Blood Flashcards
What are the 3 main functions of the blood?
- Transport
- Acid-Base Balance
- Protection
Name 5 transport roles that the blood plays.
nutrients, gasses, waste, hormones, temperature regulation
What is the normal pH of blood?
7.35-7.45
What are the 3 major components of the blood? State their percentages.
Plasma [55%] , Buffy layer [ins.], RBC [45%]
What proportion of the body mass does blood make up?
about 7%
Having a normal blood volume is called […]
Normovolemia
Having a lower blood volume than normal is called […]
Hypovolemia
Having higher blood volume than normal is called […]
Hypervolemia
What is hematocrit?
The percentage of blood volume occupied by RBC.
What is the normal hematocrit value?
45%
Knowing that blood has a volume of about 5 L and that normal hematocrit is 45%, what is the total blood volume occupied by red blood cells? By plasma?
RBC:
5*0,45 = 2,25 L
Plasma:
5-2,25 = 2,75L
What are the 4 major components of plasma?
- Over 90% water
- Ions, mainly Na+ and Cl- [approximated to 0,9% saline for replacing fluids]
- Nutrients, respiratory gasses, waste
- Proteins
The plasma is […]% water
90%
What are the major and minor ions in plasma?
Major: Na+, Cl-
Minor: K+, Ca2+, Mg2+, HCO3-
What are the major nutrients found in the plasma?
Glucose, amino acids, lipids
Give 2 examples of wastes in the plasma.
Urea, lactic acid
What are the major respiratory gases found in the plasma?
O2, CO2
What is the major difference in composition between plasma and interstitial fluid? Why?
Interstitial fluid has the same composition minus the proteins. They are too big to cross the capillary wall and go into the interstitial space
What are the main 3 proteins found in the plasma? State their concentration in g%.
Albumin [4%]
Globulins [2.7%]
Fibrinogen [0.3]
What method of plasma protein separation is the most commonly used?
Electrophoretic Mobility
Explain how electrophoresis works.
This method is based on the movement of charged particles along a voltage gradient. The migration will help determine the characteristics of each particle and its density. (bigger stain= more particle)
Rate of migration in electrophoresis is influenced by the […] and […] of each protein.
distribution of charges, Molecular weight
Name the order in which the major blood proteins appear after electrophoresis. What does that order say on the proteins?
(beginning)
Gamma globulins
Fibrinogen
Other globulins
Albumin
The furthest proteins are smaller since they travel a greater distance and are more negatively charged because they get closer to the positive voltage gradient.
After electrophoresis, you notice that there is no fibrinogen line visible. Why is this?
The electrophoresis was done with a serum solution, meaning the fibrinogen [a coagulant] was taken out to stop its properties and to keep the plasma liquid,
After electrophoresis, you notice that the albumin peak is shorter than normal. What does this indicate? Explain why.
This indicates the patient has some renal disease. Because of that disease, the albumin goes through the now more permeable membrane and is lost in urine.
After electrophoresis, the Y globulin peak is higher than normal. What does this indicate? Explain why.
There are more globulins in response to the body battling a bacterial infection
Where are plasma proteins produced?
what are the proteins?
Albumin, Fibrinogen, Alpha1, 2 and beta globulins are synthesized in the liver
Gamma globulins are synthesized in the lymphoid tissue [immune system]
A diseased liver will resulted in […] production of plasma proteins.
Lower
Describe the shape of the three major plasma proteins.
Albumin, small and round
Globulins, many shapes and sizes
Fibrinogen, long [fibrous] and median size
State the molecular weight of the three major plasma proteins.
Albumin: 69 KDa
Globulins: 90-800 KDa
Fibrinogen: 350 KDa
What is the major role of plasma proteins?
They play a role in determining the distribution of fluids between the plasma and the ISF compartment
Explain how plasma proteins determine the distribution of fluid between the plasma and the interstitial fluid
They control transcapillary dynamics
The osmotic effect exerted by plasma proteins is called […]
Colloidal Osmotic Pressure [C.O.P.]
