Chapter 21 Flashcards
(158 cards)
1
Q
What is/are the main function(s) of the respiratory system?
A
Provide oxygen to body tissues for cellular respiration, remove carbon dioxide waste, and help maintain acid-base balance. Also involved in sensing odors and speech production.
2
Q
How do we breathe?
A
Breathing (pulmonary ventilation) involves muscle contraction (mainly the diaphragm and intercostal muscles) expanding the thoracic cavity. This increases lung volume and decreases pressure inside the lungs (intrapulmonary pressure) below atmospheric pressure, causing air to flow in (inspiration). Relaxation of these muscles decreases thoracic volume, increases lung pressure above atmospheric pressure, forcing air out (expiration).
3
Q
Why do we inhale oxygen and exhale carbon dioxide?
A
Cells need oxygen for cellular respiration to produce energy (ATP). Carbon dioxide is a waste product of this process. We inhale to bring oxygen into the lungs for transport to cells, and exhale to remove the carbon dioxide transported from the cells to the lungs.
4
Q
Describe and distinguish between the upper and lower respiratory tracts.
A
Upper: Includes nose, nasal cavity, paranasal sinuses, and pharynx. Primarily filters, warms, and humidifies incoming air. Lower: Includes larynx, trachea, bronchi, bronchioles, and lungs (containing alveoli). Involved in conducting air and gas exchange.
5
Q
Describe and distinguish between the conducting and respiratory zones of the respiratory tract.
A
Conducting Zone: Includes structures from the nose to the terminal bronchioles (nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles). Its function is to transport, filter, warm, and humidify air. Respiratory Zone: Includes structures directly involved in gas exchange: respiratory bronchioles, alveolar ducts, and alveoli.
6
Q
Describe the major functions of the respiratory system.
A
Gas exchange (O2 in, CO2 out), helps regulate blood pH, contains receptors for smell, filters inspired air, produces vocal sounds, excretes small amounts of water and heat.
7
Q
Define and describe the four respiratory processes-pulmonary ventilation, pulmonary gas exchange, gas transport, and tissue gas exchange.
A
- Pulmonary Ventilation: Breathing; the movement of air into and out of the lungs. 2. Pulmonary Gas Exchange (External Respiration): Diffusion of O2 from alveoli into pulmonary capillaries and CO2 from pulmonary capillaries into alveoli. 3. Gas Transport: Transport of O2 from lungs to tissues and CO2 from tissues to lungs via the blood. 4. Tissue Gas Exchange (Internal Respiration): Diffusion of O2 from systemic capillaries into tissue cells and CO2 from tissue cells into systemic capillaries.
8
Q
Term: Respiratory tract
A
Definition: The pathway air follows during breathing, divided into upper (nose to pharynx) and lower (larynx to alveoli) tracts.
9
Q
Term: Conducting zone
A
Definition: The parts of the respiratory tract that transport air but are not involved in gas exchange (nose to terminal bronchioles).
10
Q
Term: Respiratory zone
A
Definition: The parts of the respiratory tract where gas exchange occurs (respiratory bronchioles, alveolar ducts, alveoli).
11
Q
Term: Respiration
A
Definition: The overall process of gas exchange between the atmosphere, blood, and cells. Includes pulmonary ventilation, pulmonary gas exchange, gas transport, and tissue gas exchange.
12
Q
Key Concept: What is respiration? Which processes make up respiration?
A
Respiration is the exchange of gases (O2 and CO2) between the atmosphere, blood, and tissues. It comprises four processes: pulmonary ventilation (breathing), pulmonary gas exchange (external respiration), gas transport in the blood, and tissue gas exchange (internal respiration).
13
Q
Key Concept: What are the other functions of the respiratory system, and how do they help maintain homeostasis?
A
Besides gas exchange, it helps regulate blood pH (by controlling CO2 levels), produces sound (larynx), aids smell (nasal cavity), filters/warms/humidifies air, and assists in venous/lymph return (respiratory pump). pH regulation is crucial for enzyme function and overall homeostasis.
14
Q
Trace the pathway through which air passes during inspiration.
A
Nose/Mouth -> Nasal Cavity/Oral Cavity -> Pharynx (Nasopharynx, Oropharynx, Laryngopharynx) -> Larynx -> Trachea -> Primary Bronchi -> Secondary Bronchi -> Tertiary Bronchi -> Bronchioles -> Terminal Bronchioles -> Respiratory Bronchioles -> Alveolar Ducts -> Alveoli.
15
Q
Describe the gross anatomical features and function of each region of the respiratory tract, the pleural and thoracic cavities, and the pulmonary blood vessels and nerves.
A
Nose/Nasal Cavity: Warms, filters, humidifies air; smell. Pharynx: Passageway for air and food. Larynx: Voice box, prevents food entry into trachea. Trachea: Windpipe, conducts air to bronchi. Bronchial Tree: Branching tubes conducting air deep into lungs. Alveoli: Tiny sacs for gas exchange. Lungs: Paired organs containing alveoli. Pleural Cavities: Contain lungs, fluid reduces friction. Thoracic Cavity: Chest cavity housing lungs, heart. Pulmonary arteries/veins: Transport blood between heart and lungs for gas exchange. Nerves (phrenic, vagus): Control breathing muscles and airway diameter.
16
Q
Describe the histology of the different regions of the respiratory tract, the types of cells present in alveoli, and the structure of the respiratory membrane.
