Chapter 13 Respiratory System

Chapter 13
The Respiratory System
1. Organs of the system
a. Nose
b. Pharynx
c. Larynx
d. Trachea
e. Bronchi
f. Lungs/alveoli(us)
2. Functions of the system
a. Gas exchange between blood and external environment:
i. Occurs in the alveoli of the lungs
ii. Passageways to the lungs purify, humidify, and warm the incoming air
b. Specific functions in parts of the system
3. Nose
a. Only external visible part of the respiratory system
b. Air enters the nose through the external nostrils (nares)
c. Interior of the nose consists of a nasal cavity divided by a nasal septum
d. Nasal cavity
i. Olfactory receptors are located in the mucosa on the superior surface
ii. The rest of the cavity is lined with respiratory mucosa that:
1. Moisten air
2. Trap incoming foreign particles
iii. Lateral walls have projections called conchae:
1. Increase surface area
2. Increase air turbulence within the nasal cavity
iv. The nasal cavity is separate from the oral cavity by the palate:
1. Anterior hard palate (bone)
2. Posterior soft palate (muscle)
v. Cavities within bones surrounding the nasal cavity are called sinuses
1. Frontal bone
2. Sphenoid bone
3. Ethmoid bone
4. Maxillary bone
5. Functions
a. Lighten the skull
b. Act as resonance chambers for speech
c. Produce mucus that drains into the nasal cavity
4. Pharynx
a. Muscular passage from nasal cavity to larynx
b. Three regions:
i. Nasopharynx- superior region behind nasal cavity
ii. Oropharynx- middle region behind mouth
iii. Laryngopharynx- inferior region attached to larynx
c. The oropharynx and larngopharynx are common passageways for air and food
d. Eustacean = auditory=pharyngotympanic tubes
e. Tonsils
i. Pharyngeal
ii. Palatine
iii. Lingual

5. Larynx
a. Routes air and food into proper channels
b. Plays a role in speech
c. Made of eight rigid hyaline….. cartilage
i. Thyroid- largest of the hyaline cartilages
1. Protrudes anteriorly (adam’s apple)
ii. Epiglottis – protects the superior opening of the larynx
1. Routes food to the esophagus and air toward the trachea
2. When swallowing, the epiglottis rises and forms a lid over the opening of the larynx
d. Vocal folds (true vocal cords)
i. Vibrate with expelled air to create sound (speech)
ii. Glottis
6. Trachea
a. Four inches long tube that connects larynx with bronchi
b. Walls are reinforced with C-shaped hyaline cartilage
c. Lined with ciliated mucosa:
i. Beat continuously in the opposite direction of incoming air
ii. Expels mucus loaded with dust and other debris away from lungs
7. Main bronchi(us)
a. Formed by division of the trachea
b. Enters the lung at the hilum (medial depression)
c. Bronchi subdivide into smaller and smaller branches
8. Lungs
a. Anatomy
i. Occupy most of the thoracic cavity
ii. Heart occuples central portion (middle wall) called mediastinum
iii. Apex is near the clavicle (superior portion)
iv. Base rests on the diaphragm (inferior portion)
v. Each lung is divided into lobes by fissures
1. Right- three lobes
2. Left- two lobes
b. Coverings
i. Serosa covers the outer suface of the lungs
ii. Pulmonary (visceral) pleura covers the lung surface
iii. Parietal pleura lines the walls of the thoracis cavity
iv. Pleural fluid fills the area between layers of pleura to allow gliding
v. These two pleural layer resist being pulled apart
c. Bronchial tree
i. Bronchi divisions
1. All but the smallest of theses passageways have reinforving cartilage in their walls
2. Primary bronchi, secondary bronchi, tertiary bronchi
ii. Bronchioles
1. Terminal bronchioles
iii. Respiratory zone
1. Alveolar ducts
2. Alveolar sacs
3. Alveoli(us)
a. Site of gas exchange= alveoli only
b. Respiratory membrane = air/blood barrier
i. Thin squamous epithelium layer lines alveolar walls
ii. Alveolar pores connect neighboring air sacs
iii. Pulmonary capillaries cover external surfaces of alveoli
iv. On one side of the membrane is air and on the other side is blood flowing past
c. Gas exchange – the ultimate goal
9. Gas exchange via diffusion only
a. Oxygen
b. Carbon dioxide
c. Macrophages
d. Surfactant
10. Events of respiration
a. Breathing
b. External respiration
i. Oxygen
ii. Carbon dioxide
c. Respiratory gas transport
d. Internal respiration

Chapter 13 – Respiration – Part B
9. Gas 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. 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 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 leads to pressure changes, which leads 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. Diaphragm and external intercostals muscles contract
ii. 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 elasticity
ii. As muscles relax, air pushed out of lungs due to:
1. Decrease in intrapulmonary volume
2. Increase in gas pressure
3. Forced expiration can occur mostly by contracting internal intercostals muscles to depress the rib cage
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 and sneezing- clears lungs of debris
b. Crying- emotionally induced mechanism
c. Laughing- similar to crying
d. Hiccup- sudden inspirations
e. Yawning- very deep inspiration
i. Pandiculation = yawning +stretching
f. Talking – communication
13. Respiratory volumes and capacities
a. Normal breathing = tidal volume (TV) = 500 mL
i. Affected by a person’s size, sex, age, physical condition
b. Inspiratory reserve volume (IRV)= 2100 and 3200 mL
i. Amount of air that can be taken in forcibly over the tidal volume
c. Expiratory reserve volume (ERV) = 1200 mL
i. Amount of air that can be forcibly exhaled
d. Vital capacity- all the way in to all the way out, the total amount of exchangeable air, vital capacity= TV + IRV + ERV
e. Residual volume (RV) =
f. Dead space volume (DSV) = air that remains in conduction zone and never reaches alveoli (about 150 mL)
g. Functional volume = air that actually reaches the respiratory zone, usually about 350 mL, a low percentage of capacity
h. Respiratory capacities are measured with a spirometer
i. Capacities = two or more volumes together
i. Spirometer
ii. Vital capacity (VC) = TV + IRV + ERV
iii. Total Lung Capacity (TLC) = VC + RV
14. Respiratory sounds
a. Monitored with a stethoscope
b. Two sounds
i. Bronchial- produced by air rushing through trachea and bronchi
ii. Vesicular breathing- 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 from blood
i. Blood returning from tissues had 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. Almost all oxygen attached to hemoglobin to form oxyhemoglobin (HbO2)- 98%
ii. Small dissolved amount is carried in the plasma 2%
iii. Carbon monoxide will outcompete oxygen for hemoglobin sites  suffocation due to CO poisoning
b. Carbon dioxide transport in the blood
i. Most is transported in the plasma as bicarbonate ion (HCO3- ) (Acid)
ii. Small amount 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