The COP of plasma proteins is equal to […]. What is it?
25 mm Hg
The osmotic pressure that the non-diffusable solutes (proteins) create as they cannot become equally distributed on each side of the membrane.
It’s only present in the plasma as ISF doesn’t have any proteins .
If the COP increases, water will flow from the […] to the […]
ISF to the plasma
There are […] major forms of fluid transport across the capillary wall: […]
2, Filtration and osmotic Flow
What is the difference between diffusion and and the starling forces?
Diffusion is responsible for the exchange of nutrients, gasses and waste across the capillary wall Whereas the starling forces determine the distribution of ECF volume between the ISF and plasma.
How does bulk flow relate to filtration in the capillaries?
Filtration is Bulk flow across a porous membrane.
So, molecules small enough [H2O] go across the capillary wall when there is a difference in pressure
Filtration tends to […] fluid from the capillaries because […], while osmotic flow tends to […] fluid in the capillaries because […]
Push out, because the fluid in the blood vessel is under pressure [trying to relieve pressure]
Pull in / retains, C.O.P. [protein exert and osmotic pressure]
The two transport forces in the capillaries, […] and […], come together to form the […]
Filtration and osmotic flow, Starling forces
Explain how blood pressure changes as it travels through the circulatory system.
The hydrostatic pressure starts at about 120 mm Hg when it’s pumped by the heart. With friction, it reaches about 35 mmHg when it enters the capillaries and goes down to 15 mm Hg on it’s way back to the heart.
Exchanges between the plasma and the ISF take place in the […]
Capillaries
The COP is equal to […]
25 mm Hg
Describe the major forces involved in transcapillary dynamics and where net absorption and net filtration are observed in the capillary bed.
There are two major forces involved. The osmotic pressure (COP) created by the proteins is 25 mm Hg and pulls in the plasma all along the capillaries. The other force is the hydrostatic pressure (filtration) that pulls the plasma out of the capillaries at 35 mm Hg at the arterial end and at about 15 mm Hg at the venous end.
Because of that, the difference in pressure near the artery is producing a net FILTRATION pressure (10 mm Hg). That’s where the plasma moves into the interstitial space.
On the other hand, the difference in pressure near the vein is producing a net ABSORPTION pressure (10 mm hg). That’s where 90% of the interstitial fluid in reabsorbed into the capillaries.
Name the 4 substances that exchange through the capillary wall (aside from fluid) and the mode of transport.
Nutrients, O2, CO2, and waste move by simple diffusion
Starling’s capillary dynamics determine the […] of the […] volume between […]
distribution, ECF, plasma and ISF
Filtration/absorption takes place […]
along the whole length of the capillary bed, but at different efficiency levels.
Describe how filtration/absorption varies across the length of the capillary.
There is a strong filtration pressure near the artery because of the difference in hydrostatic and osmotic pressure. As we move along to the middle, the filtration is done in smaller volumes and is slowly replaced by a absorption. This new movement of the molecules gets stronger as we move towards the vein. where the pressure difference is more noticeable.
[…]% of the fluid that leaves the capillary is reabsorbed. The other [..]% goes into the […]
90%, 10%, lymphatic vessels
The walls of the lymphatic vessels are made up of […] and are permeable to […]. Why?
a single layer of endothelial cells, everything.
By being more permeable, the lymphatic vessels are able to pick up any proteins that got out of the capillaries so they don’t create an osmotic pressure in the interstitial fluid. So, the lymphatic system is more permeable to clean up all the interstitial fluid.
Each protein fraction exerts an osmotic pressure, which is […]
- Directly related to the concentration in the plasma ―> the more there is, the stronger the osmotic pressure
- inversely related to the molecular wight of that protein ―> for the same total weight, you need more smaller molecules than big ones (bigger concentration of small molecules)
Explain the relationship between plasma protein COP and molecular weight. What are the COP’s of the plasmic proteins?