A
Nasal cavity to bronchi: Pseudostratified ciliated columnar epithelium (respiratory mucosa) with goblet cells. Bronchioles: Ciliated simple columnar to cuboidal epithelium. Alveoli: Primarily Type I alveolar cells (thin squamous, for gas exchange), Type II alveolar cells (cuboidal, secrete surfactant), and alveolar macrophages (immune cells). Respiratory Membrane: Extremely thin barrier for gas diffusion; consists of alveolar epithelium (Type I cells), fused basement membranes of alveolar and capillary cells, and capillary endothelium.
17
Q
Explain how the changes in epithelial and connective tissue in air passageways relate to their function.
A
From trachea to bronchioles: Epithelium thins (pseudostratified columnar -> simple cuboidal), cilia and goblet cells decrease (less mucus needed deeper), cartilage rings/plates disappear (replaced by smooth muscle for diameter control), elastic fibers increase (for recoil).
18
Q
Describe the structure of the lungs and pleural cavities.
A
Lungs: Spongy, cone-shaped organs in thoracic cavity. Right lung has 3 lobes, left has 2 (due to heart position). Apex is superior, base rests on diaphragm. Hilum is entry/exit point for bronchi, vessels, nerves. Pleural Cavities: Each lung enclosed by a double-layered pleural membrane (visceral pleura on lung surface, parietal pleura lining thoracic wall). Pleural fluid fills the space between layers, reducing friction and creating surface tension that helps keep lungs inflated.
19
Q
Term: Nasal cavity
A
Definition: The space within the nose, posterior to the nostrils, lined with mucous membrane; functions to warm, filter, and humidify air, and house olfactory receptors.
20
Q
Term: Paranasal sinuses
A
Definition: Air-filled spaces within certain skull bones (frontal, ethmoid, sphenoid, maxillary) that open into the nasal cavity; lighten the skull and resonate sound.
21
Q
Term: Respiratory mucosa
A
Definition: The mucous membrane lining most of the conducting zone (pseudostratified ciliated columnar epithelium with goblet cells); traps debris and moves it toward the pharynx.
22
Q
Term: Pharynx
A
Definition: The throat; a muscular tube connecting the nasal cavity and mouth superiorly to the larynx and esophagus inferiorly. Divided into nasopharynx, oropharynx, and laryngopharynx.
23
Q
Term: Larynx
A
Definition: The voice box; a cartilaginous structure connecting the pharynx to the trachea; contains vocal folds for sound production and the epiglottis to prevent food entry.
24
Q
Term: Epiglottis
A
Definition: A flap of elastic cartilage superior to the larynx; covers the laryngeal inlet during swallowing to prevent food/liquid entering the trachea.
25
Term: Vocal folds
Definition: True vocal cords; folds of mucous membrane in the larynx containing elastic ligaments that vibrate to produce sound as air passes over them.
26
Term: Trachea
Definition: The windpipe; a cartilaginous tube extending from the larynx to the primary bronchi; conducts air to the lungs.
27
Term: Bronchial tree
Definition: The branching system of air tubes within the lungs, starting from the primary bronchi and ending at the terminal bronchioles.
28
Term: Alveoli
Definition: Tiny, thin-walled air sacs clustered at the end of the respiratory bronchioles; the primary sites of gas exchange in the lungs.
29
Term: Respiratory membrane
Definition: The thin barrier (approx. 0.5 micrometer) across which gas exchange occurs between alveoli and pulmonary capillaries; composed of alveolar epithelium, capillary endothelium, and their fused basement membranes.
30
Term: Lung
Definition: One of the pair of organs of respiration occupying the pleural cavities, where gas exchange occurs between air and blood.
31
Term: Pleural cavity
Definition: The potential space between the visceral and parietal layers of the pleura surrounding each lung, containing lubricating pleural fluid.
32
Key Concept: Where are the paranasal sinuses located? What are their functions? Could they perform these functions if they were lined with stratified squamous epithelium instead of respiratory epithelium?
Located within frontal, sphenoid, ethmoid, and maxillary bones surrounding the nasal cavity. Functions: Lighten skull, resonate sound, produce mucus. Stratified squamous epithelium is protective but lacks cilia and goblet cells; it couldn't effectively trap/remove debris or produce mucus like respiratory epithelium, impairing sinus function.
33
Key Concept: What delineates the three different regions of the pharynx? How do they differ, structurally and functionally?
Nasopharynx: Posterior to nasal cavity, superior to soft palate; air passage only; lined with pseudostratified ciliated columnar epithelium. Oropharynx: Posterior to oral cavity, from soft palate to epiglottis; passageway for air and food; lined with stratified squamous epithelium. Laryngopharynx: Inferior to oropharynx, from epiglottis to esophagus; passageway for air and food; lined with stratified squamous epithelium.
34
Key Concept: How does the change in tension on the vocal cords and the size of the glottis affect the loudness and pitch of the sound produced?
Pitch: Determined by tension and length of vocal folds; tighter/shorter folds vibrate faster = higher pitch. Looser/longer folds = lower pitch. Loudness: Determined by the force of air passing over the vocal folds; more forceful airflow = louder sound.
35
Trace the pathway of air flow from the nares through the bronchial tree to the alveoli.
Nares -> Nasal Vestibule -> Nasal Cavity -> Nasopharynx -> Oropharynx -> Laryngopharynx -> Larynx -> Trachea -> Primary Bronchi -> Secondary Bronchi -> Tertiary Bronchi -> Bronchioles -> Terminal Bronchioles -> Respiratory Bronchioles -> Alveolar Ducts -> Alveolar Sacs -> Alveoli.
