Lungs: anatomy, ventilation and gases

Question 1

The lungs are two cone shaped organs separated by the heart. Name the 4 surfaces of the lung:

Answer 1

1. Apex (extends above clavicle)
2. Base (over diaphragm)
3. Costal (rib) surface
4. Medial surface

Question 2

From what artery is blood supplied to the lungs?

Answer 2

Pulmonary artery

Question 3

How many lobes are there in the right and left lungs?

Answer 3

Left lung has 2 lobes (due to the heart)

Right lung has 3 lobes

Question 4

What are pleura?

Answer 4

Pleura are serous membranes that surround the lungs.

Question 5

Name the two layers of the pleura and the cavity between.

Answer 5

visceral layer, parietal layer and pleural cavity.

Question 6

The visceral and parietal pleura form a double layer separated by 5-10ml of serous fluid, what does the fluid do?

Answer 6

Prevent friction

Question 7

What is ventilation the process of?

Answer 7

Ventilation is the process through which O2 and CO2 are transported to and from the lungs.

Question 8

Name the two main phases of ventilation…

Answer 8

1. Inhalation

2. Exhalation

Question 9

Breathing can come from which two areas?

Answer 9

1. Abdominal (diaphragmatic) breathing (where most breathing should come from)
2. Upper rib breathing

Question 10

Name the two Primary ventilation muscles.

Answer 10

1. Intercostal muscles

2. Diaphragm

Question 11

Give examples of secondary ventilation muscles…

Answer 11

Trapezius, sternocleidomastoid and the scalenes.

Question 12

The average pair of human lungs can hold about six litres of air.
What does the term ‘tidal volume’ represent?

Answer 12

The normal volume of air that enters the lungs during inspiration when no extra effort is applied.

(a normal tidal volume is 500ml)

Question 13

Inspired air of gases:
Oxygen: 21%
Carbon Dioxide: 0.04%
Nitrogen and rare gases: 78%

Give the percentages of expired air per gas.

Answer 13

Oxygen: 16%
Carbon Dioxide 4%
Nitrogen and rare gases: 78%

Question 14

Fill in the missing word:

98.5% of oxygen in the blood is transported by ______ in red blood cells.

Answer 14

Haemoglobin (Hb)

Question 15

What do the terms ‘Oxyhaemoglobin’ and ‘Deoxyhaemoglobin’ mean?

Answer 15

Oxyhaemoglobin is when plenty of oxygen inbound to haemoglobin.

Deoxyhaemoglobin is haemoglobin that lacks oxygen.

Question 16

Why is oxygen an essential gas in the body?

Answer 16

Because cells use oxygen to create the energy that is required for various processes.

Question 17

What percentage of oxygen is dissolved in plasma?

Answer 17

1.5% of oxygen is dissolved in plasma

Question 18

Carbon dioxide diffuses into the blood from respiring cells easily. It is transported in the following 3 ways:

Answer 18

1. 70% found in plasma as HCO3- ( Bicarbonate)
2. 23% carried in red blood cells (bound to haemoglobin)
3. 7% dissolved in plasma (the water component of blood)

Question 19

Bicarbonate buffer reaction.

What does that mean?

Answer 19

Bicarbonate is alkaline, which buffers the acidity of blood to keep pH stable.

Question 20

Fill in the missing words:

CO2 diffuses down its concentration gradient from ____ into the ____.

Answer 20

tissues

blood

Question 21

Fill in the missing word:

Because of the high water content of blood, CO2 combines with water to produce _____.
(also name the chemical formula)

Answer 21

Carbonic acid

H2CO3

Question 22

As carbonic acid is unstable, it decomposes immediately into _______ and ___.

Answer 22

Bicarbonate and H+ (hydrogen ion)

Question 23

pH is the measure of acidity, alkalinity and neutrality.
Blood pH needs to be controlled within very narrow limits.
What does Low pH =
What does High pH =

Answer 23

Low pH = elevated H+ ion concentration > more acidic

High pH = more alkaline

Question 24

How does ventilation help to lower the acidity of body fluids?

Answer 24

Because ventilation means the exhalation of CO2. (Carbon dioxide)

Question 25

Raised CO2 levels causes a low pH (acidity) in the blood. What can this lead to?

Answer 25

Respiratory acidosis

Question 26

List the three ways in which increased acidity is managed by the body…

Answer 26

1. Buffer systems.
2. Increased exhalation of CO2
3. Kidney excretion of H+

Question 27

Cell respiration describes the process of energy production (ATP) within cells. Name the two ways energy is produced and give ATP yield.

Answer 27

1. Aerobic respiration = with oxygen
   38 ATP yield + water + CO2
   (36 net)
2. Anaerobic respiration = no oxygen
   2 ATP yield + lactic acid

Question 28

Where is the ‘respiratory centre’ located?

Answer 28

Located in the brainstem.

Medulla oblongata and pons

Question 29

What do chemical receptors in the brainstem measure?

Answer 29

CO2 and acidity (H+ concentration)

Question 30

What do chemical receptors in the aorta and carotid artery measure?

Answer 30

CO2, O2 and acidity levels

Question 31

What do stretch receptors in the walls of the bronchi and bronchioles detect?

Answer 31

over inflation