Everything is functioning well enough. The kidneys are fully developed and can function on their own and the lungs are nearly matured too. Viability outside the womb is very high. As many as 99% of babies born in this week of pregnancy would be able to survive outside the womb with relatively few problems. Depending on the birth weight, among other things, the baby may first need to be nursed in an incubator.
The baby can easily distinguish between light and dark, as his eyes already work perfectly.
Cramp and varicose veins
Something else pregnant women often suffer from is cramp in their calves. The best thing to do if this happens, is to stretch your leg and flex your toes (point them towards you). This will hurt at first, but will usually stop the cramp almost immediately.
The hormone progesterone relaxes the walls of your blood vessels resulting in varicose veins, another common problem during pregnancy. Not everyone will get them but if you ever had them before you were pregnant, you stand a good chance of getting them again now. Avoid wearing high heels and try to rest your legs regularly by raising them above hip level.
You may feel a little pain or discomfort as the fetus baby starts to drop and engage in your pelvic cavity. This is called lightening and may cause a hard bump or contraction pains in your lower abdomen. A first child need not be engaged until 37 weeks and a subsequent baby might engage much later, perhaps not until the actual delivery! This is because everything has already been stretched before, so he'll have a little more space.
As your baby continues to grow he will have less and less room to move. It is quite normal for you to feel less activity now than a few weeks ago when he could kick quite hard. Now you will mostly feel a hand or a foot slide across.