Ch 14 Breathing and exchange of gas Flashcards
(211 cards)
1
Q
How does the mechanism of breathing vary among animals?
A
The mechanism of breathing varies based on their habitats and levels of organization.
2
Q
How do lower invertebrates like sponges, coelenterates and flatworms respire?
A
They exchange oxygen (O₂) with carbon dioxide (CO₂) by simple diffusion over their entire body surface.
3
Q
What structure do earthworms use for respiration?
A
Moist cuticle
4
Q
How do insects transport atmospheric air within their bodies?
A
Insects use a network of tubes called tracheal tubes for respiration.
5
Q
What are gills and which organisms use them?
A
Gills are vascularized structures used for branchial respiration, mainly by aquatic arthropods and molluscs.
6
Q
What is pulmonary respiration, and who uses it?
A
Pulmonary respiration involves vascularised bags called lungs, used by terrestrial animals like reptiles, birds, and mammals.
7
Q
Which vertebrates use gills for respiration?
A
Fishes use gills for respiration.
8
Q
How do amphibians like frogs respire?
A
Frogs respire through their moist skin (cutaneous respiration)
9
Q
What type of respiration is observed in terrestrial vertebrates?
A
Terrestrial vertebrates primarily respire through lungs.
10
Q
What are the external openings of the human respiratory system called?
A
The external openings are called nostrils, located above the upper lips.
11
Q
What is the function of the nasal chamber?
A
The nasal
chamber opens into the pharynx, a portion of which is the common
passage for food and air.
12
Q
What is the pharynx, and what is its role?
A
The pharynx is a common passage for food and air.
13
Q
What is the larynx, and why is it called the “sound box”?
A
The larynx is a cartilaginous box responsible for sound production, earning it the name “sound box.”
14
Q
What prevents food from entering the larynx during swallowing?
A
The epiglottis, a thin elastic cartilaginous flap, covers the glottis to prevent food entry.
15
Q
What is the trachea, and where does it divide?
A
The trachea is a straight tube extending to the mid-thoracic cavity and divides into the right and left primary bronchi at the 5th thoracic vertebra.
16
Q
How are bronchi further subdivided?
A
Primary bronchi divide into secondary and tertiary bronchi, which further branch into bronchioles and terminal bronchioles.
17
Q
What supports the trachea and bronchi?
A
Incomplete cartilaginous rings support the trachea, primary, secondary, and tertiary bronchi, and initial bronchioles.
18
Q
What are alveoli?
A
Alveoli are thin, irregular-walled, vascularized bag-like structures where gas exchange occurs.
19
Q
What is the double-layered membrane covering the lungs called?
A
It is called the pleura, with pleural fluid between the layers to reduce friction on the lung surface.
20
Q
What is the difference between the conducting and respiratory parts of the respiratory system? (PYQ 2022)
A
The conducting part (from external nostrils to terminal bronchioles)
1. Transports the atmospheric air to the alveoli
2. Clears it from foreign particles
3. Humidifies
4. Brings the air to body temperature.
Exchange part is the site of actual diffusion of O2 and CO2
between blood and atmospheric air.
21
Q
What constitutes the thoracic chamber?
A
The thoracic chamber is formed dorsally by the vertebral column, ventrally by the sternum, laterally by the ribs, and on the lower side by the dome-shaped diaphragm.
22
Q
Why is the thoracic chamber’s air-tight nature important?
A
It allows changes in thoracic volume to be reflected in lung volume, essential for breathing.
(see this question)
23
Q
What are the main steps involved in respiration?
A
- Breathing or pulmonary ventilation by which atmospheric air is drawn in and CO2 rich alveolar air is released out.
- Diffusion of gases (O2 and CO2 ) across the alveolar membrane.
- Transport of gases by the blood.
- Diffusion of O2 and CO2 between blood and tissues.
- Utilization of O2 by the cells for catabolic reactions and resultant release of CO2 (cellular respiration as dealt in the Chapter 12).
24
Q
What is the role of the epiglottis?
A
The epiglottis prevents food from entering the larynx during swallowing by covering the glottis.
25
How does the respiratory system ensure that the air is clean, humidified, and at body temperature?
The conducting part
1. Transports the atmospheric air to the alveoli
2. Clears it from foreign particles
3. Humidifies
4. Brings the air to body temperature.
26
What is the significance of the incomplete cartilaginous rings in the trachea and bronchi?
These rings provide structural support, preventing the airway from collapsing while allowing flexibility.
(see the question)
27
How many alveoli are present in the human lungs, and what is their purpose?
There are millions of alveoli in the human lungs, and their primary purpose is to facilitate gas exchange between the air and the blood.
(see the question)
28
What is pleural fluid, and what is its function?
Pleural fluid is the liquid present between the two layers of the pleura. It reduces friction on the lung surface during breathing movements.
29
Why can changes in thoracic cavity volume directly affect pulmonary volume?
The lungs are anatomically linked to the thoracic cavity, making any volume change in the thoracic cavity directly reflect in the pulmonary volume, aiding in breathing.
