NUTR 225 Ch. 3

• 1) Energy for body processes
• 2) Heat for body temperature regulation
• 3) Building blocks for growth and maintenance of body tissues

Physiological sensation to eat regulated by internal cues

Psychological desire to eat; strong drive to eat even when we're not hungry

The feeling of being full

Physiological need for food yet have no appetite

Nerve cells in stomach and small intestine sense food and send message to hypothalamus to indicate if the stomach is full or empty.

• chemicals produced in specialized glands that travel in the bloodstream to target organs in other parts of the body
• - Some hormones stimulate hunger
• - Some hormones produce satiety

• 1) Break these large molecules down to smaller molecules
• 2) Absorb the smaller molecules into the cells of the body

Smallest unit of matter; they bond together to form molecules

• groups of atoms bonded in specific configurations
• e.g.: H2O, CO2

the smallest unit of life

• outer layer enclosing each cell of the body
• -two layers of phospholipids
• -long lipid "tails" face toward interior of membrane
• -phosphate "heads" line the interior/exterior surfaces of the membrane
• -cholesterol and proteins in membrane

liquid within the cell

• tiny structures that perform many different cellular functions
• e.g.: nucleus, mitochondria

• group of cells acting together to perform a common function
• e.g.: muscle tissue, nervous tissue

• a sophisticated organization of tissues that perform a special function
• e.g.: stomach, heart, brain

• group of organs working together for a particular function
• e.g.: gastrointestinal system

• 1) Digestion
• 2) Absorption
• 3) Elimination

these processes occur in the gastrointestinal tract

• series of organs arranged as a long tube through which the food passes.
• Includes:
• - Organs such as the stomach and intestines
• - Sphincters: muscles that control the passage of material from one organ to the next

• Process of breaking large food molecules down to smaller molecules.
• 1) Mechanical digestion: the physical breakdown of food.

2) Chemical digestion: enzymatic reactions that break down large food molecules

• Mouth-> Chewing, salivary amylase, epiglottis, peristalsis
• Stomach-> Gastric juice (HCl, Pepsin, Gastric lipase, Mucus), Chyme
• Small Intestine-> Chemical digestion of chyme w/pancreatic enzymes and bile
• Accessory organs-> Salivary glands, Liver(breaks fat into liquid), Pancreas(digestive enzymes/neutralize chyme), Gall bladder(stores bile)

• The process of taking molecules across a cell membrane and into cells of the body.
• Occur in three areas:
• - Duodenum
• - Jejunum
• - Ileum

• Water-soluble nutrients enter portal vein
• Fat-soluble nutrients enter lymphatic vessels

Large intestine-> undigested food, very little digestion, stored 12-24 hrs before elimination, water and nutrients are absorbed

• 1) Heartburn: HCl acid builds up in the esophagus
• 2) Gastroesophageal reflux disease (GERD): persistent heartburn
• 3) Peptic ulcers: regions of the GI tract eroded by HCl and pepsin
• 4) Diarrhea: food intolerance, infection of GI tract, stress, bowel disorders
• 5) Constipation: No stool passes for 2+ days
• 6) Irritable bowel syndrome (IBS)

• Intolerance for gluten
• - Can damage small intestine-> poor absorption of nutrients
• - Diet lacking wheat, rye, barley
• - May be genetic component to disease