Msc fourth semester mgkvp#20 Portal Systems.ppt

Science notes

1. A Portal System
in the Cardiovascular System
A vascular arrangement linking 2 capillary beds in series from one organ to
another by connecting vessels (often veins, but not always).
It involves two distinct sets of capillaries before returning to the heart.
Artery
Arteriole
Capillary
Bed # 1
Capillary
Bed #2
Vein
?
Aorta IVC

2. There are three (3) examples of
Portal Systems in the Body:
1) Hepatic Portal System
2) Renal (Nephron)
3) Hypothalamic - Hypophyseal

3. Blood Sample #1 Blood Sample #2 Blood Sample #3
Artery
Arteriole
Capillary
Bed # 1
Capillary
Bed #2
Hepatic Portal Vein
Small Intestine
Liver
Hepatic Vein
Inferior
Vena
Cava
Aorta
1) Hepatic Portal System

4. Blood Sample #1
• O
2 Rich
• Nutrients Mod/Low
• Toxins Low
Blood Sample #2
• O
2
Low
• Nutrients High
• Toxins High
Blood Sample #3
• O
2
Poor
• Nutrients Moderate
• Toxins Low
The purpose of the Hepatic Portal system is to stabilize the
systemic blood. The results of the blood sample below explain
how this vascular arrangement achieves this.
Arteriole Hepatic Portal Vein Hepatic Vein

5. Afferent Arteriole
(incoming vessel to the glomerulus)
Efferent Arteriole
(outgoing vessel from the glomerulus)
Glomerulus – This is where Filtration occurs.
a)Peritubular Capillaries
b)Vasa Recta Capillaries
Arcuate Veins
2) Renal Portal System: In the Nephron of Kidney
Venules
Capillary Beds #2
Capillary Bed #1
Arcuate
artery
This is where Reabsorption
takes place.

6. Superior Hypothalamic Artery
(Anterior Pituitary)
Hypophyseal Portal Vein(s)
(Hypothalamic – Hypophyseal portal system)
Primary Capillary
Plexus
Secondary Capillary
Plexus
3) Hypothalamic – Hypophyseal
Between the Hypothalamus and the Anterior Pituitary gland
Hypophyseal Vein(s)
Capillary Bed #2
Capillary Bed #1
Releasing/Inhibiting Hormones
Anterior Pituitary Hormones