Blood Flashcards
Functions of blood
Transportation
Regulation
Protection
Blood
A connective tissue composed of a liquid extracellular matrix called plasma which functions to dissolve and suspend cells and cell fragments.
Temperature and pH of blood
38 degrees
7.35 - 7.45 pH
Why is blood red?
O2 saturation (more O2 more bright) and presence of iron.
Best site for blood withdrawal
Medial cubital vein
2 components of blood
- Blood plasma 55%
2. Formed elements. 44%
Components of blood plasma
91.5% H2O
7% proteins
1.5% other solutes
Plasma proteins
From hepatocytes: albumins, globulins and fibrinogen
From plasma cells: immunoglobulins and antibodies.
Buffy Coat
Part of formed elements of blood , about 1% of total blood volume.
Composed of WBC and platelets
Formed elements of blood
About 45% of total blood volume
Made of cells and cell fragments.
Three components of formed elements of blood
Red blood cells
White blood cells
Platelets
Hematocrit
Percentage if total blood volume occupied by RBC.
Six steps of hematopoeisis
- Pluripotent stem cells
- Specialized stem cells
- Progenitor cell
- Precursor
- Optional step
- Developed formed elements.
Where does hematopoiesis occur?
In utero: yolk sac, then liver, spleen and thymus.
From third trimester on: red bone marrow in spongy bone.
What does red bone marrow produce?
RBC, WBC, platelets and lymphocytes.
Pluripotent stem cell
Mesenchymal cell that gives rise to all types of stem cells.
What types of stem cell arise from pluripotent cells?
Myeloid
Lymphoid
Monocytes vs macrophage
Monocytes in the blood
Macrophage in the tissue
B lymphocyte vs plasma cell
A plasma cell is an active B cell
Jamie’s mnemonic about the proportion of different WBC
60 20 8 2 oh never let my engine blow
60-70% neutrophils 20-25% lymphocytes 3-8% monocytes 2-4 % eosinophils 0.5-1% basophils.
How much blood in an average adult?
5-6 L in males; 4-5 L in females.
Liquid-solid composition of an adult
40-45% solid
55-60% liquid
Of the liquid, 2/3 intracellular fluid and 1/3 extracellular fluid
Of the ECF 80% interstitial fluid, 20% plasma.
Plasma (which itself is 55% blood volume) is composed of 91.5% H20, 7^ proteins and 1.5% other solutes.
What do myeloid stem cells develop into?
CFU-E –> reticulocyte –> RBC
CFU-Meg –> megakaryoblast –> platelet
CFU-GM:
- -> eosinophilic myeloblast –> eosinophil
- -> basophils myeloblast –> basophil
- -> myeloblast –> neutrophil
- -> monoblast –> monocyte/macrophage
Mast cell
What do lymphoid stem cells develop into?
T lymphoblast –> T lymphocyte
B Lymphoblast –> B lymphocyte –> plasma cell
NK lymphoblast –> natural killer cell
From which germ layer do pluripotent cells develop?
Mesoderm
Progenitor cells
Derive from myeloid stem cells.
Cannot reproduce. Specialize into whatever blood cell they were programmed for.
CFU-E –> erythrocytes
CFU- Meg –> platelets
CFU-GM –> eosinophils, basophils, neutrophils, and monocytes.
Precursor cells
~blasts
Stage where blasts differentiate into actual blood cells
Proerythroblast Megakaryoblast Eosinophilic myeloblast Basophilic myeloblast Myeloblast Monoblast T lymphoblast B lymphoblast NK lymphoblast
Erythropoietin
A hemopoietic growth factor that stimulates production of RBC
From kidneys
Thrombopoietin
A hemopoietic growth factor that stimulates production of thrombocytes (platelets).
From liver.
Erythrocyte
Red blood cell
Erythropoesis
Production of RBCs
Hemoglobin
Pigment contained in RBCs that binds O2. Gives blood its red colour.
