Chapter 18- Blood Flashcards
Hematology
branch of science that studies the blood, blood-forming tissues and blood disorders
functions of blood
-nutritive & excretory function
-respiratory function
-transport of hormones and enzymes
-regulation of water & acid-base balance
-regulation of body temp
-restricts fluid loss (clotting)
-blood has white blood cells= protect against disease
Physical Characteristics of
Blood
- Blood is a type of connective tissue, the matrix is the plasma and this
dissolves and suspends various substances, cells, and cell fragments - Maintains a temperature of 38°C
- Denser and about 5 x more viscous than water
- pH of 7.35 – 7.45 (average of 7.4)
- Adult volume: male – 5-6L female 4-5L; about 8% of body weight in kg
- Regulated by several hormones (e.g., aldosterone, ADH)
why do we draw blood from veins
1)Superficial veins – easier to locate
2)Vein walls are thinner and easier to
penetrate than comparable sized arteries
3) Blood pressure lower in venous system,
puncture seals quickly
components of blood
-plasma (55% of whole blood)
-buffy coat: leukocytes and platelets (<1% of whole blood)
-erythrocytes (formed elements) (45% of whole blood)
plasma proteins
-albumins (60%) major contributors to osmotic pressure of plasma; transport lipids, steroid hormones
-globulins (36%) trasnport ions, hormones, lipids; immunity function
-fibrinogens (4%) essential component of clotting system; can be converted to insoluble fibrin
fibrinogen
-a precursor for fibrin
-soluble plasma protein fibrin
-insoluble protein
-forms clots
plasma composition
-plasma proteins 7%
-other solutes 1%
-water 92%
blood cell composition
- erythrocytes (majority RBC)
- thrombocytes (platelets)
- leukocytes (WBC)
ALL MADE IN RED BONE MARROW
hematopoiesis
-hematocytoblast (HSC)
-myeloid cell (erythropoietin, hormone from kidneys)
-progenator cell
-blast cells
-proerythroblast (EPO)
-erythroblast (last stage with nucleus)
-reticulocyte (no nucleus, found in patient with regnerative anemia)
-erythrocyte (RBC)
erythrocytes 2 functions
1) Pick up oxygen from lungs and deliver it to tissues
2) Pick up carbon dioxide from tissues and unload
it in the lungs
how does structure of erythrocytes aid function
1) Large surface area allows for rapid exchange of oxygen as cells pass through capillaries of the lungs
or peripheral tissue.
2) Allows RBCs to temporarily form stacks that smooth their flow through narrow blood vessels.
3) The strong and flexible plasma membrane allows them to deform without rupturing as they squeeze
through narrow capillaries
lifespan of erythrocytes
No nucleus, ribosomes, or mitochondria means no
repair. RBCs have a finite life span of about 120 days
Hematocrit (Hct) – percentage of blood volume occupied by RBCs
NORMAL
female 42% (range: 37 -47); male 46% (range: 40-54)
* Testosterone stimulates RBC production whereas estrogen does not
* Also, loss of blood during menstruation impact Hct in females
Hematocrit (Hct) – percentage of blood
volume occupied by RBCs
ANEMIA
- Reduction in the oxygen-carrying capacity of the RBCs
- Significant decrease in hematocrit is present
- Many types of anemia: decrease in absolute number of RBCs (increased loss –hemorrhagic/hemolytic or decreased production) or insufficient hemoglobin (or iron or
vitamin B12)
Hematocrit (Hct) – percentage of blood
volume occupied by RBCs
POLYCYTHEMIA
- Increase in hematocrit is present (>65%)
- Abnormal increase in RBC production (absolute polycythemia) or due to dehydration
(relative polycythemia) - Blood becomes too viscous, harder for heart to pump, increases blood pressure and
increase risk for stroke or heart attack
Structure of hemoglobin
-gives blood its red colour
-Hb is a protein with 4 identical chains
-Each chain is made up of a polypeptide chain called a globin, a
chemical group called a heme, which contains and iron molecule that can bind to an oxygen molecule
-1 RBC can carry 1 billion O2 molecules
Erythropoiesis occurs in the red bone marrow and typically it takes 3 – 5 days and involves four major steps
1) Reduction in cell size
2) Increase in cell number
3) Synthesis of hemoglobin (erythroblast stage)
4) Loss of the nucleus and other organelles (reticulocyte & mature RBC)
transport ions for proteins
-gastroferrin (stomach)
-transferrin (blood)
storage protein for iron
ferritin (in liver)
Correction of Hypoxemia by a Negative Feedback Loop
hypoxemia, sensed by liver and kidneys, secretion of erythropoietin, stimulation of red bone marrow, accelerated erythropoiesis, increased RBC count, increased O2 production
The Life and Death of Erythrocytes
Old RBCs are broken down by macrophages in the spleen, liver, or bone marrow, with hemoglobin splitting into heme and globin. Heme is processed into iron and biliverdin (green pigment), which converts to bilirubin (yellow pigment) and is eventually excreted as urobilin (yellow in urine) or stercobilin (brown in feces)
Agglutination of Erythrocytes
Agglutination occurs when plasma antibodies bind to antigens on RBCs, forming antibody-antigen complexes. We have antibodies for antigens not present on our own RBCs but not for our own antigens.