- The smaller molecules are a lot more present in the plasma and so exert a greater COP. Ans so, the bigger proteins are not as many and exert a smaller pressure.
- albumin, 20 mm Hg/ globulins, 5 mm Hg/ fibrinogen, 1 mm Hg
The main protein that causes the COP to rise is […]
albumin
The key function of albumin is to […]
control the COIP to have a good distribution of fluids
Name the 4 major factors involved in determining transcapillary dynamics
- Hydrostatic pressure
- COP
- Capillary permeability
- Lymphatic drainage
What is edema?
Accumulation of excess fluid in the interstitial space
When someone has edema, the proportion of […] increases, while the proportion of […] decreases
ISF, plasma
Name the four possible conditions that can lead to edema and what they cause.
All four conditions cause decreased venous return
1. increased hydrostatic pressure
2. Decreased COP
3. Increased capillary permeability
4. Obstruction of lymphatic drainage
Explain how hydrostatic pressure affects edema.
If the hydrostatic pressure is increased (high blood pressure) , the new, exaggerated, pressure differences will cause more volumes to be filtered out at the artery end. At the veinous end, the difference in pressure will be equal or greater than the COP and cause no absorption. Fluid will accumulate in the interstitial space
Explain how plasma proteins affect edema.
If the COP is decreased (less proteins in the capillaries), the net absorption near the vein will be closer to zero. The fluid is going to accumulate in the interstitial fluid instead of returning in the circulation.
Name two possible causes of decreased COP.
Kidney disease: albumin is lost in urine
Liver disease: Not enough proteins are produced
Explain how capillary permeability affects edema. (2)
If the capillary permeability is decreased, the proteins could be filtered into the interstitial space.
1. They could start and exert their own oncotic pressure
2. Even if the proteins are pick up by the lymphatic system, those proteins are going to be missing in the plasma and lower the COP (net absorption of zero)
Explain how lymphatic drainage affects edema.
If the lymphatic system is obstructed by something, it will not be able to pick up any of the fluid. It will simply accumulate in the space instead.
Obstructed lymphatic drainage can lead to a condition known as […]
Elephantiasis
The cause of elephantiasis is [..]
a blockage of the lymphatic system because of a parasite infestation
Name the 3 roles of plasma proteins.
- determining the distribution of fluid between the plasma and the ISF with the Starling forces controlling the transcapillary dynamics
- Contribute to the viscosity of the blood which contributes to the blood pressure
- Contributing top the buffering power of plasma (maintaining the pH levels)
Name the specific function(s) of fibrinogen
essential for clotting
Name the specific function(s) of globulins
Gamma: provide specific resistance to infection
Globulins clotting and carriers)
Name the specific function(s) of albumin
Carriers for lipids, minerals and hormones
The production of platelets is called […]
Thrombopoiesis
The production of white blood cells is called […]
Leukopoiesis
Red blood cells are also called […]
Erythrocytes
White blood cells are also called […]
Leukocytes
Platelets are also called […]
Thrombocytes
Erythrocytes are present at a concentration of […] in the blood and are the […] numerous blood cell type.
5 million/micro L
most
Thrombocytes are present at a concentration of […] and are the […] numerous blood cell type
250000-400000/micro L
median
Leukocytes are present at a concentration of […] and are the […] numerous blood cell type.
8000-10000/micro L
least
Erythrocytes have a diameter of […] and are the […] blood cell type.
7.2 micro m
medium sized
Thrombocytes have a diameter of […] and are the […] blood cell type.
2-3 micro m
smallest
Leukocytes have a diameter of […] and are the […] blood cell type.
10-18 micro m
biggest
Red blood cells have a lifespan of […]
120 days
Thrombocytes have a lifespan of […]
7-8 days
Leukocytes have a lifespan of […]
hours or years (memory cells in immunology)
The production of blood cells originates from […], the […], and is [the same/different] for all blood cell types.
a multipotential stem cell
hematopoietic stem cell [inducer]
same
The generation of all blood cells is called […]
Hematopoiesis
What is the role of cytokines in hematopoeisis? What are they called?
