Blood Flashcards
pH of blood
7.45 - 7.55 pH
temperature of blood
38 degrees celsius
function of blood
- transportation of respiratory gases, nutrients and wastes
- immunity
- regulation of pH, ion concentration, osmolarity, body temperature
- hemostasis
Plasma composition
92% water
7% plasma proteins
1% other solutes
Plasma proteins composition
Albumins 60%
Globulins 35%
Fibrinogen 4%
Regulatory proteins 1%
Purpose of albumin
Major contributor to osmotic pressure of plasma and transport lipids and hormones
Purpose of globulins
transport ions, lipids, hormones and immune function via immunoglobulins
purpose of fibrinogen
essential for clotting as it can form insoluble fibrin
why do erythrocytes need to replaced
- plasma membrane is fragile and prone to rupture leading to hemolysis
- no DNA/RNA/ribosomes to synthesize/repair/divide cellular components
- lifespan is 100- 120 days
how many erythrocytes is produced via erythropoiesis
2-3 x 10^6 RBC/s
Function of erythrocytes
Gas transport transport via hemoglobin for O2 and carbonic anhydrase for CO2
How is CO2 transported in the body
Carbonic anhydrase converts CO2 to HCO3 (bicarbonate) which is the primary form in blood
How is pH regulated in blood
CO2 is converted to bicarbonate and the floating H+ ions are bound to hemoglobin, thereby neutralizing it
how do erythrocytes not consume O2 when transporting them
RBCs have no mitochondria and uses glycolysis system (anaerobic) for ATP to fuel transport mechanisms to maintain ionic concentrations
Describe the process of erythropoiesis
- hematopoietic stem cell in bone marrow becomes proerythroblast
- ribosome synthesis occurs in early erythroblast
- hemoglobin accumulation in late erythroblast and normoblast
- nucleus is ejected from normoblast to form reticulocytes
- hemoglobin synthesis continues and leaves bone marrow, continuing maturation to form mature RBC
where are the sites for erythropoiesis
fetus - yolk sac, developing liver and spleen
child - most bones with red bone marrow
adult - bone marrow in ribs, sternum, vertebrae, pelvis, upper end of long bones
essential requirements of erythropoiesis
carbs, lipids, proteins, iron, vitamin b12, folate
how much iron is needed daily
10 - 15mg per day but only 10% absorbed
how much iron is lost in male and female
0.5 - 1mg daily for males
Greater for females due to menstruation and pregnancy
how much iron is given to fetus
300mg of iron
sources of vitamin b12
animal sources
where is vitamin b12 stored
0.8 - 1mg in liver
folate sources
vegetables, fruits, yeast, kidneys, liver
why is folate and b12 important
necessary for thymidylate synthesis which is the thymine nucleotide in DNA
why is iron essential
essential for myoglobin and haemoglobin
deficiency in vitamin b12 and folate leads to
macrocytic anemia
deficiency in iron leads to
microcytic anemia
describe the hemoglobin structure
- quaternary structure
- consists of 4 folded polypeptide chains
- 2alpha + 2beta chains (subunits)
- each contains 1 heme molecule (1 Fe = 1 O2)
how does o2 diffuse from blood to tissue
due to weak and reversible binding of iron
how molecules of o2 can 1 hemoglobin molecule bind to
4
how much o2 is pumped per litre of blood
200ml of o2 per L of blood
when does polycythemia occur
when there is an excess of RBC leading to an increase in hemocrit
what are the different types of polycythemia
primary which is due to tumor/tumor-like condition of bone marrow
secondary which is EPO induced as a result of an adaptive response
relative which is due to dehydration which leads to a decrease in plasma; RBC remains unchanged by concentration “increased”
what is considered anemia
below normal o2 carrying capacity of blood due to decreased erythropoiesis rate and decreased hemoglobin in RBC
what are the different types of anemia
microcytic anemia - RBC smaller than normal as a result of iron deficiency
macrocytic anemia - RBC larger than normal as a result of B12 and Folate deficiency
aplastic anemia - Bone marrow fails to produce enough despite having all ingredients readily available due to radiation or chemotherapy
explain the process of rbc turnover and recycling
- Aged and damaged RBC engulfed by macrophages of liver, spleen and bone marrow
- hemoglobin broken down into globin and heme
- globin is broken down to amino acids
- heme is broken down to iron and bilirubin
- iron is stored as ferritin and hemosiderin and then bound to transferin and then to bloodstream
- bilirubin is transported to small intestine to be metabolized to stercobilin and excreted out as feces
When is Erythropoietin (EPO) released
released by kidneys when
- hypoxia like conditions
- decreased o2 availability
- increased o2 demand by tissues
- hemorrhage or anemia
- decreased blood flow to kidneys
what kind of protein is EPO
peptide hormone
why is RBC count higher in males than females
males have androgen which increases erythropoiesis
what is the production distribution of EPO like
90% kidneys
10% liver
what does EPO do
- increase proliferation rate of proerythroblast and erythroblast
- increase Hb synthesis
- increase hematopoietic stem cell forming proerythroblast
- increase RBC production 10x
What are the different blood types
Type A, B, AB, O
Which rhesus group makes the blood positive and negative
Only RhD is positive, rest is negative
Which blood type is the universal donor for emergency situations
O- blood type
What are the different blood transfusion reactions
Allergic - facial flush, rashes
Febrile - headache, fever, chills, tachypnea, tachycardia
Hemolytic - chest pain, headaches, low back pain, decreased blood pressure, tachycardia
