Physiology 4.3

Question 1

Describe the difference between the pressure of a gas in the blood and the gas content or concentration of that gas in the.

Answer 1

The partial pressure of a gas in the blood refers to the gas in solution in the plasma, determined by solubility and the partial pressure of the gas in the gaseous phase. Gas content or concentration refers to the total amount of the gas in the blood.

Question 2

Define arterial partial pressure of oxygen (PO2) and explain how it differs from arterial oxygen concentration or arterial oxygen content.

Answer 2

Arterial partial pressure of oxygen (PO2) refers to the amount of oxygen in solution in the plasma, determined by oxygen solubility and the partial pressure of oxygen in the gaseous phase. It differs from arterial oxygen concentration or content, which refers to the total amount of oxygen in the blood.

Question 3

How are total oxygen content and partial pressure of oxygen related, and how are they different?

Answer 3

Total oxygen content and partial pressure of oxygen are related, but not the same. The partial pressure of oxygen refers to the amount of oxygen in solution in the plasma, while total oxygen content refers to the overall amount of oxygen in the blood.

Question 4

Describe the relationship between the partial pressure of a gas in solution and the partial pressure in the gaseous phase at equilibrium.

Answer 4

The partial pressure of a gas in solution is equal to the partial pressure in the gaseous phase at equilibrium, where the same number of molecules move from the gaseous space to the liquid phase as in the opposite direction.

Question 5

Explain the concept of oxygen solubility in water and its impact on the partial pressure of oxygen in the plasma.

Answer 5

Oxygen solubility in water is low, with only 0.03mls of oxygen dissolving in every litre of water or plasma for every millimetre of mercury pressure applied to it. This means that the partial pressure driving oxygen into solution in the plasma must be 100 millimetres mercury to achieve three millilitres of oxygen in every litre of plasma.

Question 6

Describe the significance of the partial pressure of oxygen in arterial blood or plasma being 100 millimetres mercury.

Answer 6

When the partial pressure of oxygen in arterial blood or plasma is 100 millimetres mercury, it indicates that the partial pressure in the alveoli is also 100 millimetres mercury, signifying equilibrium. This is sometimes referred to as the oxygen tension.

Question 7

Describe the difference between partial pressure and concentration of a gas in a liquid phase.

Answer 7

Partial pressure depends on the form of the molecule, while concentration refers to the number of molecules per litre.

Question 8

Do gases move down a partial pressure gradient in the same way they move down a concentration gradient?

Answer 8

Yes, gases move down a partial pressure gradient in the same way they move down a concentration gradient.

Question 9

Define air embolism and its potential consequences.

Answer 9

An air embolism occurs when gas forms bubbles in the blood, which can be fatal if not treated.

Question 10

How does haemoglobin cooperatively bind oxygen molecules?

Answer 10

Haemoglobin cooperatively binds four molecules of oxygen, with one being bound to each haeme group in the haemoglobin molecule.

Question 11

Describe the composition of normal adult haemoglobin.

Answer 11

Normal adult haemoglobin is made up of two alpha chains and two beta chains, with 92 percent of our haemoglobin being in this form.

Question 12

What is the percentage of oxygen bound to haemoglobin in systemic arterial blood?

Answer 12

Ninety-eight percent of the oxygen in systemic arterial blood is bound to haemoglobin.

Question 13

Explain the difference between an oxygenation reaction and an oxidation reaction in the context of haemoglobin.

Answer 13

The binding of oxygen to haemoglobin is an oxygenation reaction, not an oxidation reaction, and it is a more fleeting and fragile interaction.

Question 14

Describe the potential consequences of having gas in the gaseous form in our plasma.

Answer 14

Having gas in the gaseous form in our plasma can lead to air embolisms, which can be fatal.

Question 15

How does the concentration of oxygen molecules per litre differ in the gaseous phase and the liquid phase?

Answer 15

The concentration of oxygen molecules per litre is different in the gaseous phase than in the liquid phase, with about 30 times more oxygen molecules in one litre of gas than in one litre of plasma.

