Pulmonary System and External Respiration Flashcards
Pulmonary circuit
One of the two circuits in the circulatory system that carries blood to the lungs for gas exchange. Hemogobin in our blood i exposed to the gases we inhale, picking up molecular oxygen and unloading carbon dioxide.
Systemic circuit
The circuit that carries oxygenated blood from the heart to the body and returns deoxygenated blood back to the heart.
Blood vessels of the body…
Are divided into two circuit - pulmonary and systemic
How to RBC receive oxygen?
Alveolar cells (single layer) are next to capilliaries’ endothelium which provide them with blood. Oxygen diffuses down the concentration gradient through the two cell layers and into the haemoglobin in the RBCs
Why does the cardiovascular system need to be enclosed?
Because it is inside the body. The lungs enable the blood to be extrememly close to the atmospheric air due to the single cell endothelium of the capillaries and alveoli and the fact that it is connected to the outside world.
What are the 2 parts of the lung
Airway, ribcage and membrane that protects them (pleura).
What are the pleura attached to?
The ribcage
Two types/systems of respiration
External and Cellular
External respiration
The movement of gases between the environment and the body’s cells - system by which gas exchange occurs in the human body.
Cellular respiration
The intracellular reaction of oxygen with organic molecules to produce carbon dioxide.
Process of external respiration - Step 1
- Ecchange between air of atmosphere and air in lungs (ventillation).
Process of external respiration - Step 2
Concentration of O2 in atmospheric gas is higher than in the blood - its coming as deoxygenated from the right ventricle = diffusion gradient. O2 moves in. CO2 AND O2 are exchanged between lungs and blood.
Process of external respiration - Step 3
Exchange of gases between blood and cells
Label this diagram of the Bronchi
Label this diagram of the alveoli
Ventilation
The bulk flow exchange of air between the atmosphere and the alveoli.
What does a single respiratory cycle consist of?
Inspiration and expiration
Inspiration
The process of drawing air into the lungs, characterized by the contraction of the diaphragm (down) and an increase in thoracic volume.
Ribcage expands, external intercostal muscles contract, internal relax
Expiration
The process of expelling air from the lungs, characterized by the relaxation of the diaphragm (up) and a decrease in thoracic volume.
Ribcage down & in, internal intercostal muscles conract, external relax
Ventilation Rate
Breaht/min - completed inspiration and expiration per minutes
Lungs at rest
Skeletal muscles relax and diaphraghm is up
Boyle’s law
Pressure and volume are inversely related; if the pressure on a gas is doubled, its volume decreases by one-half.
Why does expiration take longer than inspiration?
Expiration is passive - external intercostal muscles are relaxed. Inspiration is active - external intercostal muscles are contracted.
Short expiration = lots air left in next breath = higher pressure + vol
Normal lung capacity at rest
500 mL.
Normal ventilation rate at rest
15 breaths/min.
Tidal volume (VT)
The volume of air that moves during a simple inspiration or expiration.
Inspiratory reserve volume (IRV)
Additional volume of air that can be inspired above tidal volume.
Expiratory reserve volume (ERV)
The volume of air that can be forcefully exhaled after the end of a normal expiration.
Residual volume (RV)
The volume of air remaining in the respiratory system after maximal exhalation.
Vital capacity (VC)
The total volume of air that can be exhaled after a maximal inhalation; calculated as IRV + VT + ERV.
Total lung capacity (TLC)
The total volume of air in the lungs after a maximal inhalation; calculated as IRV + VT + ERV + RV.
Describe all the parts of a spirometer tracing with this image
Familiarise yourself with this image
Typical Lung Volume for Men and Women
Label and describe the function of the parts of the alveoli shown in this image
Surfactant
A substance that decreases surface tension of liquids (water) in the alveoli by increasing its spreading and wetting properties.
Pulmonaru Surfactant
A complex mixture of specific lipids, proteins and carbohydrates produced by type II alveolar cells in the lungs.
Law of Laplace
If the radius is halved, the pressure inside doubles.
P = 2T/r
Smaller radiues = higher surface tension
Alveoli
Spherical structures in the lungs that provide the most surface area for gas exchange, averaging ~75 m². The smaller ones have more surfactant to prevent collapse and equalse pressure with larger alveoli.
Red Blood Cell (RBC)
The main purpose is to transport O2 and CO2; they are biconcave discs containing haemoglobic and are elastic and flexible. So they can go into capillaries.
Why is lung condition impirtant even when we have enough RBCs?
Collapse of alveoli reduces capacity of O2 uptake regardless of RBC concentration
Haemoglobin
A tetrameric protein composed of 2α and 2β globin subunits, each with a haeme co-factor that can bind O2 (Fe2+)
One haemoglobin binds to 4 O2/CO2
Main purpose of haemoglobin
To reversibly bind to O2, facilitating its unloading in organs and tissues.
Average lifespan of RBC
Approximately 120 days.
Diameter of RBC
Approximately 7.8 mm.
Number of haemoglobin molecules per RBC
Approximately 250 million.
Conditions affecting Hb binding to O2
pH, temperature, concentration of CO2, and 2,3-BPG.
Mechanics of breathing
The process by which air is drawn into and expelled from the lungs.
Alveolar macrophage
Cells that ingest foreign material in the alveoli.
