Respiratory System Lectures (Maria)

Question 1

What is the purpose of mucus in the airway?

Answer 1

To trap and dispose of bacteria (via macrophages), contains surfactant to prevent air sacs from sticking together, reducing surface area.

Question 2

Which cells secrete protective and defensive mediators in the respiratory system? Where are these cells located?

Answer 2

Goblet cells in the trachea and bronchi, club cells in the bronchioles and alveoli

Question 3

What are the similarities and differences between goblet cells and club cells?

Answer 3

Both secrete protective and defensive mediators. However, goblet cells secrete mucus whereas club cells produce watery secretions more suitable to smaller airways.

Question 4

What are type I pneumocytes?

Answer 4

Squamous cells responsible for gas exchange

Question 5

What are squamous cells?

Answer 5

Thin flat cells, specialised for high SA.

Question 6

What is the structure of the respiratory epithelium?

Answer 6

Type I pneumocytes line the atmospheric side, capillary endothelium lines the capillary lumen. The basement membranes of the two are fused together.

Question 7

What roles does the respiratory system carry out?

Answer 7

• Gas exchange (no duh)
• Regulation of blood’s acid base balance (CO2)
• Activation and deactivation of circulating mediators
• Filtering debris from the blood

Question 8

How is blood pressure measured?

Answer 8

In mmHg, an old conventional format

Question 9

What are the three inputs for neuronal control of breathing? In what ways do the inputs differ?

Answer 9

Mechanoreceptors, chemoreceptors and the cerebral cortex.

Mechanoreceptors and chemoreceptors are part of a negative feedback loop whereas the cerebral cortex generates original signals

Question 10

What is the primary respiratory control centre? (Take an easy guess)

Answer 10

The medulla

Question 11

What do PO2 and PaO2 mean?

Answer 11

Partial pressure of oxygen (kPa or Pa)

Partial pressure of arterial oxygen (mmHg)

Question 12

In what two ways is respiration controlled?

Answer 12

Neurally and chemically

Question 13

What is the pre-Botzinger complex of the medulla responsible for?

Answer 13

It produces a rhythmic discharge responsible for the contraction of the diaphragm

Question 14

What part of the brain is responsible for voluntary control of breathing?

Answer 14

The cerebral cortex

Question 15

In terms of breathing what is the cerebral cortex sensitive to?

Answer 15

Changes in temperature

Emotion

Question 16

How do lung transplants affect the innervation of the respiratory system? Why and why not?

Answer 16

Ventilation maintained since due to skeletal muscles

Partial loss of cough stimulation due to lower airway being swapped, tracheal stimulation maintained

Question 17

What two types of chemoreceptors are responsible for chemical control of respiration? What do they detect?

Answer 17

Central chemoreceptors - Detect [H+] and PCO2

Peripheral chemoreceptors - PO2, some input from [H+]

Question 18

Where are the peripheral chemoreceptors of respiration located?

Answer 18

In the carotid and aortic bodies

Question 19

Where are the central chemoreceptors for respiration located?

Answer 19

In the brain (specifically throughout the brainstem).

Question 20

What is the function of the gloms cells?

Answer 20

They are responsible for peripheral chemoreception of respiration. They detect changes in PO2

Question 21

In what way is the binding of O2 to Hb cooperative?

Answer 21

If a molecule of O2 binds to Hb, it makes it easier for a successive molecule of O2 to bind to Hb. In this way the process can be described as cooperative.

Question 22

In what forms is oxygen transported around the body?

Answer 22

• Bound to haemoglobin
• Dissolved in the blood

Question 23

What causes O2 to dissociate from Hb in low oxygen tissues?

Answer 23

Low oxygen tissues have a high CO2 conc. This lowers the pH of the blood, promoting the dissociation of O2 from Hb.

Question 24

What is the purpose of myoglobin?

Answer 24

To capture additional O2 from oxygenated blood in order to sufficiently supply cardiac and skeletal muscles with oxygen.

Question 25

Where is myoglobin located?

Answer 25

In the cardiac and skeletal muscles

Question 26

In what ways does myoglobin differ to haemoglobin?

Answer 26

- Myoglobin doesn't bind cooperatively whereas Hb does - Myoglobin's affinity isn't affected by pH or CO2 unlike Hb - Myoglobin has a single binding site whereas Hb has 4

Question 27

How do the association curves of Hb and Mb with oxygen differ?

Answer 27

Mb's saturation increases much more rapidly than Hb's.

Question 28

How is CO2 transported in the circulatory system?

Answer 28

Majority (70%) transported as HCO3-. Some CO2 is bound to Hb and a small quantity is dissolved.

Question 29

In which part of the body would the pO2 be the highest? Why?

Answer 29

In the alveolus and the pulmonary vein. This is because these are the blood vessels associated with blood oxygenation, or the ones thereafter.

Question 30

What is the Haldane effect?

Answer 30

The effect describing how Hb can carry increased quantities of CO2 in the deoxygenated state, but decreased quantities in the oxygenated state.

Question 31

What is ventilation perfusion matching? Why is it important?

Answer 31

Ventilation perfusion matching describes the way in which gas exchange in the alveoli ideally matches its level of blood perfusion. Without these two variables matching up, many complications can arise such as the blood becoming hypoxic.

Question 32

What is the ideal ventilation perfusion ratio? Why?

Answer 32

V/Q = 1 When V/Q = 1 then there is no mismatch between perfusion and ventilation (which is observed in healthy bodies)

Question 33

What are the two possible alterations to V/Q? Explain what causes them.

Answer 33

Hypoxaemia (Low blood O2): An area with perfusion but no ventilation Hypercapnia (Increased CO2): Increased dead space; areas with ventilation but no perfusion

Question 34

Define dead space.

Answer 34

An area with ventilation but no perfusion.

Question 35

Why do changes in altitude affect the respiratory system?

Answer 35

At higher altitudes there are lesser O2 concentrations. Thus, you must breathe in more air in order for your body to maintain oxygen intake.

Question 36

How does the body respond to an increase in altitude (and therefore a prolonged decrease in oxygen)?

Answer 36

- Increased ventilation - Pulmonary vasoconstriction (to direct where most efficient) - Increased haematocrit

Question 37

What is the healthy pH range of arterial blood?

Answer 37

pH ~ 7.36 to 7.44

Question 38

What organs are involved in determining the pH balance of the blood? In what ways are they involved?

Answer 38

Lungs - Regulates CO2 levels via ventilation Kidneys - Regulates HCO3- levels via filtration/generation and H+ via secretion

Question 39

What is the chemical formula for bicarbonate?

Answer 39

HCO3-

Question 40

What is the role of carbonic anhydrase?

Answer 40

Catalyses the reaction of carbon dioxide into carbonic acid.

Question 41

How can kidney or lung failure lead to an unhealthy blood pH?

Answer 41

Regulation of chemicals in the blood acid base balance is carried out via the lungs and the kidneys. Thus failure of either one can lead to the pH falling out of the healthy range.

Question 42

How is CO2 distributed in the blood? Provide general proportions and then percentages if possible)

Answer 42

10% is dissolved in plasma and RBCs 25-30% bound to Hb 60-65% converted into HCO3- and H+ Chloride shift offloads some HCO3- into the plasma