Unit 4: Respiratory Flashcards
6 Main Functions of the Respiratory System
1) Provide O2 and CO2 exchange
2) Regulates pH in coordination with kidneys
3) Phonation
4) Removal and screening of incoming microbes
5) Can remove arterial chemical messengers
6) Traps and dissolves blood clots
Anatomy: Epiglottis: Name meaning
Over(epi) hole (glottis)
Anatomy: Cartilaginous C Rings
Surround the trachea with the open end at the back. Prevents collapse of the trachea while sucking air in.
Anatomy: Pharynx vs. Larynx
Pharynx = above the larynx, part of both the air and food tunnels. Larynx is only part of the wind tunnel
Describe the route of air from Trachea to alveolar sacs
Trachea>Bronchi>Bronchioles>Terminal bronchioles>Respiratory bronchioles>Alveolar ducts>Alveolar sacs
What are the names of the two zones in the air hierarchy?
Conducting Zone and the Respiratory Zone
How many square meters do the alveoli have in terms of surface area?
A tennis court, 70 sq meters
What do type I cells do in the alveoli?
Type I cells are the walls
What do type II cells do in the alveoli?
They provide surfactant, and also act as a defense (macrophages)
What are the three components of the pleura moving from the inside to the outside?
Visceral pleura, intrapleural fluid, then parietal pleura.
What is the purpose of the pleura?
Like a biological slide with water between it, it is very easy for the two sheets to slide relative to each other, but it is incredible hard to separate the slides. This analogy is for the lungs and the Thoracic wall
Define respiration from a chemical standpoint
Food and O2 makes CO2, Energy, Waste, and water
What is Boyle’s Law for the purposes of this class?
P1V1=P2V2
How does Boyle’s Law show what happens during inspiration?
During inspiration, the chest expands volume, lowering the pressure below atmospheric, therefore allowing air to flow down its pressure gradient into the lungs.
What is FRC?
Functional Residual Capacity: the volume of air in the lungs after an exhale when the respiratory muscles are relaxed
What pressures are balanced to provide FRC?
The alveolar and atmospheric pressure are at relative 0 atm, and the inter pleural pressure is negative 4.
What happens in pneumothorax?
Puncture in the chest causes the pleural cavity to no longer maintain negative pressure, which causes the lungs to collapse.
4 major muscles involved in inspiration:
1) Diaphragm: contracts to flatten the muscle, expanding the thoracic space
2) Ext. Intercostals: elevates the ribs to widen cavity
3) Scalenus: lifts the rib cage
4) Sternocleidomastoid: elevates the sternum
2 major muscles involved in expiration:
1) Int. Intercostals: Depresses the ribs
2) Abdominals: abs able to flatten the belly forces air out and pushes the diaphragm in
Steps that occur during inspiration:
Diaphragm and Inspiratory Intercostals contract, thorax expands, inter pleural pressure becomes negative, increased transpulmonary pressure, lungs expand, pressure in alveoli lowers below atmospheric, and air flows into the alveoli
Describe compliance
The greater the compliance, the greater increase in volume for a step in transpulmonary pressure.
2 major determinants of lung compliance:
Collagen/Elastin: more of these = less compliance
Surface Tension: increased surface tension = less compliant, more surfactant = more compliant
F = ? for lungs?
Ppi(r^4)/8Lnu
Emphysema
loss of elastic recoil causes airway collapse. Will not require more work via muscles for exhaling. Patients adopt a high FRC (barrel chest)
Dyspnea
gas transport lowered causes anxiety and depression
Minute Ventilation: General definition and equation
Total ventilation in mL/min = Frequency of breathing x Tidal volume
Alveolar Ventilation: General definition and equation
Total ventilation of useful air (not including the dead space) = frequency x (Tidal volume - dead space)
What is the normal minute ventilation?
12 breaths/min x 500 mL/breath = 6000 mL/min
What is the normal alveolar ventilation?
12 breaths/min x (500 mL/breath - 150 mL/breath) = 4200 mL/min
How much O2 is released in our breath?
A lot, about 3/4 of the initial amount
How much CO2 is inhaled in our breath?
Practically none.
How much CO2 is kept in the body?
About 92% of it, this acts as an acid/base buffer.
What is the respiratory quotient, and what trends are seen?
Less CO2 produced than O2 used.
Dalton’s Law
The partial pressure of a gas is equal to the atmospheric pressure multiplied by the percentage of the air that is that gas.
What is the air pressure at sea level?
760 mmHg
Henry’s Law
The concentration of a gas in a solution is equal to the partial pressure of that gas in the atmosphere multiplied by the solubility.
Partial Pressure Memorization: PO2 in air
160 mmHg
Partial Pressure Memorization: PCO2 in air
0.3 mmHg
Partial Pressure Memorization: PO2 in alveoli,capillaries,after tissues
105–>100–>40
Partial Pressure Memorization: PCO2 in alveoli, capillaries,after tissues
40–>40–>46
Resting Alveolar Ventilation (L/min)
4L
What three factors affect alveolar PO2?
