Mechanism Of Breathing

Question 1

Define breathing/pulmonary ventilation…

Answer 1

Process where gases are exchanged between the lungs and atmosphere

Driven by changes in pressure

Question 2

What does Boyle’s Law state?

Answer 2

As volume increases, pressure decreases

Question 3

What is inspiration?

Answer 3

Active process during normal quiet breathing

Question 4

What is expiration?

Answer 4

Passive process during normal quiet breathing

Relies on muscle relaxation and elastic recoil to decrease lung volume

Question 5

What controls breathing!

Answer 5

Involuntary act

Automatic generation of rhythmic breathing

By respiratory centres in medulla oblongata and pons in the brain stem

Question 6

What is the main stimulus of breathing?

Answer 6

Increase in levels of carbon dioxide in the blood

Levels of carbon dioxide in blood changes- detected by receptors that relay info to respiratory centre bringing change in rate/depth of breathing

Changes in blood pH and oxygen levels stimulate changes

Question 7

What do the central chemoreceptors detect?

Answer 7

Located in the medulla

Respond to lowering pH in CFS

Determined by carbon dioxide conc. in blood (diffuses readily across blood brain barrier)

Rise in carbon dioxide decreased pH (more acidic)
Decrease in carbon dioxide increase pH

Question 8

What is the response of Central and Peripheral to increased carbon dioxide and lowered pH?

Answer 8

Stimulate respiratory centre to increase the rate/depth of breathing, lowers carbon dioxide level in blood and returns blood gases within normal levels

Question 9

What is the function of the Peripheral chemoreceptors?

Answer 9

Located in aorta and carotid bodies

Detect rises in arterial carbon dioxide

React to significant falls in oxygen levels in the blood

Question 10

What stimuli bring about a change in rate/depth of breathing?

Answer 10

1) emotional stimuli (via limbic system)
2) stretch receptors in lungs
3) talking, coughing etc.
4) carbon dioxide, oxygen and pH
5) anxiety
6) exercise
7) medicines
8) pain
9) alcohol

Question 11

What are the 4 discrete parts of the respiratory centre in the brain stem?

Answer 11

1) dorsal respiratory group
2) central respiratory group
3) apneustric centre
4) pneumotaxic centre/pontine respiratory groups

Question 12

What is the location and function of the dorsal respiratory group?

Answer 12

Medulla

Integrates chemoreceptors info and signals the ventral respiratory group

Question 13

What is the location and function of the ventral respiratory group?

Answer 13

Medulla

Basic rhythm generator

Question 14

What is the location and function of the apneustic centre?

Answer 14

Pons

Helps regulate length and depth of inspiration

Question 15

What is the location and function of the pontine respiratory group?

Answer 15

Pons

Involved in regulation of apneustic centre and medullary rhythmicity area

Question 16

What is the medullary rhythmicity area?

Answer 16

Areas located in the medulla

Control basic inspiration/expiratory cycle

Question 17

What does increased airway resistance effect?

Answer 17

Alveolar ventilation

Question 18

What are the 3 main causes of airway resistance?

Answer 18

1) inflammation (of airway lining)
2) excess mucus
3) bronchoconstriction

Question 19

What is the function of surfactant?

Answer 19

Lowers surface tension- acts like detergent- makes it easier for sides of alveoli to part/inflate

Without it, wet surfaces of lungs would stick together so won’t be able to expand/take part in breathing

Increases lung compliance

Question 20

What is compliance?

Answer 20

Indicates ‘stretchiness’

Question 21

What is lung compliance?

Answer 21

Measure of how easy it is to inflate lungs

Question 22

What is the function of elastin?

Answer 22

In the alveoli, allows for compliance

During breathing, alveoli need to expand during inspiration and contract during expiration- elastin recoil allows this to occur