Physiology 3.2

Question 1

Describe the function the pulmonary circulation.

Answer 1

The pulmonary circulation is responsible for delivering carbon dioxide to the lungs picking up oxygen from the lungs.

Question 2

Define the bronchial circulation.

Answer 2

The bronchial circulation is a branch of the systemic circulation that delivers nutritive blood supply to the lungs, providing oxygen, nutrients, enzymes, and hormones to the lung tissue.

Question 3

How does the pulmonary artery differ from typical arteries?

Answer 3

The pulmonary artery carries deoxygenated blood away from the heart, unlike typical arteries that carry oxygenated blood.

Question 4

What is the role of the pulmonary vein in the pulmonary circulation?

Answer 4

The pulmonary vein carries oxygenated blood from the lungs towards the heart, serving as the opposite of typical veins by carrying oxygenated blood.

Question 5

Describe the relationship between the pulmonary circulation and the systemic circulation.

Answer 5

The pulmonary circulation is distinct from the systemic circulation, with opposite terminology and functions. The systemic circulation is about delivering oxygen to the tissues, while the pulmonary circulation is about picking up oxygen from the lungs.

Question 6

What is the significance of the bronchial circulation in relation to the left heart output?

Answer 6

The bronchial circulation comprises about two percent of left heart output, delivering oxygen, nutrients, and removing waste products from the lung tissue.

Question 7

Do the veins of the bronchial circulation dilute the oxygenated blood in the pulmonary veins?

Answer 7

Yes, the veins of the bronchial circulation, being systemic veins, dilute down the oxygenated blood in the pulmonary veins ever so slightly.

Question 8

How does the bronchial circulation differ from the pulmonary circulation in terms of blood flow direction?

Answer 8

The bronchial circulation delivers blood to the lungs, while the pulmonary circulation carries blood away from the heart to the lungs.

Question 9

Define the unique blood supply of the lungs.

Answer 9

The unique blood supply of the lungs includes the pulmonary circulation, which is distinct from the systemic circulation and is responsible for delivering carbon dioxide to the lungs and picking up oxygen from the lungs.

Question 10

Describe the difference between pulmonary circulation and bronchial circulation.

Answer 10

Pulmonary circulation is concerned with gas exchange, while bronchial circulation is concerned with supplying oxygen, nutrients, enzymes, and hormones.

Question 11

Define the components of the pulmonary circulation.

Answer 11

The pulmonary circulation consists of the left and right pulmonary arteries that originate from the right ventricle.

Question 12

How does the volume of blood flow through the pulmonary circulation compare to the rest of the body?

Answer 12

The volume of blood that goes through the pulmonary circulation per minute is the same volume of blood that goes round the rest of the body in one minute.

Question 13

Do the pulmonary circulation and systemic circulation operate in series or in parallel?

Answer 13

The pulmonary circulation is in series with the systemic circulation.

Question 14

Describe the pressure difference between the pulmonary circulation and the systemic circulation.

Answer 14

The pressure in the pulmonary circulation is much lower than the pressure in the systemic circulation, with a systolic over diastolic pressure of 25 over 10 compared to 120 over 80 in the systemic circulation.

Question 15

How does gas exchange occur in the pulmonary circulation and systemic circulation?

Answer 15

Gas exchange occurs between the alveoli and the pulmonary circulation, as well as between the systemic circulation and the peripheral tissues.

Question 16

What are the partial pressures of oxygen and carbon dioxide in the alveoli?

Answer 16

The partial pressure of oxygen in the alveoli is 100 mmHg, and the partial pressure of carbon dioxide is 40 mmHg.

Question 17

Describe the process of diffusion in the systemic arterial blood.

Answer 17

Provided there are no barriers to diffusion, diffusion takes place until equilibrium is reached, resulting in the same partial pressures in systemic arterial blood as in the alveoli.

Question 18

Describe the process of oxygen carbon dioxide exchange between arterial blood and peripheral tissues.

Answer 18

Oxygen is drawn out of arterial blood into peripheral tissues due to a partial pressure gradient, where it is metabolized through aerobic respiration. This constant metabolism leads to a pressure gradient that ensures oxygen is continuously drawn out of the blood. In turn, carbon dioxide is produced as a waste product and moves down a partial pressure gradient into venous blood.

Question 19

Define partial pressure gradient and its role in gas exchange.

