GI Hepatosplanchnic circulation and bile formation Flashcards Preview

Physiology II > GI Hepatosplanchnic circulation and bile formation > Flashcards

Flashcards in GI Hepatosplanchnic circulation and bile formation Deck (21):
1

Hepatosplanchnic circulation

supplies blood flow to viscera (liver, stomach, small intestine, colon, pancreas, and spleen)

2

oxygenated blood

hepatic artery (25%)

3

Deoxygenated blood

portal vein (70%)

4

Is splanchnic circulation arranged in series or in parallel to the hepatic portal circulation?

Series - facilitates the delivery of absorbed nutrients to the liver

5

SNS - hepatosplanchnic circulation (arerioles, venuoles, veins)

a1 receptors - constriction of vascular smooth muscle in arterioles venules and veins

6

PNS- hepatosplanchnic circulation (arterioles, venules, veins)

Parasympathetic increases contraction and secretion of the GI tract creating vasoactive metabolites

Increased vagal stimulation creates and increase in vasoactive metabolites which causes vasodilation and increased blood flow (SECONDARY to contractile and secretory effects)

7

PNS on salivary glands

Vasodilation

8

Myogenic vasoconstriction

response to sudden increase in profusion pressure

increases local vascular resistance in order to protect the capillaries from high systemic pressures and excess fluid filtration

9

intrinsic response to low profusion pressure

low profusion results in decreased blood flow and decreased substrate delivery = accumulation of locally produced metabolic factors

metabolic factors can cause vasodilation and increase blood flow

10

increased secretory activity leads to increased _____ blood flow

mucosal

11

increased motor activity to the gut leads to increased ______ blood flow

muscularis

12

Escape phenomenon

sympathetic stimulation causes constriction of both arterioles and veins resulting in decrease in splanchnic flow (fight or flight - shunted away from the gut)

Despite continued stimulation the splanchnic arterioles (NOT veins) will spontaneously vasodialate (i.e escape)within a matter of minutes

Attempt to avoid counter current exchange and save the gut from necrosis

13

Counter current exchange

oxygenated blood dissolved in the plasma shunts from the arteriole to the venule without reaching the capillaries.

This gets exaggerated in states of low blood flow (ischemia) due to slowed blood flow velocity- risk necrosis to the villous tip

14

Primary Bile acids

from salts or newly synthesized by hepatocytes

Cholic Acid and Chenodeoxycholic Acid

15

Secondary Bile Salts

formed from the action of bacteria in the digestive tract

deoxycholic acid and lithocholic acid

16

Bile Pigments

senescent red blood cells (degraded by reticuloendothelial cells- hgb is broken down to form bilirunin)

the bilirubin is removed form the plasma by the liver and is conjucated and secreted into bile

BILE PIGMENTS ARE NOT PART OF THE MICELLE

17

What determine whether bile flows into the gallbladder or into the duodenum

resistance at the sphincter of Oddi

18

Vagal stimulation and CCK cause ____ of the gallbladder and ____ of the sphincter of Oddi

contraction

relaxation

19

presence of fats and partially digested proteins in the duodenum will cause the release of what gastrointestinal regulatory stubstance

CCK

20

What is the mechanism of concentration of bile in the gallbladder

absorption of water from the gallbladder (NaCl pumped out into intracellular lumen and water follows)

water and electorlyes are then moved into capillaries by hydrostatic pressure

21

where are bile salts absorbed

Ileum