(see the question)
30
How does the diaphragm contribute to respiration?
The diaphragm contracts and flattens during inhalation to increase thoracic volume, drawing air into the lungs, and relaxes during exhalation to expel air.
(see the question)
31
What is the glottis, and where is it located?
The glottis is the opening of the larynx through which air passes into the trachea.
(see the question)
32
How does the respiratory system interact with the circulatory system?
The respiratory system facilitates gas exchange in the alveoli, where oxygen enters the blood, and carbon dioxide is removed, transported to and from tissues by the circulatory system.
(see the question)
33
What structural adaptations in the alveoli make them efficient for gas exchange?
Alveoli are thin-walled, highly vascularized, and provide a large surface area, making them ideal for efficient gas exchange.
(see the question)
34
What is the primary role of the conducting part of the respiratory system?
The conducting part
1. Transports the atmospheric air to the alveoli,
2. Clears it from foreign particles
3. Humidifies
4. Brings the air to body temperature.
35
Why is it necessary to have an airtight thoracic chamber for respiration?
An airtight thoracic chamber ensures proper pressure changes required to facilitate lung expansion and contraction during breathing.
(see the question)
36
What is pulmonary ventilation, and why is it important?
Pulmonary ventilation is the process of drawing in atmospheric air and releasing CO2-rich alveolar air, essential for oxygen delivery and carbon dioxide removal.
(see the question)
37
What is cellular respiration, and how is it connected to the respiratory system?
Cellular respiration is the process where cells use oxygen to break down nutrients for energy, producing carbon dioxide as a by-product, which is expelled via the respiratory system.
(see the question)
38
Which bones form the boundaries of the thoracic chamber?
The thoracic chamber is formed dorsally by the vertebral column, ventrally by the sternum, laterally by the ribs, and on the lower side by the diaphragm.
39
What is the significance of the exchange part of the respiratory system?
The exchange part, consisting of alveoli and ducts, is where actual diffusion of oxygen and carbon dioxide between the blood and atmospheric air occurs.
40
What are the two stages of breathing?
The two stages of breathing are inspiration, during which atmospheric air is drawn into the lungs, and expiration, during which alveolar air is expelled.
41
How is the movement of air into and out of the lungs achieved?
The movement of air is achieved by creating a pressure gradient between the lungs and the atmosphere.
42
What conditions are necessary for inspiration to occur?
Inspiration occurs when the intra-pulmonary pressure is less than atmospheric pressure, creating a negative pressure gradient.
43
What causes expiration?
Expiration occurs when the intra-pulmonary pressure is higher than atmospheric pressure, forcing air out of the lungs.
44
Which muscles are involved in creating the pressure gradient for breathing?
The diaphragm and a specialized set of muscles called external and internal intercostal muscles are involved.
45
What is the role of external intercostal muscles during inspiration?
The external intercostal muscles contract, lifting the ribs and sternum, which increases the thoracic volume in the dorso-ventral axis.
46
How does an increase in thoracic volume affect pulmonary pressure?
An increase in thoracic volume leads to an increase in pulmonary volume, which decreases intra-pulmonary pressure, allowing air to enter the lungs.
47
What happens during expiration?
During expiration, the diaphragm and intercostal muscles relax,
reducing thoracic and pulmonary volume, increasing intra-pulmonary pressure, and expelling air.
48
How can the strength of breathing be increased?
The strength of breathing can be increased using additional muscles in the abdomen.
49
What is the average breathing rate for a healthy human?
A healthy human breathes 12-16 times per minute on average.
50
What instrument is used to measure the volume of air involved in breathing movements?
A spirometer is used to measure the volume of air involved in breathing movements.
51
What is the clinical significance of a spirometer?
A spirometer is used for the clinical assessment of pulmonary functions.
52
What happens to the diaphragm and sternum during expiration?
During expiration, the diaphragm and sternum return to their normal positions, reducing thoracic and pulmonary volume.
(see the question)
53
Why is it essential to maintain a pressure gradient between the lungs and the atmosphere?
Maintaining a pressure gradient is essential to facilitate the movement of air into and out of the lungs during breathing.
54
What determines the direction of air movement during breathing?
The direction of air movement is determined by the pressure gradient between the lungs and the atmosphere.
55
How does pulmonary volume affect intra-pulmonary pressure?
An increase in pulmonary volume decreases intra-pulmonary pressure, while a decrease in pulmonary volume increases intra-pulmonary pressure.
56
What causes the ribs and sternum to lift during inspiration?
The contraction of the external intercostal muscles causes the ribs and sternum to lift during inspiration.
57
What role does the abdominal muscles play in breathing?
The abdominal muscles assist in strengthening both inspiration and expiration when needed.
58
How does the diaphragm's movement affect thoracic volume?
Contraction of the diaphragm increases thoracic volume, and relaxation decreases it.
59
What happens if there is no pressure gradient between the lungs and the atmosphere?
Without a pressure gradient, there will be no movement of air into or out of the lungs.
60
Why is the ability to strengthen inspiration and expiration important?
