Physiology 5.2

Question 1

Describe the concept acid-base balance.

Answer 1

Acid balance refers to the maintenance of normal pH in the extracellular fluid, typically at 7.4. Disturbances in acid-base balance can cause the pH to become more alkaline or acidic.

Question 2

What is the role of the respiratory system in maintaining pH at 7.4?

Answer 2

The respiratory system helps to keep the pH at 7.4 by responding to increasing hydrogen ion concentration in the plasma, mainly through the hydrogen ions generated as a result of an increase in PCO2.

Question 3

How do peripheral chemoreceptors respond to changes in hydrogen ion concentration?

Answer 3

Peripheral chemoreceptors can respond to a fall in PO2, an increase in PCO2, and hydrogen ions generated from any source, such as lactic acid during intense exercise.

Question 4

Define the role of peripheral chemoreceptors in monitoring hydrogen ion concentration.

Answer 4

Peripheral chemoreceptors monitor hydrogen ions in the plasma and can respond to hydrogen ions generated by any means, unlike central chemoreceptors which specifically respond to hydrogen ions originating from carbon dioxide.

Question 5

Describe the indirect response of peripheral chemoreceptors to an increase in PCO2.

Answer 5

Peripheral chemoreceptors respond indirectly to an increase in PCO2 by responding to the hydrogen ions that originate from the carbon dioxide, leading to stimulation of ventilation.

Question 6

What is the linear response of the body to a change in hydrogen ion concentration in the plasma?

Answer 6

An increase in hydrogen ion concentration in the plasma leads to stimulation of ventilation, which results in a linear response of the body to maintain acid-base balance.

Question 7

Describe the relationship between plasma pH and ventilation.

Answer 7

There is a linear relationship between plasma pH and ventilation, where an increase in hydrogen ion concentration and decrease in pH stimulates ventilation, and conversely, a decrease in hydrogen ion concentration and increase in pH inhibits ventilation.

Question 8

Define metabolic acidosis and provide an example.

Answer 8

Metabolic acidosis occurs when there is an increase in hydrogen ion concentration in the plasma due to reasons other than a change in respiratory function, such as lactic acidosis caused by exercise-induced production of lactic acid.

Question 9

How does increased ventilation affect the acid-base equilibrium in the plasma?

Answer 9

Increased ventilation leads to the blowing off of more carbon dioxide, driving the equation to the left and reducing the hydrogen ion concentration, thus helping to restore normal hydrogen ion concentration in the plasma.

Question 10

Do changes in ventilation lead to acid-base disturbances?

Answer 10

Yes, changes in ventilation can lead to acid-base disturbances by altering the hydrogen ion concentration in the plasma, such as hyperventilation causing a lowering of hydrogen ion concentration and resulting in respiratory alkalosis.

Question 11

Describe the role of the respiratory system in compensating for acid-base disturbances.

Answer 11

The respiratory system can compensate for acid-base disturbances by manipulating ventilation to restore normal hydrogen ion concentration in the plasma, demonstrating negative feedback in action.

Question 12

What is the effect of inhibiting ventilation on the acid-base equilibrium?

Answer 12

Inhibiting ventilation leads to the retention of CO2, driving the equation to the right and increasing the hydrogen ion concentration, thus compensating for the fall in hydrogen ion concentration that caused the inhibition of ventilation.

Question 13

Explain the concept of negative feedback in the context of hydrogen ion concentration and ventilation.

Answer 13

Negative feedback is observed as the respiratory system compensates for an increase or decrease in hydrogen ion concentration by manipulating ventilation to restore normal hydrogen ion concentration in the plasma.

Question 14

How can the respiratory system cause acid-base disturbances?

Answer 14

By changing ventilation, the respiratory system can alter the hydrogen ion concentration in the plasma, leading to acid-base disturbances, such as hyperventilation causing a lowering of hydrogen ion concentration and resulting in respiratory alkalosis.

Question 15

Describe the relationship between hydrogen ion concentration and respiratory alkalosis.

Answer 15

Respiratory alkalosis occurs when the hydrogen ion concentration in the plasma is reduced due to driving the equation to the left, often caused by hyperventilation.

Question 16

Define respiratory acidosis and its cause.

Answer 16

Respiratory acidosis is characterized by a build-up of hydrogen ion concentration in the plasma, caused by retaining carbon dioxide which drives the equation to the right.

Question 17

How does the respiratory system compensate for an acid-base imbalance caused by a metabolic source?

Answer 17

The respiratory system can compensate for an acid-base imbalance caused by a metabolic source, such as lactic acidosis, by working together with the renal system to maintain normal extracellular fluid pH.

Question 18

Do respiratory diseases generally result in increased or decreased ventilation?

Answer 18

Most respiratory diseases result in a decrease in ventilation, either directly inhibiting ventilation or impacting diffusion.

Question 19

Describe the impact of hypoventilation on plasma PCO2 and hydrogen ion concentration.

