Respiratory Flashcards
What are the four muscles of inspiration?
External Intercostals, Sternocleidomastoid, Serratus Anterior, Scalenus Muscles
What are the two muscles of Expiration?
Abdominal rectus, Internal Intercostals
What is the normal pressure of pleura at the beginning of inspiration?
Around -5cmH20
Inspiration causes more negative or positive pressure? And to what value?
More negative, -7.5 as chest cage pulls outwards on lungs.
Pressure when glottis is open/no air flowing?
0cmH20. Air pressure in aveoli are equal to atmospheric pressure.
Inward flow of air?
Pressure of alveoli vs outside?
Pressure of alveoli < atmohspheric pressure
~ -1cmH20
Outflow of air?
Pressure of alveoli vs outside?
Pressure of aveoli> atmospheric pressure.
~ 1cmH20
Forces about 0.5 liters of inspired air out of the lungs dring 2-3 seconds of expiration.
Transpulmonary Pressure
Difference between alveolar pressure and pleural pressure. A measure of elastic forces in lungs; recoil pressure. Pressure that keeps lungs inflated and prevents collapse.
Lung Compliance
Extend to which lungs will expand for each unit increase in transpulmonary pressure (Alveolar Pressure - Pleural Pressure); force that opposites the lung’s recoil (compliance wants to expand!).
Lung Compliance= Change in Volume/ Change in Pressure
In order for a lung to expand/be compliant, what has to be present?
Surface Tension (2/3 effect), Elasticity (1/3 effect) (recoil, elasin/collagen)
Which will have more compliance, air filled or saline filled lungs?
The lung with more surface tension. Example: saline filled lung (needs less pressure to change, so compliance is better), no surface tension. Only tissue elastic forces (recoil) present). So more transpleural pressure is neeed for air-filled lungs.
Total compliance of both lungs
200 mL
If the pressure inc by 1 cm, the lung volume inc to about 200 mL.
What has more compliance, expiration or inspiration?
Expiration
Surface Tension
An elastic force of lungs on the inner surfaces of alveoli, making them want to collapse/ pushes air out.
Surfactant
Greatly reduces alveolar surface tension and thus reduces effort required by respiratory muscle to expand lungs.
What is surfactant made from and out of?
Type 2 alveolar epithelial cells; a mix of dipalmitoyl-phosphtidylcholine, apoproteins, and Ca2+ ions.
Tidal Volume
Normal breath volume in/out
Inspiratory Reserve Volume
Volume of air that can be inspired over the normal tidal volume.
3L
Expiratory Reserve Volume
Max amout of air you can breathe out (after normal tidal expiration). 1.1L.
Residual Volume
Air remaining once youve maximally breathed out
Inspiratory Capacity
TV+ Inspiratory Reserve Volume
Vital Capacity
TV+ Expiratory Reserve Volume+ Inspiratory Reserve Volume
Functional Residual Capacity
Expiratory Reserve Volume + Residual Volume
Total Lung Capacity
Vital Capacity+ Residual Volume
Respiratory Distress Syndrome
Alveoli are not very big (smaller radius) so they have more tendency to collapse. Premature newborns at risk bc not high levels of surfactant yet.
What is dead space and it’s impact on alveolar ventilation?
Anatomical dead space is air inflow that’s not used in gas exchange; Physiological or functinoal dead space is from alveoli that are not functioning properly. If ventilation is impacted, o2 and co2 exchange is impacted.
Alveolar Ventilation Equation
VA= R(VT-VD)
Respiratory Rate per minute * (Tidal Volume - Physiologic Dead Space)
R is respiratory rate, VT is tidal volume, and VD is dead space volume.
When the pulmonary valve closes, how does the pressure in the pulmonary artery change compared to the right ventricle?
It drops.
Systolic pulmonary arterial pressure? Diastolic? Mean?
Systolic: 25 mmHg
Diastolic: 8 mmHg
Mean: 15 mmHg
Left atrial and pulmonary venous pressures
2-5 mmHg
Pulmonary Capillary Pressure
7 mmHg
Blood volume of lungs?
0.45 L
(0.07 of which are in pulm.capillaries)
9% of total blood volume
Lungs serve as a blood reservoir!
