Respiratory System

Question 1

Which of the following statements is TRUE?

-blood in the bronchial arteries is deoxygenated
-blood in the pulmonary artery is deoxygenated
-the trachea is lined with D-shaped rings of cartilage
-the bronchial arteries carry blood from the right ventricle of the heart
-as the bronchial tree generation number increases the amount of cartilage increases

Answer 1

blood in the pulmonary artery is deoxygenated

Question 2

What process is responsible for the movement of oxygen and carbon dioxide across the respiratory membrane?

Answer 2

diffusion

Question 3

Which of the following best describes the pleural cavity?

-an air-filled cavity between the visceral pleura and the lung
-an air-filled cavity that is slightly higher than atmospheric pressure
-an air-filled cavity that is slightly lower than atmospheric pressure
-a fluid-filled cavity that makes sure the visceral and parietal pleurae remain attached
-a fluid filled cavity between the parietal pleura and the thoracic wall

Answer 3

a fluid-filled cavity that makes sure the visceral and parietal pleurae remain attached

Question 4

Which of the following is/are voluntary muscle(s)?

external intercostals
diaphragm
internal intercostals
abdominal muscle

Answer 4

All 4

Question 5

When it is really cold why is it better to breathe through your nose rather than your mouth?

Answer 5

the nasal cavity contains blood vessels that warms the inspired air

Question 6

What is the name of the respiratory variable that is measured using a spirometer when a subject takes a maximal inspiration and then exhales as completely as possible?

Answer 6

vital capacity

Question 7

Which of the following explain why the partial pressure of O2 in alveolar air is lower than in atmospheric air?

-alveoli contain a mixture of inspired and expired air
-the lungs are not completely emptied during each expiratory/inspiratory cycle.
-O2 diffuses out of the alveoli into the blood

Answer 7

All 3

Question 8

How much O2 does a 70 Kg normal man use at rest?

Answer 8

280 ml/min (4ml/min/kg at rest)

Question 9

Which of the following is the most important chemical regulator of breathing?

Answer 9

carbon dioxide

Question 10

The respiratory membrane consists primarily of which type of epithelium?

Answer 10

squamous epithelial cells

Question 11

Which of the following statements regarding inspiration is FALSE?

when the internal intercostal muscles contract they increase thoracic cavity volume

inspiration is produced by an increase in thoracic cavity volume

when the external intercostal muscles contract they increase thoracic cavity volume

when the diaphragm contracts it flattens

when the diaphragm contracts it increase thoracic cavity volume

Answer 11

when the internal intercostal muscles contract they increase thoracic cavity volume

Question 12

Which of the following would you NOT find in the lungs?

stretch receptors that detect the degree of stretching of the lungs

sympathetic neurones

parasympathetic neurones

irritant receptors that initiate the cough reflex

chemoreceptors that detect levels of CO2 in inspired air

Answer 12

chemoreceptors that detect levels of CO2 in inspired air

Question 13

Which of the following statements is/are TRUE?

-Lung compliance determines how easy it is to inflate the lungs
-Healthy young adults have low lung compliance
-People with cystic fibrosis have high lung compliance?

Answer 13

1 only

Question 14

Which of the following statements about O2 transport in the blood is TRUE?

-around 1.5% of O2 in the blood is bound to haemoglobin

-each Fe2+ atom can binds irreversibly to one molecule of O2

-each polypeptide in haemoglobin has hydrogen-containing core called a heme group

-haemoglobin consists of three polypeptide chains

-each heme group has a has a ferrous iron (Fe2+) atom at its core.

Answer 14

each heme group has a has a ferrous iron (Fe2+) atom at its core

Question 15

If you took a gas mixture containing 78.6% N2, 20.9% O2, 0.04% CO2 and 0.5% water vapour what would be the partial pressure of O2 at an altitude where the barometric pressure had fallen to 670 mmHg?

Answer 15

140 mmHg
(670x 0.209)

Question 16

How many cells does a gas have to pass through when it crosses the respiratory membrane?

Answer 16

2, two layers of squamous epithelial cells and their (fused) basal lamina

Question 17

Why is airway resistance so low in the later generations of the bronchial tree?

