Chapter 22 Flashcards
What is the primary function of alveoli?
Gas exchange—alveoli provide a large surface area (70m² per lung) for oxygen uptake and CO₂ removal.
How are alveoli structured for efficient gas exchange?
They are small, polygonal sacs with thin walls and pores, allowing air to move between them and exchange gases with blood.
An easy way to remember how alveoli are structured for efficient gas exchange is by using the mnemonic “STAMP”:
S – Small size → Increases surface area for gas exchange.
T – Thin walls → Single-layer simple squamous epithelium for easy diffusion.
A – Air pockets → Alveoli are connected by pores of Kohn, allowing airflow between sacs.
M – Moist lining → Helps gases dissolve for efficient diffusion.
P – Pulmonary capillaries → Dense network surrounding alveoli for rapid oxygen and CO₂ exchange.
What are the two main types of alveolar cells?
- Type I Alveolar Cells – Thin, cover 95% of the surface, facilitate gas diffusion.
- Type II Alveolar Cells – Secrete pulmonary surfactant to prevent collapse.
To Remember:
• Type I Alveolar Cells = Super Thin Walls
→ Imagine these cells like a single sheet of tissue paper. Their job is to let oxygen and carbon dioxide pass through easily, kind of like air flowing through a screen door.
• Type II Alveolar Cells = Bubble Makers
→ These guys make a special soap-like fluid (surfactant) that keeps your lungs from sticking shut—kind of like how dish soap breaks up grease and keeps bubbles from popping.
Easy Way to Remember:
- Type I = “One-Layer Window” → Super thin, lets air in and out.
- Type II = “Two Jobs” → Makes lung soap & helps repair damage.
How do alveoli stay clean?
Alveolar macrophages (dust cells) remove debris, bacteria, and foreign particles, then move up the mucociliary escalator to be swallowed.
What is the respiratory membrane, and why is it important?
A thin barrier (0.5µm thick) between alveoli and blood capillaries that allows for rapid gas diffusion.
Laymen’s Terms:
It’s the thin barrier where gas exchange happens between the alveoli (air sacs) and capillaries (tiny blood vessels).
Easy Way to Remember:
• Respiratory membrane = the “exchange zone” (where gas swapping happens).
The respiratory membrane is important because it allows oxygen to enter the blood and carbon dioxide to leave the body quickly and efficiently.
Since it’s super thin (about 0.5 micrometers—that’s 200 times thinner than a strand of hair!), gases don’t have to travel far. This makes breathing efficient and ensures your body gets the oxygen it needs while removing waste (CO₂).
Think of it Like This:
Imagine you’re handing off a baton in a relay race—if the runners are too far apart, the exchange is slow and inefficient. But if they’re right next to each other, the handoff is quick and smooth. The respiratory membrane keeps the distance short so the gas “handoff” happens fast and your body can keep running efficiently!
How do pulmonary and bronchial circulation differ?
• Pulmonary Circulation: Right ventricle → Pulmonary arteries → Alveoli for gas exchange → Pulmonary veins return oxygenated blood.
• Bronchial Circulation: Supplies lung tissues (except alveoli) with oxygen via bronchial arteries from the aorta.
Further Reading:
Pulmonary Circulation = “The Gas Exchange Highway”
It’s like a delivery route for oxygen:
• Blood leaves the right ventricle (low oxygen).
• Pulmonary arteries take it to the alveoli for oxygen pickup.
• Pulmonary veins return oxygen-rich blood to the left atrium.
• Main Job: Exchange gases (O₂ in, CO₂ out).
Bronchial Circulation = “Lung Maintenance Crew”
Think of it as the fuel line for the lungs themselves:
• The bronchial arteries come from the aorta (high oxygen).
• They supply oxygen and nutrients to lung tissues, but NOT the alveoli (those rely on pulmonary circulation).
• Main Job: Keep lung structures alive and healthy.
Mnemonic:
• Pulmonary = Picking up oxygen at alveoli (P for picking up).
• Bronchial = Bringing oxygen to lung tissues (B for bringing oxygen to the bronchi).