36
Key Concept: Which structures make up the respiratory membrane? Would the function of the membrane change if it were to become thicker? How?
Structures: Type I alveolar cell (squamous epithelium), fused basement membrane of alveolar cell and capillary endothelial cell, capillary endothelial cell. Function: Rapid gas diffusion. If thicker (e.g., due to fibrosis or edema), the diffusion distance increases, significantly slowing gas exchange, potentially leading to hypoxia.
37
Describe how pressure and volume are related, and explain how this relationship applies to pulmonary ventilation.
Boyle's Law states that at a constant temperature, the pressure of a gas is inversely proportional to its volume (Pressure increases as Volume decreases, and vice versa). In ventilation, contraction of inspiratory muscles increases thoracic/lung volume, which decreases intrapulmonary pressure below atmospheric, causing air inflow (inspiration). Relaxation decreases volume, increasing pressure above atmospheric, causing outflow (expiration).
38
Explain how the inspiratory muscles, accessory muscles of inspiration, and accessory muscles of expiration change the volume of the thoracic cavity.
Inspiratory Muscles (Quiet): Diaphragm contracts (flattens, moves inferiorly), External intercostals contract (lift rib cage up and out). Both increase thoracic volume. Accessory Inspiratory Muscles (Forced): Sternocleidomastoid, scalenes, pectoralis minor further elevate ribs, increasing volume more. Accessory Expiratory Muscles (Forced): Internal intercostals depress ribs, Abdominal muscles compress abdomen, pushing diaphragm up. Both decrease thoracic volume.
39
Explain how the values for atmospheric pressure, intrapulmonary pressure, and intrapleural pressure change with inspiration and expiration.
Atmospheric Pressure (Patm): Constant (approx. 760 mmHg at sea level). Intrapulmonary Pressure (Ppul): Pressure inside alveoli. Equal to Patm between breaths. Drops below Patm (e.g., by 1 mmHg) during inspiration. Rises above Patm (e.g., by 1 mmHg) during expiration. Intrapleural Pressure (Pip): Pressure in pleural cavity. Always negative relative to Ppul (about -4 mmHg difference). Becomes slightly more negative (e.g., -6 to -8 mmHg difference from Patm) during inspiration as chest wall expands; returns to -4 mmHg difference during expiration.
40
Explain how each of the following factors affects pulmonary ventilation: airway resistance, pulmonary compliance, and alveolar surface tension.
Airway Resistance: Friction/drag in airways. Increased resistance (e.g., bronchoconstriction in asthma) decreases airflow, hindering ventilation. Pulmonary Compliance: Ease with which lungs/chest wall expand (stretchiness). Decreased compliance (e.g., fibrosis, low surfactant) makes inspiration harder, reducing ventilation efficiency. Increased compliance (e.g., emphysema) makes expiration harder. Alveolar Surface Tension: Force exerted by fluid lining alveoli, tending to collapse them. Surfactant reduces this tension, preventing collapse and making inflation easier. Insufficient surfactant increases work of breathing, reducing ventilation.
41
Describe and identify the values for the respiratory volumes and the respiratory capacities.
Volumes: Tidal Volume (TV) approx 500mL (air/normal breath); Inspiratory Reserve Volume (IRV) approx 3100mL male/1900mL female (max air inhaled beyond TV); Expiratory Reserve Volume (ERV) approx 1200mL m/700mL f (max air exhaled beyond TV); Residual Volume (RV) approx 1200mL m/1100mL f (air left after max exhale). Capacities (sums of volumes): Inspiratory Capacity (IC = TV + IRV) approx 3600mL m/2400mL f; Functional Residual Capacity (FRC = ERV + RV) approx 2400mL m/1800mL f; Vital Capacity (VC = TV + IRV + ERV) approx 4800mL m/3100mL f; Total Lung Capacity (TLC = TV + IRV + ERV + RV) approx 6000mL m/4200mL f.
42
Term: Pulmonary ventilation
Definition: The mechanical process of breathing; moving air into and out of the lungs.
43
Term: Inspiration
Definition: Inhalation; the process of drawing air into the lungs.
44
Term: Expiration
Definition: Exhalation; the process of expelling air from the lungs.
45
Term: Pressure gradient
Definition: A difference in pressure between two areas that drives the movement of fluids or gases from the high-pressure area to the low-pressure area.
46
Term: Boyle's law
Definition: Gas law stating that the pressure and volume of a gas have an inverse relationship when temperature is held constant (e.g., P1 * V1 = P2 * V2).
47
Term: Inspiratory muscles
Definition: Muscles that contract to increase thoracic volume during inspiration; primarily the diaphragm and external intercostal muscles.
48
Term: Atmospheric pressure
Definition: The pressure exerted by the weight of the air in the atmosphere surrounding the body (approx. 760 mmHg at sea level).
49
Term: Intrapulmonary pressure
Definition: The pressure within the alveoli of the lungs; fluctuates above and below atmospheric pressure during breathing.
50
Term: Intrapleural pressure
Definition: The pressure within the pleural cavity (between visceral and parietal pleura); normally slightly subatmospheric (negative relative to atmospheric and intrapulmonary pressure).
51
Term: Airway resistance
Definition: The opposition to airflow in the respiratory passageways, primarily determined by the diameter of the airways.
