Chapter 18 - Cardiovascular System: Blood Flashcards
What makes up the cardiovascular system?
heart and blood vessels
What do arteries do?
transport blood away from the heart
What do veins do?
transport blood toward the heart
What are capillaries & their functions?
permeable, microscopic vessels between arteries and veins
- Sites of exchange between blood and body tissues
- oxygen & nutrients exit blood
- CO2 & cellular waste enter blood
What makes up blood?
- formed elements (erythrocytes, leukocytes, platelets)
- plasma
Erythrocytes (red blood cells)
transport respiratory gases in the blood (O2 & CO2)
- most numerous
- anucleate cells appear pink or pale purple on smear
- biconcave disks
Leukocytes (white blood cells)
defend the body against pathogens
- not as numerous as erythrocytes
- larger than erythrocytes
- nucleus is very visible
Platelets
help clot the blood and prevent blood loss from damaged vessels
- cellular fragments that are much smaller than erythrocytes or leukocytes
What is plasma?
fluid portion of blood containing plasma proteins and dissolved solutes
Transportation
- formed elements, dissolved molecules, and ions throughout body
- transports O2 from & CO2 to lungs for gas exchange
- nutrients absorbed from GI tract
- hormones released by endocrine glands
- heat and waste products from systemic cells
Regulation
- body temperature, body pH, and fluid balance
Body temperature
blood absorbs heat from body cells (especially skeletal muscle) as it passes through body tissue blood vessels. Heat is then released at body surface
Body pH
blood absorbs acid and base from body cells
- contains chemical buffers that bind and release H+ ions to maintain pH until the excess is eliminated
Fluid balance
water is added to blood from GI tract and lost in urine, sweat, respired air. Constant exchange of fluid between blood plasms in capillaries & interstitial fluid surround body tissue cells. Proteins and ions in blood exert osmotic pressure to pull fluid into capillaries to help maintain fluid balance
Protection
blood contains leukocytes, plasma proteins, and other molecules to protect body
oxygen-rich blood color
bright red or scarlet
oxygen-poor blood color
dark red
Volume
average adult: 5 liters but can range 4-6
Viscosity
4 - 5 times more viscous (thicker) than water
Plasma concentration
relative concentration of solutes is typically 0.9% concentration
determines whether fluids move into or out of the plasma by osmosis
Temperature
almost 2 degrees F higher than body temperature
Blood pH
blood plasma is slightly alkaline, between 7.35 and 7.45 pH
Whole blood
both plasma and formed elements
Centrifuge
device that spins blood sample in a tube so heavier components collect at the bottom
- erythrocytes bottom layer (44% sample)
- buffy coat (leukocytes & platelets) middle layer (<1% sample)
- plasma top of sample (55% of blood)
Hematocrit
percentage of the volume of all formed elements in the blood
Blood smear
all components of the formed elements can be viewed
Composition of blood plasma
- primarily water (92%). Where formed elements are suspended & proteins/solutes dissolve
- albumin (58% of plasma proteins)
- globulins (37% of plasma proteins)
- fibrinogen (4% of plasma proteins)
- Regulatory proteins (<1% of plasma proteins)
- other solutes (1% of blood plasma)
Colloid
Opaque mixture composed of water and solute
Colloid osmotic pressure (COP)
osmotic pressure exerted by plasma proteins. Responsible for drawing fluids into the blood and preventing excess fluid loss from capillaries into interstitial fluid.
