Podcast
Questions and Answers
Which of the following is NOT a function of blood?
Which of the following is NOT a function of blood?
Blood is made up of 45% plasma and 55% formed elements.
Blood is made up of 45% plasma and 55% formed elements.
False
What is the primary liquid component of blood?
What is the primary liquid component of blood?
blood plasma
Blood accounts for _____% of your total body mass.
Blood accounts for _____% of your total body mass.
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Match the formed elements of blood with their primary functions:
Match the formed elements of blood with their primary functions:
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What is the primary role of eosinophils in the immune system?
What is the primary role of eosinophils in the immune system?
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Basophils have a nucleus that is usually obscured by granules.
Basophils have a nucleus that is usually obscured by granules.
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What do neutrophils release at the site of infection to disrupt bacterial membranes?
What do neutrophils release at the site of infection to disrupt bacterial membranes?
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Agranular leukocytes, such as lymphocytes, have granules that are too small to see with a ________ microscope.
Agranular leukocytes, such as lymphocytes, have granules that are too small to see with a ________ microscope.
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Match the following leukocytes with their functions:
Match the following leukocytes with their functions:
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What triggers the movement of leukocytes towards a site of infection?
What triggers the movement of leukocytes towards a site of infection?
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Hemostasis is the same as homeostasis.
Hemostasis is the same as homeostasis.
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What is the average adult hematocrit value?
What is the average adult hematocrit value?
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Erythrocytes contain mitochondria, allowing them to consume the oxygen they carry.
Erythrocytes contain mitochondria, allowing them to consume the oxygen they carry.
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What hormone increases the number of erythrocytes in the blood?
What hormone increases the number of erythrocytes in the blood?
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The process of blood cell formation is known as __________.
The process of blood cell formation is known as __________.
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Which type of stem cells develop into multiple cell types during blood cell formation?
Which type of stem cells develop into multiple cell types during blood cell formation?
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Match the following types of leukocytes with their characteristics:
Match the following types of leukocytes with their characteristics:
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Blood cells must be replenished continuously because they are long-lived.
Blood cells must be replenished continuously because they are long-lived.
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What is the primary function of hemoglobin in erythrocytes?
What is the primary function of hemoglobin in erythrocytes?
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Study Notes
Extracellular Fluids
- Three extracellular fluids: blood, interstitial fluid, and lymph
- Nutrients move from blood to interstitial fluid to tissues
Blood: Composition and Characteristics
- Blood is formed elements (cells) in a liquid extracellular matrix (ECM) called blood plasma
- Blood is part of the cardiovascular system (blood, blood vessels, heart)
- Hematology is the study of blood and blood-forming tissues
- Blood accounts for ~8% of body mass
- Average male blood volume: 5-6 L; Average female blood volume: 4-5 L
- Blood is more viscous (thick) than water
- Blood temperature: ~38ºC; Blood pH: 7.35-7.45
- Three main functions:
- Transportation: oxygen, nutrients, hormones, heat, waste
- Regulation: pH, body temperature, osmotic pressure
- Protection: against blood loss, invasion, and disease
Blood Composition
- Two components:
- Blood plasma (55%): pale yellow liquid ECM with dissolved substances (mostly water)
- Proteins: albumin (54%): maintains osmotic pressure; globulins (38%): antibodies and transport proteins; fibrinogen (7%): blood clotting
- Other solutes (1.5%): electrolytes, nutrients, enzymes, hormones, gases, metabolic wastes
- Formed elements (45%): erythrocytes, leukocytes, platelets
- Blood plasma (55%): pale yellow liquid ECM with dissolved substances (mostly water)
Formed Elements
- Erythrocytes (red blood cells):
- Most abundant
- Transport oxygen (O2) and carbon dioxide (CO2)
- Mature cells lack organelles; filled with hemoglobin
- Leukocytes (white blood cells):