52
Term: Alveolar surface tension
Definition: The force exerted by the thin layer of fluid lining the alveoli due to the attraction between water molecules, which tends to collapse the alveoli.
53
Term: Pulmonary compliance
Definition: The measure of the lung's ability to stretch and expand (distensibility); the change in lung volume for a given change in transpulmonary pressure.
54
Term: Spirometer
Definition: An instrument used to measure respiratory volumes and capacities; assesses pulmonary function.
55
Term: Pulmonary capacities
Definition: The sum of two or more pulmonary volumes (e.g., Vital Capacity, Total Lung Capacity).
56
Key Concept: What is a pressure gradient? How do pressure gradients drive the movement of gases into and out of the lungs?
A pressure gradient is a difference in pressure between two points. Gases (like air) flow from an area of higher pressure to an area of lower pressure. During inspiration, intrapulmonary pressure becomes lower than atmospheric pressure, creating a gradient that drives air into the lungs. During expiration, intrapulmonary pressure becomes higher than atmospheric, driving air out.
57
Complete It: The main inspiratory muscle is the ___. It creates a pressure gradient when it contracts by ___ the volume of the lungs, which ___ the pressure in the lungs.
diaphragm; increasing; decreases
58
Complete It: When the pressure in the lungs, or the ___, falls below ___, air enters the lungs via ___. During forced inspiration, other muscles called ___ assist in the process.
intrapulmonary pressure; atmospheric pressure; inspiration; accessory muscles (e.g., scalenes, sternocleidomastoid)
59
Complete It: The process of expiration is largely ___ due to the ___. This causes the volume of the lungs to ___, which ___ intrapulmonary pressure. When intrapulmonary pressure is ___ atmospheric pressure, ___ occurs.
passive; elastic recoil of the lungs and chest wall; decrease; increases; above; expiration
60
Key Concept: Why is intrapleural pressure slightly lower than intrapulmonary pressure? What happens if it rises above intrapulmonary pressure?
It's lower due to opposing forces: the lungs' tendency to recoil inward and the chest wall's tendency to spring outward, creating a slight vacuum in the pleural space. This negative pressure keeps the lungs 'stuck' to the chest wall. If intrapleural pressure equals or exceeds intrapulmonary pressure (e.g., pneumothorax), the lung collapses as the surface tension is broken.
61
Predict It: Effect on pulmonary ventilation efficiency if a person inhales methacholine (causes bronchoconstriction)?
Decrease efficiency. Bronchoconstriction increases airway resistance, making airflow harder, especially during expiration.
62
Predict It: Effect on pulmonary ventilation efficiency if an infant is born premature and does not produce surfactant?
Decrease efficiency significantly. Lack of surfactant increases alveolar surface tension, causing alveolar collapse (atelectasis) and greatly reduced lung compliance, making inspiration very difficult (Respiratory Distress Syndrome).
63
Predict It: Effect on pulmonary ventilation efficiency if the premature infant is given inhalable surfactant?
Increase efficiency. Surfactant reduces surface tension, preventing alveolar collapse, increasing compliance, and reducing the work of breathing.
64
Predict It: Effect on pulmonary ventilation efficiency if a person develops emphysema (destruction of alveolar walls)?
Decreases efficiency, primarily by impairing expiration. Destruction of alveolar walls reduces elastic recoil and enlarges airspaces, increasing compliance but trapping air and making exhalation difficult (obstructive pattern).
65
Predict It: Effect on pulmonary ventilation efficiency if a person is administered epinephrine (causes bronchodilation)?
Increase efficiency. Bronchodilation decreases airway resistance, making airflow easier.
66
Predict It: Effect on pulmonary ventilation efficiency if a chest wall deformity prevents normal expansion of the lungs?
Decrease efficiency. Limits the ability to increase thoracic volume, reducing lung expansion and compliance (restrictive pattern).
67
Key Concept: What are the three physical factors that influence ventilation? How does each influence the efficiency of ventilation?
1. Airway Resistance: Higher resistance impedes airflow, reducing efficiency. 2. Alveolar Surface Tension: High tension collapses alveoli and reduces compliance, reducing efficiency (counteracted by surfactant). 3. Lung Compliance: Lower compliance makes inflation harder, reducing efficiency. Very high compliance (emphysema) hinders expiration.
68
Pulmonary Volume: Tidal volume - Definition?
Volume of air inhaled or exhaled during a normal, quiet breath (approx 500 mL).
69
Pulmonary Volume: Inspiratory reserve volume - Definition?
Maximum volume of air that can be forcefully inhaled after a normal tidal volume inhalation.
70
Pulmonary Volume: Expiratory reserve volume - Definition?
Maximum volume of air that can be forcefully exhaled after a normal tidal volume exhalation.
71
Pulmonary Volume: Residual volume - Definition?
Volume of air remaining in the lungs after a maximum forceful exhalation; cannot be voluntarily expelled.
72
Pulmonary Capacity: Inspiratory capacity - Definition?
Maximum volume of air that can be inhaled starting from the normal expiratory level (IC = TV + IRV).
73
Pulmonary Capacity: Functional residual capacity - Definition?
Volume of air remaining in the lungs after a normal tidal volume exhalation (FRC = ERV + RV).
74
Pulmonary Capacity: Vital capacity - Definition?
Maximum volume of air that can be exhaled after a maximum inhalation (VC = TV + IRV + ERV).
