ACCESSORY ORGANS FOR DIGESTION

LIVER

GALL BLADDER

PANCREAS (EXOCRINE, ENDOCRINE)

VERTEBRATE LIVER

- liver is largest internal organ

- hepatocytes function similarly in all vertebrates

- lobulated in birds, mammals,

no lobules in fish, amphibians or reptiles

LIVER

functions:

-process nutrients from intestine - CHO, AA

-break down toxins, wastes in blood → bile (exocrine)

-synthesize plasma proteins (endocrine)

blood supply

lobule structure

hepatocytes

bile production

STOMACH

SMALL INTESTINE

SPLEEN

VENOUS DRAINAGE

HEPATIC

PORTAL VEIN

HEPATIC

ARTERY

PORTAL VENULES IN

HEPATIC LOBULE

SINUSOIDS

BETWEEN HEPATOCYTES

CENTRAL VEIN HEPATIC VEIN INFERIOR

VENA CAVA

LIVER: two blood circulations

PORTAL SUPPLY

SYSTEMIC SUPPLY

LIVER LOBULE ANATOMY H69

central vein

portal triads

PORTAL TRIAD H69

branch of

hepatic

portal vein bile

duct

arteriole

sinusoids

central

vein

CENTRAL VEIN DRAINS LIVER SINUSOIDS H69

hepatocyte

sheets

BILE: made in liver, stored in gall bladder

aqueous salt solution containing:

bile acids, bile salts:

- help emulsify fats in small intestine

- promote lipase action and lipid absorption

bilirubin:

- spleen macrophages phagocytose old erythrocytes,

produce bilirubin → plasma → hepatocytes absorb,

secrete into bile

bile ductule collects bile from local canaliculi H69

ELASMOBRANCH LIVER - no lobules CVH 73

SQUALENE (lipid) IN ELASMOBRANCH HEPATOCYTES CVH73

TELEOST LIVER CVH146

bile ductule arteriole

sinusoids bile duct

TOAD LIVER CVH166

ALLIGATOR LIVER CVH171 bile ductule

HUMAN GALL BLADDER CROSS-SECTION H211

adventitia

muscularis

lamina

propria

epithelium

GALL BLADDER WALL H211

GALL BLADDER EPITHELIUM AND LAMINA PROPRIA H211

CODFISH GALL BLADDER CVH154

epithelium

muscularis

adventitia

CODFISH GALL BLADDER WALL CVH154

PANCREAS: MIXED EXOCRINE AND ENDOCRINE

-acinar glands: exocrine

- pancreatic juice - digestive enzymes

via pancreatic duct → duodenum

-pancreatic islets (islets of Langerhans): endocrine

-hormones

insulin - β cells

glucagon - α cells

peptide hormones

HUMAN PANCREAS H144

islet acinar region

PANCREATIC

DUCT AND

DUCTULE

H144

ALLIGATOR PANCREATIC ACINI AND DUCTULE CVH170

HUMAN ISLETS OF LANGERHANS CVH144

- endocrine secretion

ISLETS OF LANGERHANS IN ELASMOBRANCH PANCREAS

CVH69

CVH69