chapter 22 Flashcards
The respiratory system
major function
Major function:
-Supply oxygen for aerobic respiration and remove and dispose of carbon dioxide
Types/stages Respiration
Pulmonary ventilation
External respiration
Transport of respiratory gases
Internal respiration
Pulmonary ventilation:
breathing; the movement of air in and out of the lungs
External respiration:
Gas exchange between the blood and air filled chambers of the lungs
Transport of respiratory gases:
Movement of gases within the body, accomplished using the cardiovascular system (i.e. blood)
Internal respiration:
Exchange of gases between blood and tissues
Zones within the respiratory system
Conduction zone: rigid conduits for transport of air to respiratory passages
- Nose
- Nasopharynx
- Trachea
- Larynx
- Bronchi
- Cleanses, humidifies, and warms incoming air
Respiratory zone: Site of gas exchange
- Bronchioles
- Alveolar ducts
- Alveolar sacs
- Microscopic structures
Physical and chemical barriers in the nose Vibrissae: Olfactory mucosa: Respiratory mucosa: --Goblet cells: --Serous cells: ---Lysozyme: ---Defensins:
Vibrissae:
- Nose hairs!
- Filter course particles from entering the respiratory pathway
Olfactory mucosa:
-contains receptors for the sense of smell
Respiratory mucosa:
- Pseudostratified columnar epithelia
- -Goblet cells: Mucous
- -Serous cells: Enzymes
- –Lysozyme: Antibacterial enzyme
- –Defensins: Antibiotics that aid in bacterial defense
The Larynx
Once past the epiglottis, you reach the voice box
Sound production
- In humans, sound is produced by
- Glottis wide =
- Glottis thin =
- Loudness depends on
- In humans, sound is produced by the opening and closing of the glottis, with post-laryngeal filtering for specificity
- Glottis wide = low tones (frequency, in Hertz (Hz)
- Glottis thin = high tones (Hz)
- Loudness depends on the force of the expelled air, increasing vibration within the vocal folds
Trachea
Long, flexible tube that directs air to the bronchi
Changes in structure
- Cartilage structure changes:
- The epithelium changes:
- The amount of smooth muscle
Cartilage structure changes:
-from rings, to plates, to none being replaced by elastic fibers (found throughout the respiratory tree)
The epithelium changes:
-From ciliated pseudostratified columnar, to columnar, to cuboidal, to squamous in the ducts and sacs
The amount of smooth muscle increases:
-allowing constriction of the passageways
The respiratory membrane
- -Type I cells also secrete
- Cuboidal (Type II) cells secrete
- Simple squamous epithelia (Type I cells) with a fused basal lamina form the respiratory membrane
- -Type I cells also secrete angiotensin converting enzyme (ACE) for blood pressure regulation
-Cuboidal (Type II) cells secrete surfactant
Other important structures and cells in the lungs
- Surrounded by
- Alveolar pores allow
- Alveolar macrophages (dust cells) destroy
-Surrounded by elastic fibers
-Alveolar pores allow air pressure throughout the lung to be equalized if alveolar ducts collapse by disease or damage
-Alveolar macrophages (dust cells) destroy microorganisms and pathogens
Replace over 2 million per hour!
Lungs
Occupy the entire
Receive blood from the and are drained by the
Are surrounded by
Occupy the entire thoracic cavity except the mediastinal septum (surrounding the heart)
Receive blood from the pulmonary arteries (from the heart) and are drained by the pulmonary veins (toward the heart)
Are surrounded by pleura (parietal and visceral [serosa])
Lungs are surrounded by pleural fluid
Fluid acts as a
Fluid acts as a barrier, lubricant, and decrease surface tension between the lungs and body wall during breathing
The mechanics of breathing
Pressure is always described relative to
Patm =
If P = 756, then
Pressure is always described relative to atmospheric pressure (Patm)
Patm = 760 mmHg
If P = 756, then -4mmHg has occurred, causing a vacuum.
Intrapulmonary pressure
Palv is the pressure in the alveoli, rising and falling with the phases of breathing, but always equilibrating to external Patm
Pressure in the pleural cavity (Pip) also fluctuates, but is always negative related to the intrapulmonary pressure (intra-alveolar)
How is this negative pressure established (Pip)?
Two forces
Transpulmonary pressure
Two forces
- Lungs pulled from the thorax by pleura
- -Lungs will naturally recoil, becoming smaller
- -Surface tension of alveolar fluid causes lungs to compress to their smaller size
- -Elasticity of chest wall pulls the thorax outward, enlarging the lungs
Transpulmonary pressure
- -(Palv – Pip) keeps lungs from collapsing
- -What if that pressure is lost?
Pulmonary ventilation
Volume changes lead to
Volume changes lead to pressure changes, which lead to the flow of gases to equilibrate pressures
ΔV —> ΔP —-> F (flow of gas)
Boyle’s Law
If temperature is constant, the pressure of a gas is inversely related to its volume:
P1V1 = P2V2
P = pressure in mmHg V = volume in mm3 1 = initial condition 2 = resulting condition
Inspiration
-Muscles:
relationship between Palv and Patm
The uptake of air into the lungs (quiet inspiration)
- Muscles: Diaphragm and External Intercostals
- Diaphragm drops, increasing the volume of the thorax
- External Intercostals lift sternum outward
- -Change thorax about 500 ml in 3 dimensions
- -Palv < Patm, therefore: air into lungs
Expiration
relationship between Palv and Patm
- Passive process based on the elasticity of lungs
- Ribs relax, lungs recoil, decreasing thoracic and interpulmonary volumes
- Palv > Patm, therefore: air out of lungs
Physical factors affecting ventilation
drag:
Drag: friction of flowing molecules on surfaces
F = ΔP/R
F = flow P = pressure, where ΔP = (Patm – Palv) R = resistance