Respiratory System Functions

• The respiratory system allows oxygen to enter the bloodstream from the atmosphere and removes carbon dioxide.
• The respiratory system works with the heart and circulatory system to form the cardiopulmonary system.

Learning Topics

• The basic functions of the respiratory system will be covered.
• The difference between respiration and ventilation will be covered.
• The functions of the structures of the upper and lower respiratory tracts will be covered.
• The process of gas exchange at the alveolar level will be covered.

Gases in the Atmosphere

• Nitrogen (N2) comprises 78.08% of the atmosphere.
• Oxygen (O2) comprises 20.95% of the atmosphere.
• Argon comprises 0.93% of the atmosphere.
• Carbon dioxide (CO2) comprises 0.03% of the atmosphere.
• The atmosphere also contains trace gases such as neon and krypton.

Respiration

• Pulmonary ventilation (breathing) is the movement of air into and out of the lungs.
• External respiration is the exchange of O2 and CO2 between the lungs and the blood.
• Transport is the movement of O2 and CO2 in the blood.
• Internal respiration is the exchange of O2 and CO2 between systemic blood vessels and tissues.

Respiratory Volumes

• Tidal Volume (TV): Amount of air inhaled or exhaled with each breath under resting conditions
  • Adult male average value: 500 ml
  • Adult female average value: 500 ml
• Inspiratory Reserve Volume (IRV): Amount of air that can be forcefully inhaled after a normal tidal volume inhalation
  • Adult male average value: 3100 ml
  • Adult female average value: 1900 ml
• Expiratory Reserve Volume (ERV): Amount of air that can be forcefully exhaled after a normal tidal volume exhalation
  • Adult male average value: 1200 ml
  • Adult female average value: 700 ml
• Residual Volume (RV): Amount of air remaining in the lungs after a forced exhalation
  • Adult male average value: 1200 ml
  • Adult female average value: 1100 ml
• Spirometry is a test used to measure these volumes and assess lung function in patients

Gas Exchange

• Differences in partial pressure are responsible for the exchange of O2 and CO2 that occurs between the alveoli and the pulmonary capillaries and between the tissues and the tissue capillaries
• Oxygen diffuses into the arterial ends of pulmonary capillaries and Co2 diffuses into the alveoli because of differences in partial pressures
• Oxygen diffuses out of the arterial ends of tissue capillaries, and CO2 diffuses out of the tissue because of differences in partial pressures
• Plants take in CO2 in the atmosphere and use it for energy, then release oxygen into our atmosphere.

Inspiration

• Inspiratory muscles contract (diaphragm descends; rib cage rises).
• Thoracic cavity volume increases.
• Lungs are stretched; intrapulmonary volume increases.
• Intrapulmonary pressure drops (to -1 mm Hg).
• Air (gases) flows into lungs down its pressure gradient until intrapulmonary pressure is 0 (equal to atmospheric pressure).

Upper Respiratory Tract

• Includes the nose, mouth, pharynx, and larynx

Nose

• The nose is the only externally visible part of the respiratory system.
• The nose is a semirigid structure made of cartilage and bone.
• It is the first line of defense against airborne antigens, activating the immune system.

Nasal Regions

• Three regions: olfactory, respiratory, and vestibular.
• Olfactory region contains sensory receptors for smell.
• Respiratory region is lined with mucous membranes and possesses conchae, which provide more surface area for incoming air to contact the warm, moist nasal mucosa.
• Vestibular region is located inside the nostrils and contains coarse nasal hairs covered with sebum, acting as the first line of defense for the respiratory system.

Functions of the Respiratory System

• Heating or cooling inspired (inhaled) gases to body temperature (98.6°F [37°C]).
• Filtering particles from the inspired gases.
• Humidifying inspired gases to a relative humidity of 100%.
• Providing for the sense of smell, or olfaction.
• Producing sounds, or phonation.
• Ventilating, or conducting, the gas down to the lower airways.

Sinuses

• The sinuses are paranasal sinuses, a group of air-filled spaces lined with mucous membranes.
• Functions include respiration, immune defense, and voice resonance.
• The sinuses are the Frontal Sinus, Ethmoid sinuses, Sphenoid sinus, and Maxillary sinus

Pharynx

• Muscular structure, 2.5 in long, and lined with epithelial tissues.
• The pharynx has three regions: nasopharynx, oropharynx, and laryngopharynx.
  • The nasopharynx is lined with respiratory mucosa.
  • The oropharynx conducts food and liquid. It is lined with stratified squamous epithelium.

Larynx

• The larynx is made of eight rigid hyaline cartilages and a spoon-shaped flap of elastic cartilage (epiglottis).
  • The thyroid cartilage (Adam's apple) is the largest of the cartilages.
  • The cricoid and thyroid provide structure and support for airways.
  • The epiglottis routes food to the larynx and air toward the trachea.

Lower Respiratory Tract

• Includes the trachea (windpipe).
  • The trachea has 16 to 20 stacked C-shaped pieces of hyaline cartilage.
  • Posterior tracheal parts are smooth muscle.
  • The trachea is lined with pseudostratified ciliated mucosa with goblet cells.

Bronchial Tree

• The bronchial tree is the conducting zone.
• The branches divide into bronchi, with 23 orders of branching.
• These branches have incomplete rings of cartilage and are lined with pseudostratified ciliated columnar epithelium.
• Segmental Bronchi
• Bronchioles are less than 1mm in diameter
• No more cartilage on the bronchioles

Terminal Bronchioles

• Terminal Bronchioles are the smallest, less than 0.5 mm in diameter

Site of Gas Exchange

• Gas exchange takes place within the alveoli
  • There is about 300 million alveoli in humans
• Pulmonary capillaries cover the external surfaces of alveoli, and basement membranes connect at .5 um thick

Respiratory Zone

• Gas exchange takes place within the alveoli. - There is roughly 300 million plus alveoli
• Pulmonary capillaries cover the external surfaces of alveoli and basement membranes connect.
  • The membranes are .5 um thick

The respiratory zone consists of three major cell types

• Type 1 alveolar cells
• Type 11 alveolar cells
• Alveolar macrophages

The Lungs

• The Lungs occupy most of the thoracic cavity.
• The apex is near the clavicle (superior portion), and the base rests on the diaphragm (inferior portion).
• The coverings of the lungs are visceral and parietal pleura.
• The left lung has two lobes and Right lung has three lobes