Strengthening inspiration and expiration is important during physical exertion or when increased oxygen intake is required.
(see the question)
61
How does the body ensure air is drawn into the lungs during inspiration?
The body creates a negative pressure in the lungs relative to atmospheric pressure to draw air into the lungs.
62
What prevents air from entering the lungs during expiration?
During expiration, intra-pulmonary pressure becomes higher than atmospheric pressure, preventing air from entering and forcing it out instead.
63
What is the role of intercostal muscles in expiration?
Relaxation of the intercostal muscles during expiration reduces thoracic volume, aiding in the expulsion of air.
64
What happens to alveolar air during expiration?
During expiration, alveolar air, rich in CO2, is expelled from the lungs.
(see the question)
65
Why is the thoracic chamber described as air-tight?
The thoracic chamber is air-tight to ensure changes in its volume directly affect pulmonary volume, which is necessary for breathing.
66
How does the body regulate pulmonary volume during breathing?
Pulmonary volume is regulated through the contraction and relaxation of the diaphragm and intercostal muscles.
67
What would happen if the diaphragm failed to contract?
If the diaphragm failed to contract, inspiration would not occur efficiently, leading to reduced air intake into the lungs.
68
Can breathing rates vary, and if so, why?
Yes, breathing rates can vary depending on factors like physical activity, emotional state, and health conditions.
(see the question)
69
How does the spirometer aid in assessing lung health?
The spirometer measures the volume of air during breathing movements, helping in the diagnosis and monitoring of pulmonary diseases.
70
What is intra-pulmonary pressure?
Intra-pulmonary pressure is the pressure within the lungs that changes during breathing to facilitate air movement.
71
Why is the diaphragm dome-shaped during relaxation?
The diaphragm assumes a dome shape during relaxation to reduce thoracic volume, aiding in expiration.
72
What is the significance of thoracic volume changes?
Changes in thoracic volume are essential for creating the pressure gradients that drive air movement in and out of the lungs.
(see the question)
73
What is Tidal Volume (TV)?
Tidal Volume (TV) is the volume of air inspired or expired during normal respiration, approximately 500 mL.
74
How much air can a healthy man inspire or expire per minute during normal respiration?
A healthy man can inspire or expire approximately 6000 to 8000 mL of air per minute during normal respiration.
75
What is Inspiratory Reserve Volume (IRV)?
Inspiratory Reserve Volume (IRV) is the additional volume of air a person can inspire by forcible inspiration, averaging 2500 to 3000 mL.
76
Define Expiratory Reserve Volume (ERV).
Expiratory Reserve Volume (ERV) is the additional volume of air a person can expire by forcible expiration, averaging 1000 to 1100 mL.
77
What is Residual Volume (RV)?
Residual Volume (RV) is the volume of air remaining in the lungs even after forcible expiration, averaging 1100 to 1200 mL.
78
How is Inspiratory Capacity (IC) calculated?
Inspiratory Capacity (IC) is calculated as the total volume of air a person can inspire after a normal expiration, which includes Tidal Volume (TV) and Inspiratory Reserve Volume (IRV).
79
What does Expiratory Capacity (EC) include?
Expiratory Capacity (EC) includes the total volume of air a person can expire after a normal inspiration, consisting of Tidal Volume (TV) and Expiratory Reserve Volume (ERV).
80
What is Functional Residual Capacity (FRC)?
Functional Residual Capacity (FRC) is the volume of air that remains in the lungs after a normal expiration, which includes Expiratory Reserve Volume (ERV) and Residual Volume (RV).
81
Define Vital Capacity (VC).
Vital Capacity (VC) is the maximum volume of air a person can breathe in after a forced expiration, or the maximum volume of air a person can breathe out after a forced inspiration. It includes ERV, TV, and IRV.
82
What constitutes Total Lung Capacity (TLC)?
Total Lung Capacity (TLC) is the total volume of air accommodated in the lungs at the end of a forced inspiration. It includes Residual Volume (RV), Expiratory Reserve Volume (ERV), Tidal Volume (TV), and Inspiratory Reserve Volume (IRV) or Vital Capacity (VC) plus Residual Volume (RV).
83
Why are respiratory volumes and capacities important in clinical diagnosis?
Respiratory volumes and capacities are important in clinical diagnosis as they help assess pulmonary function and identify any abnormalities in respiratory health.
84
What is the average volume of air involved in Inspiratory Reserve Volume (IRV)?
The average volume of air in Inspiratory Reserve Volume (IRV) is 2500 to 3000 mL.
85
Which respiratory capacity includes both Tidal Volume and Expiratory Reserve Volume?
Expiratory Capacity (EC) includes both Tidal Volume (TV) and Expiratory Reserve Volume (ERV).
86
How does Residual Volume (RV) contribute to Total Lung Capacity (TLC)?
A Residual Volume (RV) is part of Total Lung Capacity (TLC) as it represents the air remaining in the lungs after maximum expiration, ensuring continuous gas exchange.
87
What is the significance of Vital Capacity (VC) in respiratory health?
