Chapter 13, Respiratory System, Part B

Chapter 13 – Respiration – Part B
9. Gas exchange crosses the respiratory membrane by diffusion:
a. Oxygen enters the blood
b. Carbon dioxide enters the alveoli
c. Alveolar Macrophages “dust cells” add protection by picking up bacteria, carbon particles, and other debris
d. Surfactant (a lipid molecule) coats gas-exposed alveolar surfaces
10. Events of respiration
a. Breathing – pulmonary ventilation—moving air in and out of the lungs (commonly called breathing)
b. External respiration—gas exchange between pulmonary blood and alveoli:
i. Oxygen is loaded into the blood
ii. Carbon dioxide carbon dioxide is unloaded from the blood
c. Respiratory gas transport—transport of oxygen and carbon dioxide via the bloodstream
d. Internal respiration—gas exchange between blood and tissue cells in systemic capillaries
11. Mechanics of breathing (pulmonary ventilation)
a. Completely Mechanical process that depends on volume changes in the thoracic cavity
b. Volume changes pressure changes: volume changes lead to pressure changes, which lead to the flow of gases to equalize pressure:
c. Charles’ Law: P = 1/V
d. Two phases:
i. Inspiration = inhalation
1. Flow of air into lungs
ii. Expiration = exhalation
1. Air leaving lungs
iii. Yoga
e. Inspiration details
i. Two sets of muscles: diaphragm and external intercostals muscles contract
ii. The size of the thoracic cavity increases
iii. External air pulled into chest due to:
1. Increase in intrapulmonary volume
2. Decrease in gas pressure
f. Expiration details
i. Largely a passive process which depends on natural lung eleasticity
ii. As muscles relax, Air pushed out of lungs due to:
1. Decrease in intrapulmonary volume
2. Increase in gas pressure
3. Forced expiration
g. Thoracic cavity pressure
i. Negative relative to the lungs
ii. Differences between lungs & pleural space
12. Nonrespiratory gas movements – can be caused by reflexes or voluntary action
a. Coughing—clears lungs of debris
b. Sneezing—clears lungs of debris
c. Crying—emotionally induced mechanism
d. Laughing—similar to crying
e. Hiccup—sudden inspirations
f. Yawning—very deep inspiration
i. Pandiculation = yawning +stretching
g. Talking—communication
13. Respiratory volumes and capacities
a. Normal breathing moves about 500 mL of air with each breath= tidal volume (TV) = 500
i. Affected by a person’s size, sex, age, physical condition
b. Inspiratory reserve volume (IRV) = amount of air that can be taken in forcibly over the tidal volume
c. Expiratory reserve volume (ERV) = amount of air that can be forcibly exhaled
i. Approximately 1200 mL
d. Residual volume (RV) = air remaining in lung after expiration
i. About 1200 mL
e. Dead space volume (DSV) = air that remains in conducting zone and never reaches alveoli
i. About 150 mL
f. Functional volume = air that actually reaches the respiratory zone
i. Usually about 350 mL, a low percentage of capacity
ii.
g. Capacities = two or more volumes together
i. Spirometer—respiratory capacities are measured with a spirometer
ii. Vital capacity (VC) = TV + IRV + ERV
1. The total amount of exchangeable air
iii. Total Lung Capacity (TLC) = VC + RV
14. Respiratory sounds
a. Sounds are monitored with a stethoscope
b. Two recognizable sounds can be hear with a stethoscope:
i. Bronchial sounds—produced by air rushing through trachea and bronchi
ii. Vesicular breathing sounds—soft sounds of air filling alveoli
15. External respiration details
a. Oxygen loaded into the blood:
i. The alveoli always have more oxygen than the blood
ii. Oxygen moves by diffusion towards the area of lower concentration
iii. Pulmonary capillary blood gains oxygen
b. Carbon dioxide unloaded out of the blood:
i. Blood returning from tissues has higher concentrations of carbon dioxide than air in the alveoli
ii. Pulmonary capillary blood gives up carbon dioxide to be exhaled
iii. Blood leaving lungs has more oxygen and less carbon dioxide than when it entered
16. Gas transport in blood
a. Oxygen transport in the blood:
i. Most oxygen attached to hemoglobin to form oxyhemoglobin (HbO2) – 98%
ii. Small dissolved amount is carried in the plasma – 2%
iii. Note - Carbon monoxide will outcompete oxygen for hemoglobin sites  suffocation due to CO poisioning
b. Carbon dioxide transport in the blood:
i. Most is transported in the plasma as bicarbonate ion (HCO3-) (acid)
ii. Small amount is carried inside red blood cells on hemoglobin and dissolved in plasma
iii. Getting out of blood:
1. HCO3- + H+  H2CO3  H2O + CO2
17. Internal respiration = exchange between
a. Opposite what happens in the lungs
i. Carbon dioxide
ii. Oxygen
18. Neural control of respiration
a. Phrenic and intercostals nerves
b. Rate and depth of breathing
i. Medulla
ii. Pons
c. Rates
i. Normal
ii. Hypernea
d. Other factors controlling breathing
i. Physical
1. Body temperature
2. Exercise
3. Talking
4. Coughing
ii. Volition
iii. Emotional factors
iv. Chemical factors
1. Getting rid of CO2
2. Oxygen levels
v. Hyperventilation
vi. Hypoventilation