Unit 3: Respiratory Physio Flashcards
Define “ventilation”.
breathing; exchange of air between the atmosphere and lungs
process of drawing fresh air into the alveolar spaces within the lungs where exchange with blood is possible
Define “respiration”.
Distinguish between systemic respiration (both external and internal) and cellular respiration.
Cellular respiration- intracellular reaction of oxygen with organic molecules to produce Co2, water, and energy in form of ATP
Systemic:
External respiration- movement of gases between environment and body’s cells; exchange between alveoli and blood
internal respiration- exchange of gases with the internal environment; occurs in the tissues; exchange between blood and tissues
Describe the major functions of the respiratory system.
Ventilation
Gas exchange
~moves fresh air into body while removing waste gases
Identify the two different functional zones of the respiratory system.
conduction zone
-airways; dead air space
-pharynx, larynx, trachea, bronchi, bronchioles [not sites of exchange]
-filters, warms, humidifies
respiratory zone
-gas exchange
-external systematic respiration takes place here
-molecules mostly moving by diffusion
Describe the roles of the conduction zone and the significance of each role.
filtration [good job of filtering out particulates so they dont make it to alveoli]
warming- up to body temp. Air that is too cold is problematic, as molecular movement is slow if cold so will not be enough gas exchange
humidifying- alveolar spaces need a water lining to work; inside of lungs must be wet and not dry out
Describe the structure of the respiratory “exchange” zone. What are the characteristics of the respiratory zone?
respiratory bronchioles
alveolar sacs
external systemic respiration
gas exchange occurring
Describe Boyle’s Law. Explain how Boyle’s Law relates to ventilation.
the pressure of gas is inversely related to its volume
[pressure = 1/ volume]
Describe the process of inhalation.
Is it active or passive?
Describe the direction of airflow.
What is causing it to move?
~process of taking air into the lungs
~active phase of ventilation- result of muscle contraction. ~ ~diaphragm contracts and the thoracic cavity increases in volume.
Describe the pressure and volume changes that are occurring during inhalation (in the lungs and in the intrapleural space).
lungs
-pressure decreases below atmospheric pressure
-thoracic/lung volume increases
intrapleural space
-pressure decreases below atmospheric pressure
What holds the lungs against the chest wall?
The lungs are held against the chest wall by the negative pressure in the intrapleural space.
The intrapleural space is the thin space between the visceral pleura (which covers the lungs) and the parietal pleura (which lines the inside of the chest cavity). This space is filled with a small amount of intrapleural fluid.
1) negative pressure in intrapleural space
and adhesive properties of water holding lungs open
lungs are elastic enough they are pulling away from chest at all times, how much depends how much chest expands
What is the significance of lung compliance to inhalation?
lungs must be very compliant, or easily stretched
during a restrictive R.D. hard to inhale due to reduced compliance…. allows a full easy inahle
Describe the process of exhalation. Is it active or passive?
Describe the direction of airflow.
What is causing it to move?
Passive because it occurs during quiet breathing and involves a passive elastic recoil rather than active muscle contraction
Active expiration occurs during voluntary expirations and when ventilation exceeds 30-40 BPM. this uses the intercostal and abdominal muscles (called the expiratory muscles)
Air flows out of the lungs, due to pressure changes
Describe the pressure and volume changes that are occurring during exhalation (in the lungs and in the intrapleural space)
lungs
-pressure increases then decreases
-volume of air decreases
intrapleural space
–pressure increases, but still negative [slightly less negative]
-volume of air decreases
What is the significance of lung elasticity to exhalation?
it facilitates the passive recoil of the lungs during both quiet and forced breathing.
as exhalation progresses, elasticity increases
What is the primary source of lung elasticity? Explain.
~due to rib cage, musculature of thoracic wall, and diaphram, but also–
~also due to tissue- the elastin in connective tissue; & also due to the water layer lying inside the alveoli surface
~The aleveoli thin water layer exhibits surface tension, meaning water molecules at the surface of this layer, are forming hydrogen bonds so they pull towards their neighbors on their side, creating surface tension. Surface tension creates force
What is the Law of LaPlace?
pressure inside of a bubble formed by a fluid film is a function of 2 factors : the surface tension of fluid & radius of the bubble
P=2T/r
Collapsing force depends on diameter of alveoli
[when alveolus is larger in diameter, collapsing force is smaller, vice versa]
The smaller the diameter of alveolus, greater the collapsing force
What is surfactant? What is the function of surfactant?
there are cells within alevolar walls that secrete an oily secretion called surfactant
~will not mix with water, so rises to surface and floats on water layer. disrupts the surface tension of water layer.
as alveolus gets smaller, surfactant molecules becomes more and more compacted to each other & have a bigger impact on breaking up surface tension
The surfactant enhances ability to reach equilibrium between alveoli and reduces the potential for them to collapse
Why is the concentration of oxygen lower in the alveoli than in the inhaled air?
How does the conduction zone contribute to alveolar ventilation?
the air entering the alveoli is a mixture of fresh and old (air with oxygen and Co2) air
As you draw a breath, the airway air gets drawn into alveoli, as well as fresh air volume; the mixed air + air already in alveoli results in dilution of gases [oxygen concentration decreases due to diluting effect]
What is the significance of the residual volume?