75
Pulmonary Capacity: Total lung capacity - Definition?
Total volume of air the lungs can hold after a maximum inhalation (TLC = TV + IRV + ERV + RV).
76
Describe the relationship of Dalton's law and Henry's law to pulmonary and tissue gas exchange and to the amounts of oxygen and carbon dioxide dissolved in plasma.
Dalton's Law: Total pressure of a gas mixture equals the sum of the partial pressures of individual gases. Gas exchange depends on partial pressure gradients (P O2, P CO2) between alveoli/blood and blood/tissues. Henry's Law: Amount of gas dissolving in a liquid is proportional to its partial pressure and solubility. Explains how O2 and CO2 dissolve in plasma based on their partial pressures and solubilities (CO2 is much more soluble than O2).
77
Describe oxygen and carbon dioxide pressure gradients and net gas movements in pulmonary and tissue gas exchange.
Pulmonary: Alveolar P O2 (approx 100 mmHg) > Capillary P O2 (approx 40 mmHg) -> O2 moves into blood. Capillary P CO2 (approx 45 mmHg) > Alveolar P CO2 (approx 40 mmHg) -> CO2 moves into alveoli. Tissue: Capillary P O2 (approx 100 mmHg) > Tissue P O2 (approx 40 mmHg) -> O2 moves into tissues. Tissue P CO2 (>45 mmHg) > Capillary P CO2 (approx 40 mmHg) -> CO2 moves into blood.
78
Explain how oxygen and carbon dioxide movements are affected by changes in partial pressure gradients.
Gas movement (diffusion) is directly proportional to the partial pressure gradient. A larger gradient (steeper difference) leads to faster diffusion. Factors like high altitude (lower atmospheric P O2) or impaired ventilation/perfusion reduce gradients and slow gas exchange.
79
Describe the mechanisms of ventilation-perfusion matching.
Efficient gas exchange requires matching alveolar ventilation (airflow, V) to pulmonary capillary perfusion (blood flow, Q). If ventilation is poor, pulmonary arterioles constrict to redirect blood to better-ventilated alveoli. If perfusion is poor, bronchioles constrict to redirect air to better-perfused alveoli. This optimizes the V/Q ratio across the lungs.
80
Explain the factors that maintain oxygen and carbon dioxide gradients between blood and tissue cells.
Continuous cellular respiration in tissues consumes O2 (keeping tissue P O2 low) and produces CO2 (keeping tissue P CO2 high). Continuous breathing replenishes O2 in alveoli (keeping alveolar P O2 high) and removes CO2 (keeping alveolar P CO2 low). Continuous blood flow transports gases between lungs and tissues.
81
Term: Pulmonary gas exchange
Definition: Exchange of oxygen and carbon dioxide across the respiratory membrane between the alveoli and the pulmonary capillaries (External Respiration).
82
Term: Tissue gas exchange
Definition: Exchange of oxygen and carbon dioxide between the systemic capillaries and the body's tissue cells (Internal Respiration).
83
Term: Dalton's law of partial pressures
Definition: Law stating that the total pressure exerted by a mixture of gases is the sum of the partial pressures exerted independently by each gas in the mixture.
84
Term: Henry's law
Definition: Law stating that the quantity of a gas that dissolves in a liquid is proportional to the partial pressure of the gas and its solubility in the liquid, at a constant temperature.
85
Term: Ventilation-perfusion matching
Definition: The coupling of alveolar ventilation (airflow) and pulmonary perfusion (blood flow) to optimize gas exchange efficiency in the lungs.
86
Complete It: Each gas in a mixture exerts its own pressure, known as ___. The partial pressures determine if gases move by ___ - from ___ pressure to ___ pressure.
partial pressure; diffusion; higher partial; lower partial
87
Complete It: Henry's law states a gas's ability to dissolve in liquid is proportional to its ___ and its ___ in the liquid.
partial pressure; solubility
88
Complete It: Pulmonary gas exchange: O2 moves from ___ partial pressure (alveoli) to ___ partial pressure (blood). CO2 moves from ___ partial pressure (blood) to ___ partial pressure (alveoli).
high; low; high; low
89
Complete It: Tissue gas exchange: O2 moves from ___ partial pressure (blood) to ___ partial pressure (tissues). CO2 moves from ___ partial pressure (tissues) to ___ partial pressure (blood).
high; low; high; low
90
Key Concept: In which direction would oxygen diffuse if its partial pressure in the blood were 40 mm Hg and its partial pressure in the alveoli were 35 mm Hg? How would this affect homeostasis overall?
Oxygen would diffuse from the blood *into* the alveoli (down its partial pressure gradient: 40 -> 35 mmHg). This is the reverse of normal pulmonary gas exchange and would prevent oxygen loading into the blood, leading to severe hypoxemia and disruption of homeostasis.
91
Practice It: Effect on gas exchange if emphysema causes destruction of alveolar walls?
Decreased gas exchange. Reduces the surface area available for diffusion.
92
Practice It: Effect on gas exchange if long-standing pulmonary hypertension thickens pulmonary capillary walls?
Decreased gas exchange. Increases the diffusion distance across the respiratory membrane.
93
Practice It: Effect on gas exchange if vasodilators increase perfusion to a systemic capillary bed?
Increased tissue gas exchange (temporarily). Delivers more blood flow, potentially increasing the O2 delivery and CO2 removal rate if tissue demand is high.