Type A
The RBCs: surface antigen A
In plasma: Anti-B antibodies
Type B
The RBCs: surface antigen B
In plasma: Anti A antibodies
Type AB
The RBCs: surface antigens A and B
In plasma: neither anti-A nor anti-B antibodies
Type O
The RBCs: neither A nor B surface antibodies
In plasma: Anti-A and anti-B antibodies
A+
give to: A+, AB+
receive from: A+, A-, O+. O-
B+
give to: B+, AB+
receive from: B+, B-, O+, O-
O+
give to: O+, A+, B+, AB+
receive from: O+, O-
AB+
give to: AB+
receive from: all
A-
give to: A+, A-, AB+, AB-
receive from: A-, O-
O-
give to: all
receive from: O-
B-
give to: B+, B-, AB+, AB-
receive from: B-, O-
AB-
give to: AB-, AB+
receive from: A-, B-, O-, AB-
Effects of a Mismatched Transfusion
1) Disrupts oxygen-carrying capacity
2) Agglutinated cells block small
blood vessels – damage to brain,
heart and kidney
3) Macrophages destroy
agglutinated RBCs due to immune
response releasing large amounts
of hemoglobin (Hb) – can lead to
kidney failure; recycling of Hb
causes increase in bilirubin which
can result in jaundice
There are five types of white blood cells (WBCs) and these are also called
leukocytes
Neutrophils (most common)
Lymphocytes
Monocytes
Eosinophils
Basophils (least common)
-large, most are found in connective tissue and lymphatic system organs, small number in blood
neutrophils
-acute infection
lymphocytes
-inflammation
-chronic infection
B lymphocytes, T lymphocytes, natural killer cells
monocytes
-become macrophages after leave bloodstream
-chronic infection
eosinophils
-allergies
-parasite infection
basophils
-allergic reaction
-secrete histamine and heparin
-anaphylaxis
characteristics of all WBC
1) Emigration via diapedesis
2) Ameboid movement
3) Positive chemotaxis
granulocytes
-neutrophils
-eosinophil
-basophils
neutro. eos. can phagocytose pathogens, debris or other material
agranulocytes
-monocyte
-lymphocyte
largest, monocytes become macrophages once they leave peripheral blood stream, can also phagocytose
platelets
-originate from megakaryocytes
- Platelet production is stimulated by the hormone thrombopoietin (TPO) which is produced by the kidneys
- Platelets have a short life span of
approximately 9 – 12 days, removed by phagocytes in spleen
- Platelets are important in the clotting response
- Spleen is a storage site – contains about 1/3 of all platelets; mobilize during
Hemostasis -a sequence of responses that stop bleeding
-vascular spasm
-platelet plug formation
-platelet adhesion
-platelet aggregation
-coagulation (clotting)
coagulation 3 pathways
-extrinsic (factor III or tissue factor or thromboplastin
-intrinsic (factor XI)
-common (factor X)
firbrinolysis
Plasmin – the enzyme that
digests fibrin threads and
inactivates some clotting factors
Hemophilia
– blood disorder caused by lack of, or inaction, of one or more clotting factor.
-Most common type is hemophilia A, in which clotting factor VIII is missing.
- Symptoms: severe hemorrhage after minor injuries, frequent nosebleeds, hematomas, blood in urine (hematuria)