-Terminal bronchioles are so numerous that collectively they contribute little to the overall airway resistance.
-They are able to expand as the lungs expand during inspiration
-Their resistance reduces during inspiration

Answer 17

All 3

Question 18

Which of the following functions is part of external respiration?

-the transport of O2 in the blood

-the expulsion of air carrying CO2 during expiration

-the movement of CO2 from peripheral tissues into the blood

-the transport of O2 in the blood supplying peripheral tissues

-the movement of CO2 from blood draining from peripheral tissues into air to be expired

Answer 18

the movement of CO2 from blood draining from peripheral tissues into air to be expired

Question 19

What does spirometer contain?

Answer 19

Pulley, recorder, counter weight, floating drum, water filled drum, mouthpiece

Question 20

Why is spirometer values different for patient when sitting compared to standing

Answer 20

Ribs constricting breathing when lying down and the force of gravity while standing allows maximal contraction of diaphragm

Question 21

What are variables that causes differences in spirometer readings between patients?

Answer 21

Sex, age, weight, height, ethnicity

Question 22

What is a good FEV1/FVC ratio?

Answer 22

More than 80%

Question 23

Why is FEV1 (rather than FVC) used to assess airway resistance clinically?

Answer 23

To measure size of airway which determines how quickly volume of air can escape. FVC is measure of total air expired so it is less useful in detecting obstructions

Question 24

Why is FEV1/FVC a more useful measure of airway resistance when comparing values from different patients?

Answer 24

Accounts for age/sex/height/weight variations. True measure of effectiveness of lung expiration and therefore lung health. If FEV1 close to FVC, % will be high

Question 25

When you hold your breath, what processes make you breathe eventually?

Answer 25

Increased CO2 signals chemoreceptors which sends signal to dorsal and ventral communicating centres in respiratory centre of medulla oblongata which relays to abdominal and intercostal muscles to relax diaphragm

Question 26

What happens with exercise to change voluntary apnoea time

Answer 26

Increase of CO2 levels as increase of oxygen needed during exercise and CO2 needs to be expelled more rapidly Once inside the brain the CO2 reacts with H20 to form carbonic acid which then dissociates to form bicarbonate ions and H+ (as occurs in red blood cells). The central chemoreceptor neurones appear to be unusually sensitive to H+ concentration and through connections with the medullary and pons respiratory centres can directly influence the depth and frequency of ventilation to restore CO2 levels to normal.

Question 27

What sensory neurones do the lungs contain and what is their function? (Hint: 3 answers)

Answer 27

Stretch receptors- detect degree of stretching in lungs, during inspiration Irritant receptors- detect chemicals or irritants that could damage lungs, initiate cough reflex Nociceptors- detect pain in pleurae

Question 28

What is partial pressure of 75% N2 gas mixture at sea level?

Answer 28

760x 0.75= 570 mmHg

Question 29

Oxygen has solubility coefficient of 0.03 ml/L/mmHg. How much O2 would be dissolved in liquid at sea level. O2 20% in gas mixture

Answer 29

760x0.2= 152 mmHg 152 x 0.03 =4.56 mL/L

Question 30

CO2 has solubility coefficient of 0.680ml/L/mmHg. How much CO2 would be dissolved in liquid at altitude where barometric pressure has fallen to 510mmHg. CO2 1% in gas mixture

Answer 30

510x0.01= 5.1mmHg 5.1x0.680 =3.47mL/L

Question 31

Air moves into the lungs during inspiration because why?

Answer 31

Pressure in lungs is less than atmospheric pressure

Question 32

What is pulmonary ventilation?

Answer 32

Movement of air into and out of lungs

Question 33

Most of oxygen transported by blood is transported how?

Answer 33

Bound to haemoglobin

Question 34

Most of CO2 in blood is transported by what?

Answer 34

Bicarbonate ions

Question 35

Which statement about the trachea is FALSE? -Trachea is lined with pseudostratified columnar epithelial cells -Trachea wall contains C shape cartilages -Lining of trachea contains many mucous glands -Cilia lining walls of trachea push mucus and embedded particles back up into pharynx -Trachea contains bands of smooth muscle that helps move air into the lungs

Answer 35

Trachea contains bands of smooth muscle that helps move air into the lungs: The smooth muscle layer permits the oesophagus to protrude into the trachea during swallowing.

Question 36

What is external respiration?

