Breathing, which involves the physical movement of air into and out of the lungs is
pulmonary ventilation(respiratory system)
transport of oxygen and carbon dioxide between lungs and
tissue
(circulatory system)
transport
exchange of O2 and CO2 between the lungs and the blood(respiratory system)
External respiration (respiratory system)
O2 and CO2 exchange between systemic blood vessels and tissues
Internal respiration(circulatory system)
Four processes that supply the body with O2 and dispose of CO2
pulmonary ventilation, External respiration, transport, Internal respiration
site of gas exchange
Respiratory zone
conduits to gas exchange sites
Conducting zone
diaphragm and other muscles that promote ventilation ( expand volume of chest cavity)
Respiratory muscles
microscopic structure of respiratory zone
respiratory bronchioles, alveolar ducts, and alveoli
account for most of the lungs’ volume and are the main site for gas exchange
alveoli
how many alveoli do we have
approximately 300 milion
the thickness of air-blood barrier in respiratory membrane
~ 0.5 micrometer
the Single layer of squamous epithelium
alveolar wall
the simple squamous lining the alveoli is called
type 1 cells
type 2 cell secrete
surfactant
alveoil is Surrounded by and contain
fine elastic fibers, open pore
open pores that Connect adjacent alveoli
–Allow air pressure throughout the lung to be equalized
_____ House alveolar macrophages that keep alveolar surfaces sterile
Alveoli
lung that is smaller, has two lobes and an oblique fissure
left lung
right lung has
is larger has three lobes separated by oblique and horizontal fissures
blood supply
there are two circulations:
1. pulmonary (low pressure, high
volume)
2.bronchial ( high pressure, low volume) provides these
tissues with oxygen and nutrients
thin double layered serosa, produce pleural fluid
pleurae
Parietal pleura cover
thoracic wall and superior face of diaphragm
pleura on external lung surface
visceral
function of the pleural fluid
fills the slitlike pleural cavity and Provides lubrication and surface tension
Pulmonary ventilation consists of how many phase
2, inspiration and expiration
gases flow into the lungs
inspiration
expiration
gases exit the lungs and has positve pressure
Pressure exerted by the air surrounding the body
Atmospheric pressure (Patm)
Atmospheric pressure (Patm) is _____ at sea level
760 mm Hg or 1 atm
is the pressure within the aveoli, its always very close to the
(Patm)
It fluctuates with breathing but equalizes quickly with
the (Patm)
Intrapulmonary (intra-alveolar) pressure (Ppul)
Negative respiratory pressure is less than or greater than Patm or equal to Patm
less than
positive respiratory pressure is less than or greater than Patm or equal to
greater than Patm
zero respiratory pressure is less than or greater than Patm or equal to Patm
equal to Patm
is the pressure within the pleural cavity between lungs and thoraciv wall. This pressure is always slightly less than the (Ppul) and atmospheric pressure and always a negative pressure
Intrapleural pressure (Pip)
Negative Pip is caused by
opposing forces
___force promote lung collapse and ____ force tends to enlarge the lungs
inwards force, outward force
Two inward forces promote lung collapse in intrapleural pressure
- Elastic recoil of lungs decreases lung size
- Surface tension of alveolar fluid reduces alveolar size
Elasticity of the chest wall pulls the
thorax outward
if intrapleural pressure is equal to intrapulmonary pressure Pip = Ppul, what happens to the lungs?
lose the negative pressure and the lungs collapse
transpulmonary pressure calculation
760 mm Hg - 756 mm Hg = 4 mm Hg
Intrapleural pressure
756 mm Hg
(- 4 mm Hg)
Intrapulmonary pressure
760 mm Hg
(0 mm Hg)
transpulmonary pressure
intrapulmonary pressure minus intrapleural pressure.
function of transpulmonary pressure
keeps the airways open (keeps the lungs from collapsing)
The greater the transpulmonary pressure, the larger or smaller the lungs
larger
Atelectasis
collapse of lung tissue
Atelectasis (lung collapse) is due to
–Plugged bronchioles ---- collapse of alveoli
–Wound that admits air into pleural cavity (pneumothorax)
Mechanical processes that depend on volume changes in the thoracic cavity
Pulmonary Ventilation
Pulmonary Ventilation
Volume changes lead to pressure changes and in turn flow of gas to quickly equalize pressure
Pulmonary ventilation
- volume changes leads to what
pressure changes
inspiration is an active or passive process
active
what happens to the inspiratory muscles during inspiration
contract
does the thoracic volume increase or decrease during inspiration?
increase
what happens to the lungs and intrapulmonary volume during inspiration?
lungs stretch
intrapulmonary VOLUME increases
what happens to the intrapulmonary pressure during inspiration and expiration?
inspiration-it drops to -1 mm Hg
expiration- Ppul rises (to +1 mm Hg)
what happens to air during inspiration and expiration?
during inspiration air flows into the lungs, down its pressure gradient, until Ppul = Patm while in expiration Air flows out of the lungs down its pressure gradient until Ppul = 0
is forced expiration passive or active
active
what happens to the inspiratory muscles during expiration
they relax
what happens to the thoracic volume during expiration
decrease
what happens to the lungs and intrapulmonary volume during expiration
lungs recoil
intrapulmonary volume decreases
what happens to the intrapulmonary pressure as lung volume increases during inspiration?
pressure inside the lung decreases
during each breath, the pressure gradient moves how many liters/ml of air into and out of the lungs?
