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Week Three.docx

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Department
Nutrition
Course
NUTR 1010
Professor
Jess Haines
Semester
Fall

Description
Week Three Monday, Sept 17th 2012 Why do you eat? - Comfort, to survive, bored, stress, socially, Hunger: physiological NEED for food (your body needs it) Appetite: psychological WANT for food (your brain wants it); ex. That cake looks good, I want it; everyone was having cake; I was sad so I ate cake. How does our body tell us we are hungry? Nerve signals: your stomach and intestines send nerve signals to the hypothalamus of the brain; “we’re empty,eat” Blood sugar levels drop: insulin and glucagon levels in the blood change (these are hormones); this is a signal for your hypothalamus; “time to eat”; there are lots of other hormones that send messages. Basics of Digestive System 1) Digestion: breaking food into tiny pieces; takes a whole sandwich and breaks it into microscopic particles and puts it into your cells. 2) Absorption: moving the tiny pieces from your intestine into the cells and blood stream. 3) Elimination: getting rid of waste. INTRODUCING ENZYMES - Very important pat in chemical digestion - Made of protein - Biological catalysts; facilitate chemical reactions in living things - You know it is an enzyme when it has a suffix of –ASE. GI TRACT Cephalic Phase: makes you salivate; gets your digestive track starting. Mechanical Digestion: your teeth break up the food Chemical Digestion: enzymes in your saliva start breaking up the food; salivary amylase breaks up starch, lingual lipase breaks up fat. Making a bolus: a moist ball of food. Swallowing: a delicate process; part conscious, part unconscious; epiglottis is open, esophagus is closed. Peristalsis: waves of muscle contractions that move food; inner circular muscles; outer length wise muscles; p starts in esophagus and continues through your GI tract; food moves into stomach via lower intestine. Stomach churns: mechanical digestion; 3 thick muscle layers churn and break up food; food turns to chime. Burns: chemical digestion; hydrochloric acid (HCl) denatures protein (unravels); pH of gastric juice is 2.0 (1 is most acidic); pepsin (an enzyme) breaks down protein Mucus lines your whole GI tract; Pancreas: produces and adds biocarbonte to neutralize the acid and enzymes. Small Intestine: Duodenum: chemical digestion and some absorption Jejunum: digestion continues but LOTS of absoroption Ileum: the last of the absorption Brush border Getting nutrients into cells: Large intestine: water absorption (small intestine doesn’t really absorb water); contains friendly bacteria (digests what you cant such as fibre); produce gas and vitamin K; produce fats that it uses; rectum: holds feces until its eliminated. BORBORIGMUS: medical terminality for stomach growling; movement of gases in the intestines; doesn’t necessarily mean your hungry. Facilitative diffusion requires membrane protein WHEN DIGESTION GOES WRONG Heartburn Gastro esophageal reflux disease (GERD); Chyme (very acidic) from the stomach in the esophagus; could be because lower esophageal sphincter may be damaged or not working hard enough; hydrochloric acid in the stomach begins to burn. Causes: 1) Physical damage – bulimia, or injury. (Dysfunctional sphincter) 2) Genetic
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