Portal Vein System – Hepatic Circulatory System (Nursing)

by Rhonda Lawes, PhD, RN

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    00:00 So, this system is pretty complex. When we say a network of blood vessels, that's what it is.

    00:07 We've shown you some of them here, but their job is to bring blood through the intestines, the stomach, and the spleen and pancreas, drain it all into that portal vein, and move it on through the liver to be processed, to be detoxified, and to choose what it's going to store, what it's going to put back in the bloodstream, and what it's going to send to the gut to be pooped out. We've talked in detail about what the portal vein system is but let's break down the 4 major things that the portal blood carries. It's not just nutrients, but it's also got some substances that have been absorbed in the intestinal mucosa or produced in the spleen.

    00:44 Number 1, drugs. Now, I'm a nerd that loves pharmacology. So this is part of the first pass effect. That's why orall drugs have to be given in larger dosages than IV drugs. Alright, so we've got drugs are in the portal blood. The second we want to talk about is toxins from food.

    01:04 So, these are things that the liver will have to help detoxify. So, so far we've talked about drugs. We've got toxins from food. The 3rd category would be bacteria. Now, some bacteria is great, some bacteria we'd like to get rid of. The liver is smart, and it knows what to do with that's coming back through that portal blood. Last, we're talking about byproducts of blood cell recycling. Okay, now I don't want to speed through this slide too quickly. So, you've got down the blood supply to the liver, but it's really important that you think about these 4 categories; drugs, toxins, bacteria, and blood cell recycling byproducts. Because if the liver is not functioning, if it's damaged, if it's cirrhotic, if it's fatty, we're going to have problems with buildup of all of these substances. So we've looked at the venous and arterial blood, but I I just wanted to remind you that blood from both the portal vein, remember coming up from my gut into my liver, blood from both the portal vein and the hepatic artery mixes together in the hepatic sinusoids. So, you see those portal triads, those 6 groups of 3 colored tubes all around the hexagonal unit that we know as the lobule. You've got blood that comes up from the portal vein, and it comes from the hepatic artery, and together it mixes in those sinusoids that are right around the hepatocytes, those tiny little cells within the lobule. So, it mixes together because the sinusoids are a type of capillary found in your liver, and you know in capillaries arterial and venous blood that's where they mix. So, we've got blood coming in from these 2 sources. It moves through the sinusoids. Right? It travels to the middle and that's where it passes out of the lobule, it joins the hepatic vein and then drains out of the liver into what, awesome, into the inferior vena cava on its way back to the right atrium. Well done.

    About the Lecture

    The lecture Portal Vein System – Hepatic Circulatory System (Nursing) by Rhonda Lawes, PhD, RN is from the course Liver Functions and Dysfunctions (Nursing).

    Included Quiz Questions

    1. Toxins from food
    2. Drugs
    3. Bacteria
    4. Bile
    5. Pancreatic enzymes

    Author of lecture Portal Vein System – Hepatic Circulatory System (Nursing)

     Rhonda Lawes, PhD, RN

    Rhonda Lawes, PhD, RN

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