W4-L3: Cardiovascular system Flashcards
What are the 4 components of the cardiovasular system?
- A pump that provides continuous linkage with the other three components
- A high-pressure distribution circuit
- Exchange vessels
- A low-pressure collection and return circuit
What is Cardiac output?
- The amount of blood (volume) pumped by the heart in one minute
- Cardiac output = QU
- Stroke Volume = SV
- Heart rate = HR
What is the function of the left & right sides of the heart?
(know the path/valves)
Right side
- Receives blood returning from elsewhere in the body
- Pumps blood to the lungs through pulmonary circulation
Left side
- Receives oxygen-rich blood from the lungs
- Pumps oxygenated blood to the rest of the body (systemic circulation)
What are Arteries?
3
High-pressure tubing that propels oxygen-rich blood to tissues
- Conducting and resistance vessels
- Comprised of layers of connective tissue & smooth muscle
No gas exchange occurs between arterial blood and surrounding tissues
- Walls are too thick
Smooth muscle in arteriole walls either constrict or relax to regulate blood flow to periphery
What is The pre-capillary sphincter?
The pre-capillary sphincter consists of a ring of smooth muscle that encircles the capillary at its origin and controls its diameter
Why do sphincters constrict?
Sphincter constriction and relaxation provide a means for blood flow regulation within a specific tissue to meet metabolic requirements
- 1/30 capillaries are open in muscle at rest
What Two factors trigger pre-capillary sphincter relaxation to open more capillaries?
- Driving force of increased local BP + intrinsic neural control
- Local metabolites produced in exercise
How does Blood Velocity change in the vessels?
Blood velocity changes in the vessels based on the cross-sectional area of the blood vessels. It is highest in the large arteries, such as the aorta, where the cross-sectional area is smaller. As the blood moves into the capillaries, which have a much larger total cross-sectional area, the velocity decreases significantly to allow for efficient exchange of gases and nutrients. Blood velocity then increases again as blood moves into the veins, where the cross-sectional area decreases.
What are Veins?
- Leaving the capillaries blood will enter small veins (venules)
- Not as muscular as arteries
- Valves prevent backflow
- Eventually reach the vena cava
- Inferior vena cava
- Superior vena cava
- Empties into right atrium
What is Blood pressure?
Blood pressure =
Cardiac output x Total peripheral resistance
What is Systolic Blood Pressure?
- Blood pressure during left ventricular contraction (systole)
- Estimate of the work of the heart against the arterial walls
What is Diastolic Blood Pressure?
- Blood pressure during cardiac relaxation (diastole)
- With high peripheral resistance pressure will remain high for longer
What is Mean Arterial Pressure (MAP)?
Weighted to account for the fact that the heart remains in diastole longer
Blood pressure during exercise
