ch 19 + 20

cardiovascular system

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