Cardiovascular 1 Flashcards
How does O2 move along this pathway
Ventilation -> Pulmonary O2 diffusion -> Circulatory O2 delivery -> Muscle O2 diffusion -> Muscle O2 Utilization -> Muscle ATP Turnover
How is blood circulated? How is blood distributed to all cells?
- blood motion
- The mechanics of blood motion (haemodynamics) relate mainly to the physical quantities of pressure, resistance and flow.
- Blood flows around and around and around…..in a closed circuit: it leaves the heart and returns to the heart, picking up oxygen and releasing cellular wastes, and visits every cell at all times.
Five cardiovascular responses during graded exercise
- Responses are based on ‘end-stage’ measurements during a graded test.
Five CV responses
- Cardiac output - the rate at which blood leaves the heart (flow)
- Mean Arterial Pressure - (pressure)
- Total Peripheral Resistance - (resistance)
- Heart Rate
- Stroke Volume
Cardiovascular design: Basic plan
- Four chambered mammalian heart.
- Pulmonary circuit lies ‘in series’ with the systemic circuit (see next slide).
- Blood flows in one direction.
- Arterial blood flows away from the heart.
- Venous blood flows towards the heart
Cardiovascular design: systemic and pulmonary circuits lie ‘in series’
- In series design, combined with one-way flow, ensures that all blood that flows through the lungs then flows through the systemic circulation and to all organs.
Cardiovascular design: system (regional) circuit lie ‘in parallel’
- Arterial blood will divide continually as it flows further away from the heart.
- All organs receive the oxygen-rich blood that left the lungs.
- No organ receives the carbon dioxide-rich blood leaving another organ (except the liver).
Cardiovascular output is continually divided as blood flows away from the heart
- Arterial blood will divide continually as it flows further away from the heart.
- This enables blood flow to be ‘distributed’ between the regional circulations.
And the blood then merges as it flows back to the heart
- Blood leaves capillaries via small venules and flows into small veins, medium-size veins, large veins, inferior or superior vena cava and then the right atrium.
- This venous ‘flow’ is sometimes called ‘venous return’.
- What leaves the heart, returns to the heart: blood flows in a circle!!
Distribution of cardiac output at rest
- parallel arrangement
In parallel arrangement enables cardiac output to be distributed to the regional circulations
(IMAGE)
Cardiac output and its distribution during exercise
- Increases in blood flows to heart, muscle and skin (except “maximal exercise”).
- Decreases in blood flows to GI tract and kidneys.
- Constant blood flow to brain.
How is blood circulated at a faster rate? How is the distribution of blood flow changed?
- The mechanics of blood motion (haemodynamics) relate mainly to pressure, resistance and flow.
- Physiological processes affect these mechanical aspects of motion to control the flow of blood.
Haemodynamic I: blood flow in a blood vessel
Blood flow = Pressure Difference / Resistance
Q = ∆P/R
Resistance - the friction between blood and blood vessel
Haemodynamic II: Blood flow in the systemic circulation
Heart -> organ/region -> heart
R = TPR
A sufficiently high arterial pressure is critical to enabling blood to flow in the vasular system
Interpreting cardiovascular responses during graded exercise
Flow - increases
Mean arterial Pressure - increases by 30%
Resistance - Decreases
From neuromuscular to cardiovascular: Blood flow, oxygen and endurance
- Restricting muscle blood flow reduces muscle endurance: try a fist-clenching exercise.
- This effect of blood flow on muscle endurance is thought to be mediated by oxygen (O2 ).
- Endurance at the highest of intensities depends on the use or consumption of O2 . (This doesnt make sense)