Imagine pulmonary circulation is like Uber for oxygen—picking it up and dropping it off for the rest of the body.
Meanwhile, bronchial circulation is like a maintenance crew—keeping the lungs working, but not handling the oxygen exchange.
Why is capillary pressure in the lungs lower than in other organs?
Prevents fluid accumulation in alveoli, which would impair gas exchange.
Simple Terms:
Think of your lungs like a sponge that needs to stay just damp enough to work properly—too much water, and it won’t function well.
In most organs, capillary pressure is higher to push nutrients and oxygen into tissues. But in the lungs, if the pressure were too high, it would force too much fluid out of the blood and into the alveoli (air sacs). This would flood the lungs, making it hard for oxygen to get in and carbon dioxide to get out—basically, drowning your own lungs.
So, the capillary pressure in the lungs is kept lower to prevent excess fluid buildup and keep the alveoli dry enough for efficient gas exchange. It’s like having a sponge that’s just damp instead of soaking wet—so it can still absorb air properly!
What are the two pleural layers, and what do they do?
• Visceral pleura: Covers lung surface.
• Parietal pleura: Lines the rib cage and diaphragm.
Both reduce friction, create a pressure gradient, and prevent infection spread.
Simple Terms:
An easy way to remember the two pleural layers is with the “V.I.P. Rule”:
V = Visceral pleura → Inside layer (Covers the lungs)
P = Parietal pleura → Peripheral layer (Lines the rib cage & diaphragm)
Think of the pleura like a double-layered ziplock bag:
• The visceral pleura is stuck to the lungs like plastic wrap.
• The parietal pleura lines the ribcage, creating a protective outer layer.
• The space in between has fluid to reduce friction (so your lungs don’t rub harshly against your ribs).
Key Functions to Remember:
✔ Reduces friction (like oil between two gears).
✔ Creates a pressure gradient (helps lungs expand).
✔ Prevents infection spread (like a barrier between lung and chest).
Quick Mnemonic:
“V.I.P. = Visceral Is Pulmonary” (touches the lungs)
“Parietal Protects Perimeter” (lines the chest wall)
What are the three functions of pleural fluid?
- Lubrication – Reduces friction between lung surfaces.
- Pressure Gradient – Helps lung inflation.
- Compartmentalization – Prevents infections from spreading.
L.P.C. = Lungs Prefer Comfort
✔ L = Lubrication → Reduces friction so lungs don’t rub harshly against the chest.
✔ P = Pressure Gradient → Helps with lung inflation by creating suction between layers.
✔ C = Compartmentalization → Prevents infection spread between lungs and other areas.
Think of Pleural Fluid Like:
• Lube for an engine (prevents friction).
• Vacuum seal (helps lungs expand).
• A plastic divider in a lunchbox (keeps infections from spreading).
Why is blood in the pulmonary veins slightly less oxygenated than expected?
Some deoxygenated blood from bronchial veins mixes in, diluting O₂ levels slightly.
“A Little Backwash” Mnemonic
✔ A = Arteries (Bronchial) carry oxygen to lung tissues.
✔ L = Leftover deoxygenated blood from bronchial veins mixes in.
✔ B = Backwash effect slightly dilutes the oxygen in the pulmonary veins.
Think of it Like This:
Imagine you pour fresh juice (oxygenated blood) into a cup, but a few drops of water (deoxygenated blood) get mixed in—the juice is still good, just a tiny bit diluted!
This happens because bronchial veins drain some deoxygenated blood into pulmonary veins, causing a small drop in oxygen levels before the blood reaches the heart.
What is pulmonary surfactant, and why is it important?
A mixture of phospholipids & proteins secreted by Type II alveolar cells to reduce surface tension and prevent alveolar collapse.
What are the two types of respiration?
Quiet respiration (relaxed, unconscious breathing) and Forced respiration (deep, rapid breathing during exercise, singing, coughing, etc.).
An easy way to remember the two types of respiration is with the mnemonic “Quiet vs. Quick”:
“Quiet vs. Quick” Mnemonic
✔ Quiet Respiration → “Calm and automatic” (like breathing in your sleep).
