This note is just the Question and Answer of LUNG ADN RESPIRATION SYSTEM.
Lung and Respiration system
The main function of respiratory system is to supply oxygenated blood to living organs and to remove carbon dioxide.
What is the main function of resipratory system?
1. pulmonary ventilation; 2. diffusion of O2 and CO2 inside alveolo of the lung; 3. transportation of O2 and CO2 to and from the body tissue. 4. regulation of ventilation.
Explain four major functions of the respiratory system.
It first flows through nasal cavity, then it passes through pharynx, trachea, bronchus, bronchiole, and finally the alveolo.
Please describe the flow path of atmospheric air in the respiration system.
There are two lungs in the respiratory system and total 23th bifurcations. The right one is slightly bigger than the left one due to middle mediastinum. The bifurcation will increase the surface area for gas exchange. The zeroth bifurcation is trachea; the first bifurcation is brochi. The 11th generation is brochioles; The 16th generation is avleolistrong>, which can exchange gas with capillary. The 23 generation is called alveoli sac.
Describe the general morpholoy of respiration system.
Describe the overall structure of human lung.
There are upper airway, Tracheo-bronchial Tree and Gas Exchange at alveoli. For Upper airway, there are Nose: nostril, nasal cavity (two channels); Pharynx: nose-mouth-glottis, velum; Larynx: division of gut, trachea, epoglottis, glottis. For tracheo-bronchial tree, there are trachea, main bronchus, right lung (56% with 3 lobes) and left lung (44% with 2 lobes). For gas exchange at alveoli, alveoli in the alveolar sacs are matched with capillaries.
What are the three zones of human lung?
Conducting Zone: there is no alveoli. It consists of bronchi and bronchioles, directly down to terminal bronchiole (TB). Bulk flow is always in there. The main function of that zone is to regulate the temperature, moisterize, capture the particle through (cilia and mucus)
Transition Zone is also the respiratory bronchiole (RB).
Respiratory Zone consists of alveolar duct (AD) and alveolar sac (AS). There is no cillia/mucus but there is surfactant. The blood vessels are mainly populated in that region. AS gas-exchange membrane and blood flows in capillaries. Blood passes through seperated air spaces between two sheets.
Describe Alveoli
First, there are 3 to the 10th power of alveoli in an adult's lung. The diameter varies widely 160-350 micrometer; the entrance opening is smaller than overall diameter. The Alveolar septum is a capillary wall between two sheet of epothelia
Describe the morphogenesis of human lung
Week 4 hung bud outgrows from a spot in intestine; form pharnyx, trachea, bronchi and internal epithlium; Single bud contect centrally to differentiate between gut and airway; Airway tube forms trachea which is divided into two bronchial buds. Week5 main trachea is formed, braching into secondary bronchi(2, 3); then lobes are formed; tertiary/segmental bronchi are formed. Week16 terminal bronchioles (TB) is formed. Month 6 each TB divides into more htan 2RB, which divide into 3-6 alveolar ducts. Month 7 terminal sacs and alveoli are formed. Epithelia change from cubical to planar shape, capillaries are foremd. In this stage, the immature baby can be survivable. However, the conducting tree is not fully developed after birth. Alveoli is totally immature. 10% at birth, 50% year 1. completed at year 8.
What are the main functions of humnan lung?
Gas Exchange: lung try to maximize gas exchange area for a given blood flow. 1ml of fresh blood carries 0.2ml of O2: only 4% CO2 carries in blood is expelled at the lung. 70%->10% O2 in vein; Gaseous CO2 5%, 88% HCO3 (26 in RBC, 62 in plasma); 250ml/min at rest of O2 consumption
Breathing: It is induced by the motion of diaphram and rib; diaphram is a thin sheet that seperates abdominal and thoracic cavities.(convex upward at rest, flat during inhalation)
Blood acidity: acidity is important to cell function. When blood is too acid or alkaline, nural function is ditributed, than coma, muscle spasm, death. The acidity is mainly determined by CO2 concentration
What are the flow characteristics in human lung
General: 1. Steady-Unsteady; 2. Cilia and Surfactant surface have no effect on air flowl; 3. Cartilage in large brochi affects air flow; 4. Turbulent jet formed in trachea past larnyx 5. change in airway diameter during breathing is negligible
Upper airway: 1. Laminar Flow from nostril to internal ostium 2. Sudden area increase after IO, inducing flow seperation and turbulent flow 3. Turbulence remains all over the main cavity'; two nasal cavities turn 90 downward.
mean axial velocity: 1m/s at trachea, 1mm/s avleoli, the profile will be skewed.
What are the four factors that affects the gas exchange?
1. the thickness and surface area of the membrane; 2. the diffusion coefficient of the gas and the pressure difference betweenm the two sides of the alveolar memebrane. 3. The bindings rate of O2 to hemoglobin 4.the volume of blood in the hung capillaries.
Two important factors in the gas tranporation and exchange in alveoli capillaries
1. the local concentration 2. total gas flux
Briefly summarize the pariticle depostion
Particle concentration is closely correlated withd death rate
Decomposition of PM (particle matter)
Big particles are deposited on TB, while the small one in AS by diffusion. The minimum deposition is 0.5 um; Velocity profile is much important; The Re effect is higher in 3D than in 2D.
non-uniform harzard hot spots are determined by the highest local concentration caused by inhalation and exhalation. when d > 10um, the particles can b e removed at nose
PM will grow due to huminity
Respiratory flow can affect the particle decomposition: 1) flow in trachea turbulent (Re-2100) can enhance deposition of particles; Glottis jet: particles are collected along the center, and collide on carina. 3) Irregularity on the airway can also suppress turbulence.
The perticle can be removed minutes at nose, bronchi for hours, and alveoli for weeeks; Deposited PMs on mucus move toward throat by cilia + gas flow in and out.
If using drug, there is less side effect, fast absorption.
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