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
How does pressure change Besides breathing, of course… -Gas flow inversely related to -Large changes in flow can occur with -Generally, air passageway resistance --Gas flow stops at --Highest resistance at --Contraction of smooth muscle changes
- Besides breathing, of course…
- Gas flow inversely related to resistance
- Large changes in flow can occur with small changes in pressure
- Generally, air passageway resistance is insignificant
- -Diameters of passages huge (relative to particles)
- -Gas flow stops at terminal bronchioles, and diffusion takes over in driving molecule movement
- -Highest resistance at medium sized bronchi
- -Contraction of smooth muscle changes resistance
Alveolar surface tension
- Molecules more
- Water (polar molecule) has a
- Lining has
- Molecules more attracted to one another at surfaces than to other types (liquid versus gas) creating tension
- Water (polar molecule) has a high surface tension
- Lining has SURFACTANT: detergent-like complex of proteins and lipids produced by type II cells
What’s so important about surfactant?
No surfactant? Lungs unable to
Interferes with the cohesiveness of water molecules, allowing expansion
The surface tension is reduced, allowing lungs to expand
No surfactant? Lungs unable to inflate!!
Lungs distensible:
Diminished by:
Lungs distensible: the amount of stretching termed complience
CL = ΔVL/Δ(Palv – Pip)
Where CL = lung compliance
And VL = lung volume
Diminished by: Fibrosis, blockage of passages, low surfactant, decreased thoracic expansion, etc.
Respiratory volumes
The amount of air in and out of lungs
Tidal volume (TV):
Air in and out normally (500 ml)
Inspiratory reserve volume (IRV):
air forced beyond tidal volume (2100-3200 ml)
Expiratory reserve volume (ERV)
air forced out of lungs (1200 ml)
Residual volume (RV):
air left in lungs, preventing collapse
Inspiratory capacity (IC):
amount that can be inspired after tidal expiration (sum of tidal and inspiratory reserve volumes) 3600
Functional residual capacity (FRC):
amount of air left in the lungs after tidal expiration (combined Expiratory reserve volume and residual volume) 2400
Vital capacity (VC):
The total amount of exchangeable air (~4800 ml)
Total lung capacity (TLC):
The sum of all capacities (~6000 ml)
Gas exchange in the body
Bulk flow of gases and diffusion in tissues
Dalton’s law of partial pressures
-Each gasses pressure, or partial pressure, is directly
Dalton’s law of partial pressures
- The total pressure exerted by a mixture is the sum of the pressures exerted independently by each gas in the mixture
- Each gasses pressure, or partial pressure, is directly proportional to it’s percentage in the mixture
Henry’s law
- In a mixture of gas, each gas will dissolve in the liquid in proportion to its partial pressure
- -The more there is, the greater and faster it will dissolve
According to Dalton’s Law
Carbon Dioxide moves out of the blood into the alveoli
Oxygen moves out of the alveoli into the blood
Water moves out of the blood into the alveoli
External respiration:
Internal respiration:
oxygen and carbon dioxide within the lungs
same gases move in the opposite direction by the same mechanism (diffusion!)
Factors influencing movement of respiratory gases
- Partial pressure and gas solubility
- Functional aspects, like matching alveolar ventilation with pulmonary blood perfusion
- Structural characteristics of the membrane (i.e. thickness)
Note that it takes only about ___ seconds for the blood to get _____
Thus, blood can flow____as fast as normal and still get ____
Note that it takes only about 0.25 seconds for the blood to get oxygenated.
Thus, blood can flow 3X as fast as normal and still get oxygenated.
Ventilation-perfusion
There must be a coupling between the amount of gas in the alveoli (ventilation) and the blood flow in the capillaries (perfusion)
Based on feedback mechanisms to control the flow of blood (often based on the PCO2)
How much surface area is there in the lungs?
All of this exchange requires a large surface area; the more area, the more efficient the exchange of gases
Total area of the lungs: 50-70 Meters2
That is about 40X the surface area of your skin!
