1. Functions

1. Gas exchange between air and blood
2. Conduction of air to the exchange surfaces
3. Protecting respiratory surfaces
4. Sound production
5. Olfaction
6. Regulation of blood pH

2. Organization

• conducting portion and a respiratory portion

1. Structures

1. Upper

• nose
• nasal cavity
• paranasal sinuses
• pharynx

1. Lower

• larynx
• trachea
• bronchi
• bronchioles
• alveoli

1. Respiratory mucosa

• epithelium + connective tissue

1. Respiratory epithelium

1. nasal cavity/pharynx => pseudostratified, ciliated columnar with goblet cells
2. lower respiratory => pseudostratified, ciliated columnar
3. bronchioles => cuboidal
4. alveoli => squamous

1. Lamina propria

• loose connective tissue

1. Respiratory Defense System

• Filtration
• Mucus
• Cilia

3. Upper Respiratory System

• nose, nasal cavity, paranasal sinuses & pharynx

1. Nose and Nasal cavity

• primary passageway for air entering respiratory system
• paranasal sinus => secretions
• hard palate/soft palate

1. Nasal mucosa

• humidify, warm and filter air
• extensive vasularization

1. Pharynx

• cavity or space
• connect nose, mouth and throat
• chamber shared by digestive and respiratory tracts
• three regions:

1. Nasopharynx
2. Oropharynx
3. Laryngopharynx

4. Larynx

• inhale air => leave pharynx by passing through a narrow opening, the glottis.

1. Cartilages of the Larynx

• larynx surround and protect the glottis
• start at fourth/fifth cervical vertebrae and end at seventh cervical vertebrae

1. Thyroid cartilage

• largest
• form anterior and lateral walls
• anterior surface => Adam’s apple
• sits on top of cricoid cartilage

1. Cricoid cartilage

• thyroid/cricoid protect glottis
• site for muscle attachment

1. Epiglottis

• project above glottis
• elastic cartilage
• prevent entry of liquid and solid food

1. Arytenoid cartilage
2. Corniculate cartilage
3. Cuneiform cartilage
4. Laryngeal ligaments

1. Intrinsic
2. Extrinsic
3. Ventricular
4. Vocal

1. Sound production

1. Phonation => sound production
2. Articulation => modification of sounds

1. Laryngeal musculature

1. Intrinsic laryngeal muscles

• open/close glottis
• regulate tension in vocal cords

1. Extrinsic laryngeal muscles

5. Trachea

• windpipe
• tough, flexible tube
• attach to cricoid cartilage
• start at sixth cervical vertebrae and end at mediastinum
• branches to form right and left bronchi
• tracheal cartilages => C-shaped

6. Primary Bronchi

• right and left
• right => larger diameter/steeper angle
• carina => mark separation between right and left bronchi

7. Lungs

1. Lobes of the Lung

• right => three lobes => superior, middle and inferior
• left => two lobes => superior and inferior

1. Bronchi

• secondary bronchi => Supply air to a lobe of the lung
• right => three secondary bronchi
• left => two secondary bronchi
• tertiary bronchi => supply air to a single bronchopulmonary segment

1. Bronchioles

• lack cartilage
• regulated by ANS
• bronchodilation => sympathetic => increase diameter of airways
• bronchoconstriction => parasympathetic => decrease diameter of airways

1. Alveolar Ducts and Alveoli

• alveolar ducts => connect bronchioles and alveoli

1. Alveolus

• functional unit of the lung
• simple squamous epithelium
• Type I cells => gas exchange
• Type II cells => produce surfactant

VIII. Pleural Cavities/Pleural Membranes

• Read on own

9. Respiratory Physiology

• Four Steps:
• Pulmonary ventilation
• Gas diffuse across respiratory membrane
• Storage/transport of oxygen/carbon dioxide
• Exchange of dissolved gases between blood and interstitial fluid

1. Pulmonary Ventilation

1. Boyles law

• relationship of pressure to volume
• increase pressure = decrease volume

1. Pressure and airflow to the lungs

• Air flows from an area of high pressure to an area of low pressure
• Inhalation/exhalation result from changes in the volume of the lungs and the pressure of the lungs
• Inhalation:
• rib cage elevate
• diaphragm contract
• increase size of thoracic cavity
• P_o > P_i
• air in
• Exahlation:
• rib cage descend
• diaphragm relax
• decrease size of thoracic cavity
• P_i > P_o
• air out
• compliance => distensibility

1. Respiratory Cycle

• A single cycle of inhalation and exhalation
• tidal volume => Amount of air moved into or out of the lungs during a single respiratory cycle.

1. Respiratory Muscles

1. Muscles used in inhalation

1. Diaphragm
2. External intercastals
3. Accessory muscles

• scalenes, sternocleidomastoid, serratus interior

1. Muscles used in exhalation

1. Internal intercostals
2. Abdominal muscles

• external/internal oblique, rectus abdominis, transversus dominis

1. Modes of breathing

1. Quiet breathing (Eupnea)
2. Forced breathing (Hyperpnea)

1. Respiratory Rates

• adult => 12-18 bpm
• child => 18-22 bpm

1. Gas exchange at the Respiratory Membranes

1. Dalton’s law

• Law of partial pressures

1. Henry’s law

• Diffusion between liquids and gases

1. Diffusion at the Respiratory Membrane

1. Large pressure differences across the respiratory membranes
2. small diffusion distance
3. solubility of gases
4. large total respiratory surface area
5. coordination of blood and air flow

1. Partial pressures

pO₂ pCO₂

alveolar space high low

lung capillaries low high

systemic capillaries high low

tissue cells low high

1. Gas pickup and Delivery

1. Oxygen Transport

1. Hemoglobin Saturation

10. Control of Respiration

1. Local Regulation

1. changes in lung perfusion
2. changes in alveolar ventilation

1. Respiratory Centers of the Brain

1. Medulla Oblongata

1. Dorsal Respiratory Group

• Inspiratory Center

1. Ventral Respiratory Group

• Expiratory Center

1. Apneustic and Pneumotaxic Centers (Pons)

1. Apneustic Center

• Stimulates DRG

1. Pneumotaxic Center

• Stimulates VRG

1. Chemoreceptor Reflexes ( oxygen and carbon dioxide)

1. Carotid bodies
2. Aortic bodies
3. Medullary chemoreceptors

1. Baroreceptor Reflexes

• blood pressure

1. Protective Reflexes

• sneezing
• coughing