Respiratory Part 2 Flashcards
3.5 Steps to Respiration
1 Pulmonary Ventilation
2. External Respiration
2.5 Gas transport to blood
3. Internal Respiration
Exchange of air between the atmosphere and the alveoli
Ventilation
Air moves INTO the lungs when the pressure inside the lungs is LESS THAN that of the atmosphere (Patm)
Inspiration
Air moves OUT OF the lungs when the pressure inside the lungs is GREATER THAN that of the atmosphere (Patm)
Expiration
Explain bulk flow of air and give equation
air moves from a region of high concentration to low concentration
F=change in pressure/R
what is the most important factor determining airway resistance
diameter of the tube
Disorders that increase resistance
emphysema
chronic bronchitis
asthma
diseases of airway obstruction and collapse
The volume of air in the conducting airways
~150 mL
Anatomic Dead Space
The volume of air in the lungs that does NOT participate in gas exchange (A functional measurement)
~equal to anatomic dead space in “normal” lungs
Physiologic Dead Space
number of breaths taken per minute
Respiratory Rate
Total amount of air entering or leaving the lungs per minute
minute ventilation
minute ventilation is equal to tidal volume x what
respiratory rate
The total volume of air entering the alveoli per minute
Alveolar Ventilation
Anatomic dead space is determined by which of the following?
The size and number of the airways
The minute ventilation of an individual with a tidal volume of 500 mL and a respiratory rate of 12 breaths per minute is which of the following?
6 L/min
Which of the following pulmonary function test results describes an individual with moderate asthma?
Increase residual volume, decreased FEV1, decreased FEV1/FVC
The ratio of CO2 produced to O2 consumed is known as the
RESPIRATORY QUOTIENT(RQ).
RQ is based on
It is based on our diet (mixture of carbs/fats/proteins)
what is the normal value of RQ
it is approximately 0.8
The __________ PO2 and PCO2 determines our systemic arterial PO2 and PCO2
alveolar
Each gas in a mixture of gases exerts its own pressure as if no other gases
were present
Dalton’s Law
“In other words…A gas will move from an area where its partial pressure his higher to where its partial pressure is low. The greater the partial pressure difference between the two areas the more rapid is the movement of gas.”
The concentration of gas in a liquid is directly proportional to the solubility and
partial pressure of that gas (at constant temperature).
Henry’s Law
“In other words…The amount of oxygen that dissolves into the bloodstream is directly proportional to the partial pressure of oxygen in alveolar air.”
What two places does gas exchange occur?
lungs
tissues
What is picked up and dropped off in the lungs?
oxygen picked up
co2 released
What is picked up and dropped off in the tissues
CO2 picked up
O2 dropped off
4 layers of Respiratory Membrane
- Alveolar wall (with type I & II cells)
- Epithelial basement membrane
- Capillary basement membrane (usually fused with epithelial BM)
- Endothelial cells of the capillary wall
the exchange of gases between blood, lungs, and external environment… occurs across the blood air barrier between alveolar air and alveolar capillaries
external respiration
(breathing) is simply air movement in/out of lungs…. maintains alveolar ventilation
Pulmonary Ventilation
Blood arriving in pulmonary arteries has lower PO2 and higher PCO2 than in alveolar air. In external respiration what occurs?
Increase pO2 (O2 enters blood)
Decrease pCO2 (CO2 leaves blood
What occurs during internal respiration
O2 dropped off at tissues
CO2 picked up
movement of O2 in the body
Moves from alveoli into blood. Blood is almost completely saturated with oxygen when it leaves the capillary
pO2 in blood decreases because of mixing with deoxygenated blood
Oxygen moves from tissue capillaries into the tissues
Movement of Carbon Dioxide in the body
Moves from tissues into tissue capillaries
Moves from pulmonary capillaries into the alveoli
Rate of gas diffusion and blood flow slow enough that complete equilibrium is reached before the blood reaches the end of the capillaries in healthy people or unhealthy people
Healthy people
What % thickness of aortic wall is the pulmonary artery?
30%
Small pulm arterial walls contain a lot or little smooth muscle compared to systemic arteries
little
what are the exceptions to the following statement?
Pulmonary vasculature accommodates a blood flow that is almost equal to that of all other organ systems in the body.
Bronchial blood flow
Coronary artery flow
what is created by these two exceptions
Small PHYSIOLOGIC SHUNT due to Blood in systemic arteries has PO2 2 mmHg less than blood equilibrated with alveolar air.
the resistance that must be overcome in order to push blood through the circulatory system and create flow.
VASCULAR RESISTANCE
The resistance to blood flow offered by all of the systemic vasculature, excluding the pulmonary vasculature is known as
SYSTEMIC VASCULAR RESISTANCE (SVR).
What does SVR represent
Reflects changes in the arterioles, which can affect emptying of the left ventricle
Two patterns observed as the body attempts to maintain homeostasis:
Constriction of blood vessels SVR INCREASES Diminished ventricular compliance Reduced
stroke volume Reduced cardiac output (CO)
Dilation of blood vessels SVR DECREASES reduces force needed for LV to open AV
Conditions that INCREASE SVR include:
hypothermia
hypovolemia
Conditions that DECREASE SVR include:
anemia
cirrhosis
PULMONARY VASCULAR RESISTANCE (PVR)
______________ with increased arterial pressure and increased cardiac output (CO)
decreases
Decrease in PPVR is due to which 2 control mechanisms
Capillary recruitment perfusion of increased number of vessels
Capillary distension higher volume of blood flow within vessel
Conditions that decrease PVR are
hypocapnia
strenuous exercise
is opening up of previously closed blood vessels resulting in more perfusion and less resistance
Capillary recruitment
increase in caliber of vessels (they dilate) resulting in increased BF and drop in resistance
Capillary distension:
in Rsided Heart Failure , If the pressure in the pulmonary vasculature is high due to INCREASED resistance, the right ventricle must work harder to move the blood forward past the pulmonic valve… What can this cause
May cause dilation of the right ventricle over time and require additional volume to meet the preload needs of the left ventricle.
What conditions cause increase PVR
Atelectasis
Hypercapnia
