Cardio Mod 1 Flashcards
Pulmonary circulation
a. Supplied by right side of the heart
• Pulmonary trunk divides into R/L pulmonary arteries to supply lungs
• Pulmonary capillaries within alveoli
• Pulmonary veins remove blood from pulmonary capillaries and send blood to the left side of the heart
Function of pulmonary circulation
- Deliver blood to lungs for gas exchange
- “Low pressure system” compared to systemic
- Volume of blood pumped per heart beat through pulmonary circulation is the same as systemic circulation
Systemic circulation
a. Supplied by left side of the heart
• Aorta supplies major blood vessels of the body
• Systemic capillaries within each organ of the body
• Inferior and superior vena cava (IVC and SVC) final venous pathway to return blood to the right side of the heart
Systemic circulation function
- Deliver blood to every region of the body for gas exchange
- “High pressure system” compared to pulmonary system
- Volume of blood pumped per heart beat through systemic circulation is the same as pulmonary circulation
Coronary Circulation
a. Blood supply to the heart itself
b. Supplied by right/left coronary arteries
• Right and left coronary arteries supply branches to different regions of heart
• Coronary capillaries
• Coronary veins eventually drain into coronary sinus
collateral arteries– anastomoses
• Connections between right/left pathways or two branches of right or left coronary artery
• Collateral growth – “arteriogenesis”
(i) Response to coronary artery obstruction
(ii) Remodeling allows for “new or alternative” blood flow pathways to supply myocardium
Right atrium
- Receives “low-oxygenated” blood from systemic and coronary circulation
- SVC, IVC and coronary sinus all empty into right atria
Tricuspid valve (right AV valve)
• Regulates blood flow from right atria to right ventricle
Right ventricle
- Receives “low-oxygenated” blood from right atrium
- Triangular shaped to function like “bellow” to allow pumping large volume of blood into “low pressure” pulmonary circulation
- Pumps blood to pulmonary circulation via pulmonary trunk
Right semilunar valve (pulmonary semilunar valve)
• Regulates blood flow between right ventricle and pulmonary trunk
Left atrium
• Receives “oxygenated” blood from pulmonary circulation via 4 pulmonary veins (2 from right and 2 from left)
Mitral Valve (left AV valve)
• Regulates blood flow between left atrium and left ventricle
Left Ventricle
- Receives “oxygenated” blood from left atrium
- “Bullet shaped” to allow forceful pumping of blood into “high pressure” systemic circulation
- Pumps blood to systemic and coronary circulation via aorta
Left semilunar (aortic semilunar valve)
• Regulates blood flow between left ventricle and aorta
Systole
a. CONTRACTION phase
b. Blood ejected from R/L ventricles into circulation
Diastole
a. RELAXATION phase of cardiac chambers,
b. Blood fills R/L ventricles
Cardiac Cycle
a. Systole
• Isovolumetric Contraction
• Ventricular ejection
b. Diastole
• Isovolumetric relaxation
• Ventricular filling
• Atrial systole
Atrial kick (Atrial systole)
- Atria contract and force additional blood into ventricles
- AV valves– remain open;
- Semilunar valves – remain closed
Isovolumetric ventricular contraction (beginning of ventricular systole)
- Ventricles begins to contract causing AV to snap shut (1st heart sound)
- Ventricular pressure increases but semilunar valves remain shut
- All valves shut
- AV valves – snap close (1st heart sound);
- Semilunar valves – remain closed
Ventricular Ejection (ventricular systole continues)
- Ventricular pressure eventually exceeds vascular pressure forcing semilunar valves open
- Blood ejects from ventricles
- AV valves – remain closed
- Semilunar valves – push open
Isovolumetric Relaxation (Diastole begins – “early” diastole)
- At start of isovolumetric relaxation ventricular pressure falls below arterial pressure forcing semilunar valves (aortic and pulmonary valves) to snap shut (2nd heart sound)
- All valves shut
- AV valves – remain closed
- Semilunar valves – snap shut – second heart sound
- NOTE: back pressure in aorta forces blood to flow into coronary arteries
- At end of this phase venous blood continues to return to heart, atrial pressure increases which then forces AV valves open (allowing the next phase to begin)
Ventricular Filling (Diastole continues – ‘late” diastole)
- Ventricles passively fill with blood
- AV valves – remain open
- Semilunar valves – remain closed
Duration of the Cardiac Cycle
• Resting heart rate of 70 bpm = 0.8 sec/beat
(i) Systolic = 0.3 sec/beat
(ii) Diastolic = 0.5 sec/beat
• Exercising heart rate of 180 bpm = 0.33 sec/beat
(i) Systolic = 0.2 sec/beat
(ii) Diastolic = 0.13 sec/beat
First Heart sound – S1 (“lub”)
• AV valves snap shut during the beginning of ventricular systole (isovolumetric ventricular contraction)
Second Heart sound - S2 (“dub”)
• Semilunar valves snap shut at the transition between ventricular systole and early diastole (isovolumetric ventricular relaxation)
Third Heart sound - S3
- **may not be heard
- Commonly heard in children/young individuals
- Vibration of ventricular walls from rush of blood into ventricles during rapid filling
Splitting of second heart sound
- Delayed interval between aortic and pulmonary semilunar valves shutting allows reduplication of sound (physiological splitting)
- Common during inspiration – right pulmonary valve delayed
- May occur in various pathologies
Murmurs
(i) abnormal sounds heard over heart
(ii) turbulent blood flow causes abnormal sound
(iii) classic cardiac murmurs = valve disease
1. stenosis – opening of valve is narrowed
2. regurgitation/insufficiency – valve mechanically incompetent allows “back flow”
Bruit
(i) abnormal sounds heard throughout vascular system
(ii) turbulent blood flow causes abnormal sound
Calculating Target HR
a. Traditional Method
• MHR x chosen % = THR
b. Heart Rate Reserve Method (Karvonen formula)
• [(MHR – RHR)] x chosen % + RHR = THR
How to Estimate Max HR
- 220 –age = MHR
* 208 – (0.7 x age) = MHR
Stroke Volume
- Average resting SV = 70 ml, Elite athlete = 90-100 ml
- “Maximum” SV during exercise = up to 150-200 ml in elite athletes
- What happens to resting and maximum SV after aerobic training?
a. Both increase
Cardiac Output
- CO = SV x HR
- Average CO at rest = 5 L/min
- “Maximum” CO during exercise = 20-30 L/min
- What happens to resting CO after aerobic training? DOES NOT CHANGE = 5 L/min
Ejection Fraction
- EF = percentage of the blood that is ejected from the ventricle
• The proportion of the blood pumped out of the left ventricle with each beat. - Calculated by dividing the SV by the EDV (end diastolic volume)
a. EF = SV / EDV - Normal Left ventricular EF (LVEF) at rest ranges 55-68%
- Normal right ventricular EF (RVEF) is slightly less
Clinical Base Lines for Ejection Fraction
- Clinical base lines (guideline vary from source to source)
a. 50-70% considered “normal” (many sources 55-70%)
b. 40-50% below normal
c. < 35-40% diagnostic and increased “at risk” arrythmia - During exercise EF can increase (approx 5-15% above resting value)
