Download Human Digestive System

Human Digestive System
Digestive System
Functions
•
•
•
•
•
Ingest food
Break down food
Move food through digestive tract
Absorb digested food and water
Eliminates waste materials
Mouth
Diagram of Teeth
Mouth
•
•
•
•
•
•
Breaks down food into small pieces
Begins starch digestion (amylase)
Saliva produces amylase and lubricates food
Moves food into esophagus
Epiglottis covers trachea
Peristalsis moves food to stomach
Esophagus
• Pushes food to Stomach
Motility: Peristalsis
Peristalsis
Copyright © 2001 Benjamin Cummings, an imprint of Addison Wesley Longman, Inc.
Figure 14.3B
Slide 14.5
Stomach
•
•
•
•
•
Muscles churn food – mechanical digestion.
Glands produce gastric juice = pepsin + HCl
Pepsin breaks down proteins (only at pH 2)
Food leaves after 2-4 hrs
Pushes food through pyloric sphincter to
small intestine
Stomach
Stomachh
Small Intestine
• Digestion is finished here
– Peristalsis finishes mechanical digestion
– Pancreatic juice produces enzymes to finish
chemical digestion of fats, proteins and
carbohydrates
Small Intestine
Small Intestine
Digestive System
Pancreas
• Makes enzymes to break down fats,
carbohydrates and proteins
Liver
• Produces bile
• Processes food for use by body
Question: What is the function of bile?
Bile is stored in the gallbladder.
Liver
• Location
– R. Hypochondrium
– Epigastric region
• 4 Lobes
–
–
–
–
Left
Quadrate
Caudate
Right
• Each lobe has lobules – Contains hepatocytes –
Surround sinusoids – Feed into central vein
19
Liver
• Functions
– Makes bile
• Detergent – emulsifies
fats
• Release promoted by:
– Vagus n.
– CCK
– Secretin
• Contains
–
–
–
–
–
–
Water
Bile salts
Bile pigments
Electrolytes
Cholesterol
Lecithin
20
Liver
– Detoxifies/removes
• Drugs
• Alcohol
– Stores
•
•
•
•
–
–
–
–
Gycolgen
Vitamins (A, D, E, K)
Fe and other minerals
Cholesterol
Activates vitamin D
Fetal RBC production
Phagocytosis
Metabolizes absorbed food
molecules
• Carbohydrates
• Proteins
• Lipids
21
Liver
• Dual blood supply
– Hepatic portal vein
• Direct input from
small intestine
– Hepatic artery/vein
• Direct links to
heart
22
Liver
Large Intestine
•
•
•
•
Absorbs water
Bacteria live here (produce methane)
Bacteria produce B vitamins and Vitamin K
Stores solid waste in rectum until
elimination.
Large Intestine
Digestive Endocrine Glands
•
•
•
•
Pancreas – insulin = blood sugar
Thyroid – thyroxine = metabolic rates
Thyroid – calcitonin = blood calcium levels
Parathyroid – PTH = calcium, phosphorus
absorption rates and helps make Vitamin D