2.1 Structure and function of the ventilatory system

Question 1

What are the three main functions of the conducting airways?

Answer 1

• Low resistance pathway for airflow
• Defence against chemicals and other harmful substances that are inhaled
• Warming and moistening the air

Question 2

Outline the function of low resistance

Answer 2

Nasal passages are a low resistance pathway for airflow. Allows ventilation to occur easily. Important for supplying the body with oxygen.

Question 3

Outline the function of defence

Answer 3

The nose and throat contain tiny hairs, called cilia. They filter the air and trap particles that are present. This stops them from entering the lungs and causing infections.

Question 4

Outline the function of warming and moistening the air

Answer 4

Air needs to be warmed to aid with thermoregulation of the body - cold air in the lungs could cause capillaries to vasoconstrict (get smaller). Environment of the lungs needs to remain moist to allow for gas exchange to take place. The nose and trachea moisten the air that is inspired.

Question 5

Define pulmonary ventilation

Answer 5

Inflow and outflow of air between the atmosphere and the lungs (also called breathing)

Question 6

Define total lung capacity (TLC)

Answer 6

Volume of air in the lungs after a maximum inhalation

Question 7

Define vital capacity (VC)

Answer 7

Maximum volume of air that can be exhaled after a maximum inhalation

Question 8

Define tidal volume

Answer 8

Volume of air breathing in and out in any one breath during normal breathing

Question 9

Define expiratory reserve volume

Answer 9

Volume of air in excess of tidal volume that can be exhaled forcibly

Question 10

Define inspiratory reserve volume

Answer 10

Additional inspired air over and above tidal volume

Question 11

Define residual volume

Answer 11

Volume of air still contained in the lungs after a maximal exhalation

Question 12

Draw the pulmonary ventilation diagram

Question 13

Explain the mechanics of ventilation regarding inspiration

Answer 13

External intercostal muscles contract which makes the ribs move up and out. This lowers the pressure relative to the outside pressure. The volume increases. This all makes air move into the lungs. Air moves from high to low pressure. Diaphragm contracts which increases volume.

Question 14

Explain the mechanics of ventilation regarding expiration

Answer 14

Internal intercostal muscles relax which makes the ribs fall. This decreases the volume in the lungs which increases the air pressure relative to the air outside. This all makes air move out of the lungs. Air moves high to low pressure. Diaphragm relaxes which decreases the volume.

Question 15

What is haemoglobin?

Answer 15

Main protein in the red blood cells that transports oxygen around the body

Question 16

Where are red blood cells produced?

Answer 16

Erythrocytes (red blood cells) are found i the red bon marrow (spongey bone) of long bones

Question 17

Which hormone regulates the production of haemoglobin?

Answer 17

Erythropoetin (EPO)

Question 18

In what form is oxygen transported?

Answer 18

Oxyhaemoglobin - the bond is unstable and reversible

Question 19

How does the shape of an alveoli maximise surface area?

Answer 19

The air that is breathed in fills the sack. The alveoli has a large surface area which allows for a faster diffusion of gases. Balloon-like structure.

Question 20

DON’T FORGET TO PRACTICE LABELLING THESE THINGS

Answer 20

diagram of ventilatory system
diagram of breathing patterns
how air comes in and out of the lungs
diagrams of alveolus and capillary

Question 21

How does the structure of an alveolus and capillary allows for gaseous exchange to take place?

Answer 21

Alveolus packed with oxygen and capillaries packed with CO2. Diffusion makes O2 and CO2 want to move to a lower concentration. CO2 is unloaded into the lungs while haemoglobin takes on the O2.

Question 22

Explain the concepts of diffusion (fick’s law)

Answer 22

‘The rate of diffusion is proportional to both the surface area and concentration difference and is inversely proportional to the thickness of the membrane’
—> rate of diffusion (weird x - is proportional to) (surface area x concentration difference)/thickness of membrane

Question 23

What are the factors that make the rate of diffusion double?

Answer 23

• Surface area or concentration difference is doubled
• Thickness of the exchange membrane is halved
• Exchange surfaces consist of cell membranes which are thin and this allows fast diffusion (high concentration to low concentration) across membranes

Question 24

What is partial pressure (Dalton’s law)?

Answer 24

Dalton’s law states that in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases
Dissolved gases always diffuse down their partial pressure gradients (high pressure to low pressure)

Question 25

What is respiration?

Answer 25

Cell respiration is the controlled release of energy in the form of adenosine triphosphate (ATP) from organic compounds in cells

Question 26

What is the difference between aerobic and anaerobic respiration?

Answer 26

Aerobic respiration produces ATP in the presence of oxygen whilst anaerobic respiration produces ATP without the presence of oxygen

Question 27

What happens to lactic acid and H+ ions during anaerobic respiration?

Answer 27

Lactic acid and H+ ions accumulate faster, further decreasing the pH of the blood

Question 28

What are the three neural controls of ventilation?

Answer 28

Lung stretch receptors
Muscle proprioceptors
Central chemoreceptors and Peripheral chemoreceptors

Question 29

Where can central chemoreceptors be found?

Answer 29

In the medulla (brain stem)

Question 30

Where can peripheral chemoreceptors be found?

Answer 30

In the aortic arch

Question 31

What do the chemoreceptors do?

Answer 31

They sense changes in CO2 levels in the blood - receives info about chemicals in the blood - tells us when to breath more when we exercise

Question 32

How do muscle proprioceptors help us to regulate ventilation?

Answer 32

During exercise they send signals to the brain to increase rate and depth of ventilation. Increase the removal of CO2. Senses movement.

Question 33

How do lung stretch receptors help regulate ventilation?

Answer 33

When they are excessively stretched, signals are sent to the expiratory centre to shorten inspiration.
This protects the lungs by decreasing the risk of over inflation of the alveoli.
This is known as the Hering-Breuer reflex

Question 34

Why does ventilation increase in regards to blood acidity levels?

Answer 34

Ventilation increases as a direct result of increases in blood acidity levels (low pH).
This is due to increased carbon dioxide content of the blood.

Question 35

How does ventilation change in relation to the blood acidity levels?

Answer 35

Ventilation increases as a direct result of increases in blood acidity levels (low pH) due to increased carbon dioxide content of the blood detected by the respiratory centre. Resulting in an increase in the rate and depth of ventilation

Question 36

Equation of minute ventilation

Answer 36

Minute ventilation = tidal volume x number of breaths per minute

Question 36

What happens to minute ventilation during exercise?

Answer 36

It increases due to tidal volume and breaths per minute increasing (breathing depth and rate).

Question 37

What do the neural controls of ventilation include?

Answer 37

Lung stretch receptors
Muscle proprioceptors (sensitive to pressure and tension)
Chemoreceptors (sense changes in CO2, O2, and pH

Question 38

What are other factors that could change ventilation?

Answer 38

Partial pressures, acidity, temperature, and hormones

Question 39

How can oxygen easily bind to haemoglobin in the lungs?

Answer 39

There is high partial pressure

Question 40

How does oxygen detach from haemoglobin?

Answer 40

In the active muscle where partial pressure is lower, oxygen detaches and diffuses into the blood into the active tissue

Question 41

How does the exchange of O2 and CO2 work in the muscle tissue?

Answer 41

The pressure gradient will drive O2 from blood into tissue and CO2 from tissue to blood

Question 42

What happens to the pressure gradient during exercise?

Answer 42

It becomes greater so more O2 can be used up

Question 43

Why do the lungs struggle during exercise?

Answer 43

They struggle to maintain resting partial pressure in the alveoli. Otherwise, exercise cannot be maintained for a long period of time.