Respiratory System Flashcards
What are the two distinct circulations of fetal circulation?
Fetoplacental and uteroplacental
What are chorionic villi?
Fetal tissue protruding into the maternal blood
What kind of blood do the umbilical arteries carry?
Deoxygenated
What is the Po2 in the intervillous space?
30 to 35mmHg
What is the fetal Hb saturation at a Po2 of 30?
85%
What does the ductus venosus do?
Shunts blood away from the liver
What does the foramen ovale do?
Shunts blood between the right and left atria
What does the ductus arteriosus do?
Connects the pulmonary artery with the descending aorta
Why is the first breath so difficult?
The lungs are fully closed, so the transpulmonary pressure is very high
What does surfactant do?
Increases lung compliance and reduces the effort of inspiration
What does cortisol do?
Stimulate the production of surfactant
What are characteristics of infant respiratory distress syndrome?
Increased work of breathing and impaired gas exchange
How do vascular resistance, arterial pressure and right ventricle pressure change at birth?
Resistance decreases, and pulmonary arterial and right ventricular pressure fall
How does the foramen ovale close?
The reversal of the pressure gradient pushes a flap of tissue against the septum
How does the ductus arteriosus close?
A few hours after birth the muscular wall contracts, which eliminated flow
Who described cystic fibrosis?
Dorothy Hansine Andersen
What kind of genetic disease is cystic fibrosis?
Autosomal recessive
What is the rate of carriers of cystic fibrosis?
1 in 20-30
Which channel is mutated in cystic fibrosis?
The cystic fibrosis transmembrane conductance regulator
What do CFTR mutations impact?
They reduce calcium and bicarbonate and dysregulate sodium channels in epithelial cells
They cause abnormal Cl homeostasis in neurons
They dysregulate calcium in muscles
Which classes of CF are severe and which are mild and why?
Classes 1, 2, and 3 are severe because they have no residual CFTR function
Classes 4, 5, and 6 are mild because they have some residual CFTR function
What is the main hypothesis for why CF is still present in the population?
Heterozygotes have an advantage in survival over some diseases
Which diseases is heterozygousity to CF an advantage against?
Cholera, typhoid, and tuberculosis
How is the mucus in CF patients different?
They do not produce as much, it remains attached to lung tissue, and it is more acidic
What does preventing infection in CF patients do?
Reduces the amount of CF related deaths, but it does not prevent lung abnormalities
What do potentiators do?
Take mutated CFTR and increase their activity
What do correctors do?
Prevent abnormal CFTRs from being destroyed before they are implanted
Which drug is newly approved and suspected to be a great help for cystic fibrosis patients?
Elexacaftor-Tezacaftor-Ivacaftor
The name brand is Trikafta
It is used when there is at least one F508del mutation
What type of treatment is required for class I mutations of CF?
Gene therapy
