intro to the respiratory system

Question 1

How many lobes are in the right lung?

Answer 1

The right lung has 3 lobes.

The superior lobe, the middle lobe and the inferior lobe.

Question 2

How many lobes are in the left lung?

Answer 2

The left lung has 2 lobes.

The superior and inferior lobe.

Question 3

The diaphragm is innervated by which nerve, of which system of the autonomic division and from which spinal nerve roots?

Answer 3

The left and right phrenic nerves innervate the diaphragm.

The phrenic nerves are from the vagus nerve, from C3,4&5.

Question 4

The internal and external intercostals are innervated by which nerve?

Answer 4

The intercostal muscles are innervated by thoracic nerves, under the parasympathetic nervous system.

Question 5

What is the role of the parietal pleura?

Answer 5

The parietal pleura is a serous membrane that lines the inside of the thorax. It prevents friction between the lungs surface and the inside of the ribcage during inspiration.

Question 6

What is the role of the visceral pleura?

Answer 6

Visceral pleura is the second serous membrane.

It lines the outside surface of the lungs, and makes contact with the parietal pleura and fluid.

Question 7

Name the key structures in the region of the upper airways.

Answer 7

The upper airways include everything between the mouth and nose and the larynx. This includes the nasopharynx, oropharynx and everything else above the larynx.

Question 8

Name the key structures in the region of the lower airways.

Answer 8

The lower airways include everything below the larynx. This includes the trachea, bronchi, bronchioles and the alveoli.

Question 9

What is the purpose of air passing through the nasopharynx?

Answer 9

The nasopharynx filters, warms and humidifies the incoming air. It ensures the air is core temperature on arrival in the lungs. Cilia filter for foreign particles.

Question 10

What is the purpose of the air passing through the larynx?

Answer 10

The larynx acts as a conduction tube for the air, directing it towards the trachea and lungs.

Question 11

Describe the special structure of the trachea.

Answer 11

The trachea is composed of:
c-shaped rings of cartilage, with a smooth muscle surface posteriorally to close it off from the eosophagus.
This cartilage prevetns the trachea from collapsing by making it sturdy.

Question 12

Describe the role of type 1 alveolar cells

Answer 12

These are the super thin, squamous cells that make up the respiratory membrane.
These cells make up 97% of the alveolar surface.
These cells are thin to enable diffusion of gases through them.

Question 13

Describe the role of type 2 alveolar cells.

Answer 13

These cells make up only 2% of the alveolar surface.

They produce surfactant and are involved in the repair of type 1 alveolar cells.

Question 14

what is surfactant used for in the alveoli?

Answer 14

Surfactant is needed to break up the surface tension of water on the alveolar surface. This stops water adhering to the respiratory membrane and blocking gas diffusion.

Question 15

Name the conducting vessels of the respiratory tree.

Answer 15

Trachea, brochi, the bronchioles, respiratory bronchioles and then the alveoli.

Question 16

Explain Boyle’s law

Answer 16

Boyle’s law states that pressure and volume are inversely proportional to each other.
Increase the volume, decrease the pressure and vice versa.

Question 17

Using pressure values, use Boyle’s law to explain how air moves in and out of the lungs.

Answer 17

Boyle’s law states that air moves from a region of high pressure to low pressure, across its pressure gradient.
During inspiration, the thoracic cage expands which increases the volume and decreases the air pressure inside to 759mmHg. The atmospheric air pressure is still 760mmHg, so air rushes into the lungs.
During expiration, the thoracic cage shrinks, its volume decreases and the pressure increases to 761 mmHg. This causes air to rush out of the lungs.

Question 18

What is the normal partial pressure of carbon dioxide in the blood?

Answer 18

35-40 mmHg

Question 19

What is the normal partial pressure of oxygen in the blood?

Answer 19

80-100 mmHg

Question 20

What is the normal bicarbonate concentration in the blood, in mmol/litre?

Answer 20

22-26 mmol/l

Question 21

What is the normal pH range of blood?

Answer 21

a pH of 7.35-7.45

Question 22

What region of our brain controls breathing rate?

Answer 22

The medulla oblongata, as part of the autonomic nervous system.

Question 23

Explain how central chemoreceptors feedback to the medulla about the state of our breathing.

Answer 23

A low breathing rate would lead to an increase in blood CO2 levels. CO2 dissociates in the blood to produce H+ ions and bicarbonate.
The increased H+ion levels (decreased pH) are detected by the chemoreceptors in the medulla. They send signals to the respiratory muscles that result in an increased rate and depth of ventilation.

Question 24

Explain how peripheral chemoreceptors feedback to the medulla about the state of breathing.

Answer 24

The peripheral chemoreceptors are found in the carotid sinus and the aorta.
Poor breathing would cause decreased oxygen levels in the blood, which are detected by the peripheral chemoreceptors. They would send a message to the medulla, and it would trigger the respiratory muscles and increase depth and rate of ventilation.

Question 25

The lungs are innervated by the sympathetic nervous system. Which nerves, neurotransmitters and receptors do this?

