Resp Responses

Question 1

What is type 1 and type 2 respiratory failure?

Answer 1

Type 1 is when there is disease of the respiratory portion, therefore you see hypoxia without hypercapnia (CO2 can be low or normal,. This is because CO2 is more soluble than oxygen so can diffuse across even when the tissue is damaged

Type 2 is when there is a blockage effectively and therefore you see hypercapnia and hypoxia.

Question 2

What does oxygen supplementation do to type 1 and type 2

Answer 2

Oxygen supplementation would make type 1 better (would diffuse better with high O2)

But would worsen 2, because it would prevent CO2 from moving over and therefore induce hypercapnia too (would mess up conc grad)

Question 3

Describe how the body responds to irritation and invasion

Answer 3

Fibres sending afferent signals for these reflexes into SAR , RAR and C fibres.
The cough reflex, involves a mixture of these receptors throughout the conducting airways especially at the bifurcation. There are also some weirdly located mechanical receptors for the cough e.g. Inner ear, pharynx, diaphragm, pericardium and stomach. Vagus nerve is the afferent, to cough centre in medulla oblongata and pons. Various efferents have an effect e.g. Phrenic to diaphragm, somatic spinal nerves to abdominal muscles and intercostals, and vagus/recur laryngeal to the larynx.
The sneeze reflex involves receptors in the nasal mucosa which respond to chemical and mechanical stimuli. The afferent nerve is the Trigeminal. This sends info to sneezing centre in MO. It has many effects: close eyes, inspire, close glottis etc. The efferent pathway is poorly understood- efferents are probably the same as the cough e.g. Vagus, phrenic, somatic plus facial nerve for eye closure

Question 4

Where are the three receptor types found, do they response to chem, mech or both? What do they cause?

Answer 4

RAR: airways: mechanical: bronchocon and mucus sec via PNS

C fibres: throughout: noxious both: bronchocon, mucus, apnoea then shallow breath, cough

SAR: bronchioles and alveoli: mechanical (most at insp): Hering Breuer

Question 5

The nasopulmonary reflex is not 100% proven. What is it said to do? What’s its afferent and efferent?

Answer 5

Nasal stim causes vasoconstriction
Trigeminal
Vagus

Question 6

Describe how the body responds to increase ventilatory demand

Answer 6

Body responds by increasing minute volume by inc RR and TV

This MUST be matched with perfusion though otherwise it’s useless

Pulm circ can increase 6 fold during exercise

This is achieved in different ways depending on the cause. If it’s fight or flight or chemoreceptors. Resp centre increases firing of dorsal respiratory group. Utilise active respiration.

Question 7

If this is persistent (high RR/depth) e.g. In disease States, what could happen?

Answer 7

Hypocapnia, as when hyperventilating removing CO2.
This reduces the drive for ventilation, as chemoreceptors detect low co2. So lowers O2 also.

Loss of co2 leads to resp alkalosis/removes H+ to replace

Demand on muscles therefore fatigue and poss metabolic acidosis. Fatigue finally leads to exhaustion, hypo ventilation and therefore hypoxia and hypercapnia further

Question 8

How do animals try to minimise resistance?

Answer 8

Lie in sternal
Mouth breathe
point elbows out to widen chest (orthopnoea)