94
Practice It: Effect on gas exchange if a pulmonary embolus blocks blood flow to part of the lung?
Decreased pulmonary gas exchange in the affected area. Creates alveolar dead space (ventilation without perfusion), leading to V/Q mismatch.
95
Practice It: Effect on gas exchange if a person inhales 100% oxygen?
Increased pulmonary gas exchange (O2 loading). Significantly increases the alveolar P O2 and the partial pressure gradient driving oxygen into the blood.
96
Practice It: Effect on gas exchange if systemic capillary beds are damaged by hyperglycemia?
Decreased tissue gas exchange. Capillary damage can impair blood flow and diffusion at the tissue level.
97
Describe the ways oxygen is transported in blood, including the reversible reaction for oxygen binding to hemoglobin.
1. Dissolved in plasma (approx 1.5%). 2. Bound to hemoglobin (Hb) within red blood cells (approx 98.5%). Reversible reaction: Hb + O2 <--> HbO2 (Deoxyhemoglobin + Oxygen <--> Oxyhemoglobin)
98
Interpret the oxygen-hemoglobin dissociation curve, and describe the factors that affect the curve.
Sigmoid (S-shaped) curve showing relationship between P O2 and percent Hb saturation. Steep part: small P O2 drop causes large O2 release (tissue level). Plateau part: Hb remains highly saturated even with moderate P O2 drop (lung level). Factors shifting curve right (decreased affinity, enhanced O2 unloading): Increased temperature, increased P CO2, increased H+ concentration (decreased pH - Bohr effect), increased 2,3-BPG. Left shift (increased affinity): Opposite factors.
99
Describe the ways carbon dioxide is transported in blood, including the reversible reaction that converts carbon dioxide and water to carbonic acid.
1. Dissolved in plasma (approx 7-10%). 2. Bound to hemoglobin (Carbaminohemoglobin, HbCO2) (approx 20-30%). 3. As bicarbonate ions (HCO3-) in plasma (approx 60-70%). Reversible reaction (in RBCs, catalyzed by carbonic anhydrase): CO2 + H2O <--> H2CO3 <--> H+ + HCO3- (Carbon dioxide + Water <--> Carbonic Acid <--> Hydrogen ion + Bicarbonate ion)
100
Predict how changing the partial pressure of carbon dioxide will affect the pH of plasma.
Increased P CO2 leads to more carbonic acid formation (H2CO3), which dissociates into H+ and HCO3-. The increased H+ concentration lowers plasma pH (makes it more acidic). Decreased P CO2 shifts the reaction left, consuming H+ and raising plasma pH (makes it more alkaline).
101
Describe the conditions hyperventilation and hypoventilation.
Hyperventilation: Breathing rate/depth is excessive for metabolic needs. Leads to blowing off too much CO2, decreasing blood P CO2 (hypocapnia) and increasing blood pH (respiratory alkalosis). Hypoventilation: Breathing rate/depth is insufficient for metabolic needs. Leads to CO2 retention, increasing blood P CO2 (hypercapnia) and decreasing blood pH (respiratory acidosis).
102
Term: Gas transport
Definition: The process by which oxygen is carried from the lungs to the tissues and carbon dioxide is carried from the tissues to the lungs, primarily via the bloodstream.
103
Term: Deoxyhemoglobin
Definition: Hemoglobin that is not bound to oxygen (HHb).
104
Term: Oxyhemoglobin
Definition: Hemoglobin that is bound to oxygen (HbO2).
105
Term: Percent saturation of hemoglobin
Definition: The percentage of hemoglobin's oxygen-binding sites that are occupied by oxygen.
106
Term: Oxygen-hemoglobin dissociation curve
Definition: A graph plotting the percent saturation of hemoglobin against the partial pressure of oxygen (P O2), illustrating hemoglobin's affinity for oxygen under different conditions.
107
Term: Bohr effect
Definition: The effect whereby changes in P CO2 and/or pH alter hemoglobin's affinity for oxygen. Increased CO2 or decreased pH (increased H+ concentration) decreases affinity, shifting the curve right and promoting O2 release.
108
Term: Bicarbonate ion
Definition: HCO3-; the main form in which carbon dioxide is transported in the blood. Also a key component of the blood buffer system.
109
Term: Carbonic anhydrase
Definition: An enzyme found primarily in red blood cells that catalyzes the rapid interconversion of carbon dioxide and water to carbonic acid (and vice versa).
110
Term: Carbonic acid-bicarbonate buffer system
Definition: A major chemical buffer system in the blood that resists changes in pH by converting strong acids/bases into weak acids/bases (using H2CO3 and HCO3-).
111
Term: Hyperventilation
Definition: Increased rate and depth of breathing that exceeds the body's metabolic need to remove CO2, leading to hypocapnia and respiratory alkalosis.
112
Term: Hypoventilation
Definition: Decreased rate and depth of breathing that is inadequate to meet the body's metabolic need to remove CO2, leading to hypercapnia and respiratory acidosis.
113
Key Concept: Why is most oxygen transported on hemoglobin?
Oxygen has very low solubility in plasma. Hemoglobin dramatically increases the oxygen-carrying capacity of blood, allowing sufficient O2 transport to meet tissue demands.
114
Key Concept: How does the percent saturation of hemoglobin affect hemoglobin's ability to unload oxygen? Why is this important to maintaining homeostasis?