Answer 25

The thoracic and cervical ganglia from the sympathetic chain innervate the lungs.
NA and A are released from the postganglionic neurons and bind to the Beta-2 receptors and cause bronchial smooth muscle relaxation (bronchodilation).

Question 26

The lungs are also innervated by the parasympathetic nervous system. Which nerves, neurotransmitters and receptors do this?

Answer 26

Branches of the vagus nerve innervate the lungs.
They release acetylcholine from the postganglionic fibres, and bind to the M3 receptors to cause increased contraction of bronchial smooth muscle (this isn’t narrowing of the airways though).

Question 27

Define external gas exchange

Answer 27

External gas exchange occurs between the alveoli and the pulmonary blood of the alveolar capillaries.
CO2 leaves the blood to enter the alveoli and oxygen enters the blood and leaves the alveoli.

Question 28

Define internal gas exchange

Answer 28

Internal gas exchange occurs between the peripheral tissues and the capillary blood. CO2 enters the blood and leaves the tissues whilst oxygen leaves the blood and enters the tissues.

Question 29

Explain Oxygen diffusion in and out of the blood, along its pressure gradient. (in the alveoli and in the tissue)

Answer 29

1. The oxygen pressure is higher in the air than in the alveolar blood, thus oxygen diffuses into the blood along this gradient.
2. In the tissues, the O2 pressure is lower in the tissues than in the blood, so oxygen dissociates from haemoglobin and enters the tissues.

Question 30

Define Dalton’s law.

Answer 30

Dalton’s law states that the total pressure of a mixture of gases is equal to the sum of partial pressures of each of the individual gases.

Question 31

what percentage of the air is made up of nitrogen?

Answer 31

79%

Question 32

What percentage of the air is made up of oxygen?

Answer 32

21%

Question 33

Using our atmospheric pressure as an example, explain Dalton’s law.

Answer 33

The total atmospheric pressure at sea level is 760 mmHg.

This is because the partial pressure of nitrogen gas is 598 mmHg, oxygen is 160 mmHg and carbon dioxide is 0.2 mmHg.

Question 34

The Pa02 in the alveoli is 160 mmHg and in the tissues it is 40 mmHg. In which direction will the oxygen move?

Answer 34

The pressure is lower in the pulomary blood of the alveolar capillaries, thus the oxygen gas will diffuse into the blood.

Question 35

The PaC02 in the alveoli is 0.2 mmHg and in the tissues it is 46 mmHg. In which direction will the oxygen move?

Answer 35

The pressure is lower in the atmosphere (other side of the alveoli) than in the tissues. Thus, C02 will diffuse out into the air.

Question 36

Explain Fick’s law.

Answer 36

Fick’s law refers to diffusion. It states that the thinner the membrane of diffusion, the easier it is for the substance to pass through it.

Question 37

Name the two main ways that oxygen gas is transported within the body.

Answer 37

1. Dissolved in blood plasma

2. Attached to haemoglobin

Question 38

Name the three main ways that carbon dioxide is transported within the body.

Answer 38

1. Dissolved in the blood plasma
2. Attached to haemoglobin
3. As bicarbonate (HCO3-)

Question 39

How does haemoglobin know to release its oxygen molecule once it reaches the tissues?

Answer 39

The tissues have the lowest concentration of oxygen in the body. In low concentrations of oxygen is where haemoglobin has the lowest affinity for it, thus it is willing to release it. The opposite is also true.

Question 40

Define the tidal volume (lung volume)

Answer 40

the amount of air moving in and out of the lungs in a single, quiet breath. (500 mls)

Question 41

Define the minute volume (lung volume)

Answer 41

the amount of air moving in and out of the entire respiratory tract in 1 minute (6 litres per minute)

Question 42

Define the residual volume (lung volume)

Answer 42

the volume of air left in the lungs that cannot be removed, even with maximum expiration. This air is left in the lung to keep it inflated.

Question 43

Define the functional residual capacity (lung volume)

Answer 43

this is the amount of air left in the lungs at the end of each, normal breath. This is in addition to, the residual volume.

Question 44

Define the total lung capacity (lung volume)

Answer 44

This is the maximum amount of air that the lung can hold when fully inflated.

Question 45

Define the inspiratory reserve (lung volume)

Answer 45

the maximum amount of additional air that you can breathe into the lungs, within one breath.

Question 46

Define the expiratory reserve (lung volume)

Answer 46

the maximum amount of air inside your lungs, that you can breathe out within one breath.

Question 47

Define the vital capacity (lung volume)

Answer 47

this is a measure of how much air would move in and out of your lungs if you took the biggest breath you could and then did the biggest exhalation ever. The difference between the two would be the vital capacity.

Question 48

Name some changes to the respiratory system that occur because of aging.

Answer 48

1. reduced collagen production (decreased lung smooth muscle compliance)
2. reduction in the number of cilia in the airway linings (increased infection risk)
3. decreased functioning of lung parenchymal cells (lower diffusion capacity)
   - these changes all lead to lower levels of oxygenation in the elderly.