1. Food: source of energy and essential molecules optimal diet: more carbohydrates than fats and significant of protein DIGESTION

2. Carbohydrates: cereals, grains, breads –4 calories per gram fats: oils, margarine, butter, fried foods, meats, snack foods –9 cal/gram Proteins: poultry, fish, meat –4 cal/gram Fiber: part of plant cannot be digested by humans –diets low in fiber result in a slow passage of food through the colon, associated with colon cancer essential minerals: calcium, phosphorous, iron Essential vitamins: vit A, B, D, C

3. A healthful diet satisfies three needs: –Fuel for an organism’s activities –Raw materials for biosynthesis –Essential nutrients –Vegetarians must be sure to obtain all eight essential amino acids 0

4. Obesity is a human health problem: –usually caused by lack of exercise and abundance of fattening foods –May partly stem from an evolutionary advantage of fat hoarding Research on mice: Has shown that a defect in the gene for leptin may cause obesity 0

5. wealthy countries: overweight 65% body mass index (BMI): estimate of body weight in kg, divided by height in meters2

6. DIGESTIVE SYSTEM alimentary canal: separate mouth and anus to transport of food is one way physical forces, chewing and grinding, first breaks the ingested food into smaller fragments chemical digestion, hydrolysis reactions that liberate the subunits products of digestion are transported by the blood molecules not absorbed are excreted

7. digestive system parts: –gastrointestinal tract –accessory organs

8. Digestion begins in the oral cavity Teeth: break up food omnivores teeth are specialized for eating both plant and animal material: Carnivores: front of the mouth, Herbivores: in the back children have only 20 teeth/// Adults: 32 adult Saliva: moistens it salivary enzymes begin the hydrolysis of starch Tongue: pushes the bolus of food into the pharynx 0

9. The food and breathing passages both open into the pharynx –food is prevented from going into the respiratory tract by the epiglottis The swallowing reflex: Moves food from the pharynx into the esophagus, while keeping it out of the trachea 0

10. The esophagus squeezes food along to the stomach by peristalsis food from the esophagus into the stomach is controlled by a ring of muscle, sphincter - when relaxed>>> stomach contents can be brought back out during vomiting and lead to acid reflux or heartburn 0

11. The Heimlich maneuver can save lives: dislodge food from the pharynx or trachea during choking 0

12. Stomach: –saclike smooth muscle for churning food –Substances release: gastric juice hydrochloric acid (HCl) with low pH to denature proteins and kill bacteria pepsin for digestion of proteins

13. Bacterial infections, Helicobacter pylori, in the stomach and duodenum are associated with ulcers 0

14. Intestines –Types: Small: carbohydrates, protein, and lipids are broken down and absorbed into the bloodstream Large: production of waste or feces

15. small intestine: –Parts: Duodenum: first part where “real” digestion and absorption of food is done Jejunem: digestion continues Ileum: water and digested products are absorbed

16. Folds of the intestinal lining, and tiny, fingerlike villi: Increase the absorptive surface 0 1

17. large intestine –wider diameter than the small intestine –no digestion takes place here –Main functions: fluid absorption from waste: water, Na, vitamin K compact and store undigested material as feces in the rectum

18. The small intestine is the major organ of chemical digestion and nutrient absorption in which 2 major organs secrete their content: 0

19. pancreas –Secretes bicarbonate to neutralize the acid chyme –And enzymes to digest food polymers trypsin, chymotrypsin digest proteins amylase digests starch lipase digests fats –Also produces h ormones: insulin and glucagon to deal with glucose storage

20. liver –largest internal organ –has a strategic location in the body: between the intestines and the hear –Many functions: produces bile and stores it in the gallbladder for fat digestion removes toxins, pesticides, carcinogens and other poisons by converting them into less toxic forms produces urea Breaks down toxins

21. Alcohol consumption can damage the liver and liver function can be impaired, as well as hepatitis

22. EXCRETORY SYSTEM Major parts: Kidneys, 2 kidneys, each of contains 1 mll nephrons ureter urinary bladder Urethra Functions: major role in homeostasis>>> expels wastes and regulates water and ion balance

23. Nephrons, the functional units of the kidneys>>> Extract a filtrate from the blood and refine it to urine>>>Urine leaves the kidneys via ureters>>>Is stored in the urinary bladder, and is expelled through the urethra

24. –Major processes of the excretory system

25. The key processes of the excretory system are filtration, reabsorption, secretion, and excretion In filtration: Blood pressure forces water and many small solutes into the nephron In reabsorption: Valuable solutes are reclaimed from the filtrate In secretion: Excess H + and toxins are added to the filtrate The product of all of the above processes is urine: Which is excreted

26. Kidney dialysis can be a lifesaver –Compensating for kidney failure –A dialysis machine removes wastes from the blood and maintains its solute concentration Line from artery to apparatus Dialyzing solution Fresh dialyzing solution Used dialyzing solution (with urea and excess ions) Tubing made of a selectively permeable membrane Pump Line from apparatus to vein