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cardiovascular system
- heart, blood, blood vessels
- 2 circulatory patterns: pulmonic and systemic
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pulmonic circulation
RV (DOB) -> lungs (exchange) -> LA (OB)
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systemic circulation
LV (OB) -> body (exchange) -> RA (DOB)
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heart
- located in mediastinum
- behind sternum, between lungs
- left of midline, tipped to front
- 4 chambers
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base of the heart
- superior
- all blood vessels enter and exit
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apex of the heart
inferior
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right atrium
- upper right chamber
- receives DOB from body
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right ventricle
- lower right chamber
- receives DOB from RA
- pumps DOB to lungs
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left atrium
- upper left chamber
- receives OB from lungs
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left ventricle
- lower left chamber
- largest chamber, thickest wall
- receives OB from LA
- pumps OB to body
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auricles
- on top of RA and LA
- increases volume
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interventricular septum
septum between the ventricles
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interatrial septum
septum between the atria
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foramen ovale
- hole in the IAS of a fetus
- allows blood to move from R to L (fetal lungs immature)
-
fossa ovalis
closed foramen ovale
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atrial septum defect
- foramen ovale fails to close after birth
- must be surgically repaired
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SVC
- superior vena cava
- returns DOB to the RA from all regions above the heart
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IVC
- inferior vena cava
- returns DOB to the RA from all regions below the heart
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CS
- coronary sinus
- returns the DOB to the RA from the heart itself
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PT
- pulmonary trunk
- DOB from RV to lungs
- splits into L & R pulmonary arteries
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PV
- pulmonary veins (4 - 2R, 2L)
- returns OB from the lungs to the LA
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aorta
- OB from LV to body
- largest BV in the body
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tricuspid
- R atrioventricular valve
- between RA/RV
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bicuspid
- aka mitra or L atrioventricular
- between LA/LV
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aortic semilunar valve
entrance to aorta
-
pulmonary semilunar valve
entrance to pulmonary trunk
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chordae tendineae
- heart strings that attach valves to papillary muscles
- keep valves moving one way
- maintain tension
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epicardium
outer thin covering of the heart
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myocardium
thick middle muscle layer of the heart
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endocardium
- thin, shiny inner lining of the heart
- lines all cavities and vessels that enter/exit the heart
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pericardial sac
- thick CT bag
- 2 layers: fibrous (outer) & serous (inner)
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conduction system
- several masses of nerve tissue
- controls rate, rhythm, force of HB
- SA -> AV -> Bundle of His -> purkinje fibers
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SA node
- sinoatrial node aka pacemaker of the heart
- located in upper RA
- receives impulses from ANS
- sends impulses to LA and AV node
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AV node
- atrioventricular node
- located in lower RA
- receives impulses from SA node
- sends impulses down Bundle of His
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Bundle of His
- runs transverse through IV septum
- R and L branches
- receives impulses from AV node
- sends impulses to apex of heart
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purkinje fibers
- terminal branch of conduction system
- receives impulses from Bundle of His
- sends impulses into ventricular myocardium
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EKG
- graphical record of electrical activity of the ehart
- 3 waves: P wave, QRS complex, T wave
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P wave
- atrial depolarization
- electricity moves through both atria
- end of P wave - atria contract
-
QRS complex
- ventricular depolarization
- electricity moves through both ventricles
- end of QRS complex- ventricles contract
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T wave
- ventricular repolarization
- end of T wave - ventricles relax
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auscultation
listening to heart sounds
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lubb
- heart sound produced when AV valves close
- longer, louder sound
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dup
- heart sound produced when semilunars close
- shorter, softer sound
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heart murmur
abnormal heart sounds (swishing)
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cardiac cycle
- all events associated with blood moving through the heart
- 3 stages: ventricular filling, ventricular systole, isovolumetric relaxation
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ventricular filling
- P-wave
- overall pressure in the heart is low
- blood enters atria, moves through to ventricles
- passive filling (70%) due to gravity and weight of blood
- both cuspids open, both semilunars closed
- atria contract to empty remaining 30%
- atria relax
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ventricular systole
- pressure in ventricles rises
- cuspids close
- for 1/10 second, ventricles are completely closed chambers
- pressure opens semilunars
- ventricles contract to force blood into aorta and pulmonary trunk (called ventricular