Transport of respiratory gases by blood
-Oxygen transport is accomplished by
- Hemoglobin-oxygen combination:
- Reduced hemoglobin,
- Oxygen transport is accomplished by hemoglobin (in erythrocytes)
- Hemoglobin-oxygen combination: oxyhemoglobin (HbO2)
-Reduced hemoglobin, deoxyhemoglobin (HHb)
Lungs
HHb + O2 —->
Oxyhemoglobin
Causes full saturation a
Fully or partially saturated heme groups
The off-loading of oxygen is not linear, instead being an S-shaped curve (the oxygen-hemoglobin disassociation curve)
Causes full saturation at 70 mmHg, and easily offloads oxygen with small pressure changes
The influence of temperature and the Bohr effect
Several factors influence the offloading of oxygen:
- Increasing these factors
- Decreasing these factors
Several factors influence the offloading of oxygen:
- H+ concentration (pH)
- PCO2
- BGP (2,3–biphosphoglycerate, which binds reversibly to hemoglobin, produced during anaerobic respiration)
- Increasing these factors decreases Hb’s affinity for oxygen
- Decreasing these factors increases Hb’s affinity for oxygen
The Bohr effect
- Increased activity raises the temperature of an area, which
- Also under_____control
Increased activity raises the temperature of an area, which shifts offloading of oxygen to these tissues
Also under hormonal control (endocrine system), such as thyroxine, epinephrine, growth hormones, and catchecholamines
The Bohr effect
-In capillaries, glucose and oxygen being used creating
-Acidosis (decreased pH) weakens
shifts curve to the
In capillaries, glucose and oxygen being used creating carbon dioxide (increasing H+ (decrease pH), PCO2)
Acidosis (decreased pH) weakens hemogloboin-oxygen bond, accelerating oxygen offloading (shifts the curve to the right), a phenomenon termed the Bohr effect
Hemoglobin (Hb) and Nitric Oxide (NO)
Local vessels _____ where gases are unloaded.
NO a vasodilator
Hb a vasoconstrictor
Local vessels dilate where gases are unloaded. WHY?!?
NO attached to a cystene group and protected from degradation by the iron group in Hb. Oxyhemoglobin unloads oxygen and NO, aiding in oxygen delivery. Deoxyhemoglobin then scavenges NO and CO2, and unloads in lungs
Carbon Dioxide transport
Transported three ways:
CO2 produced in cells (~200ml/min), the same as released by the lungs
Transported three ways:
Dissolved in plasma (7-10% as CO2)
-Chemically bound to Hb (~20% as carbaminohemoglobin)
-As Bicarbonate ion in plasma (~70% converted to HCO3-)
CO2 + H2O H2CO3. H+ + HCO3-
Carbonic Anhydrase
Bicarbonate ions diffuse from
Chloride ions move from the
Enzyme that catalyzes the conversion to carbonic acid (in RBC’s)
Bicarbonate ions diffuse from RBC’s to plasma
Chloride ions move from the plasma to RBC’s to counterbalance: ionic exchange is termed the chloride shift
Bicarbonate reconverted
CO2 + H2O H2CO3. H+ + HCO3-
Hydrogen added, splitting H2CO3 into CO2 and H2O in the lungs
CO2 then diffuses along its partial pressure gradient to the alveoli
The Haldane effect
Thus, the haldane effects allows for the formation of
-The less oxygen in the blood, the more the blood can carry carbon dioxide
If >PO2, then
because deoxyhemoglobin forms carbaminohemoglobin and buffers H+ by combining with it
Thus, the haldane effects allows for the formation of more bicarboinate ions
Influence of CO2 on blood pH
Most important function is that it acts as
The carbonic acid-bicarbinate buffer system resists shifts in
Most important function is that it acts as a bicarbonate reserve
The carbonic acid-bicarbinate buffer system resists shifts in pH by counterbalancing H+ levels
CO2 + H2O H2CO3. H+ + HCO3-
Neural control of breathing
Control from the reticular formations of the medulla and pons
Medulla forms the rhythm
Pons controls regulates the rhythm and smooths the transitions of inspiration and expiration
Factors influencing respiration rates
-Pulmonary irritants
-Neural controls (hypothalamus
and cortical controls)
-Chemical
–PO2
–PCO2
–Arterial pH
Summary of chemical influences -High CO2 stimulates -PO2 influences ; high levels diminish -PO2 drops below -Changes in arterial pH indirectly affects , changing the rate of
- High CO2 stimulates breathing (and vice verse)
- PO2 influences chemoreceptors; high levels diminish CO2 stimulation
- PO2 drops below 60mmHg, heavy stimulant
- Changes in arterial pH indirectly affects peripheral chemoreceptors, changing the rate of breathing (thus, PO2, PCO2 , and pH)
Some diseases of the Respiratory system
- Chronic Obstructive Pulmonary Disease (COPD)
- Asthma
- Tuberculosis: bacterial infection- Mycobacterium tuberculosis
- Lung Cancer
- -Squamous cell carcinoma (bronchi epithelia)
- -Adenocarcinoma (peripheral lung areas)
- -Small cell carcinoma (primary bronchi)
