5 Overview of the Respiratory System Flashcards
1
Q
Chest wall
- Respiratory system consists of…
- Chest wall includes…
A
- Respiratory system consists of…
- Lungs
- Chest wall
- Chest wall includes…
- Rib cage
- Thoracic spine
- All structures attached to the rib cage & thoracic spine
- Respiratory muscles (including the diaphragm)
- Other skeletal muscles
- Fat
2
Q
Parenchyma:
Lungs
A
- Divided into lobes, segments, and lobules
3
Q
Airways
- Upper airways
- Lower airways
- Terminal bronchioles
- Respiratory bronchioles
A
- Upper airways
- Above the vocal cords
- Nose, mouth, pharynx, larynx
- Lower airways
- Below the vocal cords
- Conducting airways, respiratory airways
- Terminal bronchioles
- Each terminal bronchiole provides gas to a separate pulmonary lobule
- Respiratory bronchioles
- Each respiratory bronchiole provides gas to a lung acinus
4
Q
Respiratory system
- Function of the respiratory system
- This depends on…
A
- Function of the respiratory system: “gas exchange”
- Maintain a normal partial pressure of oxygen (PaO2) & carbon dioxide (PaCO2) in the arterial blood
- Remove CO2 from and add O2 to the mixed venous blood
- This depends on…
- Ventilation: movement of air into and out of lungs
- Perfusion: movement of blood into and out of lungs
- Matching of ventilation & perfusion
- Gas diffusion: movement of molecules along their pressure gradients
5
Q
Ventilation
- Definition
- Functions
- Regulated by…
A
- Definition
- Repetitive movement of gas into and out of the lungs (i.e. breathing)
- Ventilation = breathing
- Functions
- Delivers oxygen to and removes carbon dioxide from the alveoli
- Controls CO2 excretion by the lungs and therefore regulates the PaCO2
- Regulated by…
- Neurons in the medulla, which receive input from the cerebral cortex and from peripheral receptors
6
Q
Ventilation
- Inspiration
- Expiration
A
- Inspiration
- Occurs when the respiratory muscles increase the volume of the respiratory system
- Active proces
- Expiration
- Occurs when the elastic recoil of the respiratory system decreases its volume
- Passive process
7
Q
Perfusion
A
- The flow of mixed venous blood from the right ventricle through the pulmonary arteries and the alveolar capillaries
- Delivers CO2 and removes O2 from the alveoli
8
Q
Ventilation-perfusion relationships
- Each alveolus receives…
- The relationship between ventilation and perfusion
- Ideally, all alveoli should receive…
- In reality…
- Ventilation-perfusion relationships are important because…
A
- Each alveolus receives…
- A certain volume of gas (ventilation; V) and blood flow (perfusion; Q) each minute
- The relationship between ventilation and perfusion
- The V/Q ratio
- Ideally, all alveoli should receive…
- The same amount of ventilation and perfusion
- I.e. V/Q should be 1.0
- In reality…
- There is a range or distribution of V/Q ratios in the lungs
- Ventilation-perfusion relationships are important because…
- The V/Q ratio of each alveolus determines the PO2 and PCO2 of the alveolar gas (PAO2, PACO2) in each alveolus
- Normal vs. lung disease
- Normally, ventilation and perfusion are well-matched
- Lung disease produces mismatching between ventilation and perfusion
- This causes the PaO2 to fall and the PaCO2 to rise as the range or distribution of V/Q ratios increases
9
Q
Diffusion
- Definition
- Affected by…
- O2 & CO2
- O2
- CO2
A
- The movement of molecules from a region of high to low partial pressure
- Affected by…
- Partial pressure gradients
- Area of contact between alveolar gas and capillary blood
- Distance for gas diffusion
- O2 and CO2 move between the alveoli and the pulmonary capillary blood along partial pressure gradients
- O2 dissolves in and diffuses through the alveolar epithelium, the capillary endothelium, the plasma (where some remains dissolved) and the erythrocyte, where it combines with hemoglobin
- CO2 diffuses in the opposite direction
10
Q
Diffusion
- The rate of gas diffusion varies directly with…
- The rate of gas diffusion varies inversely with…
A
- The rate of gas diffusion varies directly with…
- The contact area between alveolar gas and capillary blood
- The partial pressure gradient
- The rate of gas diffusion varies inversely with…
- Diffusion distance
11
Q
Diffusion
- Normally,…
- Lung disease…
A
- Normally,…
- Complete equilibration occurs, so that the alveolar gas and the capillary blood leaving the alveoli have the same PO2 and PCO2
- Lung disease…
- Can cause incomplete equilibration, which causes the PaO2 to fall and the PaCO2 to increase
12
Q
Diffusion: O2
A
- Once O2 has been added to the arterial blood, it must be transported to the tissues and organs of the body
- Almost all O2 is carried combined with hemoglobin and a very small amount is dissolved in the plasma
- In the systemic capillaries, O2 enters cells by diffusing along its partial pressure gradient
13
Q
Diffusion: CO2
A
- CO2 is a byproduct of cellular metabolism
- It diffuses out of cells and into the systemic capillary blood and is then transported back to the lungs
- Most of the CO2 combines with hemoglobin or is converted to bicarbonate (HCO3), and a small amount dissolves in the plasma
- In the pulmonary capillaries, CO2 diffuses into the alveolar gas