The S-shape of the dissociation curve means that in the high P O2 environment of the lungs, Hb becomes nearly fully saturated (picks up max O2). In the lower P O2 environment of tissues, the saturation drops significantly (steep part of curve), facilitating O2 unloading where it's needed. This ensures adequate O2 delivery to metabolically active tissues for homeostasis.
115
Practice It: Effect on O2 unloading from Hb if pH increases?
Less unloading (curve shifts left, affinity increases).
116
Practice It: Effect on O2 unloading from Hb if temperature decreases?
Less unloading (curve shifts left, affinity increases).
117
Practice It: Effect on O2 unloading from Hb if P O2 increases?
Less unloading (higher saturation at any given point, but primary effect is increased loading in lungs).
118
Practice It: Effect on O2 unloading from Hb if P CO2 decreases?
Less unloading (curve shifts left, affinity increases).
119
Practice It: Effect on O2 unloading from Hb if acidity increases?
More unloading (acidity = lower pH; curve shifts right, affinity decreases).
120
Practice It: Effect on O2 unloading from Hb if BPG concentration increases?
More unloading (curve shifts right, affinity decreases).
121
Practice It: Effect on O2 unloading from Hb if P CO2 increases?
More unloading (Bohr effect; curve shifts right, affinity decreases).
122
Practice It: Effect on O2 unloading from Hb if P O2 decreases?
More unloading (moving down the steep part of the dissociation curve).
123
Practice It: Effect on O2 unloading from Hb if temperature increases?
More unloading (curve shifts right, affinity decreases).
124
Practice It: Effect on O2 unloading from Hb during vigorous exercise?
More unloading. Exercise increases temperature, P CO2, acidity (lactic acid), and BPG, all shifting the curve right.
125
Trace It: Effect of Hypoventilation on Rate/depth of breathing -> P CO2 in blood -> Carbonic acid concentration -> Body fluid pH?
Rate/depth decreases -> P CO2 increases -> Carbonic acid increases -> pH decreases (acidosis).
126
Trace It: Effect of Hyperventilation on Rate/depth of breathing -> P CO2 in blood -> Carbonic acid concentration -> Body fluid pH?
Rate/depth increases -> P CO2 decreases -> Carbonic acid decreases -> pH increases (alkalosis).
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Key Concept: Why does the carbon dioxide level of the blood influence the pH of the blood and body fluids?
CO2 reacts with water to form carbonic acid (H2CO3), which dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3-). Therefore, higher CO2 levels lead to higher H+ concentrations, lowering pH (more acidic), and lower CO2 levels lead to lower H+ concentrations, raising pH (more alkaline).
128
Describe the overall big picture of the processes involved in respiration.
Air containing O2 is moved into the lungs (pulmonary ventilation). O2 diffuses from alveoli into pulmonary blood, and CO2 diffuses from blood into alveoli (pulmonary gas exchange). Blood transports O2 to tissues and CO2 from tissues (gas transport). O2 diffuses from systemic blood into tissue cells, and CO2 diffuses from cells into blood (tissue gas exchange). Cells use O2 and produce CO2 during metabolism.
129
Describe the locations and functions of the brainstem respiratory centers.
Located in medulla oblongata and pons. Medulla: Ventral Respiratory Group (VRG) - primary rhythm generator, controls inspiratory/expiratory neurons. Dorsal Respiratory Group (DRG) - integrates input from chemoreceptors/mechanoreceptors, modifies VRG output. Pons: Pontine Respiratory Group (includes apneustic and pneumotaxic centers) - modifies/smooths rhythm set by medulla, adapts breathing to activities like speech, sleep, exercise.
130
List and describe the major chemical and neural stimuli to the respiratory centers.
Chemical: Primarily blood P CO2 (most potent), also P O2 and H+ concentration (pH). Detected by central chemoreceptors (in medulla, sensitive to H+ in CSF derived from blood CO2) and peripheral chemoreceptors (in aortic/carotid bodies, sensitive to P CO2, pH, and large drops in P O2). Neural: Input from higher brain centers (voluntary control, emotions via hypothalamus/limbic system), stretch receptors in lungs (Hering-Breuer reflex), irritant receptors, proprioceptors in muscles/joints.
131
Compare and contrast the central and peripheral chemoreceptors.
Central Chemoreceptors: Located in medulla oblongata. Respond to changes in H+ concentration in cerebrospinal fluid (CSF), which reflects blood P CO2 changes (CO2 readily crosses blood-brain barrier). Primarily responsible for minute-to-minute control based on CO2. Peripheral Chemoreceptors: Located in aortic arch and carotid arteries (aortic/carotid bodies). Respond directly to changes in blood P CO2, pH (H+ concentration), and significantly low P O2 (below approx 60 mmHg). Provide faster response than central receptors.
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Term: Dyspnea
Definition: Difficult or labored breathing; shortness of breath.
133
Term: Eupnea
Definition: Normal, quiet breathing pattern.
134
Term: Respiratory rhythm generator
Definition: Neural circuits, primarily within the Ventral Respiratory Group (VRG) of the medulla, that establish the basic, automatic rhythm of breathing.
135
Term: Ventral respiratory group
Definition: A network of neurons in the medulla oblongata that contains rhythm generators and neurons controlling inspiratory and expiratory muscles (especially forced expiration).
136
Term: Dorsal respiratory group
Definition: A network of neurons in the medulla oblongata that receives sensory input (chemo-/mechanoreceptors) and modifies the rhythm generated by the VRG.
