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A&P 2: Respiratory System
Terms in this set (99)
Parts of upper respiratory system
Functions of upper respiratory system
Warm, humidify, filter air
Parts of lower respiratory system
All of the respiratory passageways from nose to respiratory bronchioles
Cleanse, humidify & warm incoming air
What does the conducting zone provide?
Rigid structure to make air movement into respiratory zone possible
Respiratory zone definition
Actual site of gas exchange
What does the Respiratory Zone contain?
All respiratory bronchioles, alveolar ducts, alveoli, microscopic structures
What do Type 1 alveolar cells make up?
The walls of alveoli
Site of gas exchange
What do the Capillaries and outer surface of alveoli come together to form?
Respiratory membrane that allows simple diffusion of gases
Explain simple diffusion of gases
Oxygen can pass from the alveolus into the blood, carbon dioxide leaves the blood to enter gas filled alveolus
What is the Parietal Pleura?
Covers thoracic wall & superior face of the diaphragm
What is the Visceral Pleura?
Covers external lung surface
What do Pleurae produce? What does it allow?
Pleural fluid- fills the cavity between the two pleurae.
It allows lungs to glide easily over the thorax wall during breathing
What does the Surface tension of pleural fluid do?
Resists pleurae separation, allowing lungs to cling tightly to the thorax wall & expand/recoil passively, as volume of thoracic cavity increases/decreases during breathing
What type of muscle is the diaphragm?
Skeletal, mostly under involuntary control
What does the diaphragm do during respiration?
Expands & contracts
What is Ventilation?
Movement of volume of gas into/out of lungs
What is Respiration?
Exchange of oxygen & carbon dioxide across a membrane either in the lungs or at cellular level
What is Inspiration/inhalation?
When air enters lungs
Flow of respiratory current out of lungs
Basic Mechanics of Pulmonary ventilation: What needs to move in order to breathe?
2. External intercostals- ribcage & sternum
3. Lungs expand/contract passively
Why do the lungs expand/contract passively?
-The differences in pressure
-Pleurae allow for lungs to expand and contract with the thoracic cavity
What are Inspiration sequence of events?
1. Inspiratory muscles contract (diaphragm descends, rib cage rises)
2. Thoracic cavity volume increases
3. Lungs are stretched
4. Intrapulmonary volume increases
What are the Inspiration changes in dimensions?
-External intercostals: contract
-Diaphragm moves inferiorly during contraction
What are Expiration sequence of events?
1. Inspiratory muscles relax
(diaphragm rises; rib cage descends due to recoil of costal cartilages)
2. Thoracic cavity volume decreases.
3. Elastic lungs recoil passively
4. Intrapulmonary volume decreases.
Expiration changes in dimensions
-Ribs & sternum: depressed
-External intercostals: relax
-Diaphragm moves superiorly as it relaxes
Volume increases, pressure decreases
Changes in volume -> changes in pressure -> changes in flow of gas
Boyle's Law equation
P1V1 = P2V2
Boyle's Law: Inspiration
Volume goes up
Pressure goes down
-thoracic cavity volume increases
-intrapulmonary pressure decreases
Boyle's Law: Exhalation
Volume goes down
Pressure goes up
-inspiratory muscles relax
-thoracic cavity volume decreases
-intrapulmonary pressure increases
Atmosphere (Patm): 760 mmHg
Intrapulmonary (Ppul): 760 mmHG
Intrapleural (Pip): 756 mmHg
(-4 mmHG relative to Patm)
Patm: 760 mmHg
Ppul: 759 mmHg
Pip: 754 mmHg
Inspiration leads to negative intrapleural & intrapulmonary pressures
Intrapleural Pressure- Down
Patm: 760 mmHg
Ppul: 761 mmHg
Pip: 756 mmHg
Intrapleural Pressure- Up
Pressure inside lung
See Slide 23
Pleural cavity pressure
See Slide 23
During each breath, the pressure gradients move how much air into & out of the lungs?
-Inspiratory muscles: contract
-Thoracic cavity volume: increases
-Intrapulmonary pressure: decreases
-Inspiratory muscles: relax
-Thoracic cavity volume: decreases
Intrapulmonary pressure: increases
What can affect ventilation? (3)
1. Airway resistance (Nonelastic, etc)
2. Alveolar surface tension
-The movement of gas molecules
passive, but the work of the Muscles to contract is active (Muscle contraction requires energy)
-Gas flow decreases as resistance increases
Flow= change in pressure/resistance
What would happen if only water was at the alveolar walls?
Alveoli would stick together, because surfactant isn't as sticky as water
What produces surfactant?
Type II pneumocytes
What reduces surface tension in alveoli?
Mixture of lipids & proteins
What can cause IRDS in premature babies?
Surface tension of alveoli
What is an example of tissue resistance?
What happens during asthma?
-Bronchioles inflamed & swollen, produce mucus which leads to more airway resistance
-Beta 2 agonists act as bronchodilators that relax the smooth muscle of the airway
What causes wheezing during asthma?
Turbulent flow of oxygen through constricted bronchioles
How do lungs stay open?