Vital Capacity (VC) is significant as it reflects the maximum functional capacity of the lungs during forced breathing, helping to evaluate lung performance.
88
What is the primary site of gas exchange in the body?
The primary site of gas exchange in the body is the alveoli.
How does the exchange of gases occur between blood and tissues?
Answer: The exchange of gases between blood and tissues occurs by simple diffusion, with gases moving along their concentration gradients.
89
What is meant by partial pressure in the context of gas exchange?
Partial pressure refers to the pressure exerted by an individual gas in a mixture of gases. It is represented as pO₂ for oxygen and pCO₂ for carbon dioxide.
90
What are the main factors that affect the rate of gas diffusion?
The main factors that affect the rate of gas diffusion are the concentration gradient, the solubility of the gases, and the thickness of the diffusion membrane.
91
Why does carbon dioxide diffuse more efficiently than oxygen?
Carbon dioxide diffuses more efficiently than oxygen because its solubility is 20-25 times higher than that of oxygen, allowing it to diffuse more easily through the diffusion membrane.
92
Describe the structure of the diffusion membrane in the lungs.
The diffusion membrane consists of three layers: the thin squamous epithelium of alveoli, the endothelium of the alveolar capillaries, and the basement membrane between them. The total thickness of the membrane is less than a millimeter.
93
How does the concentration gradient affect the diffusion of gases?
The concentration gradient drives the diffusion of gases, with oxygen moving from areas of higher partial pressure (in the alveoli) to areas of lower partial pressure (in the blood and tissues), and carbon dioxide moving in the opposite direction.
94
Why is the thickness of the diffusion membrane important for gas exchange?
The thinness of the diffusion membrane is important because it allows gases to diffuse quickly and efficiently between the alveoli and blood, ensuring effective exchange of oxygen and carbon dioxide.
95
What role do alveoli play in the process of gas exchange?
Alveoli are the primary sites where oxygen and carbon dioxide are exchanged between the lungs and the blood.
96
How does oxygen move from the alveoli to the blood?
Oxygen moves from the alveoli to the blood through simple diffusion, following the concentration gradient from an area of higher partial pressure in the alveoli to an area of lower partial pressure in the blood.
97
Why is carbon dioxide diffused from tissues to blood and then to the alveoli?
Carbon dioxide is produced in tissues and has a higher partial pressure in the tissues than in the blood, so it diffuses from tissues to blood. Then, it moves from the blood to the alveoli to be exhaled.
98
What is the significance of the solubility of gases in the diffusion process?
The solubility of gases affects how easily they diffuse. Since CO₂ is 20-25 times more soluble than O₂, it diffuses more efficiently across the diffusion membrane.
99
How does the partial pressure of oxygen and carbon dioxide differ between the alveoli and the blood?
In the alveoli, the partial pressure of O₂ is higher than in the blood, while the partial pressure of CO₂ is lower in the alveoli compared to the blood, allowing for efficient diffusion of gases.
100
Why is a pressure gradient important for the exchange of gases in the lungs?
A pressure gradient drives the diffusion of gases. Oxygen moves from areas of higher partial pressure (in the alveoli) to areas of lower partial pressure (in the blood), and carbon dioxide moves in the opposite direction.
101
What are the three layers that make up the diffusion membrane in the lungs?
The three layers are the squamous epithelium of the alveoli, the endothelium of the alveolar capillaries, and the basement membrane between them.
102
How does the thickness of the diffusion membrane impact the efficiency of gas exchange?
The thinner the diffusion membrane, the more efficiently gases can diffuse. A very thin membrane (less than a millimeter) allows for faster and more efficient gas exchange.
103
Why does the solubility of carbon dioxide influence its diffusion rate?
Because CO₂ is much more soluble than O₂, it can diffuse more rapidly through the diffusion membrane for a given difference in partial pressure.
104
How does the concentration gradient affect the movement of gases in the body?
The concentration gradient ensures that gases move from areas of higher partial pressure to areas of lower partial pressure, facilitating the efficient exchange of O₂ and CO₂ in the lungs and tissues.
105
What is the primary medium of transport for oxygen and carbon dioxide in the body?
Blood is the primary medium of transport for oxygen and carbon dioxide.
106
How is oxygen transported in the blood?
About 97% of oxygen is transported by red blood cells (RBCs), while the remaining 3% is carried dissolved in the plasma.
107
How is carbon dioxide transported in the blood?
Approximately 20-25% of carbon dioxide is transported by red blood cells (RBCs), while 70% is carried as bicarbonate. About 7% of carbon dioxide is transported dissolved in plasma.
108
What percentage of oxygen is carried dissolved in the plasma?
About 3% of oxygen is carried dissolved in the plasma.
109
How much carbon dioxide is carried as bicarbonate in the blood?
About 70% of carbon dioxide is carried as bicarbonate in the blood.
110
What is the role of red blood cells in the transport of gases?
Red blood cells carry about 97% of oxygen and 20-25% of carbon dioxide in the blood.
111
How much carbon dioxide is carried in a dissolved state in plasma?
