What type of tissue is blood?
connective tissue
What similarities do we see between blood and all other tissues of this type?
- connective tissue is also found in bones and adipose (fat)
- bones and blood both have a matrix
- organic matrix of bone is made of collagen fibers and the inorganic matrix of bone is made of salts; both providing durability to the bone
- matrix of blood is formed of ground substance (fluid—plasma) and fibers
What are the three main functions of blood? Go into detail – do not just list 3 words
(1) Transport
- delivering oxygen from lungs and nutrients from digestive tract
- transporting metabolic wastes to lungs and kidneys
- transporting hormones from endocrine organs to target organs
(2) Regulation
- maintaining homeostasis
- body temperature, pH levels in body tissues, and fluid volume in the circulatory system
(3) Protection
- preventing blood loss
- preventing infection
How is blood different from water?
blood is thicker, heavier, and 3-5 times more viscous than water (this is due largely because of the formed elements)
How does the temperature of blood differ from the average body temperature?
the temperature of blood on average is 100.4, while the normal body temperature is 98.6
What do you see after you put a tube of whole blood in a centrifuge?
3 layers:
- 55% plasma (least dense, so at the top of the tube)
- Less than 1% buffy coat (in the middle of the two) (buffy = leukocytes and platelets)
- 45% erythrocytes (most dense, so at the bottom of the tube)
What are the “formed elements” of blood, and what percent of blood do they usually make up?
the buffy coat (leukocytes and platelets) and erythrocytes make up the formed elements of blood (<46%)
What would you find in the buffy coat?
leukocytes and platelets
Be able to calculate the approximate blood volume of a person if you are given his weight in kilograms. (1 kg = 2.2 lbs.)
- blood is 8% of body weight
Example: Calculate the blood volume (in Liters) of a person who weighs 154 lbs. - answer: 154 lbs./2.2 lbs. = 70 kg.
- 70 kg. x 0.08 (8%) = 5.6 kg
- 5.6 kg. = 5.6 L
remember: the average blood volume is between 4-6 L!
What is an hematocrit and what does it measure?
“blood fraction”; the percent of blood volume that is erythrocytes (RBC’s)
How would the hematocrit of a male typically compare to that of a female? Why does this occur?
Male = 47% plus or minus 5% Female = 42% plus or minus 5%
men have more androgens
women bleed more during menstrual cycle
What is the erythrocyte sedimentation rate and what can it tell us?
- ESR: the rate at which blood cells sediment in a period of one hour
- ESR is a non-specific measure of inflammation: increases during infection, autoimmune diseases, and inflammation; decreases in sickle cell anemia, polycythemia, and hyperglycemia
When we remove the formed elements from blood, what is left?
only plasma
What do we have if we then remove the clotting factors? What is this used for?
- serum is what we would have left if we removed the clotting factors
- this is used for tests because serum still contains ions, nutrients, enzymes, gases, wastes, hormones, and some proteins
- antibodies are also still present
What do we call the stem cell from which all blood cells originate? Where is blood formed in a fetus? After birth?
- stem cells from which all blood originates are called hemocytoblasts through a process called hematopoiesis
- in a fetus, blood is formed by the yolk sac, liver, spleen, thymus gland, lymph nodes, and red bone marrow
- after birth, blood is formed by red bone marrow only
Describe the shape of an erythrocyte. Why is this shape important to its function?
- erythrocytes have the shape of a biconcave disc—flattened discs with depressed centers (lack nuclei and organelles)
- this shape is important because it allows RBC’s to change shape (twist, turn, bend) as necessary to travel through capillaries smaller than themselves
To achieve this shape (erythrocyte), what organelle does the cell have to lose, and how does this affect its ability to function?
since there are no mitochondria, they do not consume any of the oxygen they carry, making them perfect oxygen transporters
Describe a hemoglobin molecule. Is our hemoglobin the same throughout our life time?
