Week 8 Flashcards
(147 cards)
1
Q
What are the four processes of respiration?
A
Pulmonary ventilation (breathing)
External respiration
Transport of respiratory gases
Internal respiration
2
Q
What happens during pulmonary ventilation?
A
Air moves in (inspiration) and out (expiration) of the lungs.
3
Q
What is external respiration?
A
O₂ diffuses from the lungs to the blood, and CO₂ diffuses from the blood to the lungs.
4
Q
What is internal respiration?
A
O₂ diffuses from the blood into tissue cells, and CO₂ moves from tissue cells into the blood.
5
Q
What role does the cardiovascular system play in respiration?
A
It transports O₂ and CO₂ via the blood between lungs and body tissues.
6
Q
What structures are included in the respiratory system?
A
Nose
Nasal cavity
Oral cavity
Pharynx
Larynx
Trachea
Bronchi
Bronchioles
Alveoli
Lungs
Diaphragm
Intercostal muscles
7
Q
What is the function of the nasal cavity?
A
Filters, warms, and humidifies incoming air; lined with cilia and mucous membranes.
8
Q
What role does the oral cavity play in breathing?
A
Acts as a secondary passageway for air during breathing.
9
Q
What is the function of the pharynx?
A
A muscular tube that transports air from the nasal/oral cavity to the larynx and trachea; part of both respiratory and digestive systems.
10
Q
What is the epiglottis and its function?
A
A flap of cartilage that prevents food and liquid from entering the trachea during swallowing.
11
Q
What is the larynx and its role?
A
Also called the voice box; produces sound and prevents food from entering the trachea.
12
Q
What is the function of the trachea?
A
The main airway that connects the larynx to the bronchi; supported by cartilage rings.
13
Q
What are the bronchi?
A
Two main airways branching from the trachea into the lungs; lined with cilia and goblet cells.
14
Q
What are bronchioles?
A
Smaller airways branching from bronchi that conduct air to alveoli.
15
Q
What are alveoli and their function?
A
Tiny air sacs at the ends of bronchioles where gas exchange occurs with the bloodstream.
16
Q
Describe gas exchange in alveoli.
A
O₂ diffuses from alveoli into capillaries; CO₂ diffuses from capillaries into alveoli to be exhaled.
17
Q
How are the lungs structured?
A
Right lung has 3 lobes; left lung has 2 lobes. Each is housed in a pleural cavity and contains bronchi, bronchioles, and alveoli.
18
Q
What is the function of the diaphragm?
A
A dome-shaped muscle that contracts to pull air in and relaxes to push air out of the lungs.
19
Q
What do intercostal muscles do during breathing?
A
They contract and relax to expand and contract the rib cage during inhalation and exhalation.
20
Q
What is the oesophagus and its role?
A
A muscular tube part of the digestive system; moves food from the mouth to the stomach (not part of respiratory system).
21
Q
What are the two functional zones of the respiratory system?
A
Conducting zone
Respiratory zone
22
Q
What is the main role of the conducting zone?
A
To act as a passageway for air to reach the respiratory zone and to filter, warm, and humidify the air.
23
Q
Which structures are part of the conducting zone?
A
Nasal cavity
Pharynx
Larynx
Trachea
Bronchi
Bronchioles
Terminal bronchioles
24
Q
What is the main role of the respiratory zone?
A
To facilitate gas exchange: oxygen enters the blood, and carbon dioxide is removed.
25
Which structures are part of the respiratory zone?
Respiratory bronchioles
Alveolar ducts
Alveoli
26
How do the conducting and respiratory zones work together?
The conducting zone prepares and transports air to the respiratory zone, where gas exchange occurs.
27
What is the respiratory membrane and what is it made of?
It’s the surface where gas exchange occurs, made up of alveolar epithelial cells and pulmonary capillary endothelial cells.
28
Why is the respiratory membrane suited for gas exchange?
It is thin, smooth, and highly permeable, allowing gases to travel short distances quickly and efficiently.
29
What is the main function of the respiratory membrane?
To allow for the exchange of oxygen and carbon dioxide between the alveolar air and the bloodstream.
30
How does gas exchange support the body?
Oxygen is used by cells to make energy; carbon dioxide is a waste product that must be expelled to prevent toxic buildup.
31
What structures increase the surface area for gas exchange in the lungs?
Alveoli – there are around 480 million in an adult lung, covering about 75 m² of surface area.
32
What surrounds each alveolus to support gas exchange?
A network of blood capillaries supplied by small branches of the pulmonary artery.
33
What is the thickness of the respiratory membrane?
Around 0.5 micrometres thick (compared to a 7.5 μm red blood cell).
34
What are type I alveolar cells and their function?
