The right ventricle then pumps blood through the pulmonary artery into the lungs. 4. In the lungs, tiny blood vessels called capillaries absorb carbon diox-ide from the blood and replace it with oxygen. 5. Oxygenated blood then flows through the pulmonary vein and into the left atrium. 6.
It is this hormone progesterone that can affect your digestive system by delaying the transit time of food through the intestines and hence may lead to constipation before your period. Usually though, you should find that the period-related constipation eases with the start of menstruation.
However, several factors can increase your chances of having constipation, including: 1  not eating enough fibre, such as fruit, vegetables and cereals. 2  a change in your routine or lifestyle, such as a change in your eating habits. 3  having limited privacy when using the toilet.ometimes, constipation may be a side effect of a medicine you are taking. Common types of medication that can cause constipation include: 1  aluminium antacids (medicine to treat indigestion).