Answer 19

Hypoventilation leads to the retention of carbon dioxide, increasing plasma PCO2 and hydrogen ion concentration, causing respiratory acidosis.

Question 20

How does hyperventilation affect hydrogen ion concentration in the extracellular fluid?

Answer 20

Hyperventilation reduces hydrogen ion concentration in the extracellular fluid by driving the equation to the left, leading to respiratory alkalosis.

Question 21

Explain the role of the respiratory system in compensating for metabolic acidosis or alkalosis.

Answer 21

The respiratory system acts to compensate for metabolic acidosis or alkalosis, aiming to reduce the deviation of hydrogen ion concentration from the normal pH value of 7.

Question 22

Describe the interplay between the respiratory and renal systems in maintaining normal extracellular fluid pH.

Answer 22

The renal system works together with the respiratory system to maintain normal extracellular fluid pH. If one system causes an acid-base disturbance, the other system attempts to compensate for it.

Question 23

Describe the relationship between pH, bicarbonate, and CO2 in the body.

Answer 23

p is proportional to bicarbonate divided by CO2. An increase in bicarbonate leads to an increase in pH, making things more alkaline, while a decrease in bicarbonate leads to a decrease in pH, making things more acidic.

Question 24

How are CO2 and bicarbonate managed in the body?

Answer 24

CO2 is managed by the lungs and the respiratory system, while bicarbonate is managed by the kidneys and the renal system.

Question 25

Define the role of central chemo receptors in the body.

Answer 25

Central chemo receptors respond to changes in the partial pressure of oxygen and carbon dioxide in the cerebrospinal fluid, stimulating nerve impulses to the respiratory centres in the medulla.

Question 26

What is the response of the body to an increase in CO2 levels?

Answer 26

An increase in CO2 levels stimulates the central chemo receptors, leading to increased ventilation to blow off the extra CO2 and restore normal breathing.

Question 27

Describe the role of peripheral chemo receptors in the body.

Answer 27

Peripheral chemo receptors respond to changes in carbon dioxide, oxygen, and hydrogen ion concentration in the plasma, stimulating ventilation to maintain optimal levels of these substances.

Question 28

How does the body respond to a decrease in the partial pressure of oxygen (PO2)?

Answer 28

A significant decrease in PO2 stimulates the peripheral chemo receptors, leading to increased ventilation to top up oxygen levels and remove the initial stimulus.

Question 29

What is the significance of the peripheral chemo receptors in maintaining optimal levels of carbon dioxide, oxygen, and hydrogen ions in the plasma?

Answer 29

The peripheral chemo receptors play a crucial role in responding to changes in these substances, stimulating ventilation and activating negative feedback pathways to maintain optimal levels.

Question 30

Do changes in carbon dioxide levels affect hydrogen ion concentration in the plasma?

Answer 30

Yes, an increase in carbon dioxide leads to an increase in hydrogen ion concentration in the plasma, stimulating the peripheral chemo receptors and ventilation.

Question 31

Describe the main stimuli influence the basal rhythm the respiratory centres.

Answer 31

The main stimuli are the partial pressure of carbon dioxide, the pressure of oxygen, and the pH of plasma.

Question 32

Define the primary and secondary inputs to the respiratory centres.

Answer 32

The primary input is from the medullary chemoreceptors responding to changes in carbon dioxide, while the secondary input comes from peripheral chemoreceptors responding to changes in oxygen and pH.

Question 33

How do emotional centers and conscious thought influence respiratory function?

Answer 33

They can feed into and alter respiratory function by providing input to the respiratory centres from the limbic system and cerebral cortex.

Question 34

Describe the muscles involved in inspiration and expiration during relaxed ventilation.

Answer 34

The main muscles of inspiration are the diaphragm and external intercostal muscles, while the muscles of expiration include internal intercostal muscles and abdominal muscles.

Question 35

Do changes in blood gas composition drive the increase in ventilation during exercise?

Answer 35

No, changes in blood gas composition do not drive the increase in ventilation seen during exercise.

Question 36

Describe the relationship between ventilation and exercise.

Answer 36

During exercise, there is an increase in ventilation to meet the increased energy demand, but the exact stimulus for this increase is not fully understood.

Question 37

Define the relationship between the increase in ventilation and metabolism during moderate exercise.

Answer 37

The increase in ventilation during moderate exercise is directly proportional to the increase in metabolism, despite the arterial PO2 and CO2 remaining constant.

Question 38

How does the increase in ventilation during exercise compare to the changes in blood gas composition?

Answer 38

The increase in ventilation during exercise does not result in the expected changes in blood gas composition, as the arterial PO2 and CO2 remain constant.

Question 39

Describe the relationship between ventilation and metabolism during strenuous exercise.

Answer 39

During strenuous exercise, ventilation increases more than metabolism, likely due to increased lactic acid production leading to hyperventilation.

