Cardiovascular Physiology Flashcards
List the layers of the heart superficial to deep
Pericardium = Membrane surrounding heart
- Fibrous pericardium
- serous pericardium
- Parietal Pericardium
- Visceral pericardium
Myocardium = cardiac muscle
Endocardium = internal lining of the heart
Explain the blood flow in the pulmonary and systemic circuit
Pulmonary circuit
- Superior / inferior vena cava - poorly oxygenated blood to R atrium
- Blood flows through tricuspid valve to R ventricle
- blood passes through the pulmonary valve to the pulmonary trunk - pulmonary artery into lungs for gas exchange.
Systemic circuit
- Pulmonary veins carry oxygenated blood into L atrium
- blood gets pushed through the mitral valve to the L ventricle
- oxygenated blood passes through the aortic valve into the ascending aorta to be pumped to the rest of the body
Compare the microscopic features of skeletal muscle to cardiac muscle
Cardiac Muscle - Striated - Branched - 1-2 nuclei - intercalated discs contract via sliding phylament theory - involuntary - aerobic metabolism - Extracellular calcium - Ratio 99% contractile to 1% pacemaker cells
Musculoskeletal muscle
- striated
- multinucleated
- voluntary - ATP
Describe the intrinsic conductive system of the heart
Sinoatrial Node - Primary pacemaker begins depolarization
Atrioventricular Node - Delay depolarizarion in atrium by 0.1sec
Atrioventricular bundle - spread the impulse to the ventricles
Pujenkie fibre - help with contraction of ventricular walls and excite ventricles
What is the intrinsic conducting system of the heart (ICS)?
A network of non-contractile cells that distribute impulse in a sequential manner
works with pacemaker cells to maintain the rhythm of the heart.
What is a pacemaker cell/
Keeps sinus rhythm of the heart
What is the cardiac cycle
All events that occur in the hear in one heartbeat
What is the difference between the electrocardiogram (ECM) and electrocardiograph (ECG)?
ECM - the display of a person heartbeat
ECG - the machine that reads the signals
What are the three typical ECG deflections and their electrical/mechanical events
P wave: Atrial depolarization and contraction
QRS: ventricular depolarization and contraction
T wave: ventricular repolarization and relaxation
What causes S1/ S2 sound
S1: the closing of atrioventricular valves mitral + tricuspid
S2: closing of semilunar valves pulmonary + aortic
What is a cardiovascular centre and what are the three types?
Centres found in the medulla that influence the supply of the heart.
- Cardioaccelatory
- Cardioinhibitory
- Vasomotor
What is the interaction of Cardioaccelatory centre with CNS and ANS
Influences the SNS supply to the heart with neural projections to the horns of T1-T6
What is the interaction of Cardioinhibitory centre with CNS and ANS
Influences the PNS supply with neural projections to the Dorsal motor nucleus of Vagus
What is the interaction of vasomotor y centre with CNS and ANS
Influences sympathetic nerve supply to the anterior smooth muscle
What is the difference between systole and diastole?
Systole - Contract
Diastole - relax
List the stages of the cardiac cycle
Stage 1. Mid to late Diastole
- Ventricular filling
- Atrial contraction
Stage 2. Ventricular sistole
- Ventricular Isometric contraction
- Ventricular ejection
Stage 3. Early ventricular diastole
- Isovolumetric relaxation
Describe how ventricular volume and ventricular pressure fluctuate during cardiac cycle
Systole
Blood returning to the heart will flow into the atria and ventricles as the pressure in them is lower (due to low volume of blood)
When ventricles are ~70% full, atria will contract (atrial systole), increasing pressure in the atria and forcing blood into ventricles
As ventricles contract, ventricular pressure exceeds atrial pressure and AV valves close to prevent back flow (first heart sound)
With both sets of heart valves closed, pressure rapidly builds in the contracting ventricles (isovolumetric contraction)
When ventricular pressure exceeds blood pressure in the aorta, the aortic valve opens and blood is released into the aorta
Diastole
As blood exits the ventricle and travels down the aorta, ventricular pressure falls
When ventricular pressure drops below aortic pressure, the aortic valve closes to prevent back flow (second heart sound)
When the ventricular pressure drops below the atrial pressure, the AV valve opens and blood can flow from atria to ventricle
Throughout the cycle, aortic pressure remains quite high as muscle and elastic fibres in the artery wall maintain blood pressure
What is cardiac output
The amount of blood pumped out by each ventricle in a minute
CO = HR X SV