Question 16

What is the significance of gases traveling in the plasma in solution rather than in the gaseous phase?

Answer 16

Gases traveling in the plasma in solution is important to prevent air embolisms, as having gas in the gaseous form in the blood can be fatal.

Question 17

Describe the composition of adult haemoglobin in red blood cells.

Answer 17

Adult haemoglobin in red blood cells consists of two alpha chains and two beta chains.

Question 18

What is the significance of glycosylated haemoglobin in diabetes monitoring?

Answer 18

Glycosylated haemoglobin is important in monitoring diabetes and blood glucose control, as it reflects the patient’s blood glucose levels over a three-month period.

Question 19

Define myoglobin and its role in the body.

Answer 19

Myoglobin is an oxygen-carrying molecule found exclusively in cardiac and skeletal muscle. It has a higher affinity for oxygen than haemoglobin and tends to store oxygen.

Question 20

How does myoglobin differ from haemoglobin in terms of structure and function?

Answer 20

Myoglobin is made up of a single polypeptide chain with a haeme group, while haemoglobin is composed of four chains. Myoglobin has a higher affinity for oxygen and primarily stores oxygen, while haemoglobin transports oxygen.

Question 21

Describe the relationship between glycosylated haemoglobin and blood glucose control in diabetic patients.

Answer 21

Glycosylated haemoglobin reflects a diabetic patient’s ability to control their blood glucose over a three-month period. High levels of glycosylated haemoglobin indicate poor blood glucose control and frequent exposure to hyperglycaemia.

Question 22

What are the different types of haemoglobin found in the remaining eight percent of red blood cells?

Answer 22

The remaining eight percent of haemoglobin in red blood cells is composed of HBA2, foetal haemoglobin, and glycosylated haemoglobin, each with specific roles and clinical significance.

Question 23

Do myoglobin and haemoglobin have similar or different roles in oxygen transport?

Answer 23

Myoglobin and haemoglobin both carry oxygen, but myoglobin tends to store oxygen, while haemoglobin primarily transports oxygen.

Question 24

Describe the role of myoglobin in the body and its presence in the bloodstream.

Answer 24

Myoglobin is an oxygen-carrying molecule found exclusively in cardiac and skeletal muscle. It is not normally found in the bloodstream, except in cases of extensive muscle damage.

Question 25

How does glycosylated haemoglobin provide clinical insight into a diabetic patient’s condition?

Answer 25

High levels of glycosylated haemoglobin indicate poor blood glucose control over a three-month period, suggesting frequent exposure to hyperglycaemia and potential complications in diabetic patients.

Question 26

Describe the difference in oxygen affinity between myoglobin, foetal haemoglobin, and normal adult haemoglobin.

Answer 26

Myoglobin and foetal haemoglobin have a higher affinity for oxygen than normal adult haemoglobin.

Question 27

What is the advantage of foetal haemoglobin and myoglobin having a higher affinity for oxygen?

Answer 27

They can extract oxygen from normal adult haemoglobin, allowing the foetus to access maternal oxygen and muscles to extract more oxygen from the blood.

Question 28

Define the term ‘saturation of haemoglobin’ as used in the context of the content.

Answer 28

Saturation of haemoglobin refers to the percentage of haemoglobin molecules bound to oxygen at a given partial pressure of oxygen.

Question 29

How does the partial pressure of oxygen affect the saturation of haemoglobin for normal adult haemoglobin, foetal haemoglobin, and myoglobin?

Answer 29

At normal partial pressure of oxygen, all three molecules are 98% saturated. At lower partial pressures, foetal haemoglobin and myoglobin maintain higher saturation than normal adult haemoglobin.

Question 30

Describe the role of myoglobin in allowing muscles to extract more oxygen from the blood.

Answer 30

Myoglobin’s higher affinity for oxygen allows skeletal and cardiac muscles to extract more oxygen from the blood than they would otherwise be able to do.

Question 31

What is the clinical importance of foetal haemoglobin?

Answer 31

Foetal haemoglobin is important in allowing the foetus to access the oxygen in maternal blood, as it has a greater affinity for oxygen than maternal haemoglobin.

