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Cardiovascular System and Blood Vessels (Clinical terms related to heart…
Cardiovascular System and Blood Vessels
Anatomy of heart
Great Vessels
Arteries
Pulmonary Trunk
transports blood from right ventricle
Aorta
transports blood from left ventricle
Veins
Superior/Inferior Vena Cava
drain deoxygenated blood into right atrium
Pulmonary Veins
drain oxygenated blood into left atrium
Atrioventricular (AV) Valves
Between atrium and ventricle of each side
Right AV valve
AKA Tricuspid
Left AV valve
AKA Bicuspid or Mitral
Semilunar Valve
open to allow blood to flow through heart, closes to prevent backflow
Pulmonary Semilunar Valve
between right ventricle and pulmonary trunk
Aortic Semilunar Valve
between left ventricle and aorta
Four Chambers
Left/Right Atrium
superior chambers that receive blood and send it to ventricles
Right atrium
pectinate muscles (ridges on anterior wall within auricle
Left atrium
pectinate muscles in its auricle
Left/Right Ventricle
inferior chambers that pump blood away
Right ventricle
trabeculae carneae
irregular muscular ridges inside ventricle wall
papillary muscles
cone-shaped projections extending from internal ventricle wall
chordae tendinae
"heart strings"
Left ventricle
trabeculae carnaea on internal wall surface
2 papillary muscles anchor chordae tendinae
Left side
Oxygenated blood
Right Side
Deoxygenated blood
Separation of chambers
Interatrial septum
separates left atrium from right atrium
Interventricular septum
separates left ventricle from right ventricle
Pericardium
3-layered sac around heart
Fibrous Pericardium
outermost covering
anchors heart, prevents it from overfilling
Parietal layer of Serous Pericardium
attaches to fibrous pericardium
Visceral Layer of Serous Pericardium
attaches directly to heart
External Grooves
mark borders of heart chambers
contain coronary vessels supplying blood to heart wall
Coronary Sulcus
separates atria from ventricles
extends around circumference of heart
Interventricular Sulci
separates left from right ventricles
extends from coronary sulcus toward heart apex
Layers of Heart Wall
Epicardium
Outermost layer
Myocardium
middle layer of heart wall
thickest layer
cardiac muscle tissue that contracts to pump blood
Endocardium
covers internal surface of heart and external surface of valves
continuous with lining of blood vessels
Cardiac Muscle Contraction
Cardiac vs. skeletal muscle
Cardiac
heart only
pumps blood through blood vessels
calcium source: well-developed sarcoplasmic reticulum
stimulation: nervous control is voluntary; excitatory
Skeletal
attached to skeleton
voluntary movement of body components
calcium source: most comes from interstitial fluid
stimulation: nervous control is involuntary; excitatory or inhibitory
coronary vessels are compressed when heart contracts, temporarily interrupting blood flow
thin filaments slide past thick filaments and sarcomeres shorten within cardiac muscle cells
Physiologic processes associated with heart contraction:
Conduction system
electrical activity is initiated at SA node, and an action potential is transmitted through conduction system
Cardiac muscle cells
action potential spreads across sarcolemma of cardiac muscle cells causing sarcomeres within cardiac muscle cells to contract
Cardiac Cycle
changes within heart from initiation of one heartbeat to start of the next
Step 1: Atrial contraction and ventricular filling
Ventricles relax
AV valves open
Atria contracts, initiated by SA node stimulating cardiac muscle cells
Semilunar valves close
results in blood moving to right/ left ventricle
Step 2: Isovolumetric contraction
Atria relax
Ventricles contract, initiated by Purkinje fibers bc they stimulate cardiac muscle cells of ventricular wall
AV valves closed
Semilunar valves closed
Step 3: Ventricular ejection
Atria relax
Ventricles contract
AV valves closed bc pressure in ventricles remains greater than pressure in atria
Semilunar valves open
movement of blood from ventricles into arterial trunks
Step 4: Isovolumetric relaxation
Atria relax
AV valves closed
Ventricles relax
Semilunar valves closed
blood flows backward slightly within arterial trunks, caught by semilunar valves, causes them to close
cardiac muscle cells relax
Step 5: Atrial relaxation and ventricular filling
Atria relax
Ventricles continue to relax
AV valves open bc pressure in ventricles decrease, becoming lower than atria; AV valves open allows blood from atria to ventricles