If o2 concentration decreases below normal (73mmHg)… what happens to the blood vessels there?
What’s the important exception?
They will CONSTRICT, and vascular resistance will increase.
This is opposite to the effect observed in systemic circulation, which DILATES in response to low o2 levels.
Functions to distribute blood flow to where it’s most effective.
What do capillaries in alveolar walls get distended by and compressed by?
Blood pressure inside them and compressed by **alveolar air pressure **on the outside.
When alveolar air pressure becomes greater than the capillary blood pressure, the capillaries close and there is** no blood flow**
Zone 1of the lung
-No blood flow. Abnormal conditions.
-Aveolar pressure > capillary pressure.
Low pulmonary systole arterial pressure, or alveolar pressure is too high.
Zone 2
Intermittent Blood Flow (peaks of pulm.arterial pressure); systolic pressure is higher than alveolar pressure, but diastolic pressure isnt strong enough).
-Extends to top of lungs, flow during systole
Zone 3
CONTINUOUS blood flow. Alveolar capillary pressure> alveolar air pressure. Lower region of the lungs.
Exercise and Blood Flow
Lung blood flow increases.Zone 2–>3. Increases # of capillaries, increases rate of flow, inc pressure, surface area. These reduce pulmonary vascular resistance.
Left-Sided Heart Failure
Blood build up in left atrium. From normal pressure of 1-5 mmHG–> 40-50 mmHg. Will cause equal rise in pulmonary arterial pressure and inc load on right side too.
Pulmonary Edema
Atrial pressure rises above 30 mmHg.
What is the pleural cavity and pleural fluid?
Space between parietal and visceral pleurae. Fluid is a thin layer of mucoid-like fluid due to proteins. “Potential space”
Function of pleural cavity?
The pleural fluid pressure is negative and keeps lungs pulled against parietal pleura. ~7mmHg.
The normal collapse tendency of lungs is** -4 mmHg** so the pleural fluid pressure must be more negative than that
Pleural Effusion + Causes
Increased fluid in p.space, aka edema. Causes include lymphatic drainage blockage, cardiac failure, reduced colloid osmotic pressure,infection.
-Cardiac f: high peripheral/pulm capillary pressure, fluid leaks into cavity.
-Reduced osmotic: not as mnay proteins in blood to pull water in capillaries so fluid goes to p cavity.
-Lymphatic vessels pump fluid to mediastinum,superior diaphragmatic surface, and lateral surfaces of parietal pleura.
Define Partial Pressure of a gas; how does this influence diffusion?
Pressure exerted by that gas alone; pp influences the rate of diffusion.
Two things that determine partial pressure of a gas? Is the second thing direct or indirect?
1.Concentration
2.Solubility Coefficient (Indirect: the more soluble a gas is in water, the lower the partial pressure)
Why does Co2 move out of the capillary and into the aveoli and O2 opposite?
Because Co2 has a smaller partial pressure than o2, and thus moves out of the capillary.
Important for gas exchange! We need oxygen!
The greater the solubility of a gas,
influences what in diffusion? (not pp related)
the greater number of molecles to diffuse (for any given partial pressure)
Factors that go into the Net Rate Diffusion in Fluids, which one has highest?
o Partial** Pressure**
o Solubility of the gas in fluid
o Cross-sectional area of the fluid
o Distance the gas has to diffuse
o Molecular weight of the gas
o Temperature of the fluid
PSA DWT
What is atmospheric air mainly composed of?
Nitrogen 78%, Oxygen 20%
What does humidity do in the gases in inspired air?
Dilutes all other gases.
Look at this table, compare/contract relative partial pressures of N2,O2,Co2,H20.
Total atm: 760 mmHg.
N2 ~580> O2 ~130. for the most part. Co2 really increases in alveolar air 40 and expired air 27. H20 is pretty constant at 47, except for atm regular air.
The 2 ways that oxygen concentration in alveoli is controlled?
1.Rate of Absorption of o2 in blood
2.Rate of Ventilation aka entry of new o2 in lungs/alveoli
While exercising, O2 is being absorbed by the blood more rapidly, so the body will increase ventilation to replace the absorbed oxygen back in the alveoli.