Question 32

Do myoglobin and foetal haemoglobin have a higher or lower affinity for oxygen compared to normal adult haemoglobin at the same partial pressure?

Answer 32

Both myoglobin and foetal haemoglobin have a much higher affinity for oxygen than normal adult haemoglobin at the same partial pressure.

Question 33

Describe the difference in oxygen saturation between myoglobin and normal adult haemoglobin at a partial pressure of about 6kPa.

Answer 33

At a partial pressure of about 6kPa, myoglobin is probably about 90% saturated, while normal adult haemoglobin is about 75% saturated.

Question 34

Describe hypoxaemic hypoxia.

Answer 34

Hypoxaemic hypoxia occurs due to a reduction in oxygen diffusion at the lungs, either from lung pathology or decreased oxygen partial pressure in the atmosphere, leading to inadequate oxygen supply to peripheral tissues.

Question 35

Define anaemic hypoxia.

Answer 35

Anaemic hypoxia results from a reduction in the oxygen carrying capacity of the blood, typically caused by conditions such as anaemia, red blood cell loss from haemorrhage, iron deficiency, or vitamin B12 deficiency.

Question 36

Describe stagnant hypoxia.

Answer 36

Stagnant hypoxia is characterized by inefficient pumping of blood to the lungs and around the body due to heart disease, leading to a stagnation of blood flow and inadequate oxygen delivery to tissues.

Question 37

Do you need to be aware of different types of hypoxia as a clinical student?

Answer 37

Yes, it’s important for clinical students to be aware of the five main types of hypoxia, including hypoxaemic, anaemic, and stagnant hypoxia, to understand their distinct causes and implications.

Question 38

How does living at altitude relate to hypoxaemic hypoxia?

Answer 38

Living at altitude exposes individuals to lower partial pressure of oxygen in the atmosphere, leading to reduced oxygen diffusion at the lungs and inadequate oxygen supply to peripheral tissues, resulting in hypoxaemic hypoxia.

Question 39

What are some causes of anaemic hypoxia?

Answer 39

Causes of anaemic hypoxia include red blood cell loss from haemorrhage, chronic blood loss from gastrointestinal pathology, iron deficiency, and vitamin B12 deficiency, all of which reduce the oxygen carrying capacity of the blood.

Question 40

How is stagnant hypoxia related to heart disease?

Answer 40

Stagnant hypoxia is linked to heart disease, where inefficient pumping of blood around the body results in stagnation of blood flow, leading to inadequate oxygen delivery to tissues despite normal oxygen diffusion and carrying capacity in the blood.

Question 41

Describe histotoxic hypoxia.

Answer 41

Histotoxicoxia occurs when cells are unable utilize the oxygen delivered to them, often due poisoning such as carbon monoxide or cyanide.

Question 42

What is metabolic hypoxia?

Answer 42

Metabolic hypoxia is when oxygen delivery to tissues does not meet the increased oxygen demand by the cells, which can be reversible and occur during exercise or as a chronic condition.

Question 43

Define partial pressure of oxygen in the blood.

Answer 43

Partial pressure of oxygen in the blood describes the amount of oxygen in the solution and the plasma, determining the total oxygen content of the blood by influencing the saturation of haemoglobin.

Question 44

How does foetal haemoglobin differ from adult haemoglobin?

Answer 44

Foetal haemoglobin, along with muscle myoglobin, has a greater affinity for oxygen than adult haemoglobin, allowing them to extract oxygen from the circulation.

Question 45

Describe the impact of carbon monoxide poisoning on oxygen utilization.

Answer 45

Carbon monoxide poisoning binds to haemoglobin with high affinity, preventing it from binding oxygen and thus inhibiting cells from accessing and utilizing oxygen.

Question 46

Do maternal and foetal circulation differ in terms of oxygen access?

Answer 46

Yes, foetal haemoglobin and muscle myoglobin have greater affinity for oxygen than adult haemoglobin, allowing them to extract oxygen from the maternal circulation that they would not otherwise have access to.