They influence the differentiation of pluripotential stem cells into blood cell precursors. They are called Hematopoietic Growth Factors [HGF]
The production of red blood cells is called […]
Erythropoiesis
Explain the two paths that a pluripotential stem cell can take during development.
- It can self-replicate to make more stem cells
- If stimulated, become committed stem cells and differentiate into one of the three blood cells
What are cytokines?
A substance released by one cell that affect the growth, development nd activity of another cell
In the prenatal stage, describe the major sites of hematopoiesis and the timespan of each.
- Yolk sac declines from the first month until the 3rd
- Liver and spleen, takes over during the second month and declines from the 6th to 9th month
- Bone marrow takes over in the 5th month and stays until birth
In the postnatal stage, describe the major sites of hematopoiesis and the timespan of each.
The distal long bones participate for the first 20 years of life but declines in importance through out
However, the axial skeleton stays the main source of hematopoiesis for the entirety of life
What is the axial skeleton?
Flat bones of the skull
Shoulder blades
Sternum
Vertebrae
Ribs
Pelvis
Proximal epiphyses of long bones
What is the function of erythrocytes?
Facilitate transport of respiratory gases
Erythrocytes have a […] shape due to […].
Biconcave disk
The presence of a fibrous protein called “spectrin” forms a network linked to the cell membrane, which regulates the cell’s shape.
What is CBC?
Complete blood count
Name two potential red blood cell shapes in diseased states.
Sickle cell
Spherocyte
What are the possible RBC sizes and their names
Normocytic (Normal size)
Microcytic (small)
Macrocytic (big)
Name two physiological advantages to the biconcave shape of the erythrocyte.
- A maximal area and minimal diffusion distance to increase the efficiency of O2 and CO2 diffusion
- More flexibility to go through caoilarries
Describe the subcellular organelles in erythrocytes.
There are none
The normal number of erythrocytes in males is […]
5.1-5.5 million /uL
The normal number of erythrocytes in females is […]
4.5-4.8 million /uL
What is the rate of production and rate of destruction of erythrocytes?
they are both equal at about 2 million per second
Describe the composition of erythrocytes.
Mostly water
33% Hemoglobin
lipids, proteins and ions
The major enzyme systems in erythrocytes are […]
Glycolytic enzymes and Carbonic Anhydrase
Explain the function of glycolytic enzymes in RBCs.
Generate energy anaerobically since the RBC doesn’t have the usual organelles
Explain the function of carbonic anhydrase.
Transport of CO2
Each molecule of hemoglobin can bind to […] molecules of […]
4, O2
When hemoglobin is combined with O2, it is known as […]
HbO2
Hemoglobin once the oxygen is released is called […]
DeoxyHb
Describe the structure of a hemoglobin molecule.
It’s 4 chains of polypeptides (2 beta and 2 alpha) , each associated with a heme. Each heme has a Fe2+ attached to it and can transport one O2 molecule
There are […] molecules of hemoglobin per red blood cell.
200-300 million Hb molecules/ RBC
The molecule weight of hemoglobin is […]
64 KDa, similar to the albumin
In lungs, hemoglobin appears […] because it is […]
bright red, saturated in O2
In tissues, hemoglobin appears […] because it is […]
dark red, dissociated from O2
Explain why hemoglobin is necessary in the blood.
It increases the solubility of O2 in the plasma and Hb is the transporter of O2 in the blood
Name the two other functions of hemoglobin.
it also transports CO2 and acts as a buffer
Why is the Hb in the red blood cells and not directly in the blood?
- It would increase the viscosity of the blood
- It would increase the plasma COP
- They could be lost vis the kidneys and reduce the transport of the gasses
Name the 5 factors that affect the ability of hemoglobin to bind and release oxygen.