- the protein that makes RBC’s red in color and most oxygen carried in blood is bound to hemoglobin
- consists of heme and four polypeptide chains (2 alpha and 2 beta) called globin
- the iron containing pigment (heme) binds easily and reversibly with oxygen
- beta peptides vary throughout our lifetime
Where does the oxygen bind?
to the heme component of the protein hemoglobin in red blood cells
Where can carbon dioxide bind?
at the α-amino group
When oxygen binds with hemoglobin what compound is formed?
oxyhemoglobin
What compound is formed when carbon dioxide binds with hemoglobin?
carbaminohemoglobin
What compound is formed when carbon monoxide binds with hemoglobin?
carboxyhemoglobin
Why would a person appear cyanotic?
the appearance of blue or purplish colored skin due to the tissues of near the skin’s surface having low oxygen concentration in the blood
Why is carbon monoxide dangerous?
binds more tightly to hemoglobin than oxygen, so the blood is very poorly oxygenated
Where does nitric oxide (NO) bind, and what does it do?
nitric oxide binds to sulfur atoms in the lungs and is delivered with oxygen to tissues
What is the average red blood cell count for a male (in millions of cells/mm3)?
average RBC count is 5.4 million/cubic mm
What is the average red blood cell count for a female (in millions of cells/mm3).
4.8 million/cubic mm
What is the average red blood cell count for a child (in millions of cells/mm3).
4.8 million/cubic mm
What is the average red blood cell count for a person living at high altitudes (in millions of cells/mm3).
8 million/cubic mm (this is due to low oxygen levels)
Why do red blood cells have a short life span?
- they are unable to synthesize new proteins, grow, and divide
- become “old” as they lose their flexibility, become rigid and fragile, and their hemoglobin begins to degenerate
What is a reticulocyte?
“young erythrocyte”; still contains a small reticulum (network) of clumped ribosome
What does the number of reticulocytes present in the blood stream tell us?
reticulocyte counts give a rough estimate at the rate of RBC production
What does it indicate if we see normoblasts in
circulation? (MP 196)
normoblasts in circulation? this signals near death
What enzymes and enzyme systems are found in a mature erythrocyte and what do they do?
glycolytic enzymes - assist with glycolysis
carbonic anhydrase - assists rapid inter-conversion of carbon dioxide and water into carbonic acid, protons and bicarbonate ions
What is the life cycle of a red blood cell?
- Low O2 levels in the blood stimulate kidneys to produce erythropoietin
- Erythropoietin levels rise in the blood
- Erythropoietin and necessary raw materials in the blood promote erythropoiesis in red bone marrow
- New erythrocytes enter the bloodstream; function about 120 days
- Aged and damaged RBC’s are engulfed by macrophages of the spleen, liver, and bone marrow; the hemoglobin is broken down
- Raw materials are made available in blood for erythrocyte synthesis
What happens to hemoglobin when a RBC dies?
- hemoglobin is split into heme and globin*
- heme: iron is salvaged and stored for reuse, liver cells pick up bilirubin and secrete it in bile into the intestine
- globin: broken down to amino acids, which are released to the circulation
What is transferrin?
a transport protein that iron is loosely bound to
What is ferritin?
protein-iron complexes that store iron
What is erythropoietin?
a glycoprotein hormone that stimulates the formation of erythrocytes
Where is it formed and what does it do?
erythropoietin is mainly produced in the kidneys, but some is also produced in the liver in response to hypoxia
What happens to bilirubin when the ducts from the liver to the small intestine becomes blocked?
jaundice: skin and whites of your eyes turn yellow in response to the ducts from the liver to the small intestine being blocked, so bilirubin builds up
What is anemia?
inability of the blood to carry sufficient oxygen to the body, low number of RBCs, lack of hemoglobin
What is pernicious anemia?
lack of RBCs due to lack of vitamin B12
Why does a person who is anemic feel “tired all the time”?
blood loss, not enough RBC’s produced, and/or too many RBC’s destroyed
What other vitamins and minerals are needed to prevent anemia?
- folic acid
- iron
How do we lose iron from the body?
chronic blood loss within the body — such as from a peptic ulcer, a hiatal hernia, a colon polyp or colorectal cancer — can cause iron deficiency anemia
What is sickle cell anemia?
- abnormal hemoglobin (hemoglobin S); results from a change in one of the 146 amino acids in a beta chain of the globin molecule
- beta chains link together and form stiff rods so hemoglobin S becomes spiky and sharp; interfere with oxygen delivery and leave victims gasping for air and in extreme pain
What is polycythemia?
excess of red blood cells (blood gets too thick to flow and clots)
When can it be good, and when can it be harmful?
good = secondary polycythemia: if you are a long-distance runner, you can carry more oxygen and run longer; EPO increases = higher RBC count; normal to those living in high altitude harmful = polycythemia vera: a bone marrow cancer; exceptionally high RBC count; blood volume may double, causing the vascular system to become engorged with blood and severely impairing circulation
What is the main function of leukocytes?
defense against disease
What are the three cell lines?
myeloid, lymphoid, monocytic
Name the two main types of leukocytes.