Albumin
- smallest
- most abundant of plasma proteins
- exerts greatest COP
- contributes to viscosity
- transports selected molecules
Globulins
- second largest group of plasma proteins
- Alpha-globulins (small) transport lipid and some metal ions
- beta-globulins (large) transport lipids and iron ions
- gamma-globulins(“immunoglobulins or antibodies”) immobilize pathogens
Fibrinogen
- participates in coagulation
- following trauma to walls of blood vessels, fibrinogen is turned into long, insoluble strands of fibrin that help form clots
Regulatory proteins
- Enzymes to accelerate chemical rxns in blood
- hormones being transported throughout the body to target cells
Other solutes
- electrolytes (Na, K, Ca, Cl, Fe, bicarbonate H)
- nutrients (amino acids, glucose, cholesterol, vitamins, fatty acids)
- respiratory gases (oxygen, CO2)
- wastes (breakdown products of metabolism, like lactate, creatinine, urea, bilirubin, ammonia)
Types of leukocytes
- neutrophils
- eosinophils
- basophils
- monocytes
- lymphocytes
Hematopoiesis (hemopoiesis)
production of formed elements in the blood
- begins in embryonic period of development when the yolk sac forms blood stem cells and primitive formed elements
- 5th week development: liver becomes primary site for hematopoiesis
- 5th month: begins in red bone marrow (myeloid tissue)
Hemocytoblasts
hematopoietic stem cells
immature cells in red bone marrow that produce all types of formed elements
- produce two lines for blood cell development
- myeloid line: forms erythrocytes, all leukocytes except lymphocytes, megakaryocytes
- lymphoid line: forms only lymphocytes
Colony-stimulating factors (CSFs) or Colony-forming units (CFUs)
- growth factors that promote cellular growth/differentiation, except for erythropoietin (hormone)
Erythropoiesis
production of erythrocytes (~5 days)
1. myeloid stem cell influenced by multi-CSF forms progenitor cell
2. progenitor cell forms proerythroblast (large, nucleated cell)
3. becomes erythroblast (slightly small, ribosomes producing hemoglobin protein in cytosol)
4. Normoblast (smaller w/ more hemoglobin & ejected nucleus)
5. reticulocyte (immature erythrocyte) is formed. It has lost all organelles except ribosomes so it can continue to produce hemoglobin for a short time
6. 1 - 2 days after entering circulation, ribosomes degenerate and reticulocyte becomes mature erythrocyte
Leukopoiesis
production and development of leukocytes
- three types of maturation processes
1. granulocyte maturation
2. monocyte maturation
3. lymphocyte maturation
Granulocyte maturation (Leukopoiesis)
- neutrophils, basophils, eosinophils are derived from myeloid stem cell
- stem cell stimulated by multi-CSF & GM-CSF to form progenitor cell
- granulocyte line develops when progenitor cell forms myeloblast under G-CSF influence
- myeloblast differentiates into one of three types of granulocytes
Monocyte maturation (Leukopoiesis)
- derived from myeloid stem cell
- stem cell differentiates into progenitor cell
- Progenitor cell under M-CSF influence forms. This is the monocyte line
- monoblast forms promonocyte that differentiates and matures in a monocyte
Lymphocyte maturation (Leukopoiesis)
- lymphocytes are derived from a lymphoid stem cell through the lymphoid line
- lymphoid stem cell differentiates into B-lymphoblasts and T-lymphoblasts
- B-lymphoblasts mature into B-lymphocytes & T-lymphoblasts mature into T-lymphocytes
- some lymphoid stem cells differentiate directly into NK (natural killer) cells
Thrombopoiesis
formation of blood platelets (thrombocytes)
1. myeloid stem cell produces a committed cell, megakaryoblast
2. megakaryoblast matures under thrombopoietin influence to form a megakaryocytes
3. each megakaryocytes then produces thousands of platelets
Proplatelets
long extensions from megakaryocyte that produces platelets
- proplatelets extend through blood vessel wall in the red bone marrow. Force from blood flow “slices” them into the fragments we know as platelets
Hemoglobin
a red-pigmented protein that transports O2 & CO2
- consists of four protein molecules called globins
- can bind four O2 molecules
- each chain has a heme group (binds iron, which transports O2)
- alpha chains
- beta chains
Erythropoietin (EPO)
hormone that stimulates erythropoiesis
- primarily produced by kidneys, but small amount from liver
- EPO release stimulated by decrease in blood O2 levels
- Chemoreceptors within kidneys detect low blood O2 levels and certain cells release EPO
- EPO transported through blood to red bone marrow where it will stimulate myeloid cells to increase erythrocyte production rate
- testosterone stimulates kidneys to produce more EPO
Erythrocyte destruction
- erythrocyte has finite 120 day lifespan
- does not have capabilities to replace or repair damaged membrane regions
- aging & wear-and-tear cause erythrocytes to become more fragile and less flexible
- daily, 1% of oldest circulating erythrocytes are removed from blood (phagocytized by macrophages in spleen/liver)
Erythrocyte destruction steps
- liver & spleen: hemoglobin removed. Heme w/ iron removed from globin. Globin broken into free amino acids. Iron removed from heme. Heme group released form hemoglobin converted into biliverdin (green pigment). Biliverdin converted to yellow pigmented bilirubin in macrophages
- blood: bilirubin released into blood & transported by albumin to liver
- liver: bilirubin removed from blood by liver
