Blood Composition and Function Flashcards
How much blood is in the average person?
5L
What is the volume of blood that circulates through the heart every 24 hours
14,000L
How many chambers are in the heart and what are they called?
4 (left + right ventricle, left + right atrium)
What part of the heart brings blood to the lungs?
The Pulmonary artery
What brings blood from the lung to the heart?
The Pulmonary vein
What are arteries made of?
Muscular capillaries with elastic vessel walls that contain an abundance of smooth muscle
Is blood pressure higher in veins or arteries?
Arteries
Why is venous blood pressure lower than arterial?
because veins are not elastic
What is the function of valves in veins?
to prevent back flow
What is systolic blood pressure?
is the highest pressure attained in arteries. Blood is at full compression, the left ventricle is squeezed at its tightest and the arteries walls are expanded at their greatest
What is normal blood pressure?
120/80
What does the 120 in blood pressure mean?
Your systolic blood pressure in millimetres of mercury (120mm up the tube measuring blood pressure)
What is diastolic blood pressure?
When blood pressure is at its lowest
What does the 80 in blood pressure mean?
Diastolic blood pressure
What is hypertension?
A high blood pressure
What causes hypertension?
Arteries are not expanding and contracting effectively (hardened, blocked or disease) which reduces flow and resulting in unwanted coagulation
What is a high blood pressure
above 140-150
What is the result of low blood pressure?
not enough blood going through arteries to supply tissues with blood
Common symptom of low blood pressure
fainting
What is needed to retain blood pressure?
blood volume
What loss of blood is fatal?
over 20% because pressure and flow is impaired and the result is tissue starved of O2
Why do we need blood pressure?
to ensure even and efficient blood flow through small capillaries, low enough to prevent capillary leakage but high enough to avoid coagulation.
Main components of blood
Cells, proteins, lipids, electrolytes, vitamins and hormones, glucose
Where do myeloid and lymphoid cells come from?
multipotential stem cells
What are the two types of lymphoid cells?
B and T cells
Where do B lymphocytes come from?
Bone marrow
What is the function of B lymphocytes?
They have antibodies/immunoglobulins that give adaptive immunity
Where do T lymphocytes mature?
In the thymus
What are the 3 main cells in blood?
Erythrocytes, leukocytes, thrombocytes
What is the function of Erythrocytes
to transport oxygen to tissue
How many Erythrocytes in the body
5-6 million/ml
What is the shape of a Erythrocyte
It is a flat disc that has no nucleus
What is the main protein in Erythrocytes
Haemoglobin
What is the main function of leukocytes
immune defence
What is the most common leukocyte
Neutrophil
How many leukocytes are in the body
10,000/ml
What is the function of neutrophils?
respond immediately to microbial challenge like an infection, migrate quickly from capillary tissue to the site of infection, engulf the organism
What is the function of thrombocytes?
Coagulation and tissue repair
How many thrombocytes are in the blood
400,000/ml
What is the size of thrombocytes
1/20th of a leukocyte
what do thrombocytes do when an injury occurs?
platelets link together as a part of the blood clot to block off wound to prevent leakage of blood or fluid from damaged tissue
What are the major proteins in blood?
Albumin, haemoglobin, fibrinogen, immunoglobulins
How much of blood protein is albumin?
50% of total blood protein
What is the function of Albumin
Maintains colloidal osmotic pressure and hyponeiticity, Binds and transports many small molecules, hormones.
How does Albumin maintain osmotic pressure?
It acts as a “Protein sponge” that absorbs fluid in blood and allows fluid to be balanced -
What is the function of haemoglobin
to carry oxygen from heart to other tissues in red blood cells
How much of blood is fibrinogen?
7% of total blood protein
What is the function of fibrinogen?
its cleaved in coagulation cascade to form fibrin molecules which link to form a clot (prevent tissue leakage)
What are lipids bound in?
Lipoproteins
What are the main types of lipids?
LDL, HDL, VLDL
Which lipid is bad for you?
LDL
What are the major electrolytes in the blood?
HCO3 -, Na+, Cl-, Ca++, Mg++, K+, creatine, creatinine
What electrolyte is the most tightly regulated and why?
Potassium (K) because it regulates a lot of cellular functions like nerve potential and heart muscle activity
What is the normal blood ph
7.4
How much variance can occur above/below blood pH before severe stress can occur?
0.2
What is acidosis
blood is more acidic (pH decreases)
What is alkalosis
blood is more basic (pH increases)
What are Immunoglobulins ?
antibodies
What do Immunoglobulins do
Provide a diverse repertoire of antigen binding proteins
What is complement?
proteins that “coat” bacteria targeting them for phagocytosis
What is the major complement component?
C3
What is opsonisation?
Irreversible coating of bacteria with complement so that phagocytes are attracted and can bind them.
What are first cells that go to site of infection due to complement?
Neutrophils
How many complement proteins are there?
9
Number of coagulation factors
13
What happens in a coagulation cascade?
