Digestive and Excretory System

Nutrients

6 Nutrients for Good Health 1. Waterinvolved in almost all chemical reactions

2. Carbohydrate main source of energy grains, fruits, vegetables

3. Proteingrowth and repair of body’s cells and tissue (8 out of 20 amino acids come from food) Meat, cheese, eggs

4. Fatsenergy and key componants of cell membranes, neurons, hormones animal fats (saturated) oils (unsaturated *good)

5. Mineralsinorganic materials body uses to carry out processes in cells, build and repair tissue calcium, sodium, potassium

6. Vitaminsorganic molecules that work with enzymes to regulate cell function, growth, development Vitamin D Vitamin K

Nutritional Needs for Good Health Eating a balanced diet Calorie: energy that comes from food Different foods have different amount of energy Calories should mostly come from grains, fruits, and vegetables Include physical activity

Food Labels help you make good choices Food Labels Tell you: serving size and number: different for each food item calories and calories that come from fat nutrients to limit: trans fat can cause cell damage, too much of these nutrients cause obesity nutrients to target: required for each day

Compare the total fat content on each label. Rank them from lowest to highest. Compare the vitamin C content on each label. Rank them from lowest to highest.

The Digestive System

Digestion: large complex molecules in food are broken down into smaller molecules Digestive system: organs that break down food into energy that can be used in cells Organs: mouth, esophagus, stomach, pancreas, liver, gall bladder, small intestine, large intestine, rectum, anus Sphincters: rings of muscles that keep food moving by opening and closing

Digestion Takes Place Through: Interaction of enzymes Stomach acid Hormones Bile from liver Nerves and muscles

Each organ helps break down food After digestion, nutrients are absorbed by body and transported Wastes are eliminated Food enters mouth until it leaves the body  about hours

Mechanical Digestion: physical breaking apart of food Chemical Digestion: use of other substances to break down food

Digestion in Mouth Teeth grind food into smaller pieces Salivary glands release enzymes and moisten food (ex: Amylase: digests starch) Tongue pushes food back toward esophagus Esophagus: tub that connects mouth to stomach Peristalsis: rhythmic, involuntary contraction of smooth muscles in digestive organs

Digestion in Stomach Stomach: muscular sac that can stretch up to 2 times its original size Proteins are digested in stomach and small intestine Fats/sugars digest in small intestine

Stomach muscles churn  breaks down food and mixes with digestive juices Stomach lining secretes gastic juices (HCL and pepsin) and forms a semi-liquid mixture called Chyme Stomach pushes chyme slowly into small intestine Stomach also secretes mucus to protect the lining

Digestion in Small Intestine Completed here Long narrow tube where most digestion takes place Carbohydrates, protein, fat are digested in duodenum

Enzymes/hormones from pancreas, liver, and gall bladder flow ehre Pancreas  neutralizes acid, stops pepsin Liver  filters blood and produces bile (digest fats) Bile is stored in the gall bladder Proteins  broken down to single amino acids

Absorption

Most occur in small intestine Absorption: process by which nutrients move our of digestive system Small intestine: has three main strucutres  lining, villi, microvilli

Specialized Structures Folds increase surfaces area Villi: fingerlike projections that absorb nutrients Micovilli: tiny projections on villi

3 Parts of Small Intestine: different parts absorb different molecule s

Nutrients and Liver Blood leaves small intestine and enters liver Liver enzymes can build more comple molecules Make glycogen  storage for glucose

Water and Wastes: Large Intestine (colon) Absorb water Remaining waste makes solid waste Wastes  fibers, bacteria, undigested fat/protein Stored in rectum, removed by anus Bacteria  live in colon

Excretory System

Eliminates non-solid wastes from body through sweat, urine, and exhalation to maintain homeostasis Wastes are toxic material, excess water, salts, CO 2, urea, minerals, vitamins

Organs skin, lungs, kidneys, ureteres, urinary bladder, and urethra Lungs: remove CO 2 and water vapor Sweat glands: release water/salts Kidneys: filter and clea blood to produce urine Ureter: tube carries urine from kidney to bladder Urinary bladder: store half liter of urine Urethra: release urine to outside environment

Structure of Kidney Pair about the size of fist Inner layer (medulla) outer layer (cortex) Packed with nephrons (individual filtering units) Blood enters through renal artery and leaves through renal vein

3 Functions of Homeostasis 1. Remove waste products from blood 2. Maintain fluid balances 3. Release hormones (bone health, produce red blood cells, and regulate blood pressure) Buildup of wastes in blood can cause many problems

Nephrons Clean Blood and Make Urine 3 step process 1. Filtration Supplied with blood to glomerulus (ball of capillaries inside of Bowman’s capsule) 2. Reabsorption Excess water becomes urine 3. Excretion Urine is produces Keeps blood pH at the proper level Flows to bladder  released by urethra

Urine Testing used by doctors to tell when something is wrong with kidneys (infection)

Injury/Disease Transplant: need to have similar tissues, but you can survive with one kidney Dialysis: patients blood is cleaned and chemically balanced