what are platelets
fragments of megakaryocytes
how are platelets formed
thrombopoiesis
why do platelets no adhere to cells and form clots
non-activated platelets do not adhere to endothelial cells due to ‘repulsive’ glycoproteins on platelet surface
what are the different lymphocytes present in blood
Macrophages, Basophils, Eosinophils, Neutrophils, Mast cells, Dendritic cells
which lymphocyte is involved in antigen representation
macrophages and dendritic cells
which lymphocyte is involved in allergies
basophils
which lymphocyte is involved in phagocytosis and activation of bactericidal mechanisms
neutrophils and macrophages
which lymphocyte is involved in killing parasites
basophils and eosinophils
which lymphocyte is involved in releasing granules
mast cells
what are the 3 phases that occur in blood clot formation
- vasoconstriction
- platelet phase
- coagulation phase
explain the process of vasoconstriction in blood clots
- endothelial cells contract, exposing underlying basal lamina to blood stream
- endothelial cells release chemical factors and hormones such as tissue factor, ADP and thromboxane A2
- these hormones stimulate smooth muscle contraction, vasoconstriction, stimulate division of smooth muscle cells, endothelial cells and fibroblasts for tissue repair
- endothelial membrane becomes sticky forming a partial seal that slows blood flow and blood loss
explain the process that occurs in platelet phase of blood clot formation
- circulating platelets adhere to injury site by von Willebrand factors
- platelets are then activated by exposed collagen at site
- these activated platelets secrete serotonin and thromboxane A2 which enhance vascular spasms and ADP which enhances platelet aggregation and secretion and tissue factor
- activated platelets form a positive feedback loop to activate other platelets to bind to and secrete as those above
- normal uninjured endothelium release prostacyclin and nitric oxide to inhibit further platelet aggregation and confine to injury site
- fibrin forms a mesh that traps RBC and platelets to form clot
What are the 3 pathways for blood clots
- Intrinsic pathway
- Extrinsic pathway
3, common pathway
which factors are involved in intrinsic pathway
factor XII, XI, IX, VIII
which factor is involved in extrinsic pathway
factor VII and tissue factor
what is the difference between intrinsic and extrinsic pathway
intrinsic pathway is activated when vessel endothelium ruptures and exposes underlying tissue (collagen)
Extrinsic pathway is activated when tissue cell trauma occurs releasing tissue factor
What does Thrombin (Factor IIa) do
- Releases Tissue Factor to enhance extrinsic pathway
- Releases PF3 to enhance intrinsic pathway
- Increases platelet aggregation
- Enhance its own generation
- Converts fibrinogen to fibrin
- Activates factor XIII which stabilizes fibrin mesh
Which coagulation factors need Vitamin K
Factor X, IX, VII, II
Which coagulation factors produced by liver
all except factor III, IV (3,4)
What is Tissue Factor also known as
TF/Thromboplastin/Factor III
Why is tissue factor in extrinsic pathway better
It can bypass several steps in intrinsic pathway. In severe trauma, clot formed in 15s
Why is tissue factor separated
Separated from circulating VIIa by endothelium and is triggered by blood exposure from damaged endothelium
How is clot dissolved
During clot formation, plasminogen is trapped inside the clot. Surrounding tissue and vascular endothelial cells slowly release tPA (tissue plasminogen activator) which cleaves inactive plasminogen to plasmin which digests the fibrin and dissolves the clot. Phagocytes WBC remove clot remains
What are the clotting disorders
Thrombocytopenia
Hemophilia
Thromboembolism
What are the different types of hemophilia
Excessive bleeding due to different deficiencies
Type A - Factor VIII deficiency (most common)
Type B - Factor IX deficiency
Type C - Factor XI deficiency (mild condition)
What is thrombocytopenia
- Low circulating platelets (< 50 x 10^6/mL; normally 150 - 350 x 10^6/mL)
- Spontaneous widespread hemorrhage which results in small purple spots on skin
- caused by suppression and destruction of bone marrow (cancer, radiation)
What is thromboembolism
Thrombi - solid mass forming in blood circulation w/ platelet and fibrin
- blocks circulation resulting in tissue death (deep vein thrombosis)
- thrombus in blood vessel (coronary thrombosis)
Embolus - thrombi freely floating
- Impairs body to obtain O2 (Pulmonary emboli)
- Stroke (Cerebral emboli)
What is factor XII involved in
Clot formation and plasmin activation (fast)
Clot dissolution (slow)
What is the purpose of prothrombin time test
Tests for possible factor VII deficiency
- normally 11 - 13s
- standardised by International Normalized Ration (INR)
Prolonged PT suggests
- Factor VII deficiency
- Vitamin K deficiency
- Liver disease
- Warfarin
What is the purpose of activated partial thromboplastin time (aPTT)
Measured clotting time time by adding Factor XII (12)
- Normally 25 - 40s
- Tests intrinsic pathway
Prolonged test suggests
- Factor VIII, IX, XI, XII, vWF deficiency
- Factor VIII, IX, XI, XII, vWF inhibitors
- Heparin consumption
Types of anti-coagulants
Heparin
- Found in basophils and mast cells
- co-factor of anti-thrombin III
Anti-thrombin III (Serine-Protease inhibitor)
- Plasma protein that binds to and inactivated thombin, Factor IXa and Xa
Warfarin
- inhibits vitamin K dependent coagulation factors
- Factors X, IX, VII, II
Removal of Ca2+ ions
- chelates and binds to calcium ions
- citrate, oxalate, EDTA