Combination between pressure & surfactant
- Collection of air in the Pleural space
-Can happen from trauma or can be spontaneous
-Lungs collapse when trans pulmonary pressure is lost
-One lung can be collapsed without affecting the other because the visceral pleura is not continuous
What happens when trans-pulmonary pressure is lost?
-The lungs collapse
-When Pip = Patm
Compliance is dependent on
-Distensibility of lung tissue
-Alveolar surface tension
The better the compliance, the easier for what?
Lung expansion at any given
Abnormal (too much or too little) compliance impairs what?
Ability for person to undergo gas exchange
What can decrease compliance?
-Fibrosis (chronic inflammation or infections where scar tissue replaces normal lung tissue)
What can increase compliance?
Inspiratory reserve volume
Female: 1900 ml
Male: 3100 ml
500 ml (male & female)
Expiratory reserve volume
Female: 700 ml
Male: 1200 ml
Female: 1100 ml
Male: 1200 ml
TV + IRV
Functional residual capacity
ERV + RV
Total lung capacity
Vital capacity equation
VC = TV + IRV + ERV
Tidal volume definition
Amount of air inhaled/exhaled with each breath under resting conditions
Inspiratory reserve volume definiton
Amount of air that can be forcefully inhaled after a normal tidal volume inspiration
Expiratory reserve volume definition
Amount of air that can be forcefully exhaled after a normal tidal volume expiration
Residual volume definition
Amount of air remaining in the lungs after a forced expiration
Total amount of gas that flows into or out of respiratory tract in a minute
Minute ventilation formula
Tidal volume * Respiratory rate
How much minute ventilation in normal healthy adults?
Why is alveolar ventilation rate more accurate than minute ventilation?
Because it takes into account any anatomical dead space
AVR = respiratory rate * (tidal volume- dead space)
Dalton's Law of Partial Pressures definition & equation
Total pressure exerted by a mixture of gases is the sum of the pressures exerted independently by each gas in the mixture
Ptotal= Pgas1 + Pgas2 + Pgas3
The greater the concentration of a particular gas in the gas phase, the more and faster that gas will go into solution in the liquid.
What do partial pressures have to do with gas exchange?
During external respiration: oxygen enters and carbon dioxide leaves the blood by diffusion.
At the body tissues, there is internal respiration - same gases move in opposite direction also by diffusion.
External respiration (pulmonary gas exchange) is influenced by
-Partial pressure gradients and gas solubilities
-Thickness and surface area of the respiratory membrane
-Ventilation-perfusion coupling (matching alveolar ventilation with pulmonary blood perfusion)
Inspired air volume
PO2: 160 mmHg
PCO2: 0.3 mmHg
Alveoli of lungs volume
PO2: 104 mmHg
PCO2: 40 mmHg
Blood leaving tissues & entering lungs volume
PO2: 40 mmHg
PCO2: 45 mmHg
Blood leaving lungs & entering tissue capillaries volume
P02: 100 mmHg
PCO2: 40 mmHg
PO2: less than 40 mmHg
CO2: greater than 45 mmHg
What are the factors that influence External Respiration?
1. Partial pressure gradients and gas solubilities
2. Thickness and Surface Area of the Respiratory Membrane
Why does a steep oxygen partial pressure gradient exist across the respiratory membrane?
because of the PO2 of deoxygenated blood in the pulmonary arteries is 40 mm Hg vs 104 mm Hg PO2 in the alveoli -> oxygen diffuses rapidly from the alveoli into the pulmonary capillary blood.
Respiratory membrane is how thick in healthy lungs?
Gas exchanges that occur between blood and alveoli and between blood and tissue cells take place by simple diffusion, driven by partial pressure gradients of O2 and CO2 that exist on opposite sides of the exchange membrane
During internal respiration, PO2 is always ___ in tissues than it is in systemic arterial blood, which favors what?
Lower, favors oxygen moving into tissues
How can molecular oxygen travel in the blood?
1. Dissolved in plasma
2. Bound to Hb in RBCs
98.5% of all the oxygen carried from the lungs is carried via what?
Red blood cells
Hemoglobin + oxygen
What happens after the first oxygen molecule binds to iron?
Hb changes shape, which increases ease with the other three oxygen molecules can bind
The rate at which Hb reversibly binds or releases oxygen is regulated by:
PO2, temperature, blood pH, PCO2
(Decrease of any of the above DECREASES oxygen unloading).
Increased temperature, PCO2, or H+ can what?
Enhance oxygen unloading from the blood into the tissue
-all of these things are highest at the capillaries where oxygen unloading is the goal.
-As cells metabolize glucose and use oxygen, CO2 is the byproduct, increasing PCO2 and H+... both of these things weaken Hb-O2 bonds, leading to increased oxygen unloading.
Carbon dioxide transport percentages
1. Dissolved in plasma - 7-10%
2. Chemically bound to Hb- ~20%
3. As bicarbonate ions in plasma - 70%
Bicarbonate ions can be made from what?
CO2, either in plasma or RBCs
Neural mechanisms of breathing
Medullary respiratory centers set basic breathing rhythm in a complicated pattern of on/off neuronal relays
Chemical factors of breathing
Chemoreceptors sense CO2, O2, H+ in arterial blood which relays to medulla to control changes in breathing
Arterial PCO2 chart
Carbon dioxide traveling as bicarbonate ions in plasma
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