- Temperature
- Ionic composition
- pH
- amount of CO2
- Intracellular enzyme concentration
Where does the production of RBCs take place?
Like other blood cells, the hematopoiesis changes location prenatally and is then mainly done in the bone marrow postnatally
Under the influence of cytokines, what are the two possible committed groups that pluripotent hematopoietic stem cells can differentiate into?
Under the influence of HGF they can become a lymphoid stem cell or a Myeloid stem cell.
What is a myeloid stem cell?
It’s the committed precursor to erythrocytes and platelets (and other blood cells not pertinent here)
What is a lymphoid stem cell?
It’s the committed precursor to the lymphocytes
The […] stem cell gives rise to erythrocytes.
myeloid
The main cytokine that influences red blood cell production is called […] and is secreted by the […]
Erythropoietin (EPO), the kidney
The process of division and differentiation of myeloid cells into reticulocytes takes […]
3-5 days
The differentiation of myeloid eventually gives rise to cells called [….], which are the […] to red blood cells.
reticulocyte, precursor
Once the reticulocyte is formed, it moves into the […], where it remains recognizable for […] before transforming into a […]
circulation, 24hrs, erythrocyte
Name the 3 steps of red blood cell precursor differentiation.
- it’s going to decrease in size
- It will loose it’s nucleus and organelles
- it will accumulate Hb while it still has the machinery to do so
What are the 2 main factors that determine the number of red blood cells in the body? Briefly explain.
- If the body requires more O2 during high aerobic activity, it can produce more RBCs in a span of a few days to accommodate that activity
[O2 requirement] - At high altitudes, the body will produce more RBCs to transport more O2 at a time
[O2 availability]
What is the variation in the amount of RBCs compared to the availability of O2 (high altitude)?
The less there is O2 available, the more the Body will have RBCs to transport the appropriate amount of oxygen through the body
What feature allows reticulocytes to be recognizable from regular blood cells?
It still has a few organelles, mainly the reticulum system, for about 24hrs after entering the blood circulation
The reticulocyte count is normally […]. It reflects the […] of red blood cells in […]. Why?
less than 1%, effective erythropoiesis, bone marrow
If the bone marrow is healthy, it will be producing the right amount of RBC which stays the same proportion (in health)
The stimulus for the release of erythropoietin is […], which may result from […], […], or […]
Hypoxia
decrease RBC count
decreased availability of O2
Increased tissue demand for O2
Describe how the regulation of erythropoiesis maintains homeostasis.
name the cytokines and organs involved in the process
When the kidneys sense the hypoxia, it increases the release of erythropoietin. The cytokine is then more present in the plasma and stimulates the production of RBC in the bone marrow. Once the production of RBC is increased, so is the oxygen in the plasma. The kidney’s sense increases and decreases the release of erythropoietin since it has come back to the homeostasis state
[Negative feedback]
Erythropoietin, released from […] in the presence of […], stimulates the […] to produce […], thereby maintaining […]
the kidney
hypoxia
bone marrow
erythrocytes
homeostasis
Erythropoietin acts on […] only, not the […]
the committed stem cells
Pluripotent stem cells
Explain the two functions of erythropoietin.
- it stimulates the proliferation of RBC by regulating the committed stem cells
- It can also accelerate the maturation of those committed cells into reticulocytes
Explain the effect of testosterone on erythropoietin.
Testosterone increases the release of erythropoietin and increases the sensitivity of RBC precursors to erythropoietin
Explain the effect of estrogen on red blood cells.
It decreases the release of erythropoietin and decreases the sensitivity of RBC precursors to erythropoietin
What is the typical life span of RBCs?
120 days
How can the lifespan of RBCs be prolonged?
It can’t
Explain how old RBCs get disposed of.
phagocytosis by macrophages. The white blood cell engulfs the old RBC and it’s digested. It’s content is then released
Phagocytosis of old RBCs takes place in the […]
liver and spleen
After an RBC is phagocytosed, what three components is it broken up into?
