Resp other Qs

Question 1

What is the difference between hypoxia and hypoxaemia?

Answer 1

Hypoxaemia low oxygen in the blood, hypoxia low oxygen in the tissues/

Question 2

What are the differences between systemic and pulmonary blood vessels?

Answer 2

Tunica media thinner in pulmonary vessels- because blood pressure lower as to not damage delicate lung tissue and low blood pressure only have to travel a short distance

Question 3

What is type I resp failure? What causes it?

What is type 2 resp failure? What causes it?

Answer 3

1 = Low O2
Primarily due to lung tissue damage, eg fluid filling and collapse of alveolar units
also - shunt, hypoventilation, high altitude, V/Q inequality

2= Low or normal O2 and high Co2
Drug overdose, severe asthma, COPD
(a normal O2 means peripheral chemoreceptors don’t respond to pCO2 … so relies on central chemoreceptors)

Question 4

What are the innervations of the frontal, ethmoidal, sphenoid and maxillary sinuses?

Answer 4

Frontal= V1, ethmoidal=V1+2, sphenoid= V1 and maxillary= V2

v1 = ophthalmic
v2= max

Question 5

What is the histology of the larynx?

Answer 5

All respiratory epithelium (pseudo stratified columnar) except true vocal chords- stratified squamous because of abrasion. epiglottis showing the stratified squamous non-keratinizing epithelium that covers most of its surface.

Question 6

From what part of the gut do the lungs develop and what layer of the trigeminal disc?

Answer 6

Foregut- endoderm

Question 7

What drains into the inferior meatus?

Answer 7

Lacrimal duct and Eustachian tubes (all apart from sphenoid middle,)

Question 8

Describe process of inspiration

Answer 8

1. Diaphragm contracts (phrenic) and external intercostal (T1-11) contracts drawing the rib cage up and out. This further increases the thoracic cavity.
2. This increase in volume decreases intrapulmonary pressure (one below atmospheric). This causes the transpulmonary pressure to increase.
3. The lungs expands- surface tension between pleura causes lungs to be pulled up and out as thorax expands.
4. Size of alveoli increases therefore alveolar pressure decreases. Alveoli become subatmospheric
5. Causes air to flow down pressure gradient from atmosphere to alveoli

Question 9

1. What is the equation for alveolar ventilation?

Answer 9

(Tidal volume- dead space volume) x resp. rate

Question 10

1. What is compliance of the lungs?

Answer 10

Change in volume per unit change in pressure gradient between pleura and alveoli (high compliance = expand more when exposed to same transpulmonary pressure).

Question 11

What are some physiological changing the ageing lung?

Answer 11

Decreased compliance, decrease resp. muscle strength and decrease elastic recoil, kyphosis, more V/Q mismatch.

Question 12

What is effect of pH on the O2 dissociation curve?

Answer 12

Shifts to the right – less O2 can combine to Hb (decreased pH)
-more o2 released

Question 13

How is inspiration controlled?

Answer 13

DRG mainly

Question 14

What are the four main centres that control breathing - where are they found

Answer 14

1. VRG - ventral resp group reticular formation, medulla oblongata,
   =voluntary forced exhalation
2. DRG - dorsal resp group- reticular formation, medulla oblongata
   = inspiration
3. Pneumotaxic center - various nuclei of the pons
   =speed of inhalation and exhalation
   inhibitory impulses to the inspiratory area
4. Apneustic center - nucleus of the pons
   =speed of inhalation and exhalation
   stimulatory impulses to the inspiratory area

Question 15

What does the pneumotaxic centre do?

What does the apneustic centre do?

Answer 15

controls speed of inhalation and exhalation by signalling DRG mainly to switch off

Stimulates DRG and therefore inspiration (long deep breathes)

Question 16

Where are the central chemoreceptors found, what do they monitor and how?

Answer 16

1. In Medulla,
2. H+ cannot diffuse across BBB
3. CO2 can - it dissociates H2CO3 into H+
4. DRG and VRG stimulates
5. Efferent neurones to inspiratory muscles for regulation (via vagus and intercostal muscles)
6. Increased breathing and depth

Increased H+ = increased breathing to increase Co2 removal

Question 17

When are the stretch receptors in the lung activated?

Answer 17

When the lung over stretches pulmonary stretch receptors initiate the inflation Hering-Breuer reflex in order to reduce resp rate
=prevents over inflation of the lung

-Pneumotaxic center (pons) and DGV (inspiration in medulla)