13 proteins cleaved in an ordered cascade resulting in cleavage of fibrinogen -> fibrin (forms clot)
What electrolyte is essential to coagulation?
Ca+
What is the most common form of haemophilia?
Factor VIII (8) deficiency
What is haemophilia
Haemophiliacs blot does not clot (they can bleed to death from vascular leakage)
What is the function of electrolytes?
Isotonicity and buffering
What is centrifugation?
technique used to separate blood into its different components
What is added to blood before centrifugation what is its purpose?
An anticoagulant to stop blood clotting
Example of a anticoagulant
Heparin
How many layers result from centrifugation
3
What is the top layer of a centrifuge
The plasma layer
What % is the plasma layer in a centrifuge
55%
What is the plasma layer?
blood with fibrinogen (hasn’t been clotted)
What is contained in the plasma layer?
soluble proteins, lipids and platelets
What is the middle layer of a centrifuge?
The buffy coat
What is the buffy coat?
Layer of white cells
What is in the buffy coat
lymphocytes, myeloid cells, leukocytes
What is the bottom layer of the centrifuge?
Packed Red Cells
What % is the packed red cells
45%
What is anemia
you don’t make enough red blood cells
Symptoms of anemia
difficulty breathing and become tired
What causes Cerebral Edema
making too many red blood cells (happens normally by being at high altitudes, blood becomes viscous lead)
What is plasma
The viscous liquid fraction of uncoagulated blood without cells.
What is contained in plasma
fibrinogen (this is removed with coagulation)
Why can’t plasma be electorpheresed?
fibrinogen causes problems
What is serum?
Less viscous yellow liquid remaining after removal of the clot
What is serum electrophoresis
separating blood proteins using an electric field
What are the five major protein fractions of serum electrophoresis
albumin, α1, α2, β and γ fractions
What % of serum electrophoresis is albumin
50%
What % of serum electrophoresis is globulin? (albumin, α1, α2, β and γ)
40%
What is the γ fraction
where antibodies/immunoglobulins reside
is γ fraction + or -
positively charged so migrate furthest to the negative electrode (the right) on serum electrophoresis
What is multiple myeloma?
A type of leukaemia where a aberrant B cell is present and is producing antibodies in high amounts
Where do myeloma cells reside?
in bone marrow
Where do blood cells come from?
a single multipotent stem cell in bone marrow
Are multipotent stem cells rare?
yes
What do multipotent stem cells do?
differentiate into any other mature hematopoietic cells in the body
What surface antigen is on multipotential Hematopoietic stem cells
CD34
What do CD34 HSC divide into?
Myeloid and lymphoid progenitors
What does the myeloid progenitor divide into?
other types of myeloid cells. Consist of the erythrocytes, thrombocytes, mast cells, myeloblasts > leukocytes
What does the lymphoid progenitor divide into?
Natural killer cells (large lymphocytes) , small lymphocytes which makes T lymphocytes and B lymphocytes (forms plasma cells)
What factors drive haematopoiesis?
GM-CSF, EPO, G-CSF
What produces GM-CSF
macrophages, T cells, endothelial cells and fibroblasts
What does GM-CSF stimulate?
production of neutrophils, eosinophils, basophils and monocytes
What is the function of the GM-CSF factor?
stimulate the myeloid lineage
How does GM-CSF factor work?
receptors on the myeloid progenitor cells binds to GM-CSF which stimulates cells to differentiate further into other myeloid cells
What produces EPO
kidney during adulthood and liver in perinatal
What is the function of EPO
to signal the production of red blood cells
What type of factor is used in blood transplants?
EPO
What type of factor is the target of drug testing?
EPO
What does GM-CSF stand for
Granulocyte macrophage colony-stimulating factor
What does G-CSF stand for
Granulocyte colony-stimulating factor
What is the function of G-CSF
to stimulate the production of granulocytes but also acts to mature neutrophils
What is the function of the lung in oxygen and transport exchange?
Provides a vast surface area for blood (alveoli) for efficient exchange of O2 and CO2
Colour of blood in venous system
dark red (lack of oxygen)
Colour of pulmonary blood
bright red and frothy (spurts out due to pressure)
How much of your total blood volume is red blood cells?
45%
How much of your red blood cells dry weight is haemoglobin?
96%
What carries oxygen in red blood cells?
protein haemoglobin
How many lobes are in a haemoglobin
4
What is contained in each lobe of a haemoglobin protein
a heme molecule
What is contained in each heme in a haemoglobin protein
an iron atom, ferrous form (Fe2+)
What regulates the association and dissociation of O2 from heme
partial pressure of O2 (O2 readily associates in the lungs, dissociates in the tissue)
Partial pressure of oxygen in the alveoli of the lungs
100mm Hg
Partial pressure of CO2 in the alveoli of the lungs
35 mm Hg
Partial pressure of oxygen in arterial blood
80-100 mm Hg
Partial pressure of CO2 in arterial blood
40 mm Hg
Partial pressure of oxygen in venous blood
20-40 mm Hg
Partial pressure of CO2 in venous blood
50 mm Hg
Can oxygen freely bind to iron in heme in the lung under normal conditions?
