Chapter #19: The Blood Flashcards
What does the cardiovascular system consist of?
-A pump (the heart)
-A series of conducting hoses (blood vessels)
-Fluid connective tissue (blood)
What is blood?
Specialized connective tissue
Functions of blood
-Transporting dissolved gases, nutrients, hormones, and metabolic wastes
-Regulating pH, ion composition of interstitial fluids
-Restricting fluid losses at injury sites
-Defending against toxins and pathogens
-Stabilizing body temperature
What are the parts of the blood?
-plasma
-formed elements
Plasma
fluid and proteins
Formed elements (in the blood)
-cells and cell fragments
-Red blood cells
-white blood cells
-cell fragments like platelets
Types of plasma proteins
- Albumins
- Globulins
- Fibrinogen
Albumins
-Plasma osmolarity
-Transport fatty acids, thyroid hormones, some steroid hormones, etc.
Globulins
-Antibodies (immunoglobulins)
-Transport globulins
Fibrinogen
Soluble protein that functions in clotting
Hemopoiesis
Process of producing formed elements (RBCs, WBCs, and cell fragments)
Platelets
are small, membrane-bound cell fragments that contain enzymes and other substances important for clotting
Red Blood Cells
-Also called erythrocytes
-Contain hemoglobin
Hemoglobin (Hgb)
-part of RBCs
-Red pigment
-Binds and transports oxygen and carbon dioxide
How is the RBC count measured?
-number of RBCs per microliter of whole blood
-males have a slightly higher RBC count than females
Hematocrit (HCT)
-Packed cell volume (PCV)
-Percentage of formed elements in blood
-males have a higher HCT count than females
Structure of RBCs
-Small, highly specialized cells
-Biconcave discs: Thin central region and thicker outer margin
Mature RBCs
-Anucleate (lack nuclei)
-Lack mitochondria and ribosomes
-Unable to divide, synthesize proteins, or repair damage
-Live about 120 days
Hemoglobin Structure
-Four globular protein subunits
-Iron attaches to oxygen (HbO2)
–dissociates easily
Four globular protein subunits
-Two alpha (α) chains and two beta (β) chains
-Each with one molecule of heme
-Each heme contains one iron ion
Hemoglobin function
-Each RBC contains millions of Hb molecules
–Each RBC can carry over a billion molecules of O2
-In peripheral capillaries, where O2 is low, hemoglobin
–Releases O2
–Binds CO2
-At the lungs, where O2 is high, hemoglobin
–Binds O2
–Releases CO2
Erythropoiesis
-Red blood cell formation
-In adults, occurs only in myeloid tissue (red bone marrow)
Stages of RBC maturation
-The last 2 stages of RBC maturation:
–Reticulocyte (day 5 – 7)
—Hb synthesis
—still contains RNA
-Mature RBC
Erythropoietin (EPO)
-Hormone that stimulates erythropoiesis
-Secreted by kidneys and liver when oxygen in peripheral tissues is low (hypoxia)
–Released into blood –> Red Bone Marrow –> Stem cells and developing RBC’s
—Speeds up RBC maturation
When is erythropoietin released?
-Anemia
-Decreased blood to kidneys
-Decreased air O2 content
-Damaged lungs
Peripheral Capillaries
smallest microscopic blood cell
Hemoglobin recycling
-macrophages of spleen, liver, and red bone marrow
Macrophages
-Engulf aged RBCs
-Remove Hb molecules from hemolyzed (ruptured) RBCs
-Break Hb into components
–Only the iron of each heme unit is recycled
-Iron is removed from each heme unit
–Converted to orange-yellow bilirubin
-Bilirubin is excreted by liver in bile
–Jaundice is caused by buildup of bilirubin
Surface antigens
-Substances on plasma membranes that identify cells to immune system
-Normal cells are ignored and foreign cells are attacked
Blood type
Determined by the presence or absence of surface antigens on RBCs: A, B, and Rh (or D)
Four blood types
-Type A (surface antigen A)
-Type B (surface antigen B)
-Type AB (antigens A and B)
-Type O (neither A nor B)
Rh blood group
-Based on presence or absence of Rh antigen
-Rh positive (Rh+)
–Rh surface antigen is present (e.g., Type O+)
-Rh negative (Rh–)
–Rh antigen is absent (e.g., Type O–)
Agglutinogens
-Surface antigens on RBCs
-Screened by immune system
Agglutinins
-Antibodies in plasma
-Attack antigens on foreign RBCs
–Causing agglutination (clumping) of foreign cells
Agglutinins (types of them for each blood type)
-Type A blood
–Anti-B antibodies
-Type B blood
–Anti-A antibodies