- granular leukocytes
- agranular leukocytes
Name the leukocytes that fall into those two categories.
granular - neutrophils, eosinophils, basophils
agranular - lymphocytes, monocytes
Describe and give the function of each type of white blood cell.
- Neutrophils*
- 54-62% of leukocytes
- Multi-lobed nucleus
- Younger neutrophils are called bands
- Granules take up both basic and acidic dyes (lilac in color)
- “Bacteria slayers”
- Attracted to sites of inflammation
- Are active phagocytes
- Eosinophils*
- 1-3% of all leukocytes
- Bi-lobed nucleus
- Stain red with acid
- Kill parasitic worms
- Role in allergy and asthma
- Basophils*
- Less than 1% of leukocytes
- Bi-lobed nucleus
- Stain blue with basic dyes
- Release histamine and other inflammation mediators
- Contain heparin—an anticoagulant
- Lymphocytes*
- 25-33% of leukocytes
- Few actually found in blood
- Large, dark purple nucleus
- Mount immune response by direct cell attack or via antibodies
- Monocytes*
- 3-9% of leukocytes
- Horseshoe shaped nucleus
- Phagocytosis
- Largest leukocyte
- Develop into macrophages in the tissues
What do B lymphocytes do?
produce plasma cells, which give rise to antibodies
What do T lymphocytes do?
attack invaders directly
Be able to give the relative proportions of each type of leukocyte.
neutrophils (54-62%) lymphocyte (25-33%) monocyte (3-9%) eosinophils (1-3%) basophil (<1%) [Never Let Monkeys Eat Bananas]
What is leukocytosis?
a white blood cell count over 11,000 cells/microliter (normal response to infection)
What is leukopenia?
(never normal) abnormally low WBC count (may be drug induced)
What is a “differential white blood cell count”? Why is it helpful?
you count 100 leukocytes on a slide and get percentages of each type of white blood cell
What information would you get if you asked the lab for a complete blood count?
- white blood cell count (WBC or leukocyte count)
- WBC differential count
- red blood cell count (RBC or erythrocyte count)
- hematocrit (Hct)
- hemoglobin (Hbg)
- mean corpuscular volume (MCV)
- mean corpuscular hemoglobin (MCH)
- mean corpuscular hemoglobin concentration (MCHC)
- red cell distribution width (RDW)
- platelet count
What are major histocompatibility antigens and where are they found? How do we use them?
antigens used in tissue typing; they are found on the surface of organs
Describe a platelet. What cell does it come from, and what does it do?
“thrombocytes” = cell fragments
- involved in blood clotting
- release serotonin, which contracts smooth muscle in walls of blood vessels, reducing blood flow (and blood loss)
- formed from megakaryocytes
- life span of platelets are 5-10 days
What are the three main types of protein found in blood plasma, and what does each do?
(1) Albumin: helps maintain blood osmotic pressure
(2) Globulin: transport lipids and fat-soluble vitamins (Alpha globulins, Beta globulins, Gamma globulins)
(3) Fibrinogen: plays a key role in blood coagulation
What are the lipids found in plasma?
cholesterol and triglycerides
What is a carbohydrate in plasma?
glucose, other sugars present in trace amounts
What else would you find in plasma?
92% of plasma to be water along with 8% solutes (ions, nutrients, enzymes, gases, wastes, hormones, and proteins)
How is serum different? What does serum contain?
serum is plasma WITHOUT the clotting factors // ions, nutrients, enzymes, gases, wastes, hormones, some proteins and, most importantly, ANTIBODIES
What is hemostasis?
stoppage of bleeding/prevention of blood loss
What are the four steps involved in hemostasis?
(1) vascular spasm
(2) platelet plug formation
(3) blood coagulation (clotting)
(4) clot retraction
What is vascular spasm?
smooth muscle in vessel wall contracts, causing vasoconstriction (decreasing the diameter of the blood vessel) => decreases blood flow
What causes vascular spasm?
