Cardiovascular System Design Flashcards
1
Q
two systems in series
A
- pulmonary and systemic
- systemic blood flows entirely into and out of the pulmonary circulation driven by the right heart pump
- blood is driven into the systemic circulation by the left heart pump
- flow in the systemic circulation is divided between tissues in parallel
- internal environment is the distribution of body fluids between blood, intracellular compartments, interstitial compartment
2
Q
general scheme of ciculation
A
- distribution of blood volume
- different flow rates through tissue
- comparison of flow and oxygen usage- not always matching-excess capacity
- resistance
- capacitance (storage)
- high pressure/low pressure system (low is venous)
- supply and reservoir (50-60% in venous)
- concept of capillary beds, but still closed
3
Q
distribution of blood in the circulatory system
A
- pumped into the aorta and consecutively passes through many different vessels before it returns to the right heart
- at any one time, 84% of blood in systemic circulation with the remainder in heart (7%) and pulm vessels (9%)
- venous blood contains >50% total blood
- vessels are distinguished by physical dimensions, morphological characteristics, and function
- all are lined with contiguous sheet of endothelium, cells, including heart chambers and valve leaflets
4
Q
heart as a pump key concepts
A
- 4 chambered pump with valves, names/anatomy
- no direct connection normally between right and left heart pumps
- myogenic
- central control of BP and contractility
- systole/diastole
- starlings law of heart
- beating depends on external calcium
- electrophysiology
5
Q
requirements for effective cardiac fucntion
A
- efficient ventricular pumping
- contractions of individual cells must occur at regular intervals and be synchronized-not arrhythmic
- valves must be open fully-not stenotic
- valves must not leak- not insufficient or regurgitant
- muscle contractions must be forceful-not failing
- ventricles must fill adequately during diastole
6
Q
cardiac output
A
- quantity of blood per unit time pumped into aorta by heart
- also equals quantity of blood per unit time that flows through the circulation
- stroke volume times heart rate
- normal is 5L/min
- determinants:
- ventricular preload (length of muscle at onset of contraction)
- ventricular afterload (tension of muscle during contraction
- myocardial contractility
7
Q
effects of things on CO
A
- sleep, mod change in temp- no change
- anxiety/excitement- 50-100%
- eating-30%
- exercise- up to 700%
- high temo
- preg
- epi
- sitting or standing- down 20-30%
- rapid arrhythmias down
- heart disease down
8
Q
starlings law
A
- CO determined by rate of blood flow into the heart from the veins, so called venous return
- peripheral tissue controls local blood flow, all blood back via veins/right atrium
- the heart automatically pumps that blood into arteries
- heart stretches from increased volume of inflowing blood and contracts with greater force therefore pumping a greater quantity of blood
- the larger the end diastolic volume, the larger the stroke volume
9
Q
blood circulation occurs through arteries and veins
A
- artery >50 um
- ateriole 20-50 um
- metarteriole 10-15 um
- cap bed
- venous end of cap 9 um
- collecting venule
- small venule 20 um
- veins 0.5-3 cm
- arteriolar vasoconstriction via smooth muscle leads to increase in peripheral resistance
- venous vasoconstriction via smooth muscle leads to reduced venous volume and decrease in CO
10
Q
aorta
A
- 2.5 cm d
- 2 mm thick
- 1
- 4.5 cm2
11
Q
arteries
A
-0.4 cm d
-1 mm thick wall
-160 of them
20 cm2
12
Q
aterioles
A
30 um d
-20 um wall thickness
5 x 10^7 of them
200 cm2
13
Q
cap
A
- 5 um d
- 1 um wall thickness
- 10^10 of them
- 4500 cm2
14
Q
venules
A
70 um d
-7 um wall
10^8 of them
4000 cm2
15
Q
veins
A
-0.5 cm d
0.5 mm wall
200 of them
40 cm2
