Blood Flow & Pressure Flashcards
What is the only organ that receives blood flow in excess of cardiac output?
Lungs
Why do the lungs receive blood flow in excess of cardiac output?
They receive both total pulmonic flow and some systemic flow simultaneously
What makes up the total blood flow to the lungs?
Right ventricular output (pulmonic flow) + bronchial artery flow (small portion of systemic flow)
What is the right ventricular output?
100% of cardiac output
Bronchial artery flow is about how much of cardiac output?
1-2%
What would the total blood flow to the lungs be, percentage-wise?
About 102% of cardiac output
Which ventricle pumps 1% more?
Left ventricle
Pulmonary lymphatics mainly drain into which major lymphatic duct?
Right lymphatic duct
What is the function of the pulmonary lymphatic system?
Remove plasma filtrate, particulate matter absorbed from alveoli, and escaped protein from the vascular system
What is the effect of pulmonary lymphatics on pleural pressure?
Helps maintain the negative pressure necessary to pull the alveolar epithelium against capillary endothelium (respiratory membrane) to prevent lung collapse
What sided heart failure presents a risk for pulmonary edema?
Left sided heart failure
What is a classic sign of pulmonary edema?
Dyspnea
What is the pulmonary artery pressure and its mean?
25/8, 15 mmHg
What is the aortic artery pressure?
120/80
What is the mean pressure of the pulmonary veins and left atrium?
2 mmHg
What is pulmonary blood flow equal to?
Cardiac output
How is pulmonary blood flow distribution affected by low alveolar oxygen levels?
Causes release of a local vasoconstrictor which automatically redistributes blood to better ventilated areas
What is the effect of the SNS on pulmonary vascular smooth muscle?
Mild vasoconstriction
What is the effect of the parasympathetic nervous system on pulmonary vascular smooth muscle?
Mild vasodilatation
Which receptors mediate the vasoconstriction of pulmonary vascular smooth muscle stimulated by the SNS?
Alpha receptors
What happens with alpha blockage during SNS stimulation of the pulmonary vascular smooth muscle?
Vasodilatation as beta receptors are thus unmasked
What exhibits the MAJOR constrictor effect on pulmonary vascular smooth muscle?
Low alveolar oxygen levels
What occurs in tissues with low oxygen levels: constriction or dilation?
Dilation
What occurs in the lungs with low oxygen levels: constriction or dilation?
Constriction
Under resting conditions, when does the blood become fully oxygenated?
By the time it has passed the first 1/3 of the pulmonary capillary
What is the normal transit time for the oxygenation of the blood in the pulmonary capillary?
.8 seconds
How does transit time change under high CO conditions during oxygenation of blood?
Decreased to about .3 seconds (full oxygenation still obtained)
What is the limiting factor in exercise when it comes to the oxygenation of blood in the pulmonary capillary?
Stroke volume
How does pressure change from the apex of the lung to the base?
Pressure increases due to gravity
Describe the flow in the various zones of the pressure differences in the lungs.
Zone 1 - no flow
Zone 2 - intermittent flow (apex)
Zone 3 - continuous flow (base)
Which zone of pulmonary blood flow usually doesn’t exist?
Zone 1
In which zone of pulmonary blood flow is alveolar pressure greater than capillary pressure?
Zone 1 (no flow)
What are the pressure differences during systole in zone 2 of pulmonary blood flow?
Capillary pressure > alveolar pressure
What are the pressure differences during diastole in zone 2 of pulmonary blood flow?
Alveolar pressure > capillary pressure
In which zone of pulmonary blood flow is capillary pressure greater than alveolar pressure?
Zone 3 (continuous flow)
During exercise, the entire lung is in which zone of pulmonary blood flow?
Zone 3 (continuous flow)
Where does the body exhibit the greatest amount of pressure: head or feet?
Feet (gravity effect)
Which is a greater pulmonary capillary dynamic: filtration or reabsorption forces?
Filtration (15 mmHg compared to 14 mmHg of reabsorption)
What type pressure is responsible for the greater amount of filtration forces in the pulmonary capillaries?
Hydrostatic
Which type of pressure is associated with filtration: hydrostatic or colloid osmotic?
Hydrostatic (pushes out)
Which type of pressure is associated with reabsorption: hydrostatic or colloid osmotic?
Colloid osmotic (pulls in)
