Taking the First Breath Flashcards
Define Homeostasis
Maintenance of static or constant conditions in the internal environment during changes in the external/internal environment
Explain why both high and low blood glucose concentrations are potentially dangerous
Low blood glucose concentration - lack of glucose supply to tissues/cell types that can not use alternatives
Explain why it might be difficult to maintain the blood glucose concentration after birth
Raised blood glucose concentration - osmotic effect - fluid & electrolyte imbalances
Repeat the above two questions in relation to temperature regulation
Temperature = key determinant of rate at which chemical processes occur
Thinking about the birth process and the changes that occur, identify as many stimuli for development as you can
Biological clock
Local environment
Need to undertake new roles, e.g. breathing, waste disposal, reproduction
Role becomes redundant, e.g. ability of liver to use ketone bodies
Temperature change
Altered nutrient supply
Exposure to environmental agents, e.g. bacteria, viruses, chemicals
Would any of the stimuli you have identified be ineffective if the baby was delivered prematurely &/or by Caesarean Section?
Developmental changes that are determined by the biological clock e.g. production of enzymes required for bilirubin metabolism, may not occur, or only occur at a reduced rate
Compression & recoil of rib cage does not occur – contributes initiation of breathing
Catecholamine surge is reduced in intensity & timing altered (acute rather than gradual onset) – contributes to fuel mobilisation & reabsorption of lung fluid
Activation of immune system & CNS compromised
Would the effect of any of the stimuli you have identified be influenced by how the baby was cared for after birth?
Temperature change also plays an important role in promoting release of catecholamines – necessary to achieve continued mobilisation of fuel
If baby healthy, not appropriate to put into thermally neutral environment
What is the flow of blood in postnatal circulation?
Right ventricle - pulmonary arteries
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Oxygenated blood returns to left atrium via pulmonary veins
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Left ventricle - aorta etc.
What are the differences in foetal circulation and postnatal circulation?
Oxygenated blood delivered from placenta via umbilical vein & ductus venosus which discharges into inferior vena cava above liver
Deoxygenated blood returned to placenta via umbilical artery which branches off descending aorta
Lungs must be supplied with oxygenated blood
Liver has reduced requirement for oxygenated blood
What are the 3 shunts?
- Ductus venosus – by-passes liver - supply of oxygenated blood to liver restricted
- Foramen ovale – links right & left atria - oxygenated blood can pass directly into left atrium
- Ductus arteriosus, links bifurcation of pulmonary arteries to descending aorta - about 90% of blood entering pulmonary circulation by-passes lungs
What happens to the pressures in the right and left atrium once the umbilical cord has been clamped?
Decrease in pressure in right atrium due to decrease in blood flow
There is a simultaneous increase in blood pressure in the left atrium due to what?
- Increase in systemic vascular resistance resulting from cessation of blood flow to umbilical arteries
- Return of blood from the lungs
What happens when the flap of foramen ovale closes?
Equalisation of pressure in the two atria
What happens when the baby takes its first breath?
Expansion of the lungs and 80% decrease in pulmonary vascular resistance this leads to an increase in pulmonary blood flow
Ductus arteriosus constricts and closes
How long does it take for a newborn to achieve regular respiration?
60 seconds