- Many types, fight infection and invasion
- Platelets (thrombocytes):
- Cell fragments
- Form clots
Blood Cell Formation (Hemopoiesis)
- Continuous process in red bone marrow
- Red bone marrow locations: epiphyses of long bones and most of the axial skeleton
- Starts from pluripotent stem cells
- Two lineages: myeloid and lymphoid stem cells
- Develop into precursor cells that differentiate into blood elements
- Only WBCs divide after leaving bone marrow
Regulation of Blood Cell Formation
- Hematopoietic growth factors regulate blood cell formation
- Erythropoietin (EPO): produced in kidneys; stimulates erythrocyte production
- Thrombopoietin (TPO): produced in liver; stimulates platelet production
- Cytokines: stimulate leukocyte and lymphocyte proliferation
Erythrocytes: Structure and Function
- Biconcave discs for large surface area and flexibility
- Anucleate and lack most organelles at maturity
- Filled with hemoglobin (Hb) for oxygen transport (up to 4 molecules)
- Can carry ~23% of carbon dioxide
- Contain carbonic anhydrase: converts CO2 into bicarbonate, important in blood buffering
- Nitric oxide (NO): acts as a hormone, released by endothelial cells; causes vasodilation
Erythrocyte Life Cycle
- ~120 days life span
- Worn-out/damaged RBCs are destroyed by macrophages in liver, spleen, or red bone marrow
- Components of hemoglobin broken down:
- Globin is recycled into amino acids
- Iron (Fe) is salvaged and reused
- Heme products are excreted in the bile, urine, or feces
Erythropoiesis
- Tightly controlled process
- Stimulus: low tissue oxygen (hypoxia)
- Sensors: kidney cells
- Control center: kidney cells produce EPO
- Effectors: proerythroblasts in red bone marrow, mature faster; increased reticulocytes in circulation
- Result: more erythrocytes for increased oxygen delivery
Leukocytes: Structure and Function
- Granular leukocytes: neutrophils, eosinophils, basophils
- Agranular leukocytes: lymphocytes, monocytes
- All organelles present, no hemoglobin
- Key Functions during infections/damage: inflammation, chemotaxis, emigration, tissue disinfection, tissue healing
Phagocytic Leukocytes
-
Neutrophils: most rapid responders, phagocytic, multi-lobed nucleus, release lysozyme, oxidizing chemicals. defensins.
-
Eosinophils: fight parasites, two-lobed nucleus with linker bridge,, acidic granules, secrete histaminase
-
Basophils: two-lobed or obscured nucleus, basic granules, release histamine, heparin, serotonin - inflammatory response
Agranular Leukocytes
-
Lymphocytes: various sizes, originate from lymphoid stem cells, key role in immunity and viral/cancerous cell defence
-
Monocytes: originate from myeloid stem cells, differentiate into macrophages (wandering phagocytosis)
Leukocyte Function: Inflammation and Immunity
- WBCs defend against infection and invasion.
- MHC proteins identify cells as "self".
- Mucous membranes trap invaders.
- Accumulation at infection sites upon successful invasion
- Emigration (WBC exit bloodstream into tissue)
- Chemotaxis (WBCs move towards infection site using chemical signals).
Platelets (Thrombocytes)
- Formed from megakaryocytes fragments
- Contain granules with clotting factors
- Life span: 5-9 days
- Crucial for hemostasis (preventing excessive bleeding)
Hemostasis
- Three steps:
- Vascular spasm: blood vessel constriction
- Platelet plug formation: platelets adhere, activate, aggregate
- Blood clotting: coagulation (reinforces platelet plug with protein fibers)
Blood Clots
- Coagulation requires clotting factors (calcium ions, enzymes, and substances from platelets and damaged tissues)
- Two pathways: intrinsic and extrinsic (activated by different triggers)
- Common pathway: activation of factor X, prothrombinase, thrombin, conversion of fibrinogen to insoluble fibrin, and factor XIII activation
Regulation of Blood Clotting
- Tightly regulated to prevent thrombosis (clots) or hemorrhage
- Risks of thrombosis: stroke, pulmonary embolism
- Risk of hemorrhage: excessive bleeding
- Associated diseases: Hemophilia (insufficient clotting factors, common in males), Anemia (lower than normal erythrocytes) , Polycythemia (too many erythrocytes)
Blood Groups (ABO and Rh)
- ABO blood groups based on glycolipid antigens on erythrocytes
- Agglutinins (antibodies) bind to foreign antigens
- Agglutination (clumping of RBCs) occurs upon antibody binding
- HDN (hemolytic disease of the newborn) occurs when maternal and fetal blood mix (Rh incompatibility)
Diseases of Blood
- Anemia (low RBC count)
- Sickle cell disease (genetic mutation affecting hemoglobin folding)
- Hemophilia (disorder affecting clotting factors)
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Description
Explore the fundamentals of extracellular fluids, focusing on blood, interstitial fluid, and lymph. This quiz delves into the composition, characteristics, and vital functions of blood, including its role in transportation, regulation, and protection in the body. Test your knowledge on the specifics of blood composition and its importance in human physiology.
