L16 Flashcards
What are five mechanical descriptions of breathing?
- Movement of air into and out of the lungs is caused by a pressure gradient
- ATM pressure remains constant during breathing cycle
- Alveolar pressure changes affect gradient
- Boyles Law= pressure is inversely related to volume
- Resistance to airflow is related to airway radius and mucus
What is the formula for flow?
Patm-Palv/R
At rest, diaphragm is _____
At inspiration, thoracic volume _____, diaphragm _____ and ________
At expiration, diaphragm ______, thoracic volume ______
Relaxed
increases, contracts, flattens
relaxes, decreases
Describe characteristics of inspiration
- Pressure in lungs < ATM pressure
- occurs when alveolar pressure decreases
- involves contractions of skeletal muscles of rib cage and diaphragm
Describe characteristics of expiration
- Pressure in lungs > ATM pressure
- occurs when alveolar pressure increases
- involves passive relaxation, elastic recoil returns rib cage and diaphragm to original relaxed position
What is intrapleural pressure?
This is pressure inside the pleural sac, the surface tension of intrpleural sac/fluid prevents chest walls from pulling apart
Subatompheric pressure keeps lungs inflated, what is the Normal intrapleural pressure of it? What happens during inspiration and expiration of the pressure?
3 mm Hg
Inspiration: pressure drops
Expiration: increases to normal pressure
Explain what happens to the following during quiet breathing
Alveolar pressure
Intrapleural pressure
Volume of air moved
Alveolar pressure= decreases during inspiration, increases in expiration
Intrapleural pressure= decreases during inspiration, increases in expiration
Volume of air moved= increases during inspiration, decreases during expiration
Explain what Pnemothroax is and what happens
If the sealed pleural cavity is opened to the atmosphere, air flows in. The bond holding the lungs to the chest wall is broken and lungs collapse. This creates Pnemothroax (air in thorax)
What is compliance, what happens during high compliance, what happens during low compliance?
Compliance= this is the ability to stretch
High compliance mean stretches easily
Low compliance means it requires more force and restrictive to lung diseases. Fibrotic lung diseases is inadequate for surfactant production
What does elastance mean?
This is the ability to return to resting volume when stretching forces is released (force exerted by elastic fibres)
What is surface tension? What are surfactants?
Surface tension is the thin layer of fluid that lines alveoli, the surface tension arises due to attraction between water molecules
Surfactants are surface active agents that disrupt cohesive forces of water and are mixtures containing proteins and phospholipids. More [ ] in smaller alveoli. More surfactants you have, the less surface tension you have.
what is the law of Laplace? What does the Law of Laplace state? Give examples with bubbles and surface tension.
- 2T/r
- if two bubbles had the same surface tension, the smaller bubble will have higher pressure
- in lungs, smaller alveoli have more surfactants which equalize pressure between large and small alveoli
- smaller radius means an increase in surfactants and more surfactants means a reduced surface tension
What is the primary determinant of airway resistance?
Wider airways have _______ resistance
Airway diameter
Less resistance
What is bronchocosntriction?
What is broncodialation
Bronchoconstriction:
- This is an increase in resistance.
- caused by parasympathetic and histamines
Bronchodialation:
- this is a decrease in resistance
- sympathetic, epinephrine (beta 2 receptors and Co2)
What are the five factors that impact the airway?
- Length of system (constant, not really a factor)
- Viscosity of air (usually constant, but humidity and altitude may affect)
- Diameter of airway
- Upper airways (physical obstruction is and effector, mediated by mucus)
- bronchioles (bronchodialation and constriction)
What is total pulmonary ventilation?
- volume of air moved out of lungs per minute
- TPV= ventilation rate x tidal volume
What is alveolar ventilation?
This is volume of air receiving alveoli per minute and its more accurate
Name and describe the five types of ventilations
Eupnea- Normal quiet breathing
Hyperpnea- increased respiratory rate/volume increases in response to metabolism (usually exercise based)
Tachypnea- rapid breathing, increased respiratory rate with decreased depth
Dyspnea- difficulty breathing (air hunger) various pathologies
Apnea- cessation of breathing, voluntary breath holding
What are the four steps in the ventilation cycle?
- At the end of inspiration, dead space is filled with fresh air
- Exhale 500ml of air (tidal volume)
- At end of expiration, dead space is filled with stale air from alveoli
- Inhale 500ml of fresh air (tidal volume)
When O2 entered the alveoli, O2 also enters ______
The blood
A total of ___% of fresh air goes into lungs
10
Ventilation and alveolar blood flow are _____ (to ensure efficient gas exchange)
Matched
As alveolar ventilation increases, what happens to alveolar Po2 and Pco2?