Yes (pO2 it is at ~ 100mm Hg so oxygen freely binds to Fe2+ in heme)
Does oxygen bind faster due to partial pressure?
Yes
What happens when pO2 drops in the tissue
O2 dissociates from iron in heme and is replaced by CO2 – the by-product of respiration
What can displace O2 from Fe2+ directly
CO
How does cyanide affect oxygen intake?
it targets Fe2+ containing cytochrome C oxidase in the mitochondria that is essential for respiration. Cyanide binds tightly to iron displaying the oxygen. Inhaled cyanide stops heart muscle activity within seconds
3 pathways of the complement system
Classical, lectin, alternative
What is the key purpose of the complement system?
is to opsonise and
kill foreign organisms
How does the complement system work?
Cascade of protein binding to form convertases (each one
cleaves the next)
What pathways are activated directly by pathogens
alternative pathway,
lectin pathway
What pathways are activated by pathogen-bound antibody
Classical pathway
What is the classical activation pathway
Pathway activated by antibody-antigen complex (IgM/IgG binds to the surface of the microbe)
How does the classical pathway work?
C1 (recognises antibodies on the surface of the bacteria) > creates enzyme which cleaves C4 and C2 into C2a and C4b, which make up the C3 convertase (i.e. C3 activating enzyme) > cleave C3 (major component) into C3b > cleaves C5 into C5b
Antibodies that bind to a microbe surface which is then bound by C1
IgM, IgG
complexes of proteolytic proteins
convertases
What do convertases do?
they irreversibly bind through a covalent bond to bacteria (convertase complex)
anaphylotoxins
C5a, C4a, C3a
What do anaphylotoxins do?
they cause macrophages to move in the direction of bacteria
What is opsonization?
is the coating of a particle with proteins (C3b) that facilitate phagocytosis of the particle by tissue macrophages
colour of blood with carbon monoxide poisoning
cherry red
colour of blood with cyanide poisoning
pink
When is bacteria recognised by cells
when it has been fully coated by convertases
What is the function of C5b and complements going up to 9
to form a lytic pore (inserts in some types of bacteria which will lye/kill the bacteria)
What is the membrane attack complex
Lytic pore formed by the end stage of complement
Function of C3b
Opsonisation and cleaving C5
Molecules that inhibit the complement cascade
virulence factors
Classical activation sequence
C1, C4, C2, C3, C5
Where is C1 bound to?
C1 is bound to 2 antibodies on surface of bacteria
What is the most abundant complement component in serum?
C3
What are people with deficiencies in a complement component are susceptible to
Chronic infections
What are the 2coagulation pathways
Intrinsic, extrinsic
What is coagulation
system that operates in haemostasis to prevent blood loss from damaged
vessel (also known as clotting)
What does the intrinsic pathway result from
Contact with surfaces
What does the extrinsic pathway result from
tissue damage
What is the key element of coagulation
Thrombin
What is thrombin and what does it do?
(it is an inactive enzyme until factor Xa activates it) which cleaves fibrinogen to fibrin
What is essential for coagulation
Ca
What happens if Ca is not present in coagulation
blood will not clot
Intrinsic (Contact) pathway factors
XII, XI, IX, VIII
Common factor for coagulation pathway
X (Factor X (10) is the key enzyme common to both pathways)
Extrinsic (tissue damage) pathway factors
V, VII and tissue factor
How does coagulation work?
Coagulation is initiated by the conversion of prothrombin to thrombin, which then converts fibrinogen to fibrin. The clot is dissolved by the conversion of plasminogen to plasmin
How does fibrin build a clot
it cross links with other fibrin molecules to form a clot
Which coagulation pathway is faster
Fewer steps than intrinsic pathway, so acts faster (can be within seconds)
Where does the tissue factor in the extrinsic pathway come from
TF is released from cells outside the blood vessels
What is thrombolysis
the dissolving of a clot by plasmin
examples of Plasminogen activators
TPA (Tissue Plasminogen Activator) or Streptokinase
What do parasite and microbes that reply on blood flow do?
produce powerful anticoagulants that typically target the thrombin step.
What are zymogens
Proteins secreted in an inactive form and activated by cleavage - Complement (C’) proteins are a group of zymogens (inactive until cleaved) essential for phagocytosis
Highly concentrated source of HSC’s
Umbilical cord blood
What is the alternative activation pathway for complement
C3 is activated just by being close to the surface of the microbe
What is the lectin activation pathway for complement
When complement proteins condense on bound lectins
What are lectins
Lectins are proteins in the blood that bind to unusual carbohydrates only found on the surface of microbes. Possesses its own proteases that cleave C2 AND C4 to produce C2a and C4b, which form the C3
convertase (convergence with the classical pathway)