- Globulin
- Hb –> Heme
- Fe
After an RBC is phagocytosed, explain the fate of heme.
it is released in the circulation and is converted into bilirubin, a yellow-brown pigment. The bilirubin enters the liver and is secreted with the bile into the gut. Finally, it is excreted in urine and mostly feces.
The substance […] gives feces and urine their characteristic colour.
Bilirubin
Bilirubin is present in a concentration of […] in the plasma.
1 mg/dL
After a RBC is phagocytosed, explain the fate of the iron.
The iron binds to transferrin and is then stored in the liver, the spleen and the gut to be reused in the production of new RBC
After a RBC is phagocytosed, explain the fate of the globin.
The globin is stored in an amino acid pool to produce other proteins
What is jaundice?
A yellow appearance to the skin due to a high concentration of bilirubin in the plasma
What is the effect of jaundice on the health of adults and newborns?
In adults, it’s harmless
In newborns, the bilirubin could penetrate the brain and cause neurological issues.
Name and explain the 3 possible causes of icterus.
- Excessive hemolysis: RBCs are too fragile and break up too easily, releasing excess heme into the plasma
- Liver damage: causing an accumulation of bilirubin in the blood
- Bile duct obstruction: the bile is unable to be carried to the intestinal tract, resulting in the bilirubin backing up into the plasma
If an individual has a hematocrit of 35%, name two possible causes.
- fluid retention (higher proportion of plasma)
- Anemia (fewer RBC)
If an individual has a hematocrit of 70%, name two possible causes.
- Dehydration (lower proportion of plasma)
- Polycythemia (more RBC)
Explain how polycythemia compares to normal conditions in terms of hemoglobin content and concentration of RBCs in the blood.
The amount of hemoglobin and the concentrations of RBC in the blood are going to be higher than normal.
What are the three types of polycythemia?
Relative: the percentages are unbalanced due to a decreased plasma volume
Absolute physiological: An exterior factor affecting the cycle of production of RBC
Absolute pathological: There is an abnormality inside disrupting the production of RBC
Name four possible causes of physiological polycythemia. Explain them.
- high altitude
- Increased PA
- Chronic lung disease
- Heavy smoking
[increased O2 requirements or decreased O2 availability]
Name two possible causes of pathological polycythemia.
Tumors of the cells producing EPO
Unregulated production of EPO in the bone marrow
What problem(s) does polycythemia create in the body?
It increases the blood viscosity which slows down the blood flow and can cause blood clots
What is anemia?
A decrease in the oxygen-carrying capacity of the blood
Describe the characteristics of anemia in terms of RBC count and Hb content in men.
if anemic, males have less than 4 million RBC/ micro L and less than 11g% of Hb
Describe the characteristics of anemia in terms of RBC count and Hb content in women.
if anemic, females have less than 3.2 million RBC/ micro L and less than 9g% of Hb
Name the 5 possible morphological conditions of RBCs in anemia.
microcytic
normocytic
macrocytic
Normochromic
Hypochromic
How can you differentiate normochromic and hypochromic RBCs visually?
Hypochromic cells appear less opaque
What are the three major etiologies of anemia?
- Diminished Production
- Ineffective maturation
- Increased RBC destruction1 decrease survival
What are three possible causes of diminished production of RBCs? Name the type of anemia associated with each.
An abnormality at the site of production is going to cause Aplastic Anemia
An inadequate stimulus causes stimulation failure anemia
Inadequate raw materials cause an iron deficiency anemia
Explain the possible causes of aplastic/hypoplastic anemia.
Exposure to radiation
chemicals or drugs
Describe the types of RBCs found in the case of aplastic/hypoplastic anemia.
normocytic and nomochromic
Explain the possible cause of stimulation failure anemia.
Renal disease (less EPO production)
Describe the types of RBCs produced in the cause of stimulation failure anemia.