Thin, squamous cells covering 95% of alveolar surface; they allow for rapid gas diffusion.
35
What are type II alveolar cells and what do they do?
Cuboidal cells that:
Repair alveolar epithelium when damaged
Secrete pulmonary surfactant
36
What is pulmonary surfactant and why is it important?
A mix of phospholipids and proteins that prevents alveoli from collapsing by reducing surface tension during exhalation.
37
What happens to alveoli without surfactant?
The walls would stick together like wet paper and be difficult to reinflate.
38
What are alveolar macrophages and their role?
The most numerous cells in the lungs; they phagocytose debris in the alveolar lumen and connective tissue.
39
What does Boyle’s Law state?
Pressure and volume are inversely proportional in a closed container:
P1V1 = P2V2
40
What happens to gas pressure when lung volume increases?
Pressure decreases – molecules have more space and collide less often.
41
What happens to gas pressure when lung volume decreases?
Pressure increases – molecules have less space and collide more often.
42
Why is Boyle’s Law important in breathing?
Breathing depends on changing lung volume to create pressure gradients that move air in and out of the lungs.
43
What are the two phases of breathing?
Inspiration (inhalation)
Expiration (exhalation)
44
What happens to the diaphragm during inspiration?
It contracts and moves downward.
45
What do the intercostal muscles do during inspiration?
They contract, pulling the ribs up and outward.
46
What effect does inspiration have on thoracic volume?
It increases thoracic cavity and lung volume.
47
How does inspiration affect lung pressure?
Lung pressure decreases, becoming lower than atmospheric pressure.
48
Why does air enter the lungs during inspiration?
Air flows from high (outside) to low (lungs) pressure due to the gradient.
49
What happens to the diaphragm during expiration?
It relaxes and moves upward into the chest cavity.
50
What do the intercostal muscles do during expiration?
They relax, allowing the ribs to move down and in.
51
What effect does expiration have on thoracic volume?
It decreases thoracic cavity and lung volume.
52
How does expiration affect lung pressure?
Lung pressure increases, becoming higher than atmospheric pressure.
53
Why does air leave the lungs during expiration?
Air flows from high (lungs) to low (outside) pressure due to the gradient.
54
Why do we measure lung volumes and capacities?
To assess the efficacy and function of the respiratory system in clinical practice.
55
What is the most common test to assess lung function?
Spirometry – it measures airflow in and out of the lungs over time.
56
What is tidal volume (TV)?
The amount of air exchanged during normal breathing – about 500 mL.
57
What is inspiratory reserve volume (IRV)?
The additional air inhaled above tidal volume during a deep breath in.
58
What is expiratory reserve volume (ERV)?
The additional air exhaled beyond tidal volume during a forced breath out.
59
What is residual volume (RV)?
The air remaining in the lungs after a full forced exhalation.
60
What makes up the total lung volume?
TV + IRV + ERV + RV = Total lung capacity (TLC)
61
What is vital capacity (VC)?
TV + IRV + ERV — the maximum air exhaled after full inhalation.
62
What is inspiratory capacity (IC)?
TV + IRV — the maximum air inhaled after a normal exhalation.
63
What is functional residual capacity (FRC)?
ERV + RV — the air remaining in lungs after normal exhalation.
64
What is total lung capacity (TLC)?
The maximum amount of air the lungs can hold after maximal inhalation.
65
What is forced vital capacity (FVC)?
The amount of air exhaled forcefully after a full inhalation.
66
What is FEV₁?
Forced Expiratory Volume in one second – the amount of air exhaled in the first second of FVC.
67
What is the FEV₁/FVC ratio and what does it indicate?
The % of FVC exhaled in the first second. Normal = 70–80%. Lower values may indicate lung disease.
68
What is minute ventilation and how is it calculated?
Total gas flow in/out per minute:
Minute ventilation = breaths/min × tidal volume
e.g., 12 breaths/min × 500 mL = 6000 mL/min
69
What is anatomical dead space?
About 150 mL of inhaled air remains in the conducting zone and does not participate in gas exchange.
70
What is alveolar ventilation rate and how is it calculated?
The volume of air reaching alveoli per minute:
Alveolar ventilation = (TV − dead space) × breaths/min
e.g., (500 − 150) × 12 = 4200 mL/min
71
What can variation in lung volumes indicate?
Possible lung disease — needs to be assessed via pulmonary function tests.
72
What are the two categories of lung disease?
Obstructive (e.g., COPD, asthma, emphysema)
Restrictive (e.g., pulmonary fibrosis)
73
What is partial pressure?
It’s the pressure exerted by a specific gas in a mixture of gases, measured in millimetres of mercury (mmHg).