About 7% of carbon dioxide is carried in a dissolved state in plasma.
112
What is haemoglobin and what role does it play in oxygen transport?
Haemoglobin is a red-colored, iron-containing pigment present in red blood cells (RBCs). It binds to oxygen in a reversible manner to form oxyhaemoglobin, allowing oxygen transport in the blood.
113
How many molecules of oxygen can a single haemoglobin molecule carry?
A single haemoglobin molecule can carry a maximum of four molecules of oxygen.
114
What factors influence the binding of oxygen to haemoglobin?
The binding of oxygen to haemoglobin is primarily influenced by the partial pressure of oxygen (pO₂). Other factors such as partial pressure of CO₂, hydrogen ion concentration, and temperature can also affect the binding.
115
What is the Oxygen dissociation curve?
The Oxygen dissociation curve is a sigmoid curve that shows the percentage saturation of haemoglobin with oxygen (oxyhaemoglobin) plotted against the partial pressure of oxygen (pO₂). It helps in studying the effects of factors like pCO₂, H+ concentration, etc., on the binding of oxygen to haemoglobin.
116
How do conditions in the alveoli favor the formation of oxyhaemoglobin?
In the alveoli, the high partial pressure of oxygen (pO₂), low partial pressure of CO₂, low hydrogen ion concentration (H+), and lower temperature all favor the formation of oxyhaemoglobin.
117
Why is oxygen dissociation favored in the tissues?
In the tissues, the low partial pressure of oxygen (pO₂), high partial pressure of CO₂, high hydrogen ion concentration (H+), and higher temperature create conditions that favor the dissociation of oxygen from oxyhaemoglobin.
118
How much oxygen can be delivered to tissues by every 100 ml of oxygenated blood under normal conditions?
Every 100 ml of oxygenated blood can deliver around 5 ml of oxygen to the tissues under normal physiological conditions.
119
What is oxyhaemoglobin?
Oxyhaemoglobin is the compound formed when oxygen binds to haemoglobin in a reversible manner.
120
How does the partial pressure of oxygen affect oxygen binding to haemoglobin?
The binding of oxygen to haemoglobin is directly related to the partial pressure of oxygen (pO₂); as pO₂ increases, the binding of oxygen to haemoglobin also increases.
121
How does the concentration of CO₂ influence oxygen binding to haemoglobin?
A High partial pressure of CO₂ (pCO₂) reduces the affinity of haemoglobin for oxygen, promoting the dissociation of oxygen from oxyhaemoglobin.
122
What effect does a high concentration of hydrogen ions (H+) have on oxygen binding?
A high concentration of hydrogen ions (low pH) reduces the affinity of haemoglobin for oxygen, facilitating oxygen release in tissues.
123
How does temperature affect the binding of oxygen to haemoglobin?
Higher temperatures decrease the affinity of haemoglobin for oxygen, promoting oxygen release in the tissues.
124
What is the significance of the sigmoid shape of the oxygen dissociation curve?
The sigmoid shape of the oxygen dissociation curve reflects the cooperative binding of oxygen to haemoglobin, where binding of one oxygen molecule increases the affinity for the next.
125
Why does oxygen dissociation occur more readily in active tissues?
In active tissues, the low pO₂, high pCO₂, high H+ concentration, and higher temperature create conditions that promote oxygen dissociation from haemoglobin for tissue use.
126
What is the role of haemoglobin in the transport of oxygen in the body?
Haemoglobin binds to oxygen in the lungs and carries it through the blood to tissues, where it releases oxygen for cellular use.
127
How is oxygen release regulated in tissues?
Oxygen release in tissues is regulated by factors such as low pO₂, high pCO₂, high H+ concentration, and increased temperature, which all favor the dissociation of oxygen from oxyhaemoglobin.
128
How much oxygen is delivered to tissues per 100 ml of oxygenated blood?
Every 100 ml of oxygenated blood can deliver approximately 5 ml of oxygen to the tissues under normal physiological conditions.
129
What is haemoglobin and its role in oxygen transport?
Haemoglobin is a red-colored, iron-containing pigment in RBCs that binds to oxygen reversibly to form oxyhaemoglobin, facilitating oxygen transport in the blood.
130
How many oxygen molecules can a haemoglobin molecule carry?
A haemoglobin molecule can carry a maximum of four oxygen molecules.
131
What factors influence the binding of oxygen to haemoglobin?
The binding of oxygen to haemoglobin is influenced by the partial pressure of oxygen (pO₂), partial pressure of carbon dioxide (pCO₂), hydrogen ion concentration (H+), and temperature.
132
What is the Oxygen dissociation curve?
The Oxygen dissociation curve is a sigmoid curve that plots the percentage saturation of haemoglobin with oxygen against pO₂ and is used to study factors affecting oxygen binding.
133
Why is oxyhaemoglobin formation favored in the alveoli?
In the alveoli, high pO₂, low pCO₂, lesser H+ concentration, and lower temperature favor the formation of oxyhaemoglobin.
134
Why does oxygen dissociate from oxyhaemoglobin in tissues?