Normocytic and nomrochromic
Explain the possible causes of iron deficiency anemia.
Increase in the requirement for Fe
Inadequate supply of Fe
Describe the types of RBCs produced in the case of iron deficiency anemia.
Microcytic and hypochromic
Describe the breakdown of iron in the body.
the 4g of iron in our body is not free in solution because it would be toxic. THat’s why it’s split up:
65% Hb
30% stored
5% myoglobin
1% enzymes
Explain why women are more susceptible to iron deficiency anemia.
a lot of iron can be lost through the blood during menstruation
What are the possible causes of maturation failure anemia?
Deficiencies in vit. B12 and folic acid
Anemia caused by vitamin B12 deficiency is called […], and is caused by […]
Pernicious anemia (maturation failure)
a bad absorption of B12 done by the intrinsic factor.
Hemolytic anemias may be accompanied by […]. Explain why.
jaundice because the RBC are broken down faster than planned and release Heme into the plasma
What are the two types of hemolytic anemias?
Congenital and acquired
What are the possible causes of hemolytic anemias?
Abnormal RBC membrane structure
Abnormal Enzyme systems
Abnormal Hb structure
Explain what is implied in an abnormal RBC membrane structure
The blood cells are often spherocytic. They are less flexible and more fragile which causes their early death
Explain what is implied in an abnormal enzyme system
The cell can not produce energy and so can not live
Explain the possible causes of acquired hemolytic anemia.
toxins, drugs or antibodies
What are the 3 major clinical indices used to assess blood health?
Number of RBC
Amount of Hb
Hematocrit
Maturation failure anemia leads to RBCs that are […]
Macrocytic and normochromic
Loss of blood is called […]
Hemorrhage
What are the two type of hemorrhage?
External and internal
Internal bleeding is called […]
Hematoma
The arrest of bleeding is called […]
Hemastasis
Describe the various components of the body’s hemostasis response when there is tissue damage.
There’s a vascular response, a platelet response and a clot formation
The vascular and platelet responses are primary hemostasis, while the clot formation is considered secondary hemostasis.
What are the four steps of injury healing?
- There’s a vascular injury
- Vasoconstriction to reduce the amount of blood circulating in that area
- Platelet plug formation
- Blood clots forming
Describe what happens during vasoconstriction.
The nervous reflex makes the opposed endothelial cells stick together. There is then a myogenic response, where smooth muscle cells in the vessel wall respond to injury by contracting.
The platelet plug is also called […]
The white thrombus
The blood clot is also called […]
The red thrombus
How big are platelets?
2-4 um diameter
Describe the structure and organelles of platelet cells
They don’t have a nucleus, but they do have many granules, including factors for vasoconstriction, platelet aggregation, clotting, and growth.
What is the lifespan of platelets?
7-10 days
Where does the production of platelets take place?
n the axial skeleton in adults- identical to all other blood cells [hematopoiesis]
Platelet production is stimulated on the […] by […], which is produced in the […]
Committed stem cell
thrombopoietin
liver
Describe the steps involved in platelet production.
They start with a pluripotential stem cell, which becomes a committed stem cell (myeloid cell) on which thrombopoietin acts. It then grows into a megakaryocyte, a large cell with a nucleus. The nucleus divides and the megakaryote eventually leaves the bone marrow and goes into the bloodstream, breaking into platelets.
What are the 4 steps in platelet plug formation?
- Adhesion
- Activation and release of cytokines [thrombopoietin]
- Aggregation
- Consolidation
Describe the adhesion step of platelet plug formation.
When there is damage to the vessel wall and collagen is exposed, platelets will stick there. A plasma protein called the von Willebrand factor promotes the adhesion of platelets to the endothelium.
Describe the activation, aggregation, and consolidation steps of platelet plug formation.
Once the platelets adhere to the endothelium, they are activated and release cytokines and other factors [Thromboxane A2, serotonin, ADP, and Platelet Factor 3], which further promote the aggregation and consolidation of platelets to make the plug firmer.
