Respiratory Mechanisms

Question 1

Describe how vesicular breath sounds sound, where are they normally heard?

Answer 1

Sound rusty and less harsh than bronchial breath sounds
Inspiratory phase longer than expiratory phase
They are normally heard at the lung surfaces

RIV rusty inspiratory vesicular

Question 2

Describe how bronchial breath sounds sound, where are they normally heard?

Answer 2

Harsher
Expiratory phase > inspiratory phase (gap)
Heard normally over trachea in chest (large airway)

Question 3

What is FVC forced vital capacity?

Answer 3

Maximum amount of air than can be forced out of the lungs after a deep breath in

Question 4

What is FEV1 forced expiratory volume in 1 second?

Answer 4

Amount of air that can be forced out of the lungs in the 1st second after a deep breath in

Question 5

What does the definitions of V (ventilation) and Q (perfusion) in the V/Q ratio mean and what is the normal human range?

ideally 1

Answer 5

0.8-1.2
Alveolar ventilation: (breaths per min) x [the amount of air entering the alveoli (tidal volume) - amount of air in the anatomical dead space]

Perfusion: blood flow through the pulmonary capillary surrounding the alveoli

Question 6

What is the Henderson-Hasselbach equation?

Answer 6

pH=pK + log ([HCO3-]/([pCO2]x0.23))

Question 7

Where is HCO3- reabsorbed in the nephron?

And how?

Answer 7

PCT: glutamine -> a-ketoglutarate -> 2HCO3- -> basolateral membrane Na/HCO3- cotransporter to ECF

DCT: CO2 + H20 in a-intercalated cell -> H+ + HCO3- -> basolateral membrane Cl/HCO3- exchanger to ECF

Question 8

Where is H+ secreted in the nephron?

And how?

Answer 8

PCT: glutamine -> NH4+ -> NH3 + H+ -> NH3 freely move into lumen and H+ pumped into lumen -> NH3 + H+ -> NH4+ excreted

DCT: CO2 + H20 in a-intercalated cell -> H+ + HCO3- -> H+ actively pumped out of apical surface -> H+ + HPO4- -> H2PO4- excreted

Question 9

The anion gap is the difference between measured cations and anions.

What is the anion gap equation and normal value range?

Answer 9

10-18 mmol.l-1

[(Na+) + (K+)] - [(Cl-) + (HCO3-)]

Question 10

Name the 3 forms that CO2 is transported from the tissue to the lungs and their relative percentages

1.8mmol.l-1 of total CO2 in venous and arterial is transported to lungs, the remaining CO2 stays in the venous and arterial blood to act as a buffer

Answer 10

60% hydrogen carbonate HCO3-
30% carbamino compound (CO2 + protein of Hb)
10% dissolved CO2

Question 11

Name 2 peripheral chemoreceptors, where are they found, what nerves innervate them and what do they detect?

Answer 11

Carotid bodies found at the bifurcation of the common carotid artery, innervated by glossopharyngeal CN IX nerve

Aortic bodies found at the arch of the aorta, innervated by vagus CN X nerve

Both detect a change in partial pressure of oxygen in the blood (pO2)

Question 12

If blood pH decreases, what will happen to the oxygen-haemoglobin dissociation curve, what state of haemoglobin will be present and what will haemoglobin’s affinity for oxygen be?

Answer 12

Shift to right
T state haemoglobin (tense)
Lower affinity for oxygen

Question 13

What are the axis’ on a Compliance curve?

Name 2 conditions that increases lungs compliance.

Name 2 conditions that decrease the lungs compliance.

Answer 13

x: kpa y: volume

Increase: Emphysema (due to loss of elastic tissue), COPD (due to loss of alveoli)
Decrease: Fibrotic lung and pulmonary embolism

Question 14

Where is surfactant found in the lungs?

If surfactant levels are high, what does this do to surface tension and what does this mean?

Answer 14

In the lining of liquid inside the alveoli (surfactant reduces the liquids surface tension)

Surface tension reduces

Question 15

The minute volume is also called what?

And, how do you calculate it?

Answer 15

Pulmonary ventilation rate

tidal volume x rr

Question 16

At the resting expiratory level, how does the chest wall elasticity (pulling it outwards) cause a more negative intrapleural pressure (-3 kPa) compared to the atmospheric pressure (0 kPa)?

Answer 16

The parietal pleural being pulled out and away from the visceral pleura leads to the intrapleural volume increasing so its pressure decreases.

Question 17

Describe how inspired air is warmed and humidified

Answer 17

Paranasal sinuses and Vascula mucosa on turbinates/conchae warm and humidify

Conchae also increases the SA:V for inspired air causing turbulent flow so have more time for moisture and humidification

Question 18

Describe how inspired air is filtered

Answer 18

1. Nose hairs trap particles
2. Goblet cells release mucus that trap particles <5micrometers
3. Cilia sweeps mucus down to oropharynx

Question 19

List the 4 parts of the parietal pleura and their innervations

Answer 19

Cervical pleura
Costal pleura (intercostal nerve)
Mediastinal pleura (phrenic nerve)
Diaphragmatic pleura (central: phrenic nerve. lateral: intercostal nerve)