Answer 36

The transfer of the O2 in inspired air to blood supplying peripheral tissues and the removal of CO2 from blood draining from peripheral tissues into air destined to be expired.

Question 37

What is gas transport?

Answer 37

The transport of O2 in the blood supplying peripheral tissues and CO2 draining from peripheral tissues

Question 38

What is internal respiration?

Answer 38

The delivery of O2 to cells of peripheral tissues and the removal of CO2 from these cells by gas exchange.

Question 39

What is order of pleurae from outermost to innermost?

Answer 39

Parietal pleura, pleural cavity, visceral pleura

Question 40

What happens to bronchi structure as generation number increases?

Answer 40

Diameter, cartilage, mucus secreting cells and cilia decrease. Smooth muscle increases. At generation 4 becomes bronchioles. At generation 16 terminal bronchioles as no gas exchange. At generation 17 alveoli appear and gas exchange occurs and are respiratory bronchioles. Divide into alveolar ducts and at generation 23 are alveolar sacs

Question 41

How do lungs get supplied with blood?

Answer 41

Pulmonary arteries carry deoxygenated blood from RV into capillaries and gas exchange oxygenates blood and is returned to heart via pulmonary veins. Bronchial arteries from LV contain oxygen branch and provide oxygenated blood to conducting airways and associated tissues so they can continue to perform oxidative metabolism that is required for them to function

Question 42

What is relationship between intrapleural pressure, pulmonary pressure and lung volume during inspiration and expiration

Answer 42

Inspiration: lung volume and pulmonary pressure increase, intrapleural pressure decreases Expiration: lung volume and pulmonary pressure decrease, intrapleural pressure increases

Question 43

What cells synthesise surfactant (covers alveoli) and what does surfactant do?

Answer 43

Type 2 alveolar cells. Decreases surface tension of alveoli. This surfactant is important because: (i) The pressure required to stop the alveoli collapsing is reduced. (ii) The pressure required to inflate the alveoli during inspiration is much smaller. (iii) The increased compliance means that less energy is required for inspiration.

Question 44

What is Poiseuille’s Law?

Answer 44

indicates that this resistance is directly proportional to the viscosity of the fluid and the length of the tube, and inversely proportional to the radius to the power of four (4). This means that the airflow is very sensitive to minor changes in airway diameter.

Question 45

What are type 1 alveolar cells?

Answer 45

form 90% of the surface area the walls of each alveolus. These are thin and flat squamous epithelial cells supported by a thin basal lamina.

Question 46

What are alveolar macrophages?

Answer 46

move freely around the inner surface of alveoli and between alveoli. These cells find and then phagocytose the large numbers of particles and micro organisms that find their way into the alveoli with each inspiration. They are swept back up through the airways by the movements caused by the beating of cilia and are eventually swallowed or expectorated.

Question 47

What is the basal lamina?

Answer 47

Support endothelium (squamous epithelial cells) in bronchial capillaries. Together with 2 layers of squamous epithelial cells, they are the barriers between air in alveoli and blood flowing through pulmonary capillaries (respiratory membrane)

Question 48

What are the 2 gas laws in understanding the concentrations of gases on either side of the respiratory membrane?

Answer 48

Daltons Law- PTotal = PN2 + PO2 + PCO2 + PH2O Henry's Law- V = s.P V = volume of gas (in ml) dissolved in 1 litre of a liquid, s = solubility coefficient (in ml/L/mmHg) and P = partial pressure of the gas (in mmHg)

Question 49

How does the pons assist in control of respiration?

Answer 49

Modulate basic pattern of inspiration and expiration by number of nuclei. Respiratory centres smooth out coarse pattern of breathing generated by medulla. Pneumotaxic centre inhibits medullary respiratory centres. Apneustic centres excite medulla

Question 50

How does arterial pH affect control of respiration?

Answer 50

Declining pH (elevated H+ concentration) stimulates increased ventilation in order to remove CO2 and thereby reducing carbonic acid formation and the subsequent production of H+ when it dissociates. As the blood-brain barrier has a low permeability to H+ the central chemoreceptors in the medulla are not able to detect direct changes in arterial pH. Instead the peripheral chemoreceptors in the aortic arch and carotid bodies perform this function in addition to the O2 sensing role.