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Nutrition: Process of acquiring / processing into Chapter 34: usable form Nutrition and Digestion Function of Nutrients: 1) Fuel cellular  Measured in calories (energy required to raise 1 g of water 1°C)  Calorie = 1000 calories (kilocalorie)  Human at rest = 1550 calories burned/day

2) Building blocks to construct complex molecules

3) Molecules to assist in metabolic reactions

Nutrient Classifications: Classifications: 1) Carbohydrates: 3) Proteins: • Energy source (~ 46% for humans) • Energy source (~ 16% for humans)  Body cells burn glucose (some exclusively)  Urea: Byproduct of protein breakdown • Energy storage (short-term) : Glycogen ( / muscles) • Provide building materials (amino acids) • Obtained via animal products (e.g. muscle) and plants (starch)  Essential amino acids: Can not be synthesized by 2) Lipids: body (9 / 20 amino acids)

• Energy source (~ 38% for humans) 4) Minerals (Elements / Inorganic molecules - Table 34.3): • Energy storage (long-term) : Fats • Structural material (e.g. calcium, iron, iodine)  1 pound = 3600 Calories (Carbs = 1600 Calories / pound)  Hydrophobic; no excess water storage • Assist in physiological functions (e.g. sodium, , calcium) •Sodium, potassium, calcium, magnesium, etc are also called electrolytes • Provide building materials (e.g. phospholipids, cholesterol)

Electrolytes Nutrient Classifications:

• Required to maintain 5) (Organic compounds - diverse group) : • Water-soluble: Cleared from body () certain functions  C = Maintenance of connective tissues Muscles, neurons, etc.  B-vitamin complex = Coenzymes • Imbalance causes death • Water-insoluble: Stored in body (fat) Excess water drinking  = Produces visual pigments leads to fatal electrolyte imbalance  = Promotes bone growth  = antioxidant  Sport drinks contain electrolytes to prevent  = Regulates blood clotting water intoxication

Page 1 1 Vitamin deficiencies Vitamin deficiencies

• Vitamin A : blindness • Vitamin B complex Several different vitamin B We consume beta Thiamin (Vitamin B1) carotene, which is  (Vitamin B2) converted to Vitamin A  (Vitamin B6) in our bodies.   Beta Carotene is found Choline in red/orange • Deficiencies lead to diseases vegetables. beriberi, pellagra, , & mental disorders. Hand of someone with pellagra Sources: grains, legumes, animal products

Vitamin deficiencies Vitamin deficiencies • Ascorbic acid • Vitamin D : Rickets Deficiencies lead to Scurvy Caused by lack of calcium absorption in Especially affected sailors bones. Professional sailors always carried limes or other citrus fruits to ward off scurvy Sunlight, eggs, cod liver oil, dairy products

Vitamin deficiencies Vitamin deficiencies

• Vitamin E • Vitamin K Anemia, neurological problems Bleeding, hemorrhages

Deficiencies are very rare Deficiencies rare due to Mainly due to genetic production of vitamin K disorders the prevent the absorption of fat. with the help of intestinal (E. coli). Seeds, green leafy Excessive use of broad vegetables, oils spectrum antibiotics can result in deficiencies.

Page 2 2 Fat soluble vitamins can lead to overdoses Fat soluble vitamins can lead to overdoses • Fat soluble vitamins are stored in the fatty tissues in the body • More than 15,000 IU of The reason why deficiencies Vitamin D per day can are rare with modern diets. lead to overdoses Overdoses are becoming more common due to Most deaths are due to supplements, , etc. children eating sugar • Vitamin A : 15,000 IU per coated vitamins. day or more can be toxic Especially toxic to developing fetuses = birth defects Liver damage

Fat soluble vitamins can lead to overdoses Nutrient acquisition

• More than 1,500 IU of • Herbivore Vitamin E per day can Eat plants lead to overdoses • Carnivore Excess leads to Eat animals anticoagulation in blood. • Omnivore Eat plants & animals

Digestion: Mechanical and chemical breakdown of Animal Digestive Systems:

