Introduction into the Cardiovascular System Flashcards
Mechanical contractions of the heart constitute two pumps, in series:
- Right ventricle propels blood to pulmonary circulation
- Left ventricle propels blood to systemic circulation
During moderate exercise, total cardiac output =
12.5 L/min
At rest, total cardiac output =
5 L/min
Cardiac output equation
CO = HR x SV
What happens to venus return during exercise
Rises because of compression if veins contracting skeletal muscle which increases cardiac output
What happens to Sympathetic nervous system during exercise
Increases by higher brain centres which initiate exercise and in part by receptors in exercising muscles so heart rate increases which leads to increase in cardiac output
What happens to parasympathetic nervous system activity during exercise
Inhibited during exercise which increases heart rate
What happens to cardiac hypertrophy during exercise
This develops with prolonged training so left ventricle enlarges which raises stroke volume
Factors affecting heart rate
Autonomic innervation
Fitness level
Age
Factors affecting stroke volume
Heart rate
Gender
Duration of contraction
Aorta and large arteries: structure and function
thick walled, highly elastic
distribution, handles high pressure reservoir, forward propulsion
Arterioles: structure and function
Thick walled, muscular, highly innervated
Tissue distribution if flow, variable resistance
Capillaries: structure and function
Thin walled (single cell), lacking elastic tissue and smooth muscle
Exchange
Venues and Veins: structure and function
Thin walled, some muscle and innervation, valves (unidirectional)
Reservoir, at est approximately 60% blood volume
Constant flow rate (CO) equation
CO = Blood flow velocity x cross-sectional area
