There is decrease in magnitude of umbilical venous volume flow.  In response to this, proportion of umbilical venous blood diverted to fetal heart increases.  This eventually leads to elevation of pulmonary vascular resistance and increased right ventricular afterload .    This redistribution of blood flow is early response to placental insufficiency. Blood flow is selectively redirected to myocardium, adrenal glands and, particularly, brain. The last phenomenon is called "brain-sparing effect"  or cerebral redistribution .
This entry describes 4 <p> This subsection of the ‘Sequence’ section lists the alternative protein sequences (isoforms) that can be generated from the same gene by a single or by the combination of up to four biological events (alternative promoter usage, alternative splicing, alternative initiation and ribosomal frameshifting). Additionally, this section gives relevant information on each alternative protein isoform.<p> <a href='/help/alternative_products' target='_top'> More...</a> </p> isoforms i produced by alternative splicing . Align Add to basket Added to basket
Immunity wears off over time. So, the current recommendation is that everyone needs a booster shot for tetanus and diphtheria every 10 years after first being immunized. That booster comes in the form of a vaccine called Td . But since immunity to pertussis also wears off during childhood, a weaker form of the pertussis vaccine has been added to the booster to make the vaccine Tdap. The current recommendation is that one dose of the Tdap vaccine be substituted for one dose of the Td vaccine between the ages of 11 and 64. Pregnant women are also advised to get the Tdap vaccine, preferably between 27 and 36 weeks' gestation.