Chapter 36 – Digestive and Excretory System

2/2 Classwork – Copy vocabulary terms from the board

Homework 2/2 (due Wednesday)

Keep a record of what you eat (breakfast, lunch, dinner) on Tuesday and bring in on Wednesday.

Food and Energy

Nutrients are substances that the body requires for energy, growth, repair and maintenance.

Fuel Other Essential Nutrients

Carbohydrates

Proteins

Fats

Vitamins

Minerals

Water

Calories vs. calories

When the body breaks down food through digestion, the chemical bonds in nutrients are broken and energy is released. Energy

The energy release when bonds break is measured in calories. 1000 calories is equal to 1 Calorie (information found on food labels).

Calorie Determination

Calories are determined by a process called calorimetry.

Energy Requirements

Calories

Exercise

The body needs energy to carry out both voluntary (Running, swimming, biking) and involuntary (breathing, growing, blinking) activities.

When you consume more calories than you burn, those calories get store in the body as fat.

Body Fuels

Carbohydrates

Simple sugars (Glucose)

Complex Sugars (starch and cellulose)

Found in fruits, honey and onions

Found in fruits, vegetables, cereal grains, potatoes, and corn.

Body Fuels, cont.

Proteins

Amino Acids (made in the body)

Essential Amino Acids(found in foods)

Proteins

Enzymes

Antibodies

Muscles

EggsMilkFish

PoultryBeef

Contain all of the essentialAmino acids

Only some are found in plants

Body Fuels, Cont

Fats (One type of lipid)

Used for storing energy, padding and insulating organs, making hormones and cell membranes, and dissolving fat soluble vitamins

WaterRegulates body temperature, and transports gases, nutrients and wastes.

VitaminsFat soluble vitamins – A, D, E, K

Stored in body fat and can become toxic in large amounts

Water soluble vitamins – B, CExcess amounts are excreted in the urine and can be replaced by the

diet.

MineralsNaturally occurring substances that are not made by the body (Na, K, Fe, Ca)These substances are needed for nervous system function, muscle contraction, transporting oxygen in the blood and normal immune function.

Essential Nutrients

Healthy Eating Habits

Nutritional and Health

Body Mass Index (BMI)Healthy Adult Weight Range (BMI = 18.5-25.0)

703..........................

xBMI (Weight in pounds)

(Height in inches)2

Excess body fat can result in increased risk of:

Heart disease

Osteoarthritis

Type II diabetes

Eating Disorders

Anorexia

Obsession with being thin

Bulemia

Binge eating followed by behaviors to reduce weight (vomiting, fasting, over-exercising)

Abnormal eating habits may result in dehydration, fatigue, organ failure and death.

Breaking Down Food Into Nutrients

DigestionThe body takes in food, breaks it down into molecules that the body can use, and gets rid of undigested molecules and waste.

Chemical Digestion – breaking of chemical bonds

Complex carbohydrates Simple sugars

Proteins Amino acids

Fats Fatty Acids

Mechanical Digestion – Physical breakdown of food

Chewing and churning

Starting Digestion – Mouth

Mouth Mechanical breakdown of food by teeth Chemical breakdown of food by saliva

Contains amylase – an enzyme that breaks down starches

Swallowing The epiglottis covers the trachea and food moves into

the esophagus Peristalsis begins in the esophagus

Starting Digestion – Stomach

Stomach Chemical breakdown of proteins by Gastric

juices (HCL and pepsin) HCL unfolds proteins Pepsin breaks bonds in proteins to form amino acid

chains

Mechanical breakdown occurs as the stomach churns food and mixes it with gastric juices

Absorbing Nutrients

Absorption of nutrients mostly takes place in the small intestine and is aided by secretions from the liver and pancreas.

Liver- Secretes bile that breaks fat globules into tiny fat droplets and aids in the absorption of vitamins A, D, E, and K

Gallbladder – Stores bile

Pancreas – Secretes lipases to breakdown fat droplets

Other Important Functions of the Liver and Pancreas

Homeostasis – Blood sugar regulationThe liver converts extra sugar into glycogen (a stored source of energy). When energy is needed, the liver breaks down glycogen and releases glucose. The pancreas makes insulin that regulates the conversion of glycogen to glucose.

Storage and DetoxificationBesides glycogen, the liver stores fat soluble vitamins and iron. It also, removes poisons from the bloodstream and monitors the production of cholesterol.

Small Intestine

The small intestine further breaks down food and reabsorbs nutrients through the villi and microvilli that cover its lining.

Capillaries in the villi, transport nutrients to the blood stream.

Removing Waste

The Large Intestine (No digestion occurs here) Water and minerals are absorbed Vitamins B and K are synthesized here by

bacteria Bacteria transform undigested material into

feces

Excretion

Osmotic (amount of dissolved particles) and pH balance of the blood is maintained through excretion.

Excretory OrgansSkin removes excess water, salts and nitrogenLungs remove carbon dioxideKidneys primary excretory organs that remove all of the

above and other cellular wastes.

Water

Most chemical reactions must take place in water Water absorbs and distributes heat Water transports gases, nutrients and wastes in

and out of cells

DRINK WATERA health person should drink at least 2.5qt of water

each day to replenish the water lost through excretion

Cleaning the BloodKidneys contain Nephrons that carry out 3 main functions:Filtration of blood (Glomerulus)Reabsorption of water and other nutrients (renal tubule)Secretion of wastes, toxins and water (collecting ducts)

Urinary Excretion

The resulting product of filtration, absorption and secretion is Urine.

Urine flows through:UretersBladderUrethra

Kidney Disease

Kidneys are vital to maintaining homeostasis, so damage to the kidneys may eventually become life threatening.

Most common causes of kidney damage:InfectionDiabetesHigh blood pressureAutoimmune diseases

Treatment for Kidney Disease

Dialysis (not a cure)

A process for filtering blood to remove substances from the blood.

Kidney Transplant