Answer 19

Partial pressure gradient refers to the difference in partial pressure of a gas between two areas, such as arterial blood and peripheral tissues. In the context of gas exchange, it drives the movement of gases like oxygen and carbon dioxide between the blood and tissues, ensuring that oxygen is delivered to the cells and carbon dioxide is removed.

Question 20

How does the partial pressure of oxygen and carbon dioxide change as blood travels from systemic arteries to systemic veins?

Answer 20

The partial pressure of oxygen decreases from 40 mmHg in systemic arteries to 40 mmHg in systemic veins, reflecting its utilization in peripheral tissues. Conversely, the partial pressure of carbon dioxide increases from 40 mmHg in systemic arteries to 46 mmHg in systemic veins, reflecting its production in the tissues.

Question 21

Describe the role of the pulmonary artery in gas exchange.

Answer 21

The partial pressures in the pulmonary artery are the same as those in systemic veins, reflecting the gas exchange that occurs in the peripheral tissues. In the pulmonary artery, the partial pressure of oxygen is 40 mmHg, and the partial pressure of carbon dioxide is 46 mmHg, setting the stage for gas exchange in the alveoli.

Question 22

Do the partial pressure gradients for oxygen and carbon dioxide in the alveoli mirror those in the peripheral tissues?

Answer 22

Yes, the partial pressure gradients for oxygen and carbon dioxide in the alveoli are similar to those in the peripheral tissues, but they operate in the opposite direction. This results in carbon dioxide diffusing into the alveoli and oxygen diffusing into the pulmonary artery, facilitating gas exchange.

Question 23

Describe the relationship between systemic arterial partial pressures and alveolar partial pressures.

Answer 23

In a healthy state, systemic arterial partial pressures are expected to be the same as those found in the alveoli. This reflects the efficient exchange of gases between the lungs and the systemic circulation, ensuring that oxygen is delivered to the tissues and carbon dioxide is removed during respiration.

Question 24

Describe the abbreviations used to define partial pressures in different places.

Answer 24

Abbreviations include A for alveoli, little a arterial blood, and v for mixed venous.

Question 25

what is meant by a capital with a subscript a2.

Answer 25

It refers to the partial pressure of oxygen in arterial blood.

Question 26

How are the values for systemic arterial blood and alveoli related?

Answer 26

The values for systemic arterial blood are the same as those found in the alveoli.

Question 27

Do the values for venous blood reflect what’s going on in the tissues?

Answer 27

Yes, the values for venous blood reflect what’s going on in the tissues.

Question 28

Describe the units used for measurements and their relevance to clinical practice.

Answer 28

Millimetres of mercury are used in physiology, while kilopascals are used in clinical practice.

Question 29

What does a capital A refer to in the context of the discussion?

Answer 29

It refers to what’s going on in the alveoli.

Question 30

How do the values for the alveoli and systemic arterial blood differ?

Answer 30

The values for the alveoli and systemic arterial blood are the same.

Question 31

Define the abbreviation ‘v’ in the context of the discussion.

Answer 31

It refers to mixed venous blood, specifically systemic venous blood in the large veins or the pulmonary artery.

Question 32

Describe the process gas movement between the alveoli and blood.

Answer 32

Gas movement occurs by diffusion, following the rules of simple diffusion, across a permeable membrane down its partial pressure gradient.

Question 33

What factors affect the rate of diffusion of gases?

Answer 33

The rate of diffusion is directly proportional to the partial pressure gradient, gas solubility, and available surface area, and inversely proportional to the thickness of the membrane.

Question 34

Define partial pressure gradient in the context of gas diffusion.

Answer 34

Partial pressure gradient refers to the difference in partial pressure of a gas between two points, driving the diffusion of gases across a membrane.

Question 35

How does the partial pressure gradient for oxygen compare to that of carbon dioxide?

Answer 35

The partial pressure gradient for oxygen is 10 times greater than that of carbon dioxide, with a difference of 60 mmHg for oxygen and 6 mmHg for carbon dioxide.

Question 36

Do concentration gradients and partial pressure gradients work in the same way during gas diffusion?

Answer 36

While not identical, concentration gradients and partial pressure gradients work in a similar way, driving gases to move across a permeable membrane until equilibrium is reached.

Question 37

Describe the relationship between the rate of diffusion and the thickness of the membrane.

Answer 37

The rate of diffusion is inversely proportional to the thickness of the membrane, meaning that thinner membranes allow for faster diffusion.

Question 38

How does the solubility of a gas affect its diffusion across the alveolar membrane?