• Required to absorb nutrients (complex → simple) 1) Intracellular Digestion (e.g. protists, sponges) • Cells engulf microscopic particles (no specialized system) Tasks of Digestive System: 1) Enclosed in food vacuole 1) Ingestion = Food enters system (mouth) 2) (organelle w/ enzymes) breakdown food 2) Mechanical Breakdown = Food physically broken down 3) Waste expelled (exocytosis)

3) Chemical Breakdown = Food broken down via enzymes  Increased surface area (enzyme attack)

4) Absorption = Nutrients from digestive cavity into body

5) Elimination = Indigestible material cleared

(Figure 34.4)

Page 3 3 (Figures 34.6 & 34.7) Animal Digestive Systems: Animal Digestive Systems:

3) Tube Digestion (e.g. worms, arthropods, vertebrates) 2) Sac Digestion (e.g. jellyfish) • Tube present; two openings (mouth, anus)  Chamber present (gastrovascular cavity); single opening • Efficient digestion of food (one-way system) :  Extracellular Digestion (enzymes released into chamber)  Crop / #1 = Food storage  Food enters / waste exits same opening  Stomach #2 / Gizzard = Mechanical digestion  Intestines = Chemical digestion / Absorption

(Figure 34.5) Worm: Bird:

gizzard Crop

• Many toothless animals (i.e., birds) will • Pigeons, doves and flamingoes produce crop swallow stones to aid digestion. Stones help grind food inside the gizzard A secretion produced by the crop that is used to feed the young.

Highly Specialized Tube Digestion: (Figures 34.6) :

Ruminants Digest Cellulose...

Rumination: Regurgitating & rechewing food

• Mixes food with cellulase  Cellulase produced by bacteria in the (Figure 34.9)

Page 4 4 (Figure 34.9) (Figure 34.11) Process of Human Digestion: Process of Human Digestion: 2) Esophagus conveys food to stomach 1) Breakdown of Food begins in Mouth • Peristalsis: Rhythmic contraction of smooth muscle; propels food • Mechanical breakdown = Teeth • Bolus: Compacted food  Incisors: Snip food  Canines: Tear food  Premolars/Molars: Grind food

• Chemical Digestion = Salivary Glands  Amylase: Enzyme → Carbohydrates

(Figure 34.10)

Process of Human Digestion: Process of Human Digestion: 3) Stomach: 4) = Chemical digestion & absorption: • Stores food (2 - 4 liters = 0.5 - 1 gallon) • Longest portion of digestive system (~ 3.5 m) • Chemical Digestion: • Mechanically breaks down food (smooth muscle → churns) • (pancreatic juice) • Chemically breaks down food • Bicarbonate ion = neutralizes chyme  Acidic environment (pH 1 - 3 → HCl secretion) • Amylase = Enzyme → carbohydrates  : Enzyme → Proteins • Lipase = Enzyme → lipids  Bleeding Ulcers • = Enzymes → proteins • Chyme = Thick, acidic liquid • Liver ()

• Water, Alcohol, Drugs (e.g. aspirin) • Bile stored / concentrated in gallbladder absorbed through stomach wall • Bile salts = Assist in breakdown of fats • Emulsify fats (separate into small droplets)

Small Intestine and Related Organs: Process of Human Digestion: 4) Small Intestine = Chemical digestion & absorption: • Absorption:  Large surface area (2200 square feet) • Villi: Finger-like projections tube surface • Microvilli: Projections of cell membrane

• Blood / lymph vessels (lacteals) run up villi (nutrient absorption)  Requires energy (ATP) • Movements:  Segmentation (mixing)  Peristalsis (propulsion)

Page 5 5 Process of Human Digestion: Process of Human Digestion: 5) = absorption & elimination: 5) Large Intestine = absorption & elimination: • ~ 1.5 m long (colon & rectum): • ~ 1.5 m long (colon & rectum):

• Contain bacteria:  Produce Vitamin B complexes and Vitamin K

• Absorbs water, vitamins, salts

• Movement via peristalsis & defecation  Feces = Indigestible waste (semi-solid)

Control of Digestion: 1) : • Food stimuli activates digestive system (e.g. smell, taste, stretch)  Secretes saliva (mouth), HCl (stomach)

2) Endocrine System: • : Stimulates HCl secretion (stomach)

• Secretin: Stimulates bicarbonate release (pancreas)

• Cholecystokinin: Stimulates bile release (gallbladder)

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