The RV is essential as it prevents alveolar collapse and provides a source of gas exchange between breaths.
What is a partial pressure?
What is it used for?
pressure exerted by a specific gas within a mixture of gases; determined by concentration of each molecule
way of measuring driving force
Describe the process of gas exchange
(describe the driving forces causing molecular movement, the path of molecular movement, and the mechanisms that enhance molecular movement in the desired direction).
Gas exchange- pure diffusion driven by partial pressure gradients
Gradient favors oxygen diffusion from the alveoli into the capillary blood
as the capillary blood runs around the alveoli, there is continued oxygen diffusion into the blood, even as it leaves the capillaries due to the partial pressure
Gradient consistently favors oxygen movement from the alveoli into the blood
Describe how oxygen is transported in the blood.
What factors enhance oxygen movement into the blood when in the lungs and oxygen movement from the blood when in the tissues?
98% transported by hemoglobin
[oxygen molecule latches onto hemoglobin]
Hemoglobin
2% dissolved in plasma [first]
Factors enhancing O2 movement:
Partial Pressure of Oxygen (PaO2):
higher PP = more oxygen movement
Bohr Effect: Increased acidity (lower pH) in tissues enhances the release of oxygen from hemoglobin.
Higher temperatures
higher Co2
Describe how carbon dioxide is transported in the blood. Where is it distributed in the blood and in what proportions?
7% dissolved in plasma
23% bound to amino groups of hemoglobin
70% transported as bicarbonate
[bicarbonate will diffuse out the cell and enter plasma]
Describe the relationship between carbon dioxide and bicarbonate.
70% of Co2 is transported as bicarbonate
Co2 + H20 < > H2Co3 < > HCo3 + H
Bicarbonate diffuses out the cell, into plasma
Bicarbonate is a negative ion; when it leaves the cell it alters the cell’s resting potential and will be counterbalanced by negative chloride ions diffusing into cell while bicarbonate is diffusing out of the cell.
Describe the chloride shift.
Bicarbonate is a negative ion; when it leaves the cell it alters the cell’s resting potential and will be counterbalanced by negative chloride ions diffusing into cell while bicarbonate is diffusing out of the cell.
[To maintain electrochemical neutrality within the red blood cell, there is an exchange of chloride ions (Cl-) for bicarbonate ions (HCO3-) across the cell membrane.
Chloride ions move into the red blood cell, compensating for the outward movement of bicarbonate ions].
Describe the relationship between carbon dioxide, hemoglobin and oxygen.
Co2 will drive oxygen off of hemoglobin (binds at diff sites)
Hemoglobin binds O2
Co2 also binds to hemoglobin - decreases oxygen ability to bind to hemoglobin
less co2 there is, more oxygen can bind
Describe the location and chemical sensitivity of the different respiratory chemoreceptors.
Aortic & carotid bodies [peripheral chemoreceptors]
-directly respond to plasma Co2 & pH
-trigger reflex increase in ventilation
-directly exposed to plasma
-both highly sensitive to changes in plasma Co2
-can also respond to oxygen
-carotid bodies: also respond to changes in pH
Medulla Oblongata [central chemoreceptors]
-set respiratory rate
-measure pH in CSF
-can only respond to plasma Co2 (not pH)
What is the primary stimulus for breathing?
Describe how carbon dioxide, pH and oxygen are related to the regulation of ventilation
level of carbon dioxide (CO2) in the blood, specifically the partial pressure of carbon dioxide (PaCO2).
What is the Hering-Breuer reflex?
stretch receptors that inhibit inhalation
prevents over-inhalation
Eupnea
normal respiratory rate and depth; normal total minute volume
Apnea
temporary cessation of spontaneous breathing; often due to reduced chemoreceptor stimulation
Hyperventilation
increased total minute volume which does NOT match the metabolic needs; generally caused by sympathetic NS and results in decreased pCo2 and increased pH
Hyperpnea
increased total minute volume during exercise in proportion to metabolic need; unlike hyperventilation, the blood Co2 levels do NOT change because the increased ventilation matches the metabolic demands
Hypoxia
reduced oxygen (below amount needed to meet tissue demands)
Anoxia
deprivation of oxygen (possibly to point of tissue damage)
Tachypnea
rapid breathing rate; increased rate not associated with metabolic demands and may not result in increased total minute volume
Hypercapnia
excessive concentration of carbon dioxide in blood
Dyspnea
difficult and/or painful breathing
Asphyxia
unconsciousness or death resulting from lack of oxygen
Respiration is the process of capturing, delivering, and using :
oxygen O2 during aerobic cellular production of ATP
The respiratory system’s role is to :
capture oxygen for the blood to deliver to the cells and eliminate Co2 waste produced by cells
Breathing (ventilation) is the process of :
moving fresh air into alveolar spaces where exchange with blood takes place
Which of the following pressures is always the lowest:
intrapleural
atmospheric
intra-alveolar (aka intrapulmonary)
intrapleural
Identify 2
2- tidal volume
Identify 3, 4
3- Inspiratory reserve volume IRV
4- expiratory reserve volume ERV
Identify 5, 6
5- residual volume
6- vital capacity
Identify 8
8- total lung capacity
