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How is gas diffusion between the lung and the blood maximized?
By making aveoli only a single cell thick
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What are the principal functions of the respiratory system?
- Supplies blood with O2 and Removes CO2.
- Ventilation and External respiration
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What is Ventilation?
movement of air in/out of lungs
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What is External Respiration?
transfer of gases between lungs and blood (short distance, cross membrane)
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What is transport as it pertains to the Respiratory System?
movement of gases via blood: lungs ↔ tissues (long distance, no membrane)
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What is internal respiration?
ransfer of gases between tissues and blood (short distance, cross membrane)
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Name the different cell types in the lung.
- Type 1
- Type 2
- Alveolar Pores
- Alveolar Macrophages
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What is the function of Type 1 cells?
epithelial cells forming exchange surface with capillaries
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What is the function of Type 2 Cells?
- ? scattered among Type I cells
- ? make surfactant that coats alveoli to reduce surface tension
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What is the Function of Alveolar Pores?
connect adjacent alveoli and equalize air pressure
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What is the function of Alveolar Macrophages?
phagocytic cells that consume microbes and dust particles
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How is air taken into the lungs during inhalation?
Inhilation occurs when contractions of the diaphragm and intercostal muscles create negative pressure in the thoracic cavity by expansion of the pleural cavity
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How is air expelled from the lungs during exhalation?
Exhalation occurs when relaxation of the diaphragm and intercostal muscles increases pressure in the thoracic cavity causing the pleural cavity to contract pushing air out
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What determines whether inhalation or exhalation occurs?
- Pressure gradients (relative to atm. pressure)
- determine whether exhalation or inhalation occurs
- -air moves down pressure gradient
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What is the shape of the diaphragm when it is relaxed?
normally relaxed in convex (dome shape) position
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Which cells in the lung produce surfactant?
lung alveoli
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What is the purpose of surfactant?
Decreases surface tension of liquid making lung inflation easier
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Distinguish between external respiration and internal respiration
- External Respiration:Lungs and Blood
- Internal Respiration: Tissue and Blood
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What is tidal volume? What is the normal tidal volume?
- Tidal Volume is how deep a person breaths.
- Typical values are around 500ml or 7ml/kg bodyweight.
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What is dead space volume? Does it change during respiration?
Air that is inhaled but not used in respiration. It does change.
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Name the two major types of alveolar cells in the lung and their function.
- • Alveolar pores
- - connect adjacent alveoli and equalize air pressure
- • Alveolar macrophages (dust cells)
- - phagocytic cells that consume microbes and dust particles
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How is oxygen transported in the blood?
Oxygen is reversibly bound to hemoglobin (Hb) in red blood cells
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Trace the steps from oxygen pick-up in
the lung to oxygen drop off in the tissues.
- • Oxygen is reversibly bound to hemoglobin (Hb) in red blood cells
- • Each Hb molecule can carry four O2 molecules maximum.
- • Affinity of Hb for O2 depends on the PO2 to which the Hb is exposed.
- • Hb gives up O2 in metabolically active tissues (low tissue pO2)
- • Hb picks up O2 as it flows through respiratory exchange structures (high pO2
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How is carbon dioxide transported in the blood? Trace the steps from carbon
dioxide pick-up in the tissues to carbon dioxide drop-off in the lung.
- Carbon dioxide (CO2 ) is a cellular metabolic waste product
- • CO2 is carried in the blood principally as bicarbonate ions
- • Bicarbonate buffers pH in blood
- • Affinity of Hb for oxygen is decreased in acidic environments
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What controls the affinity of hemoglobin for oxygen?
Affinity of Hb for O2 depends on the PO2 to which the Hb is exposed.
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What is the effect of a left-ward shift in the oxy-hemoglobin dissociation curve on
hemoglobin affinity for oxygen?
Oxygen Affinity decreases.
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Rank order the following hemoglobins in terms of affinity for oxygen:
hemoglobinm, fetal hemoglobin, myoglobin
Myoglobin, fetal hemoglobin, hemoglobin
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Which blood gas is the primary control for breathing rate?
The most important feedback stimulus for breathing is level of CO2 in the blood
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How does the structure of lung alveoli facilitate gas exchange?
Creates more surface area for the gas exchange to take place in. Also very thin, recall Fick's Law.
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Alveolar ventilation
volume of air reaching alveoli each minute (removing dead space volume)
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Alveolus
Grape-like cluster that are in the lungs
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Bicarbonate ion
How CO2 is transported in blood
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Bronchiole
Attach to the aveoli
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Bronchus
Right and left sections that deviate from the trachea
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Carbonic anhydrase
Enzymes that catalyze the rxn turning CO2 into bicarbonate
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Dead space volume
Gas that is inhaled but does not take place in exchange
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Diaphragm
Located in the thoracic cavity, it changes shape to enable lungs to expand
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Exhalation
Movement of air out of the lungs
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External respiration
transfer of gases between lungs and blood
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Fetal Hemoglobin
Fetal hemoglobin has a higher affinity for O2 than does maternal hemoglobin, allowing fetal blood to pick up O2 from maternal blood in the placenta
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Hemoglobin
Carries Oxygen in the blood stream
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Inhalation
The intake of air into the lungs
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Intercostal muscles
connected to the diagraphm, they enable for the expansion/relaxation of lungs
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Internal respiration
transfer of gases between tissues and blood
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Medulla
Breathing rhythm is an autonomic function generated by neurons in the medulla of the brain
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Mucociliary escalator
normally functions in trachea and lungs to clear smoke and particulate matter
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Myoglobin
has a very high affinity for oxygen and serves as an oxygen reserve in muscle.
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Oxygen affinity
How much a molecule "wants" to bind to Oxygen
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Oxygen-hemoglobin dissociation curve
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Partial pressure of carbon dioxide
Partial pressure of carbon dioxide, put simply, is the measurement of carbon dioxide in arterial blood.
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Pulmonary ventilation
tidal volume x respiratory rate
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Surfactant
- Decreases surface tension of liquid making lung inflation easier.
- Mostly Phospholipid
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Tidal Volume
the volume of gas inhaled and exhaled during one respiratory cycle.
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Ventilation
Movement of air in/out of the lungs
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