Question

Scenario: DW is a 65-year-old, 135 kg male who visited his primary care physician for a routine examination. His blood pressure was 158/100 mmHg and his heart rate was 71 bpm. Stroke volume and cardiac output were normal. Serum renin levels were in the normal range.   A chest x-ray revealed left ventricular hypertrophy. Other clinical findings were unremarkable.

1. Fully describe, in your own words, the following terms related to cardiovascular physiology, and explain where they occur in the cardiac cycle. (Do not describe them related to this patient. Just describe and explain them for normal physiology): preload, end-diastolic volume, contractility, turbulent flow, venous return

Answer 1

Preload- Is the amount of tension present on the muscle when they are relaxed.

In heart, it corresponds to amount of blood present in the ventricles at the end of the diastole.

End-diastolic volume- It is the amount of bloos present in the heart at the end of diastole or before beginning of the systole.

Contractility- It is defined as the intrinsic strength and vigour of contraction of a muscle fiber independent of preload and afterload.

Turbulent flow- Turbulent flow is defined as the chaotic flow of fluid(blood) in a tubular structure(arteries). In contrast, laminar flow occurs when flow is parallel in smooth layers to each other.

Venous return- The amount of blood returning to the right atrium from Superior and inferior vena cava is known as venous return.