Blood Flashcards
Intro
- blood is a liquid connective tissue made up of plasma (55%) and formed elements (45%)
- formed elements are the various kinds of blood cells
- 3 general functions: transportation, regulation, and protection
Formed elements of blood
- 45% total blood volume
- RBCs, WBCs, and platelets
Blood volume
- about 8% of total body weight in average-sized adults
- blood volume varies according to age, body type, sex, and method of measurement
- females = 4-5L
- males = 5-6L
Hematocrit
The volume percent of red blood cells in whole blood (centrifuge)
Blood plasma
- plasma = whole blood - formed elements
- the liquid part of blood; clear, straw-colored fluid made of 90% water and 10% solutes
- maintains normal circulation
- solutes 6-8% of plasma solutes are proteins, consisting of 3 main compounds
1. Albumins: maintain osmotic balance of blood
2. Globulins: essential component of the immunity mechanism
3. Fibrinogen: key role in blood clotting
Erythrocytes
Bicóncavo discs to increase surface area
- hemoglobin: red protein pigment is the primary component
- RBCs are the most numerous of the formed elements
Functions of RBCs
- transport of oxygen and carbon dioxide in the body
- both of these functions depend on hemoglobin (280 million hemoglobin molecules/RBC)
- the total surface area of all RBCs in an adult is enormous
Hemoglobin
- approx 200-300 million molecules of hemoglobin within each RBC
- each hemoglobin is made of 4 protein chains
- each protein chain is bound to red pigment which contains one iron atom (heme group)
- the structure allows each hemoglobin molecule to attach with four O2 which allows RBC to transport O2 where it it needed
Anemia
Lack of blood
- used to describe a reduction in the number or volume of functional RBCs in a given unit of whole blood
- an adult who has a hemoglobin content of less than 10g/100ml of blood
Erythropoiesis
Entire process of RBC formation
- RBC formation begins in the red bone marrow with hematopoietic stem cells that go through several stages of development to become erythrocytes
- the entire maturation process requires approx 4 days
- myeloid or lymphoid stem cells
- RBC are formed and destroyed at a rate of approx 100 million/min in an adult
- RBC production speeds up if blood oxygen levels reaching the tissues decrease
- oxygen deficiency increases RBC numbers by increasing the excretion of a hormone named EPO (erythropoietin)
Destruction of RBC
- life span avg = 105-120 days
- they often break apart, in capillaries as they age
- macrophage cells ingest and destroy the aged abnormal, or fragmented RBC
- iron is returned to the bone marrow for use in synthesis of new hemoglobin
Blood types
Refers to the type of cell markers or antigens present on RBC membranes
- presence or absence of these antigens determines a persons blood type
ABO pic
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ABO pic
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ABO explanation
A) antigen A
B) antigen B
AB) both antigen A and antigen B; universal recipient
O) neither antigen A nor antigen B RBS; universal donor
leukocytes
WBC (5 types)
- classified according to the presence or absence of granules and the staining quality of cytoplasm
- granular: include 3 WBC that have large granules in cytoplasm
- agranular: include 2 WBC without cytoplasmic granules
Granulocytes vs agranulocytes
Never Eat Bananas Like Monkeys G: 1. Neutrophils 2. Eosinophils 3. Basophils A: 1. Lymphocytes 2. Monocytes
Granulocytes
- make up approx 65% of total WBC in normal blood sample
- active phagocytosis cells
- migrate out of blood vessels and enter the tissue space
- early responders to tissue damage. Release enzymes that can lose bacteria and oxidants (defensins) that exhibit a broad range of antibiotic activity
Eosinophils
- typically 2-5% of circulating WBC
- weak phagocytes, but are capable of ingesting antigen-antibody complexes
- provide protection against infections caused by parasitic worms and allergic reactions
- release enzymes like histaminase
Basophils
- Least numerous of WBC (only 0.5-1%)
- these granules intensify inflammation during allergic reactions (histamine - heparin - serotonin)
Lymphocytes
- smallest of WBC
- second most numerous type of WBC, next to neutrophils
- account for approx 25% OF CIRCULATING WBC
- T lymphocytes, B lymphocytes, and natural killers (NK)
Monocytes
Largest type of leukocyte
- migrate from the blood into the tissues where they enlarge and differentiate into macrophages
- they are mobile and highly phagocytosis cells
- capable of engulfing large bacterial organisms and viral-infected cells
WBC numbers
- microliter of normal blood usually contains 5000-10000 leukocytes
- WBC numbers have clinical significance because they change with certain abnormal conditions
Formation of WBC
- granular and agranular leukocytes mature from the undifferentiated hemopoietic stem cell
- Neutrophils, eosinophils, basophils, and a few lymphocytes and monocytes originate in red bone marrow; most lymphocytes and monocytes develop from hemopoietic stem cells (lymphoid stem cells) in lymphatic tissue
Platelets
- small, nearly colorless bodies that usually appear as irregular spindles or oval discs
- 3 physical properties of platelets
1. Agglutination
2. Adhesiveness
3. Aggregation
Hemostasis
The stoppage of blood flow and may occur as an end result of any one of several body defense mechanisms
- mechanisms to reduce blood loss: vascular spasms, platelet plug formation, coagulation
- reduces infection risk
Functions of platelets
- important roles in hemostasis and blood coagulation
- 1-5 sec after injury to a blood capillary, platelets will adhere to the damaged lining of the vessel and to each other to form a hemostatic platelet plug that helps stop the flow of blood into the tissues
Formation of platelets
- formation of platelets is refereed to as thrombopoiesis
- formation and life span of platelets is typically 7-10 days
- formed in red bone marrow, lungs, and spleen
Blood clotting
- when necessary formed elements of blood become trapped in a network of insoluble protein fibers called fibrin = blood clot
- coagulation
- if blood clots too easily = thrombosis
- if blood takes too long to clot = hemorrhage
Current explanation of coagulation
Production of prothrombinase activated by the following pathways
- extrinsic pathway: chemicals released from damaged tissues
- intrinsic pathway: chemicals present in the blood
Stage 2: conversion of prothrombin to thrombin
Stage 3: conversion of fibrinogen to fibrin and production of fibrin clot
Conditions that oppose clotting
- the perfectly smooth surface of an intact blood vessel is opposed to clotting
- platelets won’t adhere to such a smooth surface
- blood contains antithrombins which are substances that oppose or inactivate thrombin; prevent thrombin from converting to fibrinogen to fibrin
Conditions that hasten clotting
- rough spots in the endothelium (atherosclerosis or fatty deposits in blood vessels)
- abnormally slow blood flow (immobilizations like surgery and bed rest)
Blood cell pic
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Blood disorders
- WBC
- RBC
- Clotting disorders
- Anemia
- Multiple myeloma; leukemia
- Hemophilia (inherited deficiency of clotting)