74
What causes gas pressure in a mixture?
The impact of moving molecules against each other and surrounding surfaces.
75
Do gases dissolved in body fluids have partial pressures?
Yes — and differences in partial pressure allow gases to move between compartments like alveoli and blood.
76
How do gases move across the alveolar membrane?
Gases diffuse from areas of higher partial pressure to lower partial pressure, determining the direction of gas exchange.
77
What is the partial pressure of oxygen in fresh air entering the lungs?
About 160 mmHg.
78
What is the partial pressure of oxygen in the alveoli (due to moisture)?
Reduced to about 104 mmHg.
79
What is the partial pressure of CO₂ in fresh air entering the lungs?
Around 0.3 mmHg.
80
What is the partial pressure of CO₂ in the alveoli (from blood)?
Increases to 40 mmHg.
81
How does oxygen diffuse in the lungs?
From the alveoli (104 mmHg) to the blood (40 mmHg) in pulmonary capillaries.
82
How does carbon dioxide diffuse in the lungs?
From the blood (45 mmHg) to the alveoli (40 mmHg).
83
What happens at the venous end of pulmonary capillaries after gas exchange?
Partial pressures of O₂ and CO₂ in blood = alveoli (O₂ = 104 mmHg, CO₂ = 40 mmHg), so no net diffusion occurs.
84
How does oxygen move in systemic tissues?
From the arterial blood (104 mmHg) into tissue fluid and cells (40 mmHg).
85
How does carbon dioxide move in systemic tissues?
From cells (45 mmHg) into the tissue fluid and then blood (40 mmHg).
86
What happens at the venous end of tissue capillaries?
O₂ and CO₂ partial pressures in blood = tissue fluid, so no further gas movement occurs.
87
How does blood carry gases back to the lungs?
It returns low-O₂, high-CO₂ blood to the lungs for oxygenation and CO₂ removal.
88
Are gas exchanges in the body continuous or isolated?
They occur simultaneously and continuously throughout the body.
89
Why must the respiratory system be controlled?
To constantly adjust breathing to meet the body's oxygen needs and remove CO₂ efficiently.
90
Which muscles receive signals to control breathing?
The diaphragm and intercostal muscles.
91
What do the intercostal muscles do during inspiration?
They contract, causing the ribs to rise.
92
What does the diaphragm do during inspiration?
It descends when stimulated by nerve impulses, increasing thoracic volume.
93
What part of the brain contains the ventral and dorsal respiratory groups?
The medulla oblongata.
94
What is the role of the ventral respiratory group (VRG)?
Controls deep, forceful inhalation and exhalation.
95
What is the role of the dorsal respiratory group (DRG)?
Always active; regulates breathing rate and rhythm and responds to blood levels of O₂, CO₂, and pH.
96
What do pontine respiratory centres do?
Adjust the depth and length of breathing by receiving input from higher brain centres and modulating medullary activity.
97
What higher brain centres influence breathing?
Cerebral cortex
Limbic system
Hypothalamus
98
What do higher brain centres control in respiration?
Voluntary control, emotion-driven breathing changes, and homeostatic adjustments.
99
What are chemoreceptors and their role in breathing?
They detect chemical changes (CO₂, pH, O₂) and send signals to adjust respiration.
100
Where are central chemoreceptors located and what do they detect?
In the medulla oblongata; detect decreased pH (increased H⁺ ions) due to high CO₂.
101
What effect does central chemoreceptor activation have?
It increases respiration, raises O₂, and lowers CO₂.
102
Where are peripheral chemoreceptors located?
In the carotid bodies (common carotid artery) and aortic bodies (aortic arch).
103
What do peripheral chemoreceptors detect?
↓ O₂
↓ pH
↑ CO₂
104
What do peripheral chemoreceptors do when activated?
Send nerve signals to the medullary respiratory centres to adjust breathing rate.
105
Where does oxygen first enter the bloodstream?
In the lung capillaries surrounding the alveoli.
106
How much of the oxygen in plasma is taken up by red blood cells?
About 98% binds to haemoglobin, while 2% remains dissolved in plasma.
107
What is haemoglobin and why is it important?
Haemoglobin is an oxygen-binding protein in red blood cells. It contains four heme groups, each capable of binding one O₂ molecule.
108
What is oxyhaemoglobin?
Haemoglobin that is fully saturated with four oxygen molecules — it appears bright red.
109
What is deoxyhaemoglobin?
Haemoglobin that has released its oxygen — it appears purplish-blue.
110
What triggers oxygen release from haemoglobin in tissues?
A low partial pressure of oxygen in tissues causes haemoglobin to release oxygen.
111
What does the oxygen dissociation curve show?
