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What occurs during systole?
- Systole is the contracting or pumping phase. It is shorter than diastole.
- Both ventricles contract and eject blood into pulmonary artery and aorta via the open aortic and pulmonic valves.
- AV valves are closed.
What occurs during diastole?
- Diastole is the relaxation or filling phase.
- Ventricles are relaxed.
Is are extra heart sounds S3 and S4 normal?
- S3 is usually okay in young adults.
- S4 is related to pathologic conditions.
What is cardiac output?
- It is expressed as CO=SV x HR.
- It is the amount of blood the heart pumps to the rest of the body per unit time.
What is stroke volume?
The amount of blood pumped per beat?
Stroke volume can be variable. What affects it?
Preload, afterload, and contractility
What is preload?
- The degree of myocardial fiber stretch at the end of diastole and before contraction. Also considered to be the loading condition of the heart at the end of diastole. Increased preload increases CO up to a point.
- It is determined by the the amount of blood returning to the heart.
What is afterload?
- The pressure and resistance the ventricles must overcome to eject blood from the filled heart.
- The main components include: SVR and ventricular wall tension.
- Related to BP and blood vessel diameter.
What is contractility?
It is the force of cardiac contraction.
What influences preload?
- Volume status
- Heart rhythm (if it's too fast, not enough time to fill)
- Right or Left ventricular relaxation
- Alteration in afterload. If afterload increases, residual volume increases because the heart cannot fully empty.
What influences afterload?
- Systemic hypertension
- Pulmonary hypertension
- Aortic stenosis
What are the factors at contribute to inotropy?
- Sympathetic activation (MCC)
- Parasympathetic inhibition
- Afterload (Anrep effect: increased afterload increases inotropy)
- Heart rate (Bowditch effect: increased HR increased contractility)
- Circulating catecholamines
What is ejection fraction?
Percentage of ventricular volume ejected with each contraction
What is the normal ejection fraction?
What are some drugs that reduce afterload?
- ACEIs (arterial vasodilator)
- BNPs (Natrecor)
What are some drugs that reduce preload?
- Venous vasodilators (nitrates)
What are some drugs that enhance contractility?
What are the determinants of blood pressure?
Cardiac output and peripheral vascular resistance
What stage of HTN is 156/92?
What stage of HTN is 160/100?
What stage of HTN is 118/64?
What stage of HTN is 144/92?
What stage of HTN is 137/84?
What are the normal ranges for BP?
What are the normal ranges for pre-HTN?
What are the ranges for Stage 1 HTN?
What are the ranges for Stage 2 HTN?
What effect does elevated insulin levels have on blood vessels?
It decreases nitric oxide release from the endothelium, which inhibits vasodilation.