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Chapter 30 Section 30.2 Food and Nutrition

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1 Unit 1: Biochemistry, Nutrition, and Digestion Chapter 30: Nutrition and Digestion

2 Chapter 30 Section 30.2 Food and Nutrition

3 Food Energy Measured in calories calorie Dietary Calories
Amount of heat needed to raise the temperature of 1 gram of water 1 degree celsius Dietary Calories Also called kilocalories Equal to 1000 calories Written with capital C

4 What Do You Use Food For? Energy Build and repair body tissues
There are at least 45 different components in food that the body needs that it can’t make itself These components are called nutrients

5 Nutrients Water Found in all cells Necessary for chemical reactions
Helps maintain body temperature 1 liter of water a day is necessary to replace what is lost Can be lost through urination, sweating, breathing

6 Nutrients Carbohydrates
Provide about 4 Cal/gram Simple carbs provide quick energy Complex carbs take longer to break down, and provide energy over a longer period of time Complex carbs provide fiber, or cellulose, which helps move waste through the digestive system Complex carbs with lots of fiber are healthiest to eat

7 Carbs and Stored Energy
Carbs that are not immediately used can be stored as a complex carb Converted into glycogen Stored in the liver, muscles, and brain Carbs that are not used can also be turned into body fat


9 Nutrients Fats Unsaturated fats are the healthiest to eat
Provide about 9 Cal/gram Help the body absorb fat-soluble vitamins Are a part of cell membranes Provide insulation and protect organs Can act as hormones Store energy long-term Unsaturated fats are the healthiest to eat Absorbed least by the body


11 Nutrients Proteins Provide 8 essential amino acids
Are the raw materials for many body parts, especially muscles Also control chemical reactions (enzymes!) Can act as hormones Provide about 4 Cal/gram Provide 8 essential amino acids Any animal product has all 8 A combination of plant products will have all 8 Lean meat is the healthiest to eat (93% fat or less)


13 Nutrients Vitamins Fat-soluble vitamins Water-soluble vitamins
Organic molecules that the body needs in very small amounts Needed for chemical reactions Fat-soluble vitamins A, D, E, K Can be stored in fat tissue Water-soluble vitamins B complex, C Cannot be stored, and are lost through urination


15 Nutrients Minerals Inorganic molecules that the body needs in very small amounts Many of them are elements Water-soluble, and are lost through sweat, urination, and solid waste


17 What Should You Eat? A balanced diet is based on Percent Daily Values
For a 2000-Calorie diet Calories can change with age, activity level, and age 2200 Cal for female teens, 2800 Cal for male teens A balanced, healthy diet contains: Lean proteins for 8 essential amino acids Complex carbs for energy and fiber Unsaturated fats in small amounts

18 Chapter 30 Section 30.3 The Digestive System

19 Functions of the Digestive System
Ingestion Take food into body Digestion Mechanical Physical breakdown of food into small pieces Chemical Enzymes break down food into individual nutrients Absorption Nutrients absorbed into body Elimination Waste is compacted and eliminated

20 The Mouth Teeth Saliva Tongue Pharynx
Incisors, cuspids, and bicuspids cut and tear food Molars grind food Saliva Amylase breaks down starch Tongue Forms a bolus, or ball of food Pushes food into back of throat, or pharynx Pharynx Contains epiglottis, which blocks the trachea and prevents choking

21 The Esophagus Connects the pharynx to the stomach
Moves food by peristalsis Smooth, wave-like muscle contractions


23 The Stomach Is a muscular sac that continues mechanical and chemical digestion Chemical digestion Protein is broken down by the enzyme pepsin Hydrochloric acid (HCl) also breaks down food Mechanical digestion Stomach squeezes and churns food to produce chyme Chyme is the mixture of food and digestive enzymes

24 The Small Intestine Connects to the stomach
Ends at the large intestine First section is called the duodenum Chemical digestion by enzymes continues after food is pushed from stomach Enzymes are made in the small intestine walls, or are from the pancreas


26 The Small Intestine Absorption of nutrients into the blood occurs through villi Villi are fingerlike projections that line the small intestine, and are covered with microvilli Microvilli are tiny projections of cells on villi that aid nutrient absorption


28 The Pancreas Connects to the small intestine by a duct
Makes and secretes sodium bicarbonate, which neutralizes stomach acid Makes and secretes enzymes, which break down food