Cytokines
Glycoproteins that act as local hormones. Stimulate proliferation of progenitor cells in RMB.
Include colony-stimulating factors (CSFs) and interleukins
Life span of the average RBC
120 days
How many RBCs are contained in blood?
Male: 5.4 million/microlitre
Female: 4.8 million/microlitre
What happens during the optional stage of blood cell development?
Reticulocyte ejects its nucleus –> Erythrocyte
Megakaryocyte shatters –> Platelets
How much of an RBC is composed of its cytosol?
33% by weight
How much hemoglobin does each RBC contain?
280 million, give or take
What is hemoglobin composed of?
Globin protein + 4 Heme
Globin
Protein portion of hemoglobin. Composed of 4 polypeptide chains (2 alpha helix, 2 beta sheet)
Heme
Non-protein portion of hemoglobin.
Composed of a ringlike pigment bound to each of the glob in protein chains (hence there are four hemes per hemoglobin).
At the centre of each ring is an iron ion, which can combine with one oxygen molecule.
What percentage of CO2 is transported by RBCs to the lungs?
23% directly.
70% is catalyzed by carbonicanhydrase into HCO3 (bicarbonate), which combines with amino acids in glob in and transported that way.
Remaining 7% dissolves in plasma
How do RBCs regulate blood flow and blood pressure?
Binding of nitric oxide
Why is carbon monoxide so deadly?
It binds competitively to heme group, with 200 times the affinity of O2.
Why do RBCs die after 120 days?
Wear and tear, and the inability to repair themselves.
What happens to ruptured RBCs?
Destroyed by fixed phagocytic macrophages in the spleen and liver
What happens to globin when RBCs are recycled?
Broken down into amino acids, which are recycled
What happens to heme when RBCs are destroyed?
Iron is removed.
Remaining heme is covered to biliverdin (green) and then to bilirubin (yellow-orange).
Bilirubin enters blood and is transported to liver.
Bilirubin released into bile, then passed into the small and then the large intestines, where it is converted into urobilinogen.
Most urobilinogen is converted into stercobilin and pooped out.
Some urobilinogen is absorbed into the blood, taken to the kidneys, converted to urobilin and peed out.
What happens to Fe+ when RBCs are destroyed?
Fe+ attaches to transferrin, which transports it to the liver, muscle and/or spleen, where it attaches to ferritin for storage.
When needed, it attaches again to transferrin, which transports it to RBM, where it meets up with globin, B12 and erythropoetin, and new RBCs are created.
Transferrin
A plasma protein which binds to and transports iron
Ferritin
An iron storage protein found in muscles, the liver, and the spleen
Biliverdin
What heme converts into at the beginning of the recycling process.
Green.
Bilirubin
What biliverdin converts into.
Yellow-orange
Travels through blood to liver, where it is released into bile, and passed into the small and large intestines.
Urobilonogen
What bilirubin gets converted into in the large intestine. Some gets absorbed into blood, some continues through intestine.
Urobilin
What urobilinogen gets converted into if it goes to the kidneys.
Yellow.
Excreted in urine
Stercobilin
What urobilinogen is converted into in the large intestine before being excreted in feces.
Brown.
How is the rate of erythropoesis measured?
Reticulocyte count.
Stages of erythropoesis.
Kidneys secrete erythropoeitin, which travels to RBM
In RBM, proerythroblast begins to synthesize hemoglobin.
Ejects nucleus, becomes reticulocyte.
Passes into blood stream. Within 1-10 days matures into RBC.
What determines rate of erythropoesis?
The amount of oxygen delivered to tissues.
Negative feedback system.
Hypoxia
Low levels of cellular oxygen.
Hypercapnia
Too much CO2. Goes hand in hand with hypoxia.
Leukocytes
White blood cells. Produced in RBM
Major Histocompatibility Antigens
MHC
Proteins on the PM of all nucleated cells that identifies the cell as “self”.
Unique for each person.