Question 40

Define lactic acidosis and its role in stimulating hyperventilation during strenuous exercise.

Answer 40

Lactic acidosis is the condition of having a high concentration of lactic acid in the body, which likely stimulates hyperventilation during strenuous exercise.

Question 41

How does the body respond to increased hydrogen ion concentration during strenuous exercise?

Answer 41

The body responds to increased hydrogen ion concentration during strenuous exercise by experiencing lactic acidosis, which likely stimulates hyperventilation.

Question 42

Do voluntary actions have complete control over breathing? Explain.

Answer 42

Voluntary actions do not have complete control over breathing, as involuntary stimuli, particularly arterial gas composition or arterial pH, cannot be overridden voluntarily.

Question 43

Describe the consequences of prolonged breath-holding.

Answer 43

Prolonged breath-holding leads to a point where oxygen levels fall too low to maintain brain function, resulting in loss of consciousness and the body’s automatic resumption of breathing control.

Question 44

Define hyperventilation and its potential dangers.

Answer 44

Hyperventilation is the rapid or deep breathing that can lead to blowing off carbon dioxide and topping up oxygen levels, but it can also be dangerous, potentially resulting in drowning due to the body’s response to low carbon dioxide levels.

Question 45

How does hyperventilation affect free divers and why is it dangerous?

Answer 45

Hyperventilation allows free divers to hold their breath for longer by topping up oxygen levels and blowing off carbon dioxide, but it is dangerous as it can lead to drowning due to the body’s response to low carbon dioxide levels.

Question 46

Describe the relationship between voluntary and involuntary control of breathing.

Answer 46

While there is a large degree of voluntary control over breathing from the cerebral cortex to respiratory motor neurons, involuntary stimuli such as arterial gas composition or arterial pH cannot be voluntarily overridden.

Question 47

Describe the potential risk of losing consciousness underwater due to oxygen levels falling faster than CO2 levels rising.

Answer 47

The risk is that if oxygen levels fall below the required level to maintain consciousness, a person may lose consciousness underwater before being aware of the need to return to the surface to expel carbon dioxide.

Question 48

Do hyperventilation and imbalance in oxygen and CO2 levels underwater have potential consequences?

Answer 48

Yes, hyperventilation can allow a person to hold their breath longer underwater, but it can also lead to unconsciousness underwater if oxygen levels fall too low.

Question 49

Define the impact of different gas compositions on individuals in the experiment.

Answer 49

Individuals reported chamber one, with normal oxygen and carbon dioxide, as highly distressing, while chamber two, with low oxygen and no carbon dioxide, caused mild discomfort at most.

Question 50

How did individuals in the experiment react to the different gas compositions?

Answer 50

Those in chamber one found it highly distressing, while those in chamber two reported mild discomfort, if anything.

Question 51

Describe the sensitivity of humans to carbon dioxide.

Answer 51

Humans are exquisitely sensitive to carbon dioxide, as evidenced by the distress caused by breathing in carbon dioxide in the experiment.

Question 52

Explain the potential disruption caused by breathing in carbon dioxide.

Answer 52

Breathing in carbon dioxide disrupts the partial pressure gradient, affecting the removal of carbon dioxide from the blood and tissues.

Question 53

What is the potential cause of a number of drowning incidents according to the content?

Answer 53

The content suggests that hyperventilation before entering the water, leading to an imbalance in oxygen and CO2 levels, may be the cause of some drowning incidents.

Question 54

How does the content illustrate the impact of different gas compositions on individuals?

Answer 54

The experiment showed that individuals found chamber one, with normal oxygen and carbon dioxide, highly distressing, while chamber two, with low oxygen and no carbon dioxide, caused mild discomfort at most.

Question 55

Describe the normal partial pressure of carbon dioxide in alveoli and the pulmonary artery.

Answer 55

partial pressure of carbon dioxide in alveoli normally 40 mmHg, it’s 46 mmHg in the pulmonary artery.

Question 56

Define the impact of adding carbon dioxide to alveoli on the partial pressure gradient.

Answer 56

Adding carbon dioxide to alveoli reduces the partial pressure gradient, hindering carbon dioxide’s release from the blood.

Question 57

How does high levels of carbon dioxide in the blood affect the tissues?

Answer 57

High levels of carbon dioxide in the blood have a toxic effect on the tissues.

Question 58

Describe the response of the central chemo receptors to high levels of carbon dioxide in the blood.

Answer 58

High levels of carbon dioxide cause the central chemo receptors to signal the respiratory centres to hyperventilate.

Question 59

Do we actively inhibit respiration during swallowing?

Answer 59

Yes, respiration is actively inhibited during swallowing to prevent aspiration of food or fluid into the airways.

Question 60

How does the body ensure that particles of food are not inhaled or aspirated after swallowing?

Answer 60

Immediately after swallowing, the body performs a little exhalation to blow out any particles of food and ensure they don’t get inhaled or aspirated into the respiratory tract.