Gastric secretions and digestive enzymes overview

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GASTRIC SECRETIONS

Mucus - Protects underlying tissue

Pepsinogen - Inactive Protease

Hydrochloric Acid - Activates pepsinogen (converts it to pepsin)

Intrinsic Factor - Needed for vitamin B12 absorption

MUSCULARIS OF STOMACH

3 layers of muscle

Outer longitudinal

Middle Circular

Inner Obliques

3 PHASES OF GASTRIC STIMULATION

Cephalic

Gastric

Intestinal

ENTEROGASTRONES

CCK Cells in the intestinal gland of small intestine release CCK (CHOLECYTOKININ)

Initiates: - Secretion of pancreatic juice

- Contraction of Gall bladder

-Bile into cystic duct --> common bile duct

- Relaxation of sphincter of Odi (Hepaticpancreatic Ampulla)

- Promotes contraction of pyloric sphincter

- Produces Satiety (fullness)

- Promotes normal growth and maintenance of pancrease

- Enhances effects of secretin

Amount Made in a Day

Saliva : 1000-1500 mL

Chyme : 1-2 mL

Pancreatic Juice : 1200 - 1500 mL

Bile 800 - 1000 mL

pH Levels

Saliva pH 6.35 - 6.85

Pancreatic Juice pH 7.1 - 8.2

Bile pH 7.6 - 8.6

LENGTHS

Small intestine = 3 meters long / 2.5 cm diameter (6.5 meters long in cadaver)

Duodenum - 25 cm

Jejunum - 1 meter

Ileum - 2 meters

Carbohydrate Digestion

Salivary Amylase

Pancreatic Amylase

Intestinal Brush Border Enzymes (Maltase, Sucrase, Lactase)

Protein Digestion

HCL

Pepsin

Pancreatic Proteases

Intestinal Brush Border Enzymes

Lipid Digestion

Lingual Lipase

Gastric Lipase

Bile

Pancreatic Lipase

Functions of the Liver

Nutrient metabolism

Detoxifies blood

Stores vitamins

Phagocytes