- small intestine: bilirubin is converted within to urobilinogen (has two fates)
- small & large intestine: urobilinogen ca continue through small intestine and into large and eventually be converted to intestinal bacteria, stercobilin, which is expelled through feces
- blood & kidneys: urobilinogen can be absorbed back into the blood and converted to urobilin, that is excreted by the kidneys
Transferrin
globulin protein that transports iron to liver or spleen
- iron binds to storage proteins called ferritin and hemosiderin
ABO blood group
- two surface antigens called A and B
- Type A: erythrocytes with surface antigen A only
- Type B: erythrocytes with surface antigen B only
- Type AB: erythrocytes with both surface antigen A and B
- Type O: erythrocytes with neither surface antigen A or B
Surface antigens (agglutinogens)
antigens that project from the surface of an erythrocyte molecule
- determine blood type
ABO antigens
- Y-shaped protein that binds to a specific antigen that is perceived as foreign to the body
- anti-A
- anti-B
1. Type A contains anti-B in plasma
2. Type B contains anti-A in plasma
3. Type AB contains neither anti-A or anti-B in plasma
4. Type O contains both anti-A and anti-B in plasma
Rh factor (surface antigen D)
- common surface antigen on erythrocyte plasma membrane that determines Rh blood type
Rh blood type
determined by presence or absence of Rh surface antigen (Rh factor or surface antigen D)
1. Rh positive: antigen D present
2. Rh negative: antigen D absent
anti-D antibodies
appear in the blood ONLY when Rh- individual is exposed to Rh+ blood
- due to inappropriate blood transfusion or certain pregnancies
1. Rh positive: never exhibit anti-D antibodies
2. Rh negative: can exhibit anti-D antibodies, and that can occur only after exposure to surface antigen D
Agglutination
process by which cells clump due to cross-linking by antibodies
- inappropriate blood transfusion
- clumps can block blood vessels & prevent normal circulation
- clumps may eventually rupture (hemolysis)
Diapedesis
passage of leukocytes (WBC) through the intact blood vessel wall
Chemotaxis
process in which leukocytes are attracted to a site of infection by the presence of molecules release by damaged/dead cells or invading pathogens
Neutrophil (granulocyte)
- multilobed nucleus (as many as 5)
- cytosol contains neutral or pale specific granules
- phagocytize pathogens (especially bacteria)
- release enzymes that target pathogens
Eosinophil (granulocyte)
- bilobed nucleus
- cytosol contains reddish or pink-orange specific granules
- phagocytize antigen-antibody complexes and allergens
- release chemical mediators to destroy parasitic worms
Basophil (granulocyte)
- bilobed nucleus
- cytosol contains deep blue-violet specific granules
- release histamine (vasodilator & increases capillary permeability) & heparin (anticoagulant) during inflammatory rxns
Monocyte (agranulocyte)
- kidney-shaped or C-shaped nucleus
- pale staining nucleus w/ abundant cytosol
- exit blood vessels and become macrophages
- phagocytize pathogens (bacteria, viruses), cellular material, dead cells, debris
Lymphocyte (agranulocyte)
- round or slightly indented nucleus (fills cell in smaller lymphocytes)
- dark stained nucleus w/ thin rim of cytosol
- coordinate immune cell activity
- attack pathogens & abnormal/infected cells
- produce antibodies
Differential count (WBC differential count)
measures amount of each type of leukocyte in blood to determine whether any circulating are immature
Hemostasis
stoppage of bleeding when blood vessel is damaged
- vascular spasm
- platelet plug formation
- coagulation
Vascular spasm
first stage in hemostasis
- damage to smooth muscle within vessel causes smooth muscle contraction, resulting in vasoconstriction, that limits the amount of blood that can leak
- spasm continues during next phase, as platelets & endothelial cells release chemicals to further stimulate the vascular spasms
Platelet plug formation
second stage of hemostasis
- collagen fibers within connective tissue internal to the endothelial cells in the vessel wall are exposed
- platelets begin to stick to the exposed collagen fibers with the assistance of von Willebrand factor (a plasma protein)
- platelet morphology changes (cytosol degenerates, releasing chemicals)
- plug forms to close off the injury
Platelet plug response to chemical release
- prolonged vascular spasm: (due to smooth muscle contractions) release of serotonin & thromboxane A2
- attraction of other platelets: release of ADP & thromboxane A2, which facilitates degranulation and release of chemicals
- stimulation coagulation: release of procoagulants the enhance blood clotting (third phase)
- repair of the blood vessel as platelets secrete substances to stimulate epithelial tissue, smooth muscle, and fibroblasts to replicate
Coagulation phase
coagulation - formation of blood clot
- protein network of fibrin (derived from fibrinogen)
Clot retraction
occurs as the clot is forming when actinomyosin contracts to squeeze the serum out of the developing clot, making it smaller as the vessel walls pull together
plasmin degrade fibrin strands through fibrinolysis
Sympathetic response to blood loss
- severe cases when over 10% blood volume is lost, a survival response is initiated. Sympathetic division of ANS activates to increase vasoconstriction of vessels, increase heart rate, and increase force of heart contraction to maintain blood pressure
- blood volume decrease, blood pressure decreases
