Flashcards in Pulmonaryation Deck (59):
Label the respiratory system
What is air in vs air out?
Label structures involved in pulmonary ventilation
Why don't the lungs collapse?
Although the lungs are naturally elastic the pressure in the pleural cavity is naturally less that Pa. Since Pp
-primary respiratory muscle
-large dome shaped muscle that separates the thoracic cavity from the abdominal cavity
-layers of muscles between the ribs
-external and internal internal intercostal muscle fibers run at oblique angles to the ribs but in different directions
Several different groups can be involved with pulmonary ventilation mainly during expiration
Function of the respiratory muscles:
To create a pressure gradient between the atmosphere and the lungs. If Patm > PA then air will move into the lungs by diffusion. This is accomplished by changing the volume of the chest cavity
What happens during human inspiration?
-diaphragm moves downward to expand the pleural cavity
-intercostal muscles lift the rib cage upwards and outwards to increase the volume of the pleural cavity
-increased volume decreases Pp
-decrease in Pp causes a vacuum or suction effect to increase the volume of the lungs
-increased lung volume decreaes PA
How does inpiration change during exercise (muscles)?
Stronger contractions of the inspiratory muscles cause larger increases in lung volume and thus a greater pressure gradient so more air is diffused. Additional accessory inspiratory muscles (sternocleidomastoids) also become involved.
What happens during human expiration?
-diaphragm relaxes, moves upward toward its original position
-external intercostal relax, rib cage falls downward and inward toward its original position
-natural elasticity of the lung cause it to recoil, increase in PA which forces air back out to the atmosphere
-PA and Pp return to pre-inspiration values
How does human expiration change during exercise (muscles)?
-the internal intercostal muscles contract to pull the ribs inward and downward wich helps to decrease the volume in the chest cavity faster and increase PA. Several abdominal muscles can also become involved to help push diaphragm upwards.
Refers to one of the four lung divisions of total lung capacity
The volume of gas added to the lungs with each inspiration and exhaled with each expiration
Expiratory reserve volume
The volume of as that can be expired at the end of a normal spontaneous expiration
Inspiratory reserve volume
The maximum volume of gas that can be inhaled at the end of a normal spontaneous inspiration. It is the IRV that is mainly responsible for the increase in Vt during exercise
The volume of gas that remains in the lungs at the end of a maximal expiration
One of the 4 lung campartments that is measured by tests of pulmonary function
VC 4.5 L
-the maximum volume of gas that can be exhaled after the deepest possible inspiration
(VC= IRV + VT + ERV)
Functional reserve capacity
FRC 2.4 L
-the total volume of gas that remains in the lungs at the end of a normal spontaneous expiration
(FCR = ERV + RV)
IC 3.5 L
-the maximum volume of air that can be inhaled after the end of a normal expiration( or from FRC)
(IC = VT + IRV)
Total lung capacity
TLC 6 L
The total volume of gas in the lungs at the end of a maximal inspiration
TLC = RV + ERV + Vt + IRV
The volume of air moved into or out of the lungs per unit of time (L/min). The two factors that determine ventilation rate are the frequency of breathing (f) measured as the number of breaths per minute and the tidal volume. Expired ventilation rate can be calculated as 18 breathes/min * o.35 L/breath
Normal spontaneous breath of which we are usually unaware. Ventilation is proportional to metabolic demand.
Increased pulmonary ventilation that matches an increased metabolic demand. The demand is initially satisfied by increasing VT and later by increaseing breathing frequency
Increased pulmonary ventilation that exceeds metabolic demand
Pulmonary ventilation at a rate that is less than the metabolic demand
Uncomfortable awareness of a need for increased breathing and is percieved as difficult or laboured breathing
Draw a diagram of pulmonary gas exchange
V gas = A/T X (PA-Pa) X D
where A=Tissue surface arease
T= Tissue thickness
(P1-P2)= Pressure gradient across tissue
D=Diffusing contant (Solubility/sqaure root of molecular weight
Is O2 or CO2 more soluable?
D of CO2 is 20x more becuase it is carbon based
What are the relationships within ficks law?
If A increases the V increases (area of blood gas barrier is 50 to 100m2)
If T decreases V increases (thickness is <.5 micron)
If (P1-P2) increases the V increases
If D increases then V increases
Steps in exchange of O2 between the Alveoli and pulmonary capillaries
1. Air is drawn into the alveoli of the lungs. This air has a high partial pressure of oxygen relative to the blood passing by the alveoli
2. The oxygen dissolves in the moist layer of fluid on the inner surface of the alveoli
3. The oxygen diffuses through
a. The film of moisture
c. Interstitial fluid
d. Capillary cell membrane
e. Blood plasma
f. Across RBC membrane
g. Through RBC cytoplasm until it combines with hemoglobin
4. Once the pulmonary capillary has picked up the oxygen it is ready to be transported via the pulmonary vein to the left atrium to be delivered to the rest of the body
How is oxygen transported in the blood?
0.3 ml/100ml dissolved in plasma
20.8 ml/100ml transported by Hb in RBC
Hemoglobin combines with oxygen to form oxyhemoglobin (HbO2)
Each Hb molecule can combine with 4 O2 molecules. Normal blood Hb is usually 97.5% saturated with O2.