Rate of ventilation, partial pressure, and rate of metabolism
Hyperventilation: PO2 and PCO2
CO2 less than 40mmHg, PO2 more than 100mmHg
Hypoventilation: PO2 and PCO2
CO2 more than 40mmHg, PO2 less than 100mmHg
In normal lungs at rest, equilibration is complete with ___ % of the capillary length to spare
70%
Matching Ventilation: Blocked alveolus
1) Blocked alveolus
2) Decreased O2 in the alveoli
3) Vasoconstriction reduces the amount of blood that passes by this imperfect alveolus
Matching Ventilation: Clot blocking the blood vessel
1) Clot blocking CO2 from traveling through vessel
2) Lowered CO2 levels in the bronchioles
3) Constriction of bronchioles
How many oxygen subunits can hemoglobin carry?
4
What percentage of oxygen in the blood does hemoglobin carry?
98.5%
Key features of the hemoglobin / P02 curve
1) Plateau that protects you if alveolar PO2 falls
2) Steep part that helps you unload on tissues.
3) Sigmoid shape due to cooperative binding
Venous blood still has ___ % of Hgb still bound to O2
75%
Hemoglobin curve: Systemic Arterial PO2 and Hgb%
Systemic Arterial: 100 mmHg PO2, and 98% Hgb
Hemoglobin curve: 90% Hgb corresponds to what PO2?
60mmHg
Hemoglobin curve: Systemic Venous PO2 and Hgb%
40 mmHg PO2 , and 75% Hgb
How does Hemoglobin create a gradient useful for loading and unloading oxygen?
When oxygen is carried by hemoglobin, it becomes invisible to the concentration gradient, allowing oxygen to continue to fill into the blood across a gradient. When unloading, the same gradient helps with unloading.
Three nasty tricks of CO
1) binds to hemoglobin and reduces the amount of oxygen that can bind to hemoglobin
2) Changes the Hgb O2 curve so that less oxygen will unload in tissues
3) Chemoreceptors can only sense levels of unbound oxygen, not the lack of bound oxygen to hemoglobin, so you suffocate without gasping or dyspnea.
How does CO2 cause blood acidity?
It combines with water to create H2CO2, which in turn can split into H+ and HCO3-
Hemoglobin is ___ able to bind to oxygen in low acidity, but ___
more, but this will shift the unloading curve.
O2 is more easily unloaded in __ temps, and more easily loaded in __ temps
high, low
What happens at prolonged lower levels of O2?
leads to production of DPGs, it shifts the curve to the right, helping with unloading, but not with loading.
When is 100% O2 helpful vs. harmful?
If the alveoli have fluid or something, it can help by creating a greater diffusion gradient, but otherwise it hurts tissues.
What percentages of CO2 go where in the body?
10% is dissolved, 30% bound to Hgb, and 60% in the form of HCO3-
What is needed for electroneutrality in cells?
The chloride shift which exchanges a chloride for an HCO3-
Why don’t RBCs explode from acidity in the tissues?
Hemoglobin is a great buffer for H+ when O2 is not bound.
Respiratory Motor Pathways: Where spatially do you lose function at the site of damage?
At the site of damage in the spine, and any control centers below it
Respiratory Motor Pathways: Which nerves control the diaphragm for quiet breathing and deep inspiration?
C3-C5 via the phrenic nerve
Respiratory Motor Pathways: Which nerves control the SCM and the scalenus for deep inspiration?
The cervical and cranial nerves
Respiratory Motor Pathways: Which nerves control the external and internal intercostals?
T1-T12
Respiratory Motor Pathways: Which nerves control your abs?
The lumbar nerves
Which three concentrations control ventilation?
PO2, PCO2, and H+
What is true of a given change in PO2 to change in ventilation?
A large change in PO2 is required for much of a noticeable change in ventilation.
What senses partial pressures in the body and sends signals to ventilation centers?
The chemoreceptors in the aorta usually.
What is true of a given change in PCO2 to change in ventilation?
The graph is much steeper than PO2, meaning that a small change in CO2 can induce heavy breathing changes. This is what happens when you hold your breath.
What chemical equation regulates the difference between CO2 and H+?
CO2 + H2O –> H2CO3 –> H+ + HCO3
What two locations do chemosensory exist, and what is the difference between them?
Peripheral Chemoreceptors: Sense change in H+ from degradation of CO2, and general H+ concentrations from metabolic activity.
Central Chemoreceptors exist inside the brain, and can only sense H+ from CO2 degradation, but not metabolic H+ because H+ cannot cross the blood brain barrier.
How does the law of mass action (Le Chatelier’s Principle) help lower H+ when CO2 is removed?
Removing CO2 reduces amount on the left side of the equilibrium equation, and drives H+ toward CO2.