What are the functions of Thromboxane A2?
It promotes the aggregation and consolidation of platelets in the platelet plug and is a vasoconstrictor.
What is the function of serotonin?
It is a vasoconstrictor.
What is the function of PF3?
It participates in coagulation.
What is the function of ADP?
Vasoconstriction
The key proteins involved in the adherence and aggregation of platelets to form the platelet plug are […]
Thromboxane A2 and platelet factor
What are the 5 functions of platelets?
- Release vasoconstricting agents
- Form a platelet plug
- Release clotting factors
- Participate in clot retraction
- Promote maintenance of endothelial integrity
Bleeding under the skin due to the breakup of capillaries is called […]
Petechia
Name two possible causes of prolonged bleeding.
Failure of blood vessels to constrict
Platelets deficiencies [nummerical or functional]
What are the types of functional platelet deficiencies that can lead to prolonged bleeding?
Congenital and acquired
Give an example of a drug that inhibits clotting and how.
Aspirin because it inhibits the synthesis and release of TXA2
Another word for a blood clot is a […]
red thrombus
Clotting is initiated by […] and results in […]
injury to the blood vessel wall
sequential activation and interaction of a group of plasma proteins and clotting factors
Describe stage 3 of clotting.
- The blood vessel wall is injured and exposes collagen which activates the platelets
- An intrinsic and extrinsic pathway of physiological reactions take place
- There is a clot formation
What is prothrombinase
It’s the catalyzer that makes the prothrombin change into thrombin faster
What is thrombin
It changes the fibrinogen into fibrin. It has a positive feedback loop, which then produces more fibrin (the fibers forming the clot)
Explain the extrinsic pathway
A few seconds after the damage, tissue factors are released from the proteins outside of the vessel. Those activate different factors that activate Prothrombinase.
It is a rapid reaction because when the clotting begins, the outside proteins can’t release any more tissue factors
Explain the intrinsic pathway
A few minutes after the damage, the exposed collagen activates different factors that activate Prothrombinase.
Why is the extrinsic pathway important even if it does the same thing as the intrinsic pathway?
The small amount of thrombin generated rapidly is sufficient to trigger a strong positive feedback effect on the intrinsic pathway. This in all generates bigger quantities of thrombin
Clotting is kept in check by […] and […]
inhibitors of platelets adhesion and anticoagulants
What are the 3 factors involved in coagulation? Which ones tend to be lacking?
Ca++
Phospholipid
Protein Plasma factors [most likely to be lacking]
What are two types of clotting factor deficiencies?
Congenital and acquired
Explain what congenital clotting factor deficiencies are and give an example.
A single factor hereditary deficiencies of factor 8. This stops the intrinsic pathway before it can produce prothombinase
Explain what acquired clotting factor deficiencies are and give an example.
They are multi-factor deficiencies that can be caused by liver disease (no production of factors) or by vitamin K deficiency (implicated in the synthesis of factors and prothrombin)
What is clot retraction? What does it result in?
The skinking of the clot into a firmer barrier
Clot retraction depends on […], which is released by […]
a contractile protein [Trombothenin]
platelets
The process of blood clot destruction is called […]
Fibrinolysis, clot lysis or thrombolysis
Fibrinolysis is driven by the factor […
Plasminogen
Describe the process of fibrinolysis.
Intrinsic or extrinsic factors are going to release the plasminogen activators, which then change the plasminogen into plasmin. This will then break down the fibrin into fragment (break down the clot)
Give an example of a medication that inhibits platelet adhesion.
Aspirin, slows down the adhesion process (blocks stickiness)
Give two examples of medications that are anticoagulants and explain how they work.
Coumarin blocks the synthesis of functional prothrombin
Heparin stops thrombin activation and actions
They block the factors themselves and are more severe actions
What is a thrombolytic drug?
a drug that promotes clot lysis
