The Respiratory System

I. The Functional Anatomy of the Respiratory System

A. Nose1. Nares2. Nasal cavity3. Respiratory

mucosa4. Nasal conchae5. Hard palate6. Soft palate7. Paranasal

sinuses

B. Pharynx-throat

1. Common passageway

2. Three portions3. Auditory tube4. Tonsils a. pharyngeal (ad) b. palatine c. lingual

C. Larynx (voicebox)

1. Epiglottis2. Thyroid cartilage3. Vocal folds4. Glottis5. utube

http://www.youtube.com/watch?v=ajbcJiYhFKY

D. Trachea and bronchi

• 1. trachea C shaped ring• 2. windpipe• 3. ventral to esophagus• 4. bronchi branch at carina• 5. right bronchus wider

shorter and straighter• 6. Heimlich maneuver-

http://www.youtube.com/watch?v=tEIiEAn7b-U&feature=player_detailpage

Slides of respiratory mucosa

E. Lungs

1. Apex and base2. Pleural membranes3. Pleural fluid4. Pleurisy5. Right lung three

lobes6. Left lung two lobes7. Respiratory tree

F. Respiratory zone

• 1. zone where gas exchange occurs

• 2. respiratory bronchioles

• 3. alveolar ducts• 4. alveolar sacs

G. Alveoli1. Simple squamous2. Pulmonary caps3. Thinner sheet

tissue paper4. Alveolar pores5. Simple diffusion6. 50-70 meters

squared (40 X skin)7. Alveolar

macrophages8. Type II cells-

pulmonary surfactant

Alveolar Tissue

II. Respiratory physiology

• A. Volume vs. pressure• 1. gases conform to the shape of their container• 2. in a large volume, the molecules of the gas are spread out• 3. few collisions between the molecules and walls• 4. larger volume lower pressure• 5. volume decreases• 6. more frequent collisions• 7. higher pressures• 8. gases flow (like water) from areas of higher to lower

pressures

B. Events of inspiration-active process

1. Surface tension between pleural membranes

2. Diaphragm contracts3. External intercostals

contract4. Voume increases5. Pressures drop6. Air pressure higher

than pulmonary pressures

7. Air flows into lung

C. Exhalation or expiration

1. Passive process2. Elastic recoil3. Ribs return4. Diaphragm

relaxes5. Lung volume

drops6. Air compressed7. Expiration should

be effortless8. Asthma or

chronic bronchitis9. Forced expiration

D. Intrapleural pressure

1. Healthy lung intrapleural pressure is always negative

2. Prevents lung collapse

3. Air enters pulmonay space

4. Pneumothorax5. Atelectasis

E. Respiratory volumes

1. Tidal volume-5002. IRV-3000ml3. ERV-1200ml4. Residual volume-

1500 ml5. Vital capacity= TV

+ IRV + ERV6. Dead space

volume = 150 ml

III. Control of respiration

• A. Breathing control centers

• 1. brain stem-pons and medulla

• 2. VRG-self-exciting inspiratory center

• 3. phrenic and intercostal nerves

• 4. normal breathing eupnea

B. Modifiers of respiratory effort

1. Higher brain centers

2. Stretch receptors

3. Receptors in muscles

4. Peripheral chemoreceptors

C. Chemical factors1. Chemoreceptors

monitor blood chemistry

2. Main stimulus is carbon dioxide and pH

3. Carbon dioxide transport

4. Main stimulant for respiratory efforts

5. Also tied to pH6. Oxygen

concentrations are of secondary importance

D. Interesting case of emphysema

1. COPD2. Inspiration easier than expiration3. Lungs retain some of each breath4. Residual volume increases5. Diaphragm flattens6. Carbon dioxide is retained7. Oxygen levels become main stimulant for respiratory effort8. Oxygen must be administered at low levels9. If administered at high levels as might be indicated, patient

would stop breathing because the respiratory stimulus would be gone (low oxygen levels).

E. Hyperventilation

1. Young nervous women2. Increased depth of

breathing-what happens to carbon dioxide levels

3. What happens to pH4. Cerebral vessels

constrict5. May get dizzy and faint6. Breathing into paper

bag