- direct injury to vascular smooth muscle
- chemicals released by endothelial cells and platelets
- pain reflexes
How is a platelet plug formed? (3 steps)
1 - platelet adhesion (platelets stick to collagen fibers via plasma protein von Willebrand factor)
2 - platelets become activated - platelet release reaction - swell, become spiked and sticky, and release chemical messenger
3 - platelets become sticky and accumulate - platelet aggregation - serotonin and thromboxane A2 enhance vascular spasm and platelet aggregation
What is thrombosis?
formation of a blood clot within an unbroken blood vessel
What is thrombus?
blood clot that forms inside one of your veins or arteries
What is embolus?
if a clot breaks free and travels in the blood stream
What is embolism?
if a clot lodges elsewhere in the body
What are clotting factors?
- also called procoagulants
- most are clotting factors are plasma proteins synthesized by the liver (numbered I-XIII)
What are the minerals in clotting factors?
Ca2+
What vitamin is needed for the formation of clotting factors?
vitamin K
=> but it is not a clotting factor
=> required for the synthesis of four of the clotting factors by the liver
=> normally made by bacteria of the large intestine
Where are many of the clotting factors made?
clotting factors are made by bacteria in the large intestine
What are the three stages of blood clotting?
(1) formation of prothrombinase
(2) prothrombinase converts prothrombin to thrombin
(3) thrombin + calcium = conversion of soluble fibrinogen to insoluble fibrin
What are the differences between the extrinsic pathway and the intrinsic pathway?
- Intrinsic pathway: factors needed for clotting are present within the blood => triggered by activated platelets, collagen, or glass; slower because several intermediates
- Extrinsic pathway: the tissue factor it requires is outside of the blood => triggered by exposing blood to a factor found in tissues underneath damaged endothelium; faster because it bypasses several steps of intrinsic pathway
If blood clotting is a positive feedback loop, what keeps all our blood from clotting once it starts?
once we start making fibrin, the fibrin will bond to thrombin and will inactivate it
What is clot retraction and how does it occur? How does it help tissue repair?
stabilizes the clot // actin and myosin in platelets contract within 30-60 minutes // contraction pulls on fibrin strands, squeezing serum from clot // draws ruptured blood vessel edges together
How does a clot break down (what is the fibrolytic system)? How can we use this clinically?
- plasminogen (an inactive enzyme) is incorporated into a clot
- plasminogen can be activated to plasmin (fibrinolysin), which digests fibrin and inactivates other clotting factors
- plasminogen is converted to plasmin by tissue
- plasminogen activator (tPA), factor XII, and thrombin
- removes unneeded clots after healing
(begins within two days and continues for several)
// EMTs can administer tPA in the ambulance if someone has had a stroke/heart attack
What is hemophilia?
a hereditary trait due to a deficiency of one of the clotting factors causing excessive bleeding
What are some common anticoagulants, and how do they work?
Prostaglandins: inhibit the aggregation of blood platelets
Heparin: blocks the conversion of prothrombin to thrombin and prevents the release of factor III from platelets
Warfarin and Coumadin: antagonists to vitamin K
Chelating agents tie up Ca2+
Aspirin: inhibits vasoconstriction and platelet aggregation
Dabigatran: directly inhibits thrombin
What are the four major blood groups?
A, B, AB, O
What antigens are found in type A blood? Antibodies produced?
antigen A // anti-B antibodies
What antigens are found in type B blood? Antibodies produced?
antigen B // anti-A antibodies
What antigens are found in type AB blood? Antibodies produced?
antigen A/B // no antibodies
What antigens are found in type O blood? Antibodies produced?
no antigens // antibodies anti-A/anti-B
What is unusual about antibodies that are produced?
w
Who is the “universal donor”? Why?
Type O // they have no isoantigens on their surface
Who is the “universal recipient”? Why?
Type AB // they recognize A and B as self
What is the Rh factor? How is it designated in a person’s blood type?
an antigen that was found in Rhesus monkeys // either have the antigen (+) or do not have the antigen (-) // do not automatically make antibodies, must first encounter the antigen
What is erythroblastosis fetalis?
hemolytic disease of the newborn // Rh- mom exposed to Rh+ blood of fetus during delivery of first baby (1st baby healthy) // second baby is at risk b/c mom synthesized anti-Rh+ antibodies
When does erythroblastosis fetalis occur, what does it do and how can we prevent it?
Rh- mom exposed to Rh+ blood of fetus during delivery of first baby (1st baby healthy) => second baby is at risk b/c mom synthesized anti-Rh+ antibodies
- baby treated with pre-birth transfusions and exchange transfusions after birth
- RhoGAM serum containing anti-Rh antibodies can prevent Rh- mother from becoming sensitized