137
Term: Central chemoreceptors
Definition: Receptors located in the medulla oblongata that monitor the pH (reflecting CO2 levels) of the cerebrospinal fluid.
138
Term: Peripheral chemoreceptors
Definition: Receptors located in the carotid bodies and aortic bodies that monitor blood levels of O2, CO2, and pH.
139
Key Concept: What is the respiratory rhythm generator? Which nuclei work with the RRG to maintain eupnea?
The RRG is the neural network (primarily in the VRG of the medulla) that sets the basic pace of breathing. The VRG and DRG in the medulla, along with the pontine respiratory centers (pneumotaxic/apneustic), coordinate to produce smooth, rhythmic breathing (eupnea).
140
Practice It: Chemoreceptor(s) detecting decreased P O2 and resulting change in ventilation?
Peripheral chemoreceptors (significant decrease needed, <60 mmHg). Result: Increased ventilation.
141
Practice It: Chemoreceptor(s) detecting increased P CO2 and resulting change in ventilation?
Central chemoreceptors (primary stimulus) and Peripheral chemoreceptors. Result: Increased ventilation.
142
Practice It: Chemoreceptor(s) detecting decreased pH and resulting change in ventilation?
Peripheral chemoreceptors (directly sense blood H+) and Central chemoreceptors (indirectly via related CO2 changes). Result: Increased ventilation.
143
Practice It: Chemoreceptor(s) detecting increased P O2 and resulting change in ventilation?
Normally little effect unless very high (oxygen toxicity); primarily detected by peripheral chemoreceptors but usually doesn't significantly decrease ventilation unless hypoxia drive is dominant (e.g., some COPD patients).
144
Practice It: Chemoreceptor(s) detecting increased pH and resulting change in ventilation?
Peripheral chemoreceptors (sense decreased H+) and Central chemoreceptors (indirectly via related CO2 changes). Result: Decreased ventilation.
145
Practice It: Chemoreceptor(s) detecting decreased P CO2 and resulting change in ventilation?
Central chemoreceptors (primary) and Peripheral chemoreceptors. Result: Decreased ventilation.
146
Key Concept: Why is carbon dioxide such an important stimulus for the central chemoreceptors?
CO2 readily diffuses across the blood-brain barrier into the CSF. In the CSF, it converts to carbonic acid and then H+ ions. The central chemoreceptors are highly sensitive to this change in CSF H+ concentration, making CO2 the most powerful regulator of respiration under normal conditions.
147
Explain the difference between restrictive and obstructive disease patterns.
Obstructive: Characterized by increased airway resistance, making it hard to exhale air completely/quickly (e.g., asthma, COPD, chronic bronchitis, emphysema). Lung volumes like TLC and RV may be increased due to air trapping. FEV1/FVC ratio is decreased. Restrictive: Characterized by reduced lung compliance (stretchiness) or restricted chest wall expansion, making it hard to inhale fully (e.g., pulmonary fibrosis, scoliosis, neuromuscular diseases). Lung volumes (TLC, VC, FRC) are decreased. FEV1/FVC ratio is often normal or increased.
148
Describe the basic pathophysiology for certain pulmonary diseases.
COPD (Chronic Bronchitis/Emphysema): Chronic inflammation, mucus hypersecretion, airway narrowing (bronchitis); destruction of alveolar walls, loss of elastic recoil, air trapping (emphysema). Asthma: Chronic inflammatory disorder causing airway hyperresponsiveness, leading to reversible bronchoconstriction, mucus production, and edema.
149
Term: Restrictive lung disease
Definition: A category of lung diseases characterized by decreased lung volumes (reduced TLC) due to difficulty expanding the lungs (decreased compliance) or chest wall restriction.
150
Term: Obstructive lung disease
Definition: A category of lung diseases characterized by airway obstruction that limits airflow, especially during exhalation (decreased FEV1/FVC ratio).
151
Term: Chronic obstructive pulmonary disease
Definition: (COPD) A progressive lung disease characterized by persistent airflow limitation, typically involving chronic bronchitis and/or emphysema; often caused by smoking.
152
Term: Asthma
Definition: A chronic inflammatory disease of the airways characterized by reversible bronchospasm, airway edema, and mucus production, leading to wheezing, coughing, and shortness of breath.
153
Practice It: Is Vital capacity abnormal in obstructive, restrictive, or both lung diseases?
Both (Decreased in restrictive; may be normal or decreased in obstructive).
154
Practice It: Is Functional residual capacity abnormal in obstructive, restrictive, or both lung diseases?
Both (Decreased in restrictive; Increased in obstructive due to air trapping).
155
Practice It: Is Residual volume abnormal in obstructive, restrictive, or both lung diseases?
Both (Decreased in restrictive; Increased in obstructive due to air trapping).
156
Practice It: Is Inspiratory capacity abnormal in obstructive, restrictive, or both lung diseases?
Both (Decreased in restrictive; may be decreased in obstructive due to hyperinflation).
157
Practice It: Is Total lung capacity abnormal in obstructive, restrictive, or both lung diseases?
Both (Decreased in restrictive; often normal or increased in obstructive).
158
Key Concept: What is the key difference between a restrictive and an obstructive respiratory disease?
Obstructive disease involves difficulty *exhaling* due to airway narrowing/blockage (problem with airflow). Restrictive disease involves difficulty *inhaling* fully due to reduced lung/chest wall expandability (problem with volume).