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isovolumetric relaxation
- ventricles rekax
- pressure in ventricles drops
- semilunars close
- ventricles again closed chambers
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heart rate
- normal 75 bpm
- affected by age (decreases with age), gender (increased in women), exercise, body temp,
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cardiac output
- total volume of blood pumped out of each ventricle per minute
- formula: CO = HR x SV
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stroke volume
- amount of blood pumped out of each ventricle per beat
- 3 factors that affect SV: preload, contractility, afterload
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cardiac reserve
- ability to push cardiac output far above normal
- seen during exercise, emergency, and stress
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preload
amount of stretch on cardiac fibers just before contraction
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Frank-Starling Law of the Heart
- the greater the strecth, the stronger the contraction
- explains why R & L ventricles eject the same volume despite size differences
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contractility
- strength of contraction of individual cardiac fibers
- controlled by positive and negative inotropic agents
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positive inotropes
- increase strength of contraction
- ex: epinephrine, norepinephrine, digitalis
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negative inotropes
- decrease strength of contraction
- ex: anesthesia
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afterload
amount of pressure needed in both ventricles to open semilunars
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blood pressure
- the force exerted on vessel walls by contained blood
- affected by:
- -blood volume (^ vol ^ BP)
- -cardiac output (^ output ^ BP)
- -peripheral resistance (^ resistance ^ BP)
- -diameter of vessel (small diameter ^ BP)
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peripheral resistance
friction encountered by blood as it moves through vessel walls
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HIGHEST BP
in aorta and pulmonary trunk just after ventricles contract
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LOWEST BO
in SVC, IVC, CS, pulonary veins before blood enters atria
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ZERO BP
in atria just before contraction
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pulse pressure
- difference between systolic and diastolic
- working pressure of the blood that moves through the vessels
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hypertension
systolic > 140
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hypotension
systolic < 100
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essential hypertension
BP 220/120 or greater
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thrombus
stationary internal blood clot
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embolus
thrombus that dislodges and moves
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aneurysm
thin spot in the wall of a vessel that causes it to bulge and possible rupture
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blood vessels
3 major groups: arteries, veins, capillaries
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arteries
- carry blood (usually OB) away from the heart
- larger of the vessels
- empty into arterioles
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veins
- carry blood (usually DOB) to the heart
- supplied by venules
- less elastic than arteries
- lower BP than arteries
- have valves to prevent backflow
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capillaries
- connect arteries and veins
- made of endothelium (simple squamous ET)
- called microcirculation
- allows for passage of O2, CO2, nutrients, waste between blood and tissues
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tunica interna/intima
- inner layer of arteries and veins
- simple squamous
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tunica media
- middle, thickest layer of arteries and veins
- smooth muscle w/elastic fibers
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tunica externa/adventitia
- strongest, outer layer of arteries and veins
- collagen w/elastic fibers
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anastamosis
- life sustaining structures are supplied by a network of several arteries
- provides alternate ways for structures to receive blood
- ex: circle of willis in the brain
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trunk arteries
- ascending aorta
- --R & L coronary
- arch of aorta
- --brachiocephalic
- ----R common corotid
- ----R subclavian
- --L subclavian
- --L common corotid
- abdominal descending
- --renal arteries
- --R & L common iliac
- PIC
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trunk veins
- ----R & L subclavian
- --brachiocephalic
- --internal/external jugulars
- SVC
- ----R & L coronary veins
- --coronary sinus
- RA
- --R & L common iliac
- IVC
- PIC
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blood
- liquid connective tissue
- carries O2, nutrients, hormones to tissues
- carries waste to lungs, kidneys, sweat glands
- 38.0C, 100.4F
- 55% plasma, 45% formed elements
- pH 7.35 - 7.45
- 3 functions:
- --transportation
- --regulation (pH, temp, water content)
- --protection (antibodies, clotting)
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plamsa
- thin, watery, yellowish liquid
- 92% H20, 8% solute (protein, hormones, vitamins, nutrients, electrolytes)
- 3 groups of proteins: albumin, globulins, fibrinogen
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albumins
- 54% of plasma proteins
- maintains blood volume, water balance, amount of water entering cells, carrier molecules for facilitated diffusion
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globulins
- 38% of plasma proteins
- produce antibodies
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fibrinogen
- 7% of plasma proteins
- clotting
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hematopoiesis
- formation of blood or blood cells
- in embryo: cells formed in liver, spleen, thymus, lymph nodes, bone marrow, and yolk sac
- after birth: cells formed in red bone marrow (proximal epiphysis of humerus & femur, flat bones (sternum, ribs), cranial bones, vertebra, and pelvis)