Answer 38

The more soluble a gas is, the easier and faster it will diffuse across the alveolar membrane, as it needs to be in solution to cross the membrane.

Question 39

What are the key factors that affect the rate of gas diffusion?

Answer 39

The rate of gas diffusion is affected by the partial pressure gradient, gas solubility, available surface area, and the thickness of the membrane.

Question 40

Describe the difference in diffusion rates between oxygen and carbon dioxide.

Answer 40

Oxygen diffuses slightly faster than carbon dioxide, but nowhere near 10 times faster. Oxygen diffuses at a rate of about 250 millilitres per minute, whereas carbon dioxide diffuses at 200 millilitres per minute.

Question 41

Define the concept of gas solubility and its importance in the context of diffusion.

Answer 41

Gas solubility refers to the ability of a gas to dissolve in a liquid. In the context of diffusion, it is important because a gas needs to be in solution in order to be able to diffuse across the alveolar membrane.

Question 42

How does the solubility of oxygen compare to that of carbon dioxide?

Answer 42

Oxygen is not very soluble in water, while carbon dioxide is very soluble.

Question 43

Do the partial pressure gradients alone determine the rate of diffusion for oxygen and carbon dioxide?

Answer 43

No, the partial pressure gradients are important, but the solubility of the gases also plays a crucial role in determining their diffusion rates.

Question 44

Describe the factors that affect the rate of diffusion.

Answer 44

The rate of diffusion is directly proportional to the available surface area, inversely proportional to the thickness of the membrane, and most rapid over short distances.

Question 45

What are the main points affected by pathologies that disrupt gas exchange?

Answer 45

Pathologies mainly affect the surface area, the thickness of the membrane, or the distance the gas has to travel.

Question 46

How does changing alveolar ventilation affect the partial pressure gradient?

Answer 46

Changing alveolar ventilation changes the partial pressure of gas in the alveoli, thereby altering the partial pressure gradient.

Question 47

Describe the significance of the big partial pressure gradient for oxygen in crossing the alveolar wall.

Answer 47

The big partial pressure gradient helps oxygen get across the alveolar wall, and it would struggle if it didn’t have this big partial pressure gradient.

Question 48

What becomes important when considering how oxygen diffuses and is carried in the blood?

Answer 48

The lack of solubility for oxygen becomes important when considering how it diffuses and is carried in the blood.

Question 49

Describe the surface area of the alveoli in comparison to a badminton court.

Answer 49

The surface area of the alveoli is equivalent to the surface of a badminton court, 80 square meters.

Question 50

How is the large surface area of the aloli accommodated within the lungs?

Answer 50

The large surface area of the alveoli is accommodated by crumpling it up and fitting it into the volume of six liters, which is the total lung capacity.

Question 51

Define the distance between the alveolar air space and the plasma found inside the capillary.

Answer 51

The distance between the alveolar air space and the plasma in the capillary is kept as short as possible to optimize gas exchange, with the type 1 alveolar cell directly abutting the endothelium in the capillary cells.

Question 52

Describe the role of elastic fibers in the alveoli.

Answer 52

Elastic fibers in the connective tissue between alveoli allow them to expand during inspiration and release energy during expiration to facilitate air movement.

Question 53

How is the distance for gas exchange between the blood vessel and the alveoli minimized?

Answer 53

The distance for gas exchange is minimized by the direct adjacency of the type 1 alveolar cell to the capillary, and the absence of elastic fibers between the blood cell and the type 1 alveolar cell.

Question 54

What is the significance of the thin membranes in the alveoli for gas exchange?

Answer 54

The thin membranes in the alveoli optimize gas exchange by minimizing the distance for gas exchange and facilitating efficient diffusion of gases.

Question 55

Describe the relationship between the endothelium and the type 1 alveolar cell.

Answer 55

The endothelium directly abuts the type 1 alveolar cell, forming the capillary wall and creating a very short distance for gas exchange in the capillaries.

Question 56

Do the elastic fibers sit between the blood cell and the type 1 alveolar cell?

Answer 56

No, the elastic fibers do not sit between the blood cell and the type 1 alveolar cell, minimizing the distance that the gas has to move for efficient gas exchange.

Question 57

How is the alveolar structure completely optimized for gas exchange?

Answer 57

The alveolar structure is optimized for gas exchange through a combination of large surface area, thin membranes, and a very short distance for gas exchange between the alveoli and the blood vessels.