Absorption of Vitamins, Electrolytes, and Water (Nursing)

00:01 So another important aspect of the digestive system is vitamin absorption.

00:07 Vitamins are absorbed in both the small and the large intestine.

00:12 In the small intestine we're going to have absorption of are fat soluble vitamins such as Vitamin A, D, E and K.

00:22 These are then carried by micelles where they then diffuse into absorptive cells.

00:28 We also have absorption of our water soluble vitamins like vitamin C and B.

00:34 And these are going to be absorbed by either diffusion or by passive or active transport.

00:41 Another very important vitamin for our lives in order for us to be able to survive is vitamin B12.

00:48 This is a large charged molecule that binds with intrinsic factor remember intrinsic factor that's secreted from our parietal cells in the stomach and is absorbed by endocytosis.

01:01 The large intestine is going to be more responsible for the absorption of vitamin K as well as B vitamins that are produced by the bacteria that live in the large intestine.

01:15 Also important is the absorption of salts or electrolytes.

01:20 Most ions are going to be transported actively along the the length of the small intestines.

01:28 Also iron and calcium are absorbed in the duodenum of the small intestines.

01:35 Normally sodium absorption is coupled with active absorption of other molecules such as glucose and amino acids.

01:44 We also are going to transport chloride ions actively.

01:50 Also potassium is normally going to diffuse and response to osmotic gradients.

01:56 It is going to be lost if water re-absorption is poor.

02:01 Usually the amount of electrolytes in the intestines is going to be equal to the amount of electrolytes that are going to be absorbed into the blood.

02:12 Iron and calcium however are going to be absorbed based on need.

02:18 So for example ionic iron is going to be stored in our mucosal cells with ferritin.

02:25 And when it is needed it is going to be transferred in the blood by way of a molecule known as transferrin.

02:33 Calcium absorption is regulated by the vitamin, vitamin D.

02:37 This is why it's important to get sunlight from vitamin D or the reason why milk is enriched with vitamin D.

02:46 Also calcium absorption requires the action of parathyroid hormone.

02:54 So now looking at the absorption of water we have about 9 litres of water most from our GI secretions that will enter into our small intestine.

03:06 About 95% will then be reabsorbed in the small intestine by osmosis.

03:14 Most of the rest of this water is then going to be absorbed in the large intestine.

03:20 Net osmosis is going to occur if concentration gradients are established by active transport of solutes because water follows salt.

03:31 So water uptake is going to be coupled with solute uptake.

03:36 So if I'm actively transporting ions, then water will follow the ions that I am actively transporting.