cardiovascular system
consists of a pump (the heart), series of conducting hoses (blood vessels), fluid connective tissue (blood)
functions of blood
transporting dissolved gases, nutrients, hormones and metabolic wastes
regulating pH, ion composition of interstitial fluids
restricting fluid losses at injury sites (hemorrhage)
defending against toxins and pathogens (carries immune system to various parts of the body)
stabilizing body temperature
blood volume
approximately 5.25 liters
whole blood
refers to a mix of plasma and formed elements
plasma
fluid and proteins
formed elements
cells and cell fragments
red blood cells, white blood cells, platelets
dissolved gases in blood
O2 — ATP production (cellular respiration)
CO2 — removed waste and acts like an acid to maintain pH
plasma proteins
albumins, globulins, fibrinogen
albumins
provide plasma osmolarity
transports fatty acids, thyroid hormones (T3, T4), some steroid hormones
plasma osmolarity
blood vessel concentration vs. interstitial fluid concentration → controls which direction fluids will be pulled
albumins pull fluid into blood vessels from the interstitial fluid due to the higher particle concentration
globulins
antibodies (immunoglobulins) released by plasma cells
or transport globulins (that work like albumin)
fibrinogen
soluble protein that functions in clotting
hemopoiesis
process of producing formed elements
platelets
small, membrane-bound cell fragments that contains enzymes and other substances that contribute to clotting
erythrocytes
aka red blood cells, contain hemoglobin
hemoglobin
red pigment, binds and transports oxygen and carbon dioxide
red blood cell count
number of erythrocytes per cubic millimeter or microliter of blood
males have slightly higher ranges/values than females
hematocrit
percentage of formed elements in blood or packed cell volume (PCV)
PCV
centrifuged blood → white, gray layer where all RBCs are packed from the sample
RBC, HCT, Hgb
provide the same clinical information and are related to each other (if one is low, the other values will also be low)
measure of RBC in the blood
structure of RBCs
small, highly specialized cells
biconcave discs (indentation on both sides) → thin central region and thicker outer margin
disease would result in variation in the shape and size
mature RBC
anuclei, lack mitochondria and ribosomes, unable to divide/synthesize proteins/repair damage
live about 120 days (it can't synthesize anything)
last stage of RBC maturation
hemoglobin structure
two alpha chains and two beta chains → each has a molecule of heme → each heme contains one iron ion
iron
attaches to oxygen (HbO2), dissociates easily as well
hemoglobin function
each RBC contains millions of Hb molecules → each can carry billions of O2 molecules
deoxygenated (in peripheral capillaries) → Hb releases O2 and binds CO2
oxygenated (lungs) → Hb binds O2 and releases CO2
erythropoiesis
red blood cell formation
only occurs in myeloid tissue (red bone marrow)
reticulocyte
day 5-7 stage of RBC maturation
low Hb synthesis and still contains RNA
do the same things as mature RBC but not as efficient due to smaller size and less Hb
high % = body compensating for lack of mature RBC low % = body is producing enough of either
erythropoietin
hormone that stimulates erythropoiesis → secreted by kidneys/liver when O2 is low in peripheral tissues
released into blood → red blood marrow → stem cells and developing RBCs (speeds up RBC maturation)
release of EPO
released due to :
anemia
decreased blood to kidneys (part of negative feedback loop)
decreased air O2 content and damaged lungs (need more RBCs to attach to more O2)
takes a couple days - weeks to take effect
hemoglobin recycling
spleen, liver and red bone marrow macrophages engulf old RBCs
remove Hb molecules from hemolysed RBCs and break Hb into components (only the iron is recycled)
anemia
low RBC count
microcytic, normal cytic, macrocytic depending on the size of RBC
hemolysis
the rupture or destruction of red blood cells
bilirubin
orange-yellow pigment in bile; produced from the iron recycled by the breakdown of hemoglobin during hemolysis
jaundice
caused by the buildup of bilirubin, results in a yellow appearance
hemoglobinuria
free floating heme/hemoglobin in urine (broken down RBCs), results in red/brown urine
due to abnormally high hemolysis in bloodstream (could be due to artificial heart valve, capillary clot, sickle anemia)
hematuria
whole RBCs in urine (heme still inside the RBC), due to kidney or blood vessel damage (UTI, inflammation)
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 presence or absence of surface antigen on RBCs (A, B, and Rh)
type A
surface antigen A, anti-B antibodies
type B
surface antigen B, anti-A antibodies
type AB
antigens A and B
type O
neither A or B antigens, anti-A and anti-B antibodies
Rh positive
Rh surface antigen is present
Rh negative
Rh antigen is absent, anti-Rh antibodies
hypoxemia
low O2 in blood
hypoxia
low O2 in peripheral tissues
agglutinogens
surface antigens on RBCs (A, B, D) and screened by immune system
agglutinins
antibodies in plasma that attack antigens on foreign RBCs (activates the clotting system) → causes agglutination
agglutination
clumping of foreign cells
cross-reaction
may occur in a transfusion of blood or plasma from one person to another when donor/recipient blood types aren't compatible
plasma antibody meets its specific surface antigen → RBCs agglutinate and hemolysis may occur
