Chapter 19.5-Stomach

Four Regions

1) Cardia2) Fundus3) Body4) Pylorus

- Pyloric sphincter

CARDIA

BODY

FUNDUS

PYLORUS

Pyloric sphincter

Rugae of mucosaRugae of mucosa

Gastric Glands

- The rugae is covered is lined with gastric pits

- Gastric pits contain epithelial secretory cells called gastric glands- Mucous surface and neck cells: secrete mucous into lumen- Chief cells: secrete inactive enzyme pepsinogen- Parietal cells: Secrete HCl; turns pepsinogen -> pepsin

- All of these secretions are called gastric juice

- G Cells secrete gastrin into blood stream

Gastric pits

Surface mucous cell

Mucous neck cell

Parietal cell

Chief cell

G cell

Digestion and Absorption in Stomach- HCl secretions trigger nerve impulses that

initiate mixing waves- Produces chyme - Forces a small amount of chyme through

pyloric sphincter

- Different food types spend different amounts of time in stomach

Digestion and Absorption in Stomach- Protein digestion begins in the stomach

- Pepsin breaks peptide bonds between amino acids- Stomach cells protected by mucous lining

- Triglycerides broken down into fatty acids by lingual lipase

- Very little absorption takes place in stomach

Chapter 19.6-Pancreas

Structure of the Pancreas

- Lies behind the stomach

- Connected to the small intestines via hepatopancreatic duct

- Pancreatic duct combined with common bile duct from liver

- Epithelial cells secrete pancreatic juice- Mixture of fluid and digestive enzymes

- Other cells secrete hormones

Left hepatic duct

Right hepatic duct

Gallbladder

Hepatopancreatic duct to duodenum

Pancreatic duct

Common bile duct

Pancreas

Pancreatic Juice

- Consists of water, salts, sodium bicarbonate, and enzymes- Bicarbonate (pH=7.1-8.2) makes the juice basic

- Digestive Enzymes:- Pancreatic amylase -> starch- Trypsin (activated by enterokinase) -> protein- Chymotrypsin (activated by trypsin) -> protein- Carboxypeptidase (activated by trypsin) -> protein- Pancreatic lipase -> fats- Ribonuclease and deoxyribonuclease -> nucleic acids