Respiratory 3: cycle +mechanics

Question 1

Define respiration

Answer 1

To extract oxygen fro the air and together with the cardiovascular system transport it to respiring tissues
2. To remove carbon dioxide from respiring tissues and exhaust into the atmosphere

Question 2

As respiration evolved from diffusion in protozoa, to lungs in reptiles and mammals what were the main factors that drove the change

Answer 2

There was increase in the size of the tissue, therefore distance for diffusion increased.
Increase metabolic rate means more gas needed

Question 3

List the main muscles associated with breathing and their nervous innervation

Answer 3

Diaphragm is innervated by phrenic nerve which comes from phrenic motor nucleus (C3-C5)
-The internal (exp) and external (insp) intercostal muscles are innervated by the internal and external intercostal nerves that come from the intercostal motor neurones (T1-L1)

-The abdominal muscles are innervated by the abdominal nerve which comes from the abdominal motor neurones (T7-L1)

Question 4

Where do the nerves that innervate the muscles for breathing go to from the spinal cord

Answer 4

These motor neurons are excited by the brainstem (medulla oblongata +pons) which makes a neural rhythm to control expiration and inspiration to occur not at the same time. However there is the ability to voluntarily adjust breathing

Question 5

When are the abdominal muscles involved breathing

Answer 5

During active expiration. (eg cough, laugh, exercise) Doesn’t contract at rest.

Question 6

What is the intra pleural pressure vs the intra pulmonary pressure

Answer 6

The intra pleural pressure is the pressure inside the pleural cavity outside the lung and the intra pulmonary pressure is the pressure within the lung, within the respiratory zone prob

Question 7

How does the respiratory volume , intra pulmonary pressure and intra pleural pressure change during inspiration

Answer 7

The pleural pressure decreases from a negative pressure to an even more negative pressure. This causes the intra pulmonary pressure to go from atm down to negative pressure. This causes air to move from higher pressure (atm) to lower pressure, increasing volume of air in lungs. As volume increase to a peak the pulmonary pressure rises back up to atm (in a cup shape) .

Question 8

How does the respiratory volume , intra pulmonary pressure and intra pleural pressure change during exspiration

Answer 8

The intra pleural pressure starts to rise from its most negative point back to becoming less negative as air leaves. This causes the pulmonary pressure to become more positive relative to atm. This means that air moves out so the volume decreases from the peak of the bell curve back down to 0.

Question 9

Why is it important for the pleural cavity to have a negative pressure in regards

Answer 9

This means that the visceral and parietal membranes stick together joining the chest wall to the lungs. This means that the lung doesn’t collapse

Question 10

What is Pneumothorax

Answer 10

Thoracic puncture wound where air rushes into the chest and there is a loss of the negative pressure of the pleura. The lung moves away from the chest wall and deflates and its hard to maintain those changes in pressure to inflate the lungs

Question 11

How does the lungs inflate

Answer 11

As the diaphragm and intercostal muscles contract they increase the volume of the intra pleural space and this also increase the volume of the intra pulmonary space This means that the pressure of the intra pleural space decreases. As a result the atm tries to equalise the pressure by pushing air inside the lungs.

Question 12

How is lung volume measured

Answer 12

With spirometer where the oxygen volume in a floating drum (floating in water) is attached to a tube to breathe into means that while breathing you can push the drum up and down and measure the volume

Question 13

What is the difference between a respiratory volume and capacity

Answer 13

Volume is measured whereas capacity is calculated from the measured values

Question 14

What is the tidal volume

Answer 14

This is the normal resting volume that comes in when you breath (peak to trough)

Question 15

What is the inspiratory reserve volume vs the expiratory reserve volume

Answer 15

Inspiratory reserve is the maximum volume that can be inhaled after the peak of the normal tidal breath. Whereas expiratory reserve is the maximum volume that can be expired after the expiration of a tidal breath

Question 16

What is the residual volume

Answer 16

The volume of air left in lungs after maximum effort exhaling because its trapped underneath collapsed air ways due to expiration forces. It cannot be blown out

Question 17

Compare the inspiratory capacity and the functional residual capacity

Answer 17

Inspiratory capacity is tidal volume + inspiratory reserve volume

Functional residual capacity is the expiratory reserve volume and the residual volume. Thisi also known as the resting point of the lung before the next breathing in.

Question 18

What is the vital capacity

Answer 18

Expiratory reserve volume + inspiratory capacity. This the total volume of air that can be inhaled and exhaled.

Question 19

What is Total lung capacity and what parts are measurable

Answer 19

The vital capacity (can measure) + residual volume (can’t measure).

Question 20

What is minute ventilation

Answer 20

This is the respiratory volume over a certain time. (Time derivative)

=the number of tidal respiratory cycles over time (minute) (frequency) x the tidal volume.

Question 21

What is hyperventilation vs hypoventilation

Answer 21

Breathing greater than 6L/min is hyperventilation and Breathing less than 6L/min is hypoventilation

Question 22

What is alveolar ventilation, how calculated and why important

Answer 22

This is the rate of ventilation within the respiratory zone -> actually contributing to respiration.
Va = minute ventilation - dead space ventilation (the air inside the conducting zone (2.2mL/kg/ 0.15 L)

Question 23

How is special residual volume measured

Answer 23

An inert gas that doesn’t enter the blood (eg Helium) is put inside the drum of spirometer instead of oxygen. It is allowed to equilibriate inside the person and therefore C1V2 = C2 (V1 +V2) can be used to find V2 = total lung capacity which can be used to calculate residual volume.

Question 24

How is lung health found from vitalographs

Answer 24

It measures the rate at which you can blow out a maximum expiratory volume. The forced expiratory volume in 1 second is compared to the forced vital capacity (total amount of air you can blow out). If there is a ratio of 80% then healthy

Question 25

What would be the ratio % of the FEV1 to FVC for an asthmatic

Answer 25

It is more difficult to breathe out as more resistance. You cannot blow out as much and not as fast so both FEV1 and FVC would be small