Physio E3: GI pt 2

CCK causes

gallbladder contraction, relaxation of sphincter of Oddi

Which organ has amazing regenerative abilities due to mitosis of hepatocytes?

liver -also the largest organ

Sinusoids

capillaries that separate hepatic plates

-very permeable

how are products of digestion delivered to the liver?

hepatic portal vein

-GI drains into portal vein → liver

Hepatic blood flow

25% of CO

Hepatic portal system

unique pattern of capillaries → veins → capillaries → veins

How does the liver detoxify blood?

Kupffer cells: phagocytosis

Chemical alternated (hormones or drugs)

Production of urea, uric acid

Excretion

Functions of the liver

detoxify blood; secrete bile; metabolize carbs, lipids, proteins

Bile is composed of:

bile pigment (bilirubin), bile salts, phospholipids (lecithin), cholesterol, inorganic ions

Bilirubin

produced in spleen, liver, and bone marrow

-product of Hgb breakdown

-conjugated vs unconjugated

Unconjugated (free) bilirubin

not very water soluble

carried attached to albumin

Conjugated bilirubin

some free bilirubin is conjugated with glucuronic acid to make it water soluble

Conjugated bilirubin uses

-bacteria turn into urobilin → feces brown

- used to make bile

-absorbed by intestine sent back to liver

-remains in blood to be filtered by kidneys → amber color to urine (beer brown)

Bile acids are derived from

cholesterol

T/F the liver helps balance blood glucose

T

glycogenesis

creates glycogen

lipogenesis

creates triglycerides

glycogenolysis

breaks down glycogen

gluconeogenesis

creates glucose from AA

ketogenesis

creates ketones

What stimulates the conversion of fatty acids into ketone bodies

Glucagon

Excessive catabolism of fat

ketoacidosis

Liver produces

plasma albumin, most plasma globulins, clotting factors, angiotensinogen

Albumin fx

provides oncotic pressure and transport

Globulins fx

provide transport and blood clotting

Clotting factors made

1 (fibrinogen, 2 (PT), 3, 5, 7, 9, 10, 11

Chemical alteration by hepatocytes to detoxify blood

**ammonia is converted to urea, porphyrins into bilirubin, purines into uric acid

-urea returns to blood to be filtered by kidneys

-steroids and xenobiotics are altered then secreted into bile

Gallbladder fx

stores and concentrates bile from the liver

What hormone tells the gallbladder what to do?

CCK

Fx of bile

aids in excretion of bilirubin

bile salts and IgA inhibit bacterial growth

neutralize gastric acid

aid in fat absorption

emulsify triglycerides and phospholipids

T/F pancreas has both endocrine and exocrine functions

T

Pancreas endocrine fx

Islets of Langerhans cells make insulin (beta cells) and glucagon (alpha cells)

-inner portion on pic

Pancreas exocrine fx

pancreatic juice (enzymes)

-get deliver to duodenum via pancreatic duct

Pancreatic Fx

secrete bicarb to neutralize chyme from stomach

Digestive enzymes

Digestive enzymes for proteins

trypsin, chymotrypsin, caboxypolypeptidase

Digestive enzymes for carbohydrates

pancreatic amylase

Digestive enzymes for lipids

Pancreatic lipase, cholesterol esterase

What hormones regulate pancreatic secretion?

Ach, CCK, Secretin

Ach effect on pancreas

stimulates enzyme release

CCK effect on pancreas

stimulates enzyme release

Secretin effect on pancreas

stimulates large amounts of water and bicarb

Secretion in 3 phases

Cephalic- PNS release of enzymes

Gastric- more release of enzymes

Intestinal- secretin stimulates release into duodenum

PNS division of pancreas

activated while eating and stimulates insulin release

SNS division of pancreas

inhibits insulin secretion and stimulates glucagon secretion

— produces stress hyperglycemia