A disease that causes inflammation in one or both lungs, usually viral or bacterial. Can be lobular or bronchial and interferes with gas exchange
Inflammation of mucous membranes of the bronchi, either acute (infection) or chronic (irratant). Without cleansing action of the cilia bronchi become increasingly inflamed and vulnerable to infection. Mucus builds up.
How is oxygen exchange between tissue capillaries and cells?
The partial pressure of O2 in the capillaries is high. In the interstitial fluid the partial pressure of O2 is low. Therefore O2 diffuses from the capillary to the ISF. Now the ISF has a high partial pressure of O2. The cells have a low partial pressure of O2 since it has been used up by the cellular respiration of the cell. Therefore O2 diffuses from the ISF into the cells (also see diagram)
Tissue removes max of 25% oxygen
How is co2 exchanged between cells and tissue capillaries?
Carbon dioxide is a waste product of cellular respiration and therefore active cells have a high pressure of CO2. ISF has a low partial pressure of CO2. Therefore CO2 diffuses from the cell into the ISF. Arterial blood delivered to cells contains a very low partial pressure of CO2. Therefore CO2 diffuses from the ISF into the capillaries to be transported back to the heart and then the lungs.
How is CO2 transported in the blood?
CO2(aq) + H2O(l) --(carbonic anhydrase)-->H2CO3(aq)-->H+(aq) + HCO3-(aq)
H+(aq) + Hb --> H+Hb + CO2(aq) --> H+HbCO2 (carboamino hemoglobin)
How is CO2 exchanged between the pulmonary capillaries and the alveoli?
CO2(aq) + H2O(l) <-- H+HbCO2 (carboamino hemoglobin)
Once the CO2 has been released by its transport molecule it diffuses across all of the same structures as O2 but in the opposite direction.
What are some notes about pulmonary gas exchange?
1. Red blood cells only spend 3/4 of a second in the pulmonary capillary so diffusion must occur very quickly. During exercise reduced to 1/3 of a second
2. Carbon dioxide must be released before oxygen can be picked up
3. CO attaches to hemoglobin 200x more readily than CO2 or O2
Where is ventilation controlled?
The respiratory center in the medulla but it can be overridden by conscious control of the cerebral cortex (to a certain extent)
What are the steps of ventilation control?
1. Respiratory center send a nerve impulse to the muscles of inspiration causing them to contract which results in air being inspired
2.The respiratory center stops sending the nerve impulse so the inspiratory muscles relax, inspiration ends
3. Expiration occurs passively
What are the normal partial pressures of CO2 and O2?
PCO2 = 40mmHg
PO2 = 100mmHg
What is the biggest factor for regulating ventilation and how is it controlled?
The level of CO2 in arterial blood.
Central chemoreceptors to CO2 located in respiratory center
Peripheral chemoreceptors in common carotid arteries and the arch of the aorta
If the level of CO2 increases in our arterial blood the chemoreceptors signal the respiratory center to send more nerve impulses to the inspiratory muscles. This causes an increase in ventilation so more CO2 is exhaled. Once levels return to normal so does breathing.
How does oxygen levels affect ventilation?
O2 in arterial blood must get extremely low before chemoreceptors effect ventilation. If it does then ventilation will increase.
What are other factors that increase ventilation?
-decrease in Ph
-increased temperature (monitored by medulla)
-increased limb movement
-cerebral factors, anticipation of exercise
What is the Hering Bruer Reflex?
-reflexes from lungs and chest stretch receptors terminate larger than normal inspiration and terminate larger than normal expiration for the sake of the alveoli.
What are the stages of respiration?
2. External respiration: Pulmonary Gas exchange
3. Internal respiration: Tissue gas exchange
4. Cellular respiration
How does outer skin respiratory surface work?
Oxygen diffuses into a network of thin walled capillaries just below the skin. Animals usually have a high ratio of respiratory surface to body volume. They must live in damp places or in water to keep their skin moist.
How des the tracheal system work?
(Insects) An internal system of branching respiratory tubes called tracheae,. Connects body cells directly to the environment outside the insects body by even smaller tubes called spiracles that make direct contact with cells.
How do gills and counter current exchange work?
Gills are extensions or folds in the body surface that increase the surface area that gas can be exchanged as water flows over the gills. Blood flows through the gills in the opposite direction to the flow of oxygen containing water creating a diffusion gradient.
An infection of the tonsils caused by virus or bacteria. Removing can increase risk of throat infection later as tonsils help prevent bacterial and other harmful substances from entering the respiratory system
Inflammation of the larynx
Chronic inflammation of bronchi and bronchioles and overproduction of mucus. Reduces air flow. During an asthma attack muscles around the airways contract and increase mucus production. Inhalers deliver medicine that relaxes the muscles.
Walls of alveoli lose their elasticity and fuse together. Reduces respiratory surface area. Exhaling becomes difficult because the small airways collapse during exhalation. Usually caused by smoking. Chronic obstructive pulmonary disease.
A genetic disease that causes a thick build up of mucus in the lungs resulting in infection (because infection things get stuck and can't be expelled), inflammation, and damage to the lung tissues.