The relationship between O₂ saturation of haemoglobin (Y-axis) and partial pressure of O₂ (X-axis).
112
What is the partial pressure of oxygen in the lungs and tissues?
Lungs: ~100 mmHg (high saturation);
Tissues: ~40 mmHg (lower saturation)
113
What shifts the oxygen dissociation curve to the right?
↑ CO₂
↑ H⁺ (↓ pH)
↑ Temperature
↑ BPG
→ All promote oxygen release from haemoglobin.
114
Where does carbon dioxide come from in the body?
It is a waste product of cellular respiration (used to make ATP).
115
How does CO₂ move from cells into the blood?
It diffuses from tissues into plasma, then into red blood cells.
116
What are the three ways CO₂ is transported in the blood?
7–10% dissolved in plasma
~20% binds to haemoglobin (carbaminohaemoglobin)
~70% as bicarbonate ions after forming carbonic acid
117
What enzyme converts CO₂ to carbonic acid in red blood cells?
Carbonic anhydrase
118
What happens to carbonic acid in the blood?
It quickly dissociates into bicarbonate (HCO₃⁻) and hydrogen ions (H⁺).
119
What role do hydrogen ions play in gas transport?
H⁺ binds to haemoglobin, which helps release oxygen for tissue use.
120
What happens to bicarbonate in the lungs?
It re-enters red blood cells, recombines with H⁺ to form carbonic acid, which is broken down into CO₂ and H₂O.
121
How is CO₂ finally removed from the body?
CO₂ diffuses into the alveoli and is exhaled.
122
What are the main functions of the upper respiratory system?
Filters, warms, and moistens incoming air; houses olfactory receptors.
123
Which structures are included in the upper respiratory system?
Nose, nasal cavity, paranasal sinuses, pharynx.
124
What are the main structures in the lower respiratory system?
Larynx, trachea, bronchi, bronchioles, lungs, alveoli.
125
What is the function of the larynx?
Maintains open airway, routes food/air, and produces sound.
126
Describe the branching pathway of airways in the lungs.
Trachea → bronchi → bronchioles → terminal bronchioles → respiratory bronchioles → alveoli.
127
What law explains the pressure-volume relationship in breathing?
Boyle’s Law: Pressure is inversely proportional to volume.
128
What happens during inspiration?
Diaphragm & intercostals contract → thoracic volume ↑ → pressure ↓ → air flows in.
129
What happens during expiration?
Muscles relax → thoracic volume ↓ → pressure ↑ → air flows out.
130
What are the four basic lung volumes?
Tidal Volume (TV)
Inspiratory Reserve Volume (IRV)
Expiratory Reserve Volume (ERV)
Residual Volume (RV)
131
What is vital capacity (VC)?
TV + IRV + ERV — max air that can be exhaled after full inhalation.
132
What is total lung capacity (TLC)?
VC + RV — max air lungs can hold.
133
What drives external and internal respiration?
Partial pressure gradients of O₂ and CO₂.
134
What is external respiration?
O₂ diffuses from alveoli → blood; CO₂ from blood → alveoli.
135
What is internal respiration?
O₂ diffuses from blood → tissues; CO₂ from tissues → blood.
136
What parts of the brain control breathing?
Medulla oblongata (VRG & DRG) and pons (pontine centres).
137
What do central and peripheral chemoreceptors detect?
Changes in CO₂, pH, and O₂ to regulate breathing rate.
138
How is oxygen transported in the blood?
~98.5% bound to haemoglobin (Hb)
~1.5–2% dissolved in plasma
139
What is oxyhaemoglobin?
Haemoglobin fully saturated with 4 oxygen molecules.
140
What is deoxyhaemoglobin?
Haemoglobin that has released its oxygen.
141
What determines haemoglobin’s oxygen binding?
Partial pressure of O₂ (PO₂) and haemoglobin’s affinity for O₂.
142
What causes haemoglobin to release more oxygen (Bohr effect)?
↑ CO₂
↑ H⁺ (↓ pH)
↑ Temperature
↑ BPG
143
What is the oxygen dissociation curve?
Graph showing % of haemoglobin saturated with O₂ at various PO₂ levels.
144
How is carbon dioxide transported in the blood?
7–10% dissolved in plasma
20% bound to Hb (carbaminohaemoglobin)
70% as bicarbonate ions (HCO₃⁻)
145
What enzyme converts CO₂ to carbonic acid?
Carbonic anhydrase in red blood cells.
146
What is the Haldane effect?
Deoxygenated Hb binds CO₂ better, enhancing CO₂ transport from tissues.
147
What happens to bicarbonate in the lungs?
It recombines with H⁺ → carbonic acid → broken down into CO₂ + H₂O, then exhaled.