What does edema fluid in the interstitial space do to the membrane?
Increases thickness of the membrane
Emphysema
Alveoli joining/fusing together; this decreases total surface area bc of the loss of membrane that was on individual aveolar walls. GAS EXCHANGE is IMPEDED.
Co2 diffuses about … times as rapidly as o2. O2 diffuses … times as rapidly as Nitrogen.
20, 2
Respiratory Membrane’s Diffusing Capacity
Volume of gas that will diffuse through the membrane each minute for a partial pressure different of 1 mmHg.
Diffusing capacity O2
21 ml/min/mmHg
Quiet breathing pressure difference across membrane?
11 mmHg
Respiratory capacity for quiet breathing?
11mmhg * 21= 230 Ml of oxygen diffusing through the membrane each minute.
Oxygen diffusing capacity is increased or decreased during exercise?
Increased; previously dormant pulmonary capillaries/extra dilation of already opened ones. Better ventilation-perfusion ratio!
During exercise blood is pumped faster and remains in capillary for a shorter period of time, but due to the increase in oxygen capacity, blood still gets all the oxygen it needs to spread to rest of body!
Increasing blood flow raises tissue partial O2. (Decreasing it= increase pCo2!).
Describe the pressure averages of O2 in the alveoli and capillary and how it moves?
**It will move high to low. **
Alveoli: ~104 mmHg–>Entering capillary: 40mmHg
Rises as it travels in capillary.
Capillary arterial end: ~95–>Tissue/interstital space: ~40 mmhg.
From the tissues and entering the systemic vein: po2 is about 40 mmHg.
What carries o2 in the blood?
97% of O2 transported from lungs to tissue is carried in combo with Hemoglobin in RBC.
3%= dissolved state
What alter affinity of o2 for Hb?
pH (more acidic, less it binds), Co2 (indirect),Temperature (rise decreses affinity), BPG
2,3-Bisphosphoglycerate (BPG), also known as 2,3-Disphosphoglycerate (2,3-DPG), promotes hemoglobin transition from a high-oxygen-affinity state to a low-oxygen-affinity state.
Oxyhemoglobin Dissociation Curve
Alveoli po2:105 mmHg, Hb=100% sat
Tissues po2: 40 mmhg, Hb=75% sat
Utilization Coefficient: 25%, increases with exercise
What pressure range does Hemoglobin deliver O2 to tissues?
15-40 mmHg
Tissues need …ml of O2 per 100 ml of blood.
5
What are the three forms co2 can take on in the blood?
dissolved gas CO2 7%, Hgb-CO2 23%, HCO3- 70%.
Enzyme that allows co2 to react with h20?
carbonic anhydrase.
Co2 Dissociation Curve
-Not signmoidal like o2 curve.
-Pco2 Lungs: 30 mmHg
-Pco2 Venous: 45 mmHg
(LOWER range than o2).
Where is the respiratory center?
Medulla oblongata/pons of brain stem
What are the three parts of the respiratory center and their associated function?
Dorsal Respiratry Group: Inspiration
Ventral Respiratory Group: Expiration
Pneumotaxic Center: Controls rate/depth of breathing
Hering-Breuer Inflation Reflex
Prevents over-inflation of lung. Pulmonary stretch receptors present on wall of bronchi and bronchioles of airways respond to excessive stretching of lung during large inspirations.–>Action potentials via vagus nerve–>inspiratory area/Dorsal respiratory group in pons –>inhibited–>allows expiration to occur.
Excess co2 and respiration relationship?
Co2 can cross blood-brain barrier, form H+, stimulating chemo-sensitive areas strongly to induce brain stem inspiratory area. (to get oxygen in)
What does low o2 stimulate? for respiration
Stimulates peripheral chemoreceptor system. O2 has little direct effect on respiratory center itself.
What are the two peripheral chemoreceptor systems for control of respiration? Associated CN?
Carotid body (CN IX, glossopharyngeal)
Aortic Body (CN X, Vagus)
What type of cells do chemoreceptors contain?
Glomus Cells
They synpase with nerve endings and function as the chemoreceptors.
Low oxygen or high co2/h+?
What do chemoreceptors do?
Chemoreceptors increase inspiration!