-Type O blood
–Both anti-A and anti-B antibodies
-Type AB blood
–Neither anti-A nor anti-B antibodies
-Only sensitized Rh– blood has anti-Rh antibodies
Hemolysis
the breaking of any RBCs
Cross-reaction (transfusion reaction)
-May occur in a transfusion of blood or plasma from one person to another
-Occurs if donor and recipient blood types are not compatible
-Plasma antibody meets its specific surface antigen
–RBCs agglutinate and may hemolyze
Compatibility testing
-Performed in advance of transfusions
-Cross-match testing : Reveals cross-reactions between donor’s RBCs and recipient’s plasma
White blood cells (WBCs)
Also called leukocytes
Function of WBCs
-Defending body against pathogens
-Removing toxins and wastes
-Attacking abnormal or damaged cells
Types of WBCs
- Neutrophils
- Eosinophils
- Basophils
- Monocytes
- Lymphocytes
Neutrophils
-Also called polymorphonuclear leukocytes
-Pale cytoplasmic granules containing
–Lysosomal enzymes
–Bactericidal (bacteria-killing) compounds
-Very active, phagocytic cells
-Attack and digest bacteria
-Degranulation: Occurs when vesicle containing pathogen fuses with lysosomes containing enzymes and defensins
–Dead neutrophils contribute to pus
Eosinophils (acidophils)
-Attack large parasites by releasing toxic compounds
-Sensitive to allergens
-Release enzymes that reduce inflammation caused by mast cells and neutrophils
Basophils
-Cross capillary endothelium and accumulate in damaged tissues
-Release:
1. Histamine—dilates blood vessels
2. Heparin—prevents blood clotting
Monocytes
-Then enter peripheral tissues to become macrophages
–Aggressive phagocytes that engulf large pathogens
–Release chemicals that attract other phagocytic cells and fibroblasts to injured area
Lymphocytes
-Continuously migrate in and out of bloodstream
-Part of body’s specific defense system
Three classes of lymphocytes
- T cells (T lymphocytes)
- B cells (B lymphocytes)
- Natural killer (NK) cells
T cells
-Cell-mediated immunity
-Attack foreign cells or control other lymphocytes
B cells
-Differentiate into plasma cells, which synthesize antibodies
Natural killer (NK) cells
-Detect and destroy abnormal cells
Platelets (thrombocytes)
-Cell fragments involved in clotting system
Functions of platelets
-Release important clotting chemicals
-Temporarily patch damaged vessel walls
Types of Platelets
- Thrombocytopoiesis
- Megakaryocytes
Thrombocytopoiesis
-Platelet production
-Occurs in red bone marrow
Megakaryocytes
-Giant cells in red bone marrow
-Produce platelets by shedding membrane-enclosed packets of cytoplasm
Hemostasis
Cessation of bleeding
Three Phases of Hemostasis
- Vascular phase
- Platelet phase
- Coagulation phase
Vascular Phase
-A cut triggers vascular spasm
–Contraction of smooth muscle fibers of vessel wall
–Lasts about 30 minutes
–Vasoconstriction
Changes in endothelium during vascular phase
-Endothelial cells contract and expose basement membrane to bloodstream
-Endothelial cells release chemical factors and local hormones
–Cause smooth muscle contraction and cell division
-Endothelial plasma membranes become “sticky”
–Adhere to platelets
–Seal off tear and prevent blood flow
Platelet phase
-Platelet adhesion: Platelets attach to exposed surfaces
-Platelet aggregation: Platelets stick to each other and endothelium/collagen with help of von willebrand factor
–Forms platelet plug that closes small breaks
-Activated platelets release clotting compounds
Coagulation phase
-Involves chain reactions of three pathways
-Fibrin mesh
–Extrinsic + Intrinsic pathways: activates prothrombinase
–Common pathway: Prothrombinase: prothrombin –> thrombin
–Thrombin: fibrinogen –> fibrin
–Fibrin –> fibrin mesh –> stable clot
Three Pathways of the Coagulation Phase
- Extrinsic pathway (exposure)
- Intrinsic pathway (platelets)
- Common pathway (form mesh)
How does the coagulation phase help with homeostasis?
-Thrombin generated in common pathway
-Forms positive feedback loop that accelerates clotting process (important in this process to stop the clot faster)
Clot retraction
-Pulls torn edges of vessel closer together
–Reduces residual bleeding
–Stabilizes injury site
-Reduces size of damaged area
–Making it easier for repair cells to complete repairs