Semilunar valves closed bc pressure in ventricles is lower than atrial trunks
ECG
Electrocardiogram
traces cardiac action potentials generated by myocardial cells
P wave
above baseline
electrical changes of atrial depolarization that originates in SA node
QRS complex
electrical changes associated with ventricular depolarization
beings (Q) and ends (S) with small deflections from baseline, large deflection (R) above baseline, T wave above baseline
T wave
electrical changes associated with ventricular repolarization
Clinical terms related to heart function
cardiac output (CO)
volume of blood ejected by ventricle in one minute; calculated by multiplying heart rate times stroke volume
stroke volume (SV)
AV valves remain closed bc pressure in ventricles remains greater than pressure in atria
amount of blood pumped out during ventricular contraction is SV
heart rate (HR)
number of beats per minute
end-diastolic volume (EDV)
volume of blood within ventricle at end of diastole (or rest)
end-systolic volume (ESV)
volume of blood remaining in a ventricle at end of systole (contraction)
venous return
volume of blood returned to heart via great veins
directly related to stroke volume
determines amount of blood in ventricle at end of rest immediately prior to contraction
preload
volume of blood (amount of blood in ventricle) determines preload on heart
stretch of heart wall due to load to which a cardiac muscle is subjected before shortening
afterload
resistance in arteries to ejection of blood by ventricles, represents pressure that needs to be exceeded before blood is ejected from chamber
Frank-Starling Law
direct relationship of venous return and stroke volume
states that as volume of blood entering heart increases, there is greater stretch of heart wall (or preload)
more forceful ventricular contraction is generated, stroke volume increases
Structural differences in blood vessels
arteries
carry blood away from heart to body
more elastic and collagen fibers
remain open without blood in it
walls can spring back to shape
more resistant'resiliant to changes in blood pressure than veins bc of thicker tunica media
blood/ oxygen levels
systemic arteries carry blood high in O2
pulmonary arteries carry blood low in O2
pulmonary arteries
transport deoxygenated blood to lungs
elastic arteries
stretch to accomodate pulses of blood ejected from heart
recoil to propel blood through arteries
muscular arteries
regulate distribution of blood through vasoconstriction and vasodilation
capillaries
microscopic, porous, exchange of substances between blood and tissues
receive blood from arterioles and allow for exchange of substances between blood and cells
exchange processes
diffusion
from high concentration in blood to lower concentration in tissue cells
vesicular transport
pinocytosis
can be from blood ---> interstitial fluid or from interstitial fluid ---> blood
bulk flow
movement of large amounts of fluids and dissolved substances in one direction down a pressure gradient
veins
drains blood from capillaries, transports it back to heart
vein wall collapses if no blood present
wider than artery
valves present in most
blood/ oxygen levels
pulmonary veins carry blood high in O2
systemic veins carry blood low in O2
large veins serve as blood reservoir
small/ medium veins receive blood from venules; blood drains into small/medium veins and then into large veins
companion vessels
supply same body region, tend to lie next to eacchother
arteries and veins
venules
smallest veins
companion vessels with arteries
becomes a vein when diameter is greater than 100 micrometers
receive blood from capillaries
Electrical Conduction
electrical activity is initiated at SA node, then action potential is transmitted through conduction system
myocardium contracts after stimulation, allows efficient contraction of heart, allowing blood to pump through body
structures of conduction system
SA node
in wall of right atrium
initiates heart beat
internodal atrial pathways
2 conduction pathways between SA and AV node
AV node
conducting tissue between atria and ventricles
slow conduction rate
Bundle of His
takes over impulses from AV node
divides left and right bundles
Purkinje fibers
final conductive tissue
leading electrical impulses to deeper tissues of ventricles
autonomic nervous system
works unconciously to regulate body functions
sympathetic
increases heart rate and force of contraction
parasympathetic
decreases heart rate