✔ Forced Respiration → “Fast and intentional” (like blowing out candles or gasping after a sprint).
Think of it Like This:
• Quiet respiration is like a fan running on low—you don’t think about it, it just happens.
• Forced respiration is like turning up the fan to high speed—you control it when you need extra airflow.
What muscles are involved in respiration?
The diaphragm (prime mover, 2/3 of airflow) and intercostal muscles (stiffen thoracic cage and expand ribs).
An easy way to remember the muscles involved in respiration is with the mnemonic “D.I.E.”:
“D.I.E. = Diaphragm, Intercostals, Expand” Mnemonic
✔ D = Diaphragm → The main driver (prime mover, responsible for 2/3 of airflow).
✔ I = Intercostal muscles → Stiffen the ribcage and assist expansion.
✔ E = Expand the chest → These muscles work together to create space for air to flow in.
Think of it Like This:
• The diaphragm is the engine—it moves the most air.
• The intercostals are the frame—they keep the ribcage stable and flexible.
• Together, they expand the chest, making room for air to fill the lungs.
How does the diaphragm contribute to breathing?
When it contracts, it flattens, expanding the thoracic cavity and lowering pressure for inhalation. When it relaxes, it bulges upward, compressing the lungs for exhalation.
An easy way to remember how the diaphragm works is with the mnemonic “Contract = Collect, Relax = Release”:
“Contract = Collect, Relax = Release” Mnemonic
✔ Contract = Collect Air → When the diaphragm contracts, it flattens, making more space in the chest and pulling air in (like a vacuum).
✔ Relax = Release Air → When the diaphragm relaxes, it bulges upward, pushing air out (like squeezing a balloon).
Think of it Like This:
• Contracting = Making room for air (lungs fill up, like pulling a syringe plunger).
• Relaxing = Pushing air out (lungs shrink, like pressing a plunger down).
What are the three respiratory centers in the brainstem?
- Ventral Respiratory Group (VRG) - Generates the breathing rhythm.
- Dorsal Respiratory Group (DRG) - Modifies the rhythm based on sensory input.
- Pontine Respiratory Group (PRG) - Adapts breathing for special circumstances (e.g., sleep, crying, laughing).
An easy way to remember the three respiratory centers in the brainstem is with the mnemonic “V.D.P. = Very Deep Pulmonary control”:
“V.D.P. = Very Deep Pulmonary control” Mnemonic
✔ V = Ventral Respiratory Group (VRG) → “Vital Rhythm Generator” (sets the basic breathing rhythm).
✔ D = Dorsal Respiratory Group (DRG) → “Data Receiver Group” (modifies breathing based on sensory input).
✔ P = Pontine Respiratory Group (PRG) → “Pattern Regulator Group” (adjusts breathing for special activities like sleep, crying, or laughing).
Think of it Like This:
• VRG = “The Conductor” (keeps the beat—sets the rhythm).
• DRG = “The Listener” (adjusts the rhythm based on input, like hearing a faster beat).
• PRG = “The Performer” (modifies breathing for different “performances” like sleeping, laughing, or crying).
What role do central and peripheral chemoreceptors play in breathing?
• Central chemoreceptors (medulla) detect pH changes in cerebrospinal fluid, indicating CO₂ levels.
• Peripheral chemoreceptors (carotid and aortic bodies) monitor O₂, CO₂, and pH in the blood.
An easy way to remember the role of central and peripheral chemoreceptors in breathing is with the mnemonic “COPS”:
“COPS” = Chemoreceptors Observe pH & Sensors
✔ C = Central Chemoreceptors → Located in the CNS (medulla), detect CO₂ and pH changes in cerebrospinal fluid.
✔ O = O₂ Monitoring → Peripheral chemoreceptors detect oxygen (O₂) levels in blood.
✔ P = Peripheral Chemoreceptors → Located in the Periphery (carotid & aortic bodies), they track O₂, CO₂, and pH in the blood.
✔ S = Signals to Adjust Breathing → Both types send signals to the brain to increase or decrease breathing based on oxygen and CO₂ levels.
Think of it Like This:
• Central chemoreceptors are like “brain sensors”—they watch CO₂ and pH in spinal fluid (the body’s internal chemistry lab).