500 ml or 0.5 liters
Inspiratory muscles consume energy to overcome 3 physical factors that hinder air passage and pulmonary ventilation
- airway resistance
2. alveolar surface tension
3. lung compliance
As airway resistance rises, breathing movements become more
strenuous
What effect does severely constricting or obstruction of bronchioles have?
–Can prevent life-sustaining ventilation
–Can occur during acute asthma attacks and stop ventilation
can dilates bronchioles and reduces air resistance
Epinephrine
alveolar surface tension
–Attracts liquid molecules to one another at a gas-liquid interface
–Resists any force that tends to increase the surface area of the liquid
Detergent-like lipid and protein complex and can Reduces surface tension of alveolar fluid and discourages alveolar collapse
Surfactant
what is lung compliance
A measure of the change in lung volume that occurs with a given change in transpulmonary pressure
lung compliance is diminished by 3 things:
1.non-elastic scar tissue (fibrosis)
2. reduced production of
surfactant
3. decreased flexibility of the thoracic cage
Dalton's Law of Partial Pressures
total pressure= PP of a gas A+PP of gas B
the partial pressure
of each gas is directly proportional to its percentage in the mixture
Basic Properties of Gases
air is a mixture of gases carbon dioxide, oxygen and nitrogen
Henry's Law
when a mixture of gas is in a liquid (plasma) each gas will dissolve in the liquid in proportion to is partial pressure
The amount of gas that will dissolve in a liquid also depends upon its
solubilty
CO2 is ___times more soluble in water than O2
20 X
External Respiration
Exchange of O2 and CO2 across the respiratory membrane
Factors influencing external respiration
–Partial pressure gradients and gas solubilities
–Ventilation-perfusion coupling
–Structural characteristics of the respiratory membrane
does CO2 diffuses in equal amounts or greater amount or lesser amount with oxygen
equal amount
________amount of gas reaching the alveoli
ventilation
respiratory membrane
–0.5 to 1 mm thick
–Large total surface area (40 times that of one’s skin)
the respiratory membaene become what if lungs become waterlogged and edematous, and gas exchange becomes inadequate
thicken
Loading and unloading of O2 is facilitated by
change in shape of Hb
As O2 binds, Hb affinity for O2______ while As O2 is released, Hb affinity for O2 ______
increase, decease
oxygen is fully saturated when
all four heme groups carry O2
oxygen is Partially saturated when
one to three hemes carry O2
Rate of loading and unloading of O2 is regulated by
–Po2, Temperature, Blood pH, Pco2
percentage of bound O2 is unloaded during one systemic circulation
20-25%
Increases in temperature, H+, Pco2, and BPG
–Modify the structure of hemoglobin and decrease its affinity for O2
As cells metabolize glucose, Pco2 and H+
increase in concentration in capillary blood
- CO2 is transported in the blood in how many forms
three
–7 to 10% dissolved in plasma
–20% bound to globin of hemoglobin (carbaminohemoglobin)
–70% transported as bicarbonate ions (HCO3–) in plasma
HCO3–
bicarbonate ions
Control of Respiration involve
neurons in the reticular formation of the medulla and pons
Medullary Respiratory Centers
Dorsal respiratory group (DRG) and Ventral respiratory group (VRG)
Sets eupnea is
12–15 breaths/minute
Depth and Rate of Breathing are modified
in response to changing body demands
____ are the most powerful respiratory stimulant
Rising CO2 levels
_______ is increased depth and rate of breathing that makes the body remove too much CO2
Hyperventilation
what is an apnea
period of breathing cessation that occurs when Pco2 is abnormally low
what is Hyperpnea
Increase in ventilation (10 to 20 fold) in response to metabolic needs
COPD
Chronic obstructive pulmonary disease
irreversible decrease in the abilty of COPD
force air out of the lungs
COPD is exemplified by
chronic bronchitis and emphysema
common features of COPD
- History of smoking in 80% of patients
- Dyspnea: labored breathing (“air hunger”)
- Coughing and frequent pulmonary infections
- Most victims develop respiratory failure (hypoventilation) accompanied by respiratory acidosis
homeostatic imbalance that is Characterized by coughing, dyspnea, wheezing, and chest tightness. it is also an Active inflammation of the airways precedes bronchospasms
Asthma
Lung cancer
–Leading cause of cancer deaths in North America
–90% of all cases are the result of smoking
the three most common type of lung cancer
Squamous cell carcinoma, Adenocarcinoma, and Small cell carcinoma