compatibility/cross-match testing
performed before transfusions → reveals cross-reactions between donor's RBCs and recipient's plasma
white blood cells
also called leukocytes
functions of WBC
defending body against pathogens (fungi, bacteria, virus, prion), removing toxins and wastes, attacking abnormal or damaged cells
WBC types
neutrophils, eosinophils, basophils, monocytes, lymphocytes
neutrophil
multinuclei, polymorphonuclear leukocytes, pale cytoplasmic granules that contain lysosomal enzymes and bactericide (bacteria-killing compounds)
very active, phagocytic cells that attack/digest bacteria
degranulation
occurs when vesicle containing pathogen fuses with lysosomes containing enzymes and defensins
dead neutrophils contribute to pus
eosinophils
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 histamine → dilate blood vessels
release heparin → prevent blood clotting
monocytes
enter peripheral tissues to become macrophages 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
T cells, B cells, natural killer cells
T cells
cell mediated immunity, attack foreign cells or control other lymphocytes
B cells
differentiate into plasma cells and form antibodies
natural killer cells
detect and destroy abnormal cells
platelet
thrombocytes, cells fragments involved in clotting system
platelet functions
release important clotting chemicals and temporarily patch damaged vessel walls
thrombocytopoiesis
platelet production from megakaryocytes, occurs in red bone marrow
megakaryocyte
giant cells in red bone marrow that produce platelets by shedding membrane-enclosed packets of cytoplasm
hemostasis
cessation of bleeding, separated into 3 phases: vascular, platelet, coagulation
vascular phase
a cut triggers vascular spasm → contraction of smooth muscle fibers of vessel wall aka vasoconstriction for 30 min
endothelial cells contract and expose basement membrane to bloodstream, release chemical factors and local hormones → smooth muscle contraction and cell division
endothelial plasma membranes become "sticky" → adhere to platelets and seal off tear to prevent blood flow
platelet phase
adhesion → attach to exposed surfaces
aggregation → stick to each other and endothelium/collagen with von willebrand factor to form a platelet plug
activated platelets release clotting compounds
coagulation phase
involves chain reactions of extrinsic, intrinsic, common pathway → creates a fibrin mesh
extrinsic/intrinsic pathways
activates prothrombinase
common pathway
prothrombinase activates prothrombin → thrombin
thrombin
activates fibrinogen to fibrin
forms a positive feedback loop that accelerates clotting process, leading to an exponential increase in speed
fibrin
creates a fibrin mesh between clot to make it more stable
clot retraction
pulls torn edges of vessel closer together (reduces residual bleeding and stabilizes injury site)
reduce size of damaged area → makes it easier for repair cells to complete repairs
pulmonary circuit
arteries carry deoxygenated blood and veins carry oxygenated blood
(opposite of systemic circuit)
arteries
carry blood away from heart, oxygenated for systemic circuit
larger than capillaries and are visible with naked eye
veins
return blood to heart, deoxygenated for systemic circuit
capillaries
exchange vessels that are 1 cell thick, interconnect the smallest arteries and veins
exchange dissolved gases, nutrients, wastes between blood and surrounding tissues
heart
great vessels connect at base (superior) and pointed tip is the apex (inferior)
sit between 2 pleural cavities in mediastinum
pericardium
surrounds heart, consists of outer fibrous layer and inner serous layer
pericardial cavity
space between parietal and visceral layers, contains pericardial fluid
serous pericardium
consists outer parietal layer and inner visceral layer (epicardium)
epicardium
covers surface of the heart (outermost layer), covered by parietal layer of serous pericardium
myocardium
cardiac muscle tissue
endocardium
covers inner surfaces of heart
tricuspid valve
right atrioventricular valve, has 3 cusps to prevent back flow of blood
blood flows from right atrium to right ventricle
door to balloon time
90 minutes
bicuspid valve
left atrioventricular valve separating the left atrium and ventricle
aka mitral valve
right ventricle
pumps deoxygenated blood to the lungs
compared to the left ventricle, it holds and pumps the same amount of blood but has thinner walls and develops less pressure
heart valves
prevent back flow of blood
atrioventricular valves
between atria and ventricles → when ventricles contract, blood pressure closes valves
papillary muscles contract and tense chordae tendineae to prevent regurgitation of blood back into atria
when open (ventricles are relaxed), semilunar valves are closed
semilunar valves
pulmonary and aortic valves to prevent back flow of blood into ventricles
when ventricles are contracting, they are opened
heartbeat
a single cardiac contract, atria contract first then ventricles contract
autorhythmic cells
pacemaker cells, control and coordinate heart (similar to neurons)
contractile cells
make up muscles in the heart and produce contractions that propel blood
great vessels
first vessels leaving the heart (aorta and pulmonary)
conducting system
electrical impulse that stimulate contraction
components include pacemaker cells and conducting cells
autorhythmicity
cardiac muscle tissue contracts without neural or hormonal stimulation