Session 13 - Revision Lecture Flashcards
1 - Revision topics
- Control of resp for chemoreceptors
- CXRs
- Respiratory failure
- COPD
- Signs and symptoms of pneumothorax and pleural effusion (GW)
2 - Ventilation
Ventilation
• Rhythmic ventilation is an automatic, unconscious process
• Groups of cells in the medulla generate basic respiratory rhythm
- This basic rhythm can be modified by
- conscious action (via cortex), emotional input
- reflex adjustment based on input from chemoreceptors, (and others – eg stretch receptors)
• Effect on ventilation by change in output to the
motor neurons of respiratory muscles
From higher brain centers Pons Medulla oblongata Nerves Respiratory control area Spinal cord Blood to head Blood to head Carotid body Carotid artery Aorta Aortic body Blood from head Output to respiratory muscles Blood to lungs Blood from body Heart
{Control of ventilation and chem control of resp.
Rhythmic ventilation = breathing
Impulses in medulla go down to our resp muscles from time to time allowing us to breathe in, stop sending impulses down to the muscles then passive expiration takes places.
Hyperventilate - conscious action - overrides groups of cells - control from higher brain centres.
Emotional input - Limbic system - so sometimes people hyperventilate in fearful situations or panic attack.
Reflex adj from min to min - gases. Can also have influence of breathing factor.
Effect – if chemoreceptors feed back and resp centre increases the rate – the effect is increased output from muscles of resp centre to muscles of resp. Resp muscles effector organ of this system}
3 - Control of ventilation
Control of ventilation
• pO2 does not need precise control, but must be above 8kPa to avoid tissue injury
- pCO2 needs precise control to keep pH in normal range
- Acidosis – denatures enzymes
- Alkalosis – reduces ionized calcium levels
- Sometimes change in ventilation needed to correct metabolic disturbances of pH
- E.g. hyperventilation in diabetic ketoacidosis
{pO2 needs control but does not need to be PRECISE.
pCO2 needs precise control bc it will change pH - multitude of effect on body if not controlled.
Sometimes need to change regulatory pattern for disturbances in the body. Nothing to do in the lungs - need to hyperventilate - CO2, so these are the 3 areas where you might need to control ventilation}
4 - Peripheral chemoreceptors
Peripheral chemoreceptors
- Located in carotid and aortic bodies.
- Impulses via Glossopharyngeal & Vagus nerves
• Responsive to all 3 parameters
- Drop in pO2
- Increase in pCO2
- Increase in blood [H]+ due to metabolic problems e.g. Diabetic ketoacidosis
• Any of the above cause an increase in rate and depth of respiration (↑ minute volume)
• They are the only chemoreceptors sensitive to hypoxia
• Needs a large drop in pO2
to activate –
brisk response not seen until PaO2
levels fall to ≈ 8.0 kPa from the normal 13.3 kPa.
• Always remains sensitive to hypoxia (does not adapt in chronic hypoxia)
- Medulla
- Glossopharyngeal nerve
- Vagus nerve
- Carotid body
- Aortic bodies
{Carotid bodies = glossopharyngeal nerve; aortic bodies = VN
blood [H]+ = pH INDEPENDENT of pCO2 eg in DKA H+ rises due to keto acids in system. So this will impact on diff chemoR and cause hyperventi.}
5
5
6
6
7
7
8
8
9
9
10
10
11
11
12
12
13
13
14
14
15
15