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pleuripotent hematopoeitic stem cells
- cells that make all blood cells
- --myeloid stems
- -----RBCs
- -----WBCs (neutro, eosino, baso, monocytes)
- -----thrombocytes
- --lymphoid stems
- -----lymphocytes
- ---------plasma cells
- ------------B&T cells
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RBCs
- no nucleus - ejected before reticulocyte stage
- live 120 days - broken down in liver or spleen
- 2 million produced per second
- surrounded by selectively permeable membrane that enclose cytoplasm and hemoglobin
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RBC counts
- female: 4.8 million/mm3
- male: 5.4 million/mm3
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hemoglobin
- made of heme (iron) + globin (protein)
- O2 binds to iron, CO2 binds to protein
- takes up most space inside RBC (1/3 of weight)
- when RBC destroyed in liver, Hgb breaks down into hemosiderin, bilirubin, globin
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hemosiderin
- iron pigment that remains in the liver
- stored and eventually used to make new Hgb
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bilirubin
- waste product
- moves from blood into bile
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globin
protein metabolized in the liver
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erythropoiesis
- production of RBCs
- controlled by erythropoietin
-
renal erythropoietic factor
- enzyme produced and released by the kidneys that causes the production of more erythropoietin
- triggered by excessive blood loss
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WBCs
- fight infection
- all have nucleus
- live a few days to several months
- can leave circulatory system and move to sites of infection
- 2 classes: granular and agranular
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WBC count
5,000 - 10,000/mm3
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leukocytosis
WBC > 10,000
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granular WBCs
- small grains in cytoplasm
- 3 types: neutrophils, eosinophils, basophils
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neutrophils
- nucleus has 2-6 lobes
- first WBC to reach site of infection
- phagocytes
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eosinophils
- nucleus has 2 lobes
- fights parasites and worms
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basophils
- irregular shaped nucleus
- involved in allergic reactions
- produce 3 chemicals that aid in allergic response: histamine, heparin, seratonin
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agranular WBCs
- do not have grains in cytoplasm
- 2 types: monocytes and lymphocytes
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monocytes
- major phagocytes of the body
- more will arrive to site of infection than neutrophils
- turn into macrophages on the way to site of infection
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macrophages
- most active phagocytes in the body
- nucleus is kidney shaped
- 2 types: fixed and wandering
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lymphocytes
become B cells and T cells
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B cells
become plasmal cells that make antibodies to kill bacteria
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T cells
make cells that attack and kill viruses
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diapedesis
WBC slides out of vessel wall
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chemotaxis
WBC moves to site of infection
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thrombocytes
- plug damaged vessels and secrete chemicals needed for clotting
- made from megakaryocytes that shed pieces of cytoplasm, which becomes enclosed by a cell membrane
- no nucleus
- oval or disk shaped
- production controlled by thrombopoietin
- live 5-9 days - destroyed by liver and spleen
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platelet count
250,000 - 400,000/mm3
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reticulocyte count
measurement of speed of RBC formation
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hematocrit
- # of RBCs/total blood volume
- male: 42-54%
- female: 37-47%
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differential WBC
- # of each type of WBC per 100
- neutrophils - 60 - 70
- basophils - 0.5 - 1
- eosinophils - 2-4
- monocytes - 8-10
- lymphocytes - 20-25
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hemostasis
- stoppage of bleeding
- posiive feedback loop that occurs when blood vessel is injured
- 3 steps: vascular spasm, platelet plug formation, clotting
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vascular spasm
- as blood escapes, it activates stretch receptors in vessel wall
- vessel contracts rapidly to temporarily reduce blood loss
- spasm most effecient if injury is cause by dull, blunt object (more receptors stimulated)
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platelet plug formation
- in a normal vessel, wall and platelets have "+" charge
- in an injured vessel, "-" charged collagen in tunica adventita is exposed
- "-" collagen attracts "+" platelets to site
- platelets swell, stick to each other and the collagen, and then blow up
- granules inside platelets release more "-" chemicals to attract more "+" platelets
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degranulation of the platelet
positive feedback loop that plugs injury
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clotting
- a process that involves 20+ clotting factors
- 2 pathways: intrinsic, extrinsic
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clotting factors
a large group of chemicals that are ALL necessary for proper and efficient clotting
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intrinsic clotting
- occurs inside blood vessels
- more complex than extrinsic
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extrinsic
- occurs outside blood vessel
- faster than intrinsic
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common clotting pathway
both pathways merge
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clotting factors
- prothrominase - relased when platelet degranulates
- prothrombin
- vitamin k
- thrombin
- calcium
- fibrinogen
- fibrin
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