• Peripheral chemoreceptors are like “blood patrol”—they monitor oxygen, CO₂, and pH in the bloodstream (keeping an eye on oxygen supply).
• If CO₂ is too high or O₂ is too low, these sensors tell the body to breathe faster to fix the balance.
What is Boyle’s Law and how does it relate to respiration?
Boyle’s Law states that pressure is inversely proportional to volume. When lung volume increases, pressure decreases, drawing air in. When volume decreases, pressure increases, pushing air out.
An easy way to remember Boyle’s Law and how it relates to breathing is with the mnemonic “Big Volume, Low Pressure – Small Volume, High Pressure” (BLow-SHoP):
“BLow-SHoP” = Big Volume, Low Pressure – Small Volume, High Pressure
✔ B = Big Volume → Low Pressure → Air flows in (inhalation).
✔ S = Small Volume → High Pressure → Air flows out (exhalation).
Think of it Like This:
• Imagine a syringe:
• Pull the plunger out → The space inside increases (low pressure), and air rushes in (just like inhalation).
• Push the plunger in → The space gets smaller (high pressure), and air gets forced out (just like exhalation).
So, when your lungs expand, pressure drops, and air rushes in. When your lungs contract, pressure rises, and air pushes out—all following Boyle’s Law!
What are the different respiratory volumes?
• Tidal Volume (TV) - Normal breath (500 mL).
• Inspiratory Reserve Volume (IRV) - Max air inhaled beyond TV (3,000 mL).
• Expiratory Reserve Volume (ERV) - Max air exhaled beyond TV (1,200 mL).
• Residual Volume (RV) - Air left in lungs after exhalation (1,300 mL).
An easy way to remember the different respiratory volumes is with the mnemonic “TIER”:
“TIER” = Tidal, Inspiratory, Expiratory, Residual
✔ T = Tidal Volume (TV) → “Typical breath” (normal breathing, ~500 mL).
✔ I = Inspiratory Reserve Volume (IRV) → “Inhale More” (extra air you can forcefully breathe in, ~3,000 mL).
✔ E = Expiratory Reserve Volume (ERV) → “Exhale Extra” (extra air you can forcefully push out, ~1,200 mL).
✔ R = Residual Volume (RV) → “Remaining air” (air left in the lungs after full exhalation, ~1,300 mL).
Think of it Like This:
• Tidal = “Tiny breath” → Just normal breathing.
• Inspiratory = “Inhale more” → The air you can suck in beyond normal.
• Expiratory = “Exhale extra” → The air you can force out beyond normal.
• Residual = “Resting air” → The air that always stays in your lungs so they don’t collapse.
What is alveolar ventilation rate (AVR)?
The amount of air reaching alveoli per minute:
AVR = (Tidal Volume - Dead Space) × Respiratory Rate
Example: (500 mL - 150 mL) × 12 = 4,200 mL/min
An easy way to remember Alveolar Ventilation Rate (AVR) is with the mnemonic “AIR Formula”:
“AIR Formula” = (Air Inhaled - Residual) × Rate
✔ A = Air that actually reaches alveoli (Tidal Volume - Dead Space).
✔ I = Inhalations per minute (Respiratory Rate).
✔ R = Result is AVR (Amount of fresh air reaching alveoli each minute).
Think of it Like This:
Imagine you’re filling a balloon:
• You breathe in a total amount of air (Tidal Volume).
• But some of that air stays in the tube (Dead Space), never reaching the balloon (alveoli).
• To know how much fresh air actually gets into the balloon each minute, you subtract the dead space and multiply by how many breaths you take per minute.
Example Formula:
✔ AVR = (Tidal Volume - Dead Space) × Respiratory Rate
✔ AVR = (500 mL - 150 mL) × 12 breaths/min
✔ AVR = 4,200 mL/min
What factors influence airflow resistance?
- Bronchodilation (e.g., epinephrine) decreases resistance, increasing airflow.
- Bronchoconstriction (e.g., histamine, cold air) increases resistance, reducing airflow.