In tissues, low pO₂, high pCO₂, high H+ concentration, and higher temperature favor the dissociation of oxygen from oxyhaemoglobin.
135
What does the Oxygen dissociation curve indicate about oxygen transport?
The Oxygen dissociation curve indicates that oxygen binds to haemoglobin at the lung surface (alveoli) and dissociates from haemoglobin in the tissues based on varying physiological conditions.
136
How much oxygen is delivered to tissues by 100 ml of oxygenated blood under normal conditions?
Approximately 5 ml of oxygen is delivered to tissues by 100 ml of oxygenated blood under normal physiological conditions.
137
What is the chemical composition of haemoglobin?
Haemoglobin is a red-colored pigment containing iron and is present in the red blood cells (RBCs).
138
How does haemoglobin transport oxygen in the blood?
Haemoglobin binds with oxygen in a reversible manner to form oxyhaemoglobin, which transports oxygen through the blood.
139
How many oxygen molecules can each haemoglobin molecule bind?
.
Each haemoglobin molecule can bind a maximum of four oxygen molecules
140
What factors influence the binding of oxygen to haemoglobin?
The binding of oxygen to haemoglobin is influenced by the partial pressure of oxygen (pO₂), partial pressure of carbon dioxide (pCO₂), hydrogen ion concentration (H+), and temperature.
141
What happens to oxygen binding at high pO₂ levels?
At high pO₂ levels, such as in the alveoli, oxygen binds readily to haemoglobin to form oxyhaemoglobin.
142
What happens to oxygen binding at low pO₂ levels?
A At low pO₂ levels, such as in tissues, oxygen dissociates from oxyhaemoglobin to supply oxygen to cells.
143
What is the Oxygen dissociation curve?
The Oxygen dissociation curve is a sigmoid curve that shows the percentage saturation of haemoglobin with oxygen plotted against pO₂, useful for analyzing oxygen binding under different conditions.
144
What conditions favor oxyhaemoglobin formation in the alveoli?
High pO₂, low pCO₂, low hydrogen ion concentration (H+), and lower temperature favor the formation of oxyhaemoglobin in the alveoli.
145
What conditions promote oxygen dissociation from oxyhaemoglobin in tissues?
Low pO₂, high pCO₂, high hydrogen ion concentration (H+), and higher temperature promote oxygen dissociation from oxyhaemoglobin in tissues.
146
How much oxygen is delivered to tissues by 100 ml of oxygenated blood?
Approximately 5 ml of oxygen is delivered to tissues by 100 ml of oxygenated blood under normal conditions.
147
Why is oxygen delivery efficient in tissues?
Oxygen delivery is efficient in tissues because low pO₂, high pCO₂, and increased temperature enhance the dissociation of oxygen from oxyhaemoglobin.
148
Why does the oxygen dissociation curve have a sigmoid shape?
The sigmoid shape of the oxygen dissociation curve reflects the cooperative binding of oxygen to haemoglobin, where the binding of one oxygen molecule increases the affinity for subsequent oxygen molecules.
149
What is the significance of reversible oxygen binding to haemoglobin?
Reversible oxygen binding ensures oxygen uptake in the lungs and its release in tissues, maintaining efficient oxygen delivery and cellular respiration.
150
What is the physiological importance of haemoglobin in oxygen transport?
Haemoglobin ensures efficient oxygen transport from the lungs to tissues and plays a vital role in maintaining oxygen homeostasis in the body.
151
How is carbon dioxide transported by haemoglobin?
Carbon dioxide is transported by haemoglobin as carbamino-haemoglobin, accounting for about 20-25% of the total CO₂ transport.
152
What factors influence the binding of CO₂ to haemoglobin?
The binding of CO₂ to haemoglobin is influenced by high pCO₂ and low pO₂ levels, as seen in tissues.
153
Where does dissociation of CO₂ from carbamino-haemoglobin occur?
Dissociation of CO₂ from carbamino-haemoglobin occurs in the alveoli, where pCO₂ is low, and pO₂ is high.
154
What role does carbonic anhydrase play in CO₂ transport?
Carbonic anhydrase, present in RBCs and plasma, catalyzes the reversible conversion of CO₂ and water into bicarbonate (HCO₃⁻) and hydrogen ions (H+), and vice versa.
155
What happens to CO₂ at the tissue site?
At the tissue site, where pCO₂ is high due to catabolism, CO₂ diffuses into the blood and forms bicarbonate (HCO₃⁻) and hydrogen ions (H+).
156
What happens to CO₂ at the alveolar site?
At the alveolar site, where pCO₂ is low, bicarbonate (HCO₃⁻) is converted back into CO₂ and water, allowing CO₂ to be released and exhaled.
157
How is CO₂ transported as bicarbonate in the blood?
CO₂ reacts with water in the presence of carbonic anhydrase to form carbonic acid, which dissociates into bicarbonate (HCO₃⁻) and hydrogen ions, facilitating its transport.
158
How much CO₂ is delivered to the alveoli by 100 ml of deoxygenated blood?