Alveolar Po2 increases and Pco2 decreases. Opposite occurs when alveolar Op2 decreases
What is the difference between hyper and hypoventilation?
Hyperventilation: exceeding demands, therefore PP increases and CO2 decreases
Hypoventilation: isn’t meeting demands, CO2 increases and PP decreases
As the following components increase of decrease, what happens to bronchioles, pulmonary arteries and systemic arteries?
Pco2 increases
Pco2 decreases
Po2 increases
Po2 decreases
Pco2 increases= bronchioles dilate, pulmonary arteries constrict, systemic arteries dilate
Pco2 decreases= bronchioles constrict, pulmonary arteries dilate, systemic arteries constrict
Po2 increases= bronchioles constrict, pulmonary arteries dilate, systemic arteries constrict
Po2 decreases= bronchioles dilate, pulmonary arteries constrict, and systemic arteries dilate
What percentage of O2 in blood is dissolved? What is the percentage of the other half, where does it go?
<2% of the oxygen in blood is dissolved, the other 98% of oxygen is transported by hemoglobin
Hemoglobin in its normal form is called _______
While hemoglobin attached to oxygen is called _____
Hemoglobin
Oxyhemoglobin
How is saturation of Hb measured?
How much Hb is bound to oxygen measures the total saturation of it.
What happens at 100% saturation?
All four binding sites of the heme groups are bounds to oxygen
The composition of arterial blood: Hb is ____ saturated
The composition of Venous blood: Hb is ____ saturated
98%
75%
Explain the oxygen transport in the blood. Use reaction shifts to explain answer. What does a rightward and leftward shift mean?
An increase in Po2 shifts the reaction right (Hb+o2–>Hbo2)
A decrease in Po2 shifts the reaction left (Hb+o2
Basic summary of a right shift
- decrease affinity, more O2 released
- decrease in pH
- increase in both temperature and Pco2
- represented by an increase in metabolic activity
Basic summary of a left shift
- increases affinity
- less O2 released
- increase in pH
- decrease in temperature and Pco2
- this represents a decrease in metabolic activity
What is the Bohr effect?
This is a shift in the hemoglobin saturation curve resulting from from a pH change. (Lower pH increases O2 unloading)
Explain 2,3, bisphosphoglycerate (2,3BPG) and its relation to saturation curves
- this causes a shift to the right
- chronic hypoxia increases RBC production of 2,3BPG
Explain the effects of CO2 on saturation curves
- hemoglobin has a greater affinity for CO than for O2, this prevents O2 from binding to hemoglobin
- low oxygen increases 2,3 BPG—> right shift and overall increases oxygen
- increasing CO2 means Hb desaturation and results in right shift
- decreasing CO2 means Hb saturation and results in left shift
With saturation curves, what happens to temperature and pH? What are the right and left shifts?
pH:
Increase in pH—> results in left shift
Decrease in pH—> results in right shift (by increasing H+ you get a right shift)
Temperature:
Increasing in temperature—> results in right shift (less saturated)
Decreasing in temperature—> results in left shift (more saturated)
The hemoglobin in fetuses are 2 ___ and in adults are 4 ____
The total O2 content of arterial blood depends on the ______ dissolved in the plasma and bound to hemoglobin
Gamma, beta
Amount of O2
What are the carbamino effect and haldane effect?
Carbamino effect: when Co2 is bound to hemoglobin, the conformation of hemoglobin changes and decreases affinity for O2
Haldane effect: CO2 contents of blood falls as Po2 rises and binding of O2 to hemoglobin decreasing affinity of hemoglobin for CO2
Carbonic anhydrase creates a ____ shift which exchanges HCO3 for CL to maintain electrical neutrality
Chloric
Name the 8 steps for CO2 transport
- CO2 diffuses out of the cell into systemic capillaries
- Only 7% of CO2 remains dissolved in plasma
- 1/4th of CO2 binds to Hb, forming HbCO2
- 70% of CO2 is converted to bicarbonate and H+, Hb buffers H+
- HCO3 entrees plasma in exchange for CL (choleric shift)
- At lungs, dissolved CO2 diffuses out fo plasma
- CO2 unbind from Hb and diffuses out of RBC
- HCO3 is pulled back into RBC and converts to CO2
