Respiration involves four processes
Respiratory system↓
1. Pulmonary ventilation (breathing): movement of air into and out of lungs
2. External respiration: exchange of O2 and CO2 between lungs
and blood
Circulatory system ↓
3. Transport of O2 and CO2 in blood
4. Internal respiration: exchange of O2 and CO2 between systemic blood vessels
and tissues
- The process of doing gas exchange in the bodies tissues
Major Respiratory Organs
● Nasal Cavity
● Oral cavity
● Larynx: voice box and opening to trachea and lower part of our airway
● Pharynx
● Trachea
● Lungs L/R
● Diaphragm
● Left Lung: 2 lobes : reason for asymmetry: to make room for the heart
● Right Lung: 3 lobes
● Nasopharynx: how most air comes in: serves purpose of humidifying air that
comes in and trapping particulates that are in the air; mucosa in nasopharynx
traps particulates
● Oropharynx
● Laryngopharynx: where larynx is located
Lower Respiratory System
• Lower respiratory system consists of: – Larynx, trachea, bronchi, and lungs
• Broken into two zones
– Respiratory zone: site of gas exchange
• Consists of microscopic structures such as respiratory bronchioles,
alveolar ducts, and alveoli : Simple squamous epithelia (gas exchange)
– Conducting zone: conduits that transport gas to and from gas exchange sites
• Includes all other respiratory structures
• Cleanses, warms, and humidifies air (no gas exchange)
,Tissue Composition of Tracheal Wall
Contains
● Goblet cell: produces mucus
● Cilia: move particles trapped in mucus away
● Mucosa and submucosa
● Pseudostratified ciliated columnar epithelium
● Lamina propria (connective tissue)
● Seromucous gland in submucosa
● Trachealis: muscles malleable enough to displace trachea enough to swallow
The Larynx
● Hyaline Cartilage: cartilage in larynx ensures airway stays open
● Thyroid Cartilage: gives the adam's apple; adds to different pitches of voice in
the two sexes
● Epiglottis: covers over the airway everytime we swallow to prevent food or
liquid from entering the airway
● Vocal folds: bands of tissue that can close over the glottis or open up; when it
closes down it produces sound
Tracheal wall
● Trachealis is the muscle that ensures airways stays open
● Made of pseudostratified ciliated coloomnar epithelium to trap pathogens
Conducting Zone Passages
● Left Main Primary Bronchi: has a rounded course; to accommodate heart
● Carina: “bow of a ship” meeting point of left and right bronchus’s
○ If food accidentally goes into airway it will most likely go into right
bronchus; reason: more of a straight shot while left bronchus is curved
Respiratory Zone Structures
● Terminal Bronchioles: have strips of smooth muscle
○ Relax: allowing bronchioles to dilate
○ Constrict: allowing bronchioles to close down
● Respiratory Bronchioles: lead to alveolus/alveoli
● Alveolar Pores: allows air to completely fill alveoli
● Alveoli: thin-walled, simple squamous epithelium: to allow rapid and easy
diffusion
● Bronchoconostriction = asthma
,Alveoli and the Respiratory Membrane
● Alveoli: gas-filled air spaces (simple squamous epithelium)
● Type 1 Alveolar Cell: across these cells gas exchange occurs
● Type 2 Alveolar Cell: secretes surfactant: (reduces surface tension) prevents
walls of alveoli from sticking together because of the small amount of water the
alveolar walls are surrounded in.
● Respiratory Membrane: alveolar epithelium, fused basement membranes of
alveolar epithelium and capillary epithelium
Movements of the Vocal Folds
● Vocal fold (true vocal cord)
● Glottis
Transverse Section through thorax (From above)
● Lungs, pleural membranes, and major organs in the mediastinum are shown
● Lung material is posterior of heart
● All of the major pipes go through the structures called hilum
● Bronchial arteries and veins supply oxygenated blood to the tissue of the lungs
Blood Supply and Innervation of Lungs
• Lungs are perfused by two circulations
1. Pulmonary circulation
• Pulmonary arteries deliver systemic venous blood from heart to lungs for
oxygenation
– Branch profusely to feed into pulmonary capillary networks
• Pulmonary veins carry oxygenated blood from respiratory zones back to
heart
• Low-pressure, high-volume system
• Lung capillary endothelium contains many enzymes that act on different
substances in blood
– Example: angiotensin-converting enzyme activates blood pressure
hormone
2. Bronchial circulation
• Bronchial arteries provide oxygenated blood to lung tissue
– Arise from aorta and enter lungs at hilum
– Part of systemic circulation, so are high pressure, low volume
– Supply all lung tissue except alveoli
– Bronchial veins anastomose with pulmonary veins
» Pulmonary veins carry most venous blood back to heart
, • Innervation of the lungs
– Lungs are innervated by parasympathetic and sympathetic motor fibers, as
well as visceral sensory fibers
– Nerves enter through pulmonary plexus on lung root
• Run along bronchial tubes and blood vessels
– Parasympathetic fibers cause bronchoconstriction, whereas sympathetic
fibers cause bronchodilation
List of Pressures
● This is ventilation
● Intrapleural Pressure
● -4mm Hg (756mm Hg) Always Negative : or there is no way of opening
the lungs bc it creates a suction
● Pressure between parietal and visceral pleura
● Main source of function to pull in air “suction”
● If the number ever becomes positive the lung will collapse
- Transpulmonary Pressure
● The difference in pressure from outside the lungs vs pressure inside the
lungs
- Intrapulmonary Pressure
● Pressure within the lungs
Extra Information
● Negative pressure= “suction” drawing in air
● Positive Pressure= “pushing”
● Ventilation: movement of the diaphragm and the ribs changing the shape of the
thoracic wall
● Pleural Fluid: allows there to be a negative pressure in between the two pleura
Pneumothorax
● Air in the thorax: in between the visceral and parietal pleura
● Air comes in through wound causing lung to collapse
● Tension Pneumothorax: the pressure can become so great, putting pressure on
the heart and restricting vessels
● Collapsed Lung: atelectasis
Pulmonary Ventilation
● Boyle’s law: relationship between pressure and volume of a gas
– Gases always fill the container they are in
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