Chapter 3 presents the following content: Taste and smell: the beginnings of our food experience, the gastrointestinal tract, overview of digestion: physical and chemical processes, overview of absorption, assisting organs, putting it all together: digestion and absorption, circulation of nutrients, signaling systems.
Trang 1Chapter 3
The Human Body: From Food to Fuel
Trang 2Taste and Smell:
The Beginnings of Our Food
Experience
• Sight, smell, thought, taste, and sound
– Trigger a set of responses that prepare the digestive tract to receive food
Trang 4The Gastrointestinal Tract
• Variety of functions, including:
– Ingestion of food
– Transport of ingested food
– Secretion of digestive enzymes, acid, mucus, and bile
– Absorption of end products of digestion
– Movement of undigested material
– Elimination of digestive waste products
Trang 6The Gastrointestinal Tract
• Several layers to the GI tract, including
– Mucosa
– Circular muscle
– Longitudinal muscle
– Sphincters
Trang 9Overview of Digestion
• Physical movement
– Peristalsis
• Wavelike, muscular contractions
• Transport food and nutrients along the GI tract
Trang 13Assisting Organs
• Salivary glands
– Moisten food
– Supply enzymes
Trang 16Putting it All Together: Digestion and Absorption
• Mouth
– Enzymes
• Salivary amylase acts on starch
• Lingual lipase acts on fat
– Saliva
• Moistens food for swallowing
Trang 17Putting it All Together: Digestion and Absorption
Trang 18Putting it All Together:
Digestion and Absorption
digestion and activates enzymes
secretion and movement
vitamin B12
Trang 20Putting it All Together: Digestion and Absorption
• Duodenum, jejunum, and ileum
• Bicarbonate neutralizes stomach acid
• Pancreatic and intestinal enzymes
– Carbohydrates
– Protein
Trang 21Putting it All Together:
Digestion and Absorption
surface
Trang 23Putting it All Together:
Digestion and Absorption
Trang 24Putting it All Together: Digestion and Absorption
(produced by bacteria)
Trang 26Circulation of Nutrients
Trang 28Circulation of Nutrients
• Excrete water and carbon dioxide
• Excrete waste; maintain water and ion balance
Trang 29• Enteric nervous system
• Autonomic nervous system
Trang 31Influences on Digestion and
– Type of protein you eat
and the way it is
prepared
• Bacterial influences
– Hydrochloric acid kills
most bacteria
Trang 32Nutrition and GI Disorders
help reduce
Trang 33Nutrition and GI Disorders
Trang 34Nutrition and GI Disorders
constipation, and cramps
symptoms
modifications
Trang 35Nutrition and GI Disorders
and weight loss
Trang 36Nutrition and GI Disorders