulin - Subdivided into alpha, ß, gamma globulins
Fibrinogen and other clotting factors
Where do plasma proteins perform their function?
Plasma proteins are not taken up by cells - perform their functions in the circulation. Compare with organic compounds e.g. hormones which use blood as a vehicle.
Describe Albumin’s role?
transports proteins that are not water soluble
Describe Globulin’s role?
Alpha and beta globulins transport proteins but gamma globulins function as antibodies.
Describe fibrinogen and other clotting factor roles?
Lipids get carried by fat soluble plasma proteins and can leave whenever.
Explain colloid oncotic pressure?
See A4 paper
What is hypoproteinaemia?
Abnormally low levels of circulating plasma protein
Why does hypoproteinaemia occur?
-prolonged starvation - can’t make proteins
-liver diseases -all plasma proteins are synthesized in liver
-intestinal diseases- problem with gut wall and can’t absorb protein to produce
-nephrosis (kidney problems) - losing proteins as kidney decides which components of fluid component of blood to keep
-
Common characteristic of hypoproteinaemia?
oedema- build up of fluid in interstitial fluid because of loss of plasma proteins and loss of oncotic pressure.
What are erythrocytes?
Mature red blood cells
What are the types of white blood cell?
Neutrophils
Monocytes
Basophils
Eosinophil
Lymphocytes
What are the parts of formed and non formed components of blood?
formed- RBC, WBC and platelets
Non formed- plasma
What are reticulocytes?
Are almost but not quite mature red blood cells.
released into circulation and mature in next 24 hours.
Where are all blood cells in circulation from?
A population of undifferentiated pluripotent stem cells in the bone marrow. ( Pluripotent hematopoietic stem cell)
What is hematopoiesis?
The maturation of blood cells. The process by which cells develop from undifferentiated stem cells to erythrocytes and white blood cells.
Fates of undifferentiated pluripotent cells?
Either commits to being a lymphocyte or not.
If lymphocyte- differentiates to lymphocyte stem cells.
If not - uncommitted stem cell
What are committed progenitor cells?
Cells that have committed to being one particular type of blood cell.
Pathway for red blood cell?
(in bone marrow) Goes through process where has mitochondria and ribosomes to produce energy aerobically and produce protein.
-When reaching erythroblast loses ability to synthesize proteins and aerobically respire.
-As erythrocyte has to generate energy anaerobically
How much hemoglobin does RBC have?
Hemoglobin is all the protein that RBC will ever have.
Reticulocyte stage?
Un fully matured RBC is released into circulation. Goes through another 24 hours of maturation.
Megakaryocytes?
-Always stay in blood marrow but bits of their cell membrane and cytoplasm get released and are platelets.
What are myeloid cells?
All cells in circulation except from lymphocytes (lymphoid cells)
Myeloid leukemia or lymphoid leukemia?
Cancers affecting lymphoid cells or myeloid specifically.
Composition of erythrocytes?
Densely packed with Haemoglobin – protein concerned with gas transport.
Characteristics of erythrocytes?
Most abundant blood cell (4 - 6 x1012/L)
120 day lifespan.
Highly flexible, biconcave, non-nucleated, diameter 7-8m.
What does spleen do?
Checks for deformed blood cells and recycles the component parts and releases hemoglobin. Protein broken down into AA and iron part of hemoglobin gets recycled.
Function of red blood cell shape?
Increases ability to take in oxygen.
How many molecules of oxygen bind to hemoglobin?
4 iron atoms at centre bind 4 mols of oxygen
Colour change of blood?
– oxyhaemoglobin (arterial)
- deoxyhaemoglobin (venous)
When hemoglobin has oxygen is brighter and when without oxygen is bluey purple.
What is Erythropoiesis?
Synthesis of red blood cells
What controls and accelerates erythropoiesis?
Hormone erythropoetin stimulates the progression of pluripotent stem cells to erythroblasts. (Only in bone marrow)
Where is erythropoetin secreted from?
The kidney (85%)
The liver (15%)
When is erythropoetin release enhanced?
-When a lack of oxygen in blood
-When oxygen delivery to kidney is reduced- big increase
What is hypoxia?
Reduction in oxygen delivery to tissue
How long is delay from release of erythropoietin to release of RBC?
2-3 days
Reasons for erythropoietin secretion?
-haemorrhage- loss of whole blood
-anaemia- loss of RBC production
-cardiac dysfunction-heart unable to pump blood
-lung disease-lungs cannot oxygenate blood
Why is renal disease accompanied by anaemia?
Renal disease is kidney disease. Kidney is dominant source of erythropoietin and can’t produce adequate levels of RBC.
What type of feedback is erythrpoietin secretion?
Negative feedback - trying to correct reduction in oxygen delivery. Trigger is lack of oxygen and response is release of erythropoietin.
What are characteristics of leukocytes (white blood cells) ?
Larger than red blood cells and have a nucleus.
Less present than red blood cells.
Involved in defense against pathogens.
What are the two broad categories of white blood cells?
Granulocytes and Agranulocytes
Granulocytes name comes from?
Look like they have granules in cytoplasm.
What white blood cells are in granulocytes?
-neutrophils
-basophils
-Eosinophils
What white blood cells are in agranulocytes?
-Monocytes
-Lymphocytes
What cells are in lymphocyte family?
-B Cells
-T cells (Helper T cells and Killer T cells)
What are the most abundant white blood cells?
Neutrophils- account for 68%
half life of 10 hrs
What are least abundant white blood cells?
Basophils -account for less than 1 %
What percentage of white blood cells are eosinophils?
1%
What percentage of lymphocytes make up white blood cells?
25%
What percentage do monocytes make up?
5% circulating cells, after 72 hours migrate to connective tissue where they become macrophages (phagocytose pathogens )and live for 3 months
What is leukopoiesis?
White blood cell formation/ maturation of leukocytes
What controls leukopoiesis?
Controlled by a cocktail of cytokines (proteins/peptides released from one cell type which act on another). Depends on cocktail which white blood cell will be made to mature.
What is the cocktail for maturation of white blood cells composed of?
Different types of Colony Stimulating Factors
e.g. Granulocyte CSF
Different types of Interleukins (between white blood cells )
Where are cytokines released from?
-released from mature white blood cells
What do cytokines do?
Stimulate both mitosis and maturation of leukocyte.
What white blood cells target bacterial infections?
neutrophils (neutralize bacteria)
What white blood cells target viral infections?
lymphocytes
Why is cytokine cocktail dynamic?
The cytokine cocktail is therefore dynamic, changing it’s composition in response to infection to influence which white blood cell will be preferentially stimulated to form.
What does differential white cell count show?
allows you to differentiate between infection types.
What are characteristics of platelets?
membrane bound cell fragments (from megakaryocytes).
Rarely nucleated, 2-4m diameter.
Life span 10 days. (140-400x109/L)
What are role of platelets?
Adhere to damaged vessel walls and exposed connective tissue to mediate blood clotting
DO NOT adhere to healthy intact endothelium.
What is a haematocrit?
The haematocrit measures the % of red blood cells (RBC) as a fraction of whole blood.
Where do the blood cells sit in centrifuge after centrifugation?
Red blood cells at the bottom, white cells and platelets in middle and plasma on top.
What is normal range of red blood cells in whole blood?
Normal range 40-50%
How will haematocrit change if dehydrated?
Loss of fluid component- haematocrit will increase.
Increase in erythropoietin- increase in haematocrit.
Why is plasma yellow in colour?
Presence of Bilirubin.
What is bilirubin?
Break down product of red blood cells.
Jaundice cause? linking to bilirubin
Bilirubin is processed by liver and if liver is dysfunctional -cannot function and bilirubin backs up in blood. Bilirubin accumulates in blood and plasma takes on increased bilirubin . Causes skin and mucus membranes and whites of eye to turn yellow.
What is viscosity?
How thick/sticky blood is compared to water.
What is viscosity of plasma?
1.8 thicker than water
What is viscosity of whole blood?
x 3-4 thicker than water (varies)
Why does viscosity depend on haematocrit?
50% increase in haematocrit increases viscosity approx. 100%
Why does viscosity depend on temperature?
increase in temp decreases viscosity and vice versa.
1oC changes viscosity by around 2%
Why does viscosity depend on flow rate ?
decreased flow rate increases viscosity and vice versa