Approximately 4 ml of CO₂ is delivered to the alveoli by 100 ml of deoxygenated blood.
159
Why does CO₂ bind more to haemoglobin in tissues than in alveoli?
In tissues, high pCO₂ and low pO₂ favor the binding of CO₂ to haemoglobin, while in alveoli, low pCO₂ and high pO₂ promote its dissociation.
160
Why is the transport of CO₂ as bicarbonate significant?
Transport of CO₂ as bicarbonate is significant because it allows for efficient CO₂ carriage in the blood and maintains acid-base balance in the body.
161
What is the reaction catalyzed by carbonic anhydrase in tissues?
In tissues, carbonic anhydrase catalyzes the reaction of CO₂ and water to form bicarbonate (HCO₃⁻) and hydrogen ions (H+).
162
What is the reaction catalyzed by carbonic anhydrase in the alveoli?
In the alveoli, carbonic anhydrase catalyzes the conversion of bicarbonate (HCO₃⁻) and hydrogen ions (H+) into CO₂ and water for exhalation.
163
How does pO₂ affect CO₂ transport in the blood?
Low pO₂ in tissues enhances CO₂ binding to haemoglobin, while high pO₂ in alveoli promotes the release of CO₂ from haemoglobin.
164
What is the significance of CO₂ transport in maintaining homeostasis?
CO₂ transport helps regulate blood pH and ensures the efficient removal of metabolic waste, maintaining homeostasis in the body.
165
What percentage of carbon dioxide is transported as carbamino-haemoglobin?
About 20-25% of carbon dioxide is transported as carbamino-haemoglobin.
166
How does the partial pressure of CO₂ affect its binding to haemoglobin?
High partial pressure of CO₂ (pCO₂) increases its binding to haemoglobin, while low pCO₂ promotes its dissociation.
167
How does pO₂ influence CO₂ transport in tissues?
In tissues, low pO₂ favors the binding of CO₂ to haemoglobin, facilitating its transport as carbamino-haemoglobin.
168
What enzyme is involved in the conversion of CO₂ into bicarbonate?
The enzyme carbonic anhydrase facilitates the conversion of CO₂ into bicarbonate (HCO₃⁻) and hydrogen ions (H+).
169
What is the primary form in which CO₂ is transported in the blood?
The primary form in which CO₂ is transported in the blood is as bicarbonate (about 70%).
170
What happens to CO₂ at the tissue level during transport?
At the tissue level, CO₂ diffuses into blood, reacts with water to form bicarbonate and hydrogen ions, and is transported in this form.
171
What happens to bicarbonate at the alveolar level?
At the alveolar level, bicarbonate is converted back into CO₂ and water, and the CO₂ is released into the alveoli for exhalation.
172
Why is carbonic anhydrase important for CO₂ transport?
Carbonic anhydrase accelerates the reaction between CO₂ and water, facilitating its rapid conversion to and from bicarbonate, enabling efficient CO₂ transport.
173
How is CO₂ released from carbamino-haemoglobin in the alveoli?
In the alveoli, low pCO₂ and high pO₂ cause CO₂ to dissociate from carbamino-haemoglobin, allowing its exhalation.
174
What percentage of CO₂ is transported in dissolved form in plasma?
About 7% of CO₂ is transported in dissolved form in the plasma.
175
How does CO₂ transport help maintain blood pH?
CO₂ transport in the form of bicarbonate helps buffer the blood, maintaining acid-base balance and stabilizing pH.
176
What facilitates the diffusion of CO₂ into blood from tissues?
High pCO₂ in tissues, resulting from catabolism, facilitates the diffusion of CO₂ into the blood.
177
How does the direction of the CO₂ reaction depend on the site in the body?
At tissues, the reaction favors the formation of bicarbonate (HCO₃⁻) from CO₂, while at alveoli, the reaction favors the formation of CO₂ for exhalation.
178
What is the role of haemoglobin in CO₂ transport?
Haemoglobin transports CO₂ by binding to it as carbamino-haemoglobin and by assisting in buffering H+ ions formed during bicarbonate formation.
179
Why is CO₂ transport critical for metabolic processes?
CO₂ transport removes the waste product of metabolism, prevents acidosis, and ensures efficient respiratory gas exchange.
180
What is the primary function of the respiratory rhythm centre?
The respiratory rhythm centre, located in the medulla region of the brain, is primarily responsible for regulating the respiratory rhythm.
181
Where is the pneumotaxic centre located, and what is its function?
The pneumotaxic centre is located in the pons region of the brain, and it moderates the functions of the respiratory rhythm centre by reducing the duration of inspiration and altering the respiratory rate.
182
What activates the chemosensitive area near the respiratory rhythm centre?
The chemosensitive area is activated by an increase in CO₂ and hydrogen ion concentrations.
183
How does the chemosensitive area influence the respiratory rhythm centre?
When activated, the chemosensitive area signals the respiratory rhythm center to adjust the respiratory process to eliminate excess CO₂ and hydrogen ions.
184
Which receptors detect changes in CO₂ and hydrogen ion concentrations?