- Pulmonary compliance - Lung elasticity affects how easily lungs expand.
An easy way to remember the factors that influence airflow resistance is with the mnemonic “B.C.P.” = “Breathe Clearly, Please”:
“B.C.P. = Breathe Clearly, Please”
✔ B = Bronchodilation → Bigger Airways, Better Breathing (epinephrine opens airways, reducing resistance).
✔ C = Constriction (Bronchoconstriction) → Clamped Airways, Can’t Breathe (histamine, cold air, irritants narrow airways, increasing resistance).
✔ P = Pulmonary Compliance → Plastic vs. Rubber (how easily lungs stretch and expand—stiff lungs = more resistance).
Think of it Like This:
• Bronchodilation = Highways widen = Faster airflow (like when epinephrine relaxes airways).
• Bronchoconstriction = Roads narrow = Traffic jam (like when allergies or cold air cause asthma).
• Pulmonary Compliance = Balloon Stretchability → A stiff balloon (low compliance) is harder to inflate, just like stiff lungs make breathing difficult.
What is dead space in the respiratory system?
• Anatomical dead space - Air that never reaches alveoli (about 150 mL).
• Physiological dead space - Anatomical dead space plus alveoli that can’t exchange gases due to disease.
What are some variations in respiratory rhythm?
• Eupnea - Normal breathing (12–15 breaths/min).
• Hyperpnea - Increased breathing rate/depth due to exercise.
• Hyperventilation - Excess breathing, lowering CO₂ levels.
• Apnea - Temporary cessation of breathing.
• Tachypnea - Rapid breathing.
Here’s an easy way to remember the variations in respiratory rhythm using the mnemonic “Every Human Has A Tempo” (E.H.H.A.T.):
“Every Human Has A Tempo” Mnemonic
✔ E = Eupnea → Easy breathing (normal, relaxed breathing).
✔ H = Hyperpnea → Heavy breathing (deep, rapid breathing during exercise).
✔ H = Hyperventilation → Huffing too much (breathing too fast, CO₂ drops).
✔ A = Apnea → Absence of breath (temporary breathing pause).
✔ T = Tachypnea → Too fast (shallow, rapid breathing).
Think of it Like This:
• Eupnea = “Effortless” → Normal breathing.
• Hyperpnea = “Hustle” → Breathing harder during exercise.
• Hyperventilation = “Hyped Up” → Breathing too fast, CO₂ drops.
• Apnea = “Air Pause” → No breathing for a moment.
• Tachypnea = “Treadmill Breathing” → Fast, shallow breaths, like when you sprint.
What is partial pressure and how does it relate to gas mixtures?
Partial pressure is the contribution of each gas in a mixture to the total pressure. It determines the diffusion of gases across membranes, such as in respiration.
An easy way to remember partial pressure and how it relates to gas mixtures is with the mnemonic “Piece of the Pressure Pie”:
“Piece of the Pressure Pie” Mnemonic
✔ Each gas in a mixture contributes a ‘slice’ of total pressure (like slices of a pie).
✔ The bigger the slice (higher partial pressure), the more that gas moves (diffuses).
✔ Gases move from areas of high to low pressure (like air escaping a popped balloon).
Think of it Like This:
• Imagine air pressure is a pie made of oxygen, carbon dioxide, nitrogen, etc.
• Each gas ‘owns’ a slice of the total pie (total pressure)—that’s its partial pressure.
• Bigger slice = more movement → Oxygen has a higher partial pressure in the lungs, so it moves into the blood.
• Smaller slice = less movement → CO₂ has a higher partial pressure in the blood, so it moves out into the lungs to be exhaled.
Quick Summary:
✔ Partial Pressure = “Gas Slice of the Pie” (each gas contributes to total pressure).
✔ Gases move from high to low pressure (like air escaping a balloon).
✔ Essential for respiration! (O₂ diffuses in, CO₂ diffuses out).
How does the composition of inspired air differ from alveolar air?
Inspired air has more oxygen (20.9%) and less carbon dioxide (0.04%), whereas alveolar air has lower oxygen (13.7%) and higher carbon dioxide (5.3%) due to gas exchange with the blood.