Receptors associated with the aortic arch and carotid artery detect changes in CO₂ and hydrogen ion concentrations.
185
How do the aortic and carotid receptors contribute to respiratory regulation?
These receptors send signals to the respiratory rhythm centre, prompting adjustments to the respiratory process based on changes in CO₂ and hydrogen ion levels.
186
What is the role of oxygen in the regulation of respiratory rhythm?
The role of oxygen in regulating respiratory rhythm is quite insignificant compared to CO₂ and hydrogen ions.
187
How does the neural system help maintain respiratory rhythm?
The neural system maintains respiratory rhythm through the respiratory rhythm centre, pneumotaxic centre, chemosensitive area, and peripheral receptors that respond to chemical changes in the blood.
188
What happens when CO₂ levels increase in the blood?
Increased CO₂ levels activate the chemosensitive area, which signals the respiratory rhythm centre to enhance respiration to eliminate excess CO₂.
189
Why is the regulation of respiration important?
Regulation of respiration ensures proper gas exchange, maintains blood pH, and adapts respiratory activity to the metabolic demands of the body.
190
What is the effect of the pneumotaxic centre on inspiration?
The pneumotaxic centre reduces the duration of inspiration, thereby altering the respiratory rate.
191
How does the body eliminate excess hydrogen ions through respiration?
The respiratory rhythm centre increases ventilation to expel CO₂, which helps reduce hydrogen ion concentration in the blood, maintaining pH balance.
192
What is the relationship between CO₂ levels and the chemosensitive area?
The chemosensitive area is highly sensitive to CO₂ levels; increased CO₂ stimulates this area to activate the respiratory rhythm centre for necessary adjustments.
193
How do changes in blood chemistry affect respiration?
Changes in blood chemistry, such as increased CO₂ and H+ concentrations, are detected by receptors and chemosensitive areas, which adjust respiratory activity to restore balance.
194
What is the primary stimulus for respiratory regulation?
The primary stimulus for respiratory regulation is the concentration of CO₂ and hydrogen ions in the blood.
195
Where is the respiratory rhythm centre located?
The respiratory rhythm centre is located in the medulla region of the brain.
196
What happens when the pneumotaxic centre reduces the duration of inspiration?
Reducing the duration of inspiration increases the respiratory rate.
197
Why is the chemosensitive area important in respiration regulation?
The chemosensitive area detects increases in CO₂ and H+ concentrations and signals the respiratory rhythm centre to adjust breathing to maintain homeostasis.
198
How do the aortic arch and carotid artery receptors contribute to respiration?
These receptors detect changes in blood CO₂ and H+ concentrations and send corrective signals to the respiratory rhythm centre.
199
Why is oxygen's role in respiratory regulation considered insignificant?
Oxygen levels have a minimal influence compared to CO₂ and H+ concentrations, which are the primary regulators of respiratory rhythm.
200
What is the effect of high CO₂ levels on respiratory rate?
High CO₂ levels increase the respiratory rate to expel excess CO₂ and restore balance.
201
How does the respiratory rhythm adapt to tissue demands?
The respiratory rhythm adapts through signals from the pneumotaxic centre, chemosensitive area, and peripheral receptors, ensuring proper oxygen supply and CO₂ elimination.
202
What neural centres are involved in respiratory regulation?
The respiratory rhythm centre in the medulla and the pneumotaxic centre in the pons are the primary neural centres involved in respiratory regulation.
203
What are the consequences of low pCO₂ in the alveoli?
Low pCO₂ in the alveoli facilitates the dissociation of CO₂ from carbamino-haemoglobin, enabling its exhalation.
204
How does the body detect and respond to an increase in hydrogen ion concentration?
The chemosensitive area and peripheral receptors detect increased H+ concentrations, signaling the respiratory rhythm centre to increase breathing and expel CO₂, reducing acidity.
205
What is the role of the pneumotaxic centre during exercise?
During exercise, the pneumotaxic centre helps regulate breathing rate and depth to meet increased oxygen demand and CO₂ removal.
206
How does the respiratory rhythm change during rest versus activity?
During rest, the respiratory rhythm slows down, while during activity, it increases to meet the metabolic demands of the body.
207
What mechanisms ensure CO₂ removal during respiration?
CO₂ removal is ensured by the chemosensitive area detecting high CO₂ levels, signaling increased respiratory activity to expel CO₂.
208
Why is precise regulation of respiration critical for survival?
Precise regulation ensures adequate oxygen delivery, efficient CO₂ removal, and maintenance of blood pH, which are essential for cellular function and homeostasis.
209
How does the medulla interact with the pons in respiration regulation?
The medulla’s respiratory rhythm centre sets the basic rhythm, while the pons’ pneumotaxic centre modifies the rhythm to suit the body’s needs
210
Mechanisms of breathing vary among different groups of animals
depending mainly on their ............... and ..................................
habitats and levels of organisation.
211
Lower invertebrates like sponges, coelenterates, flatworms, etc., exchange O2
with CO2 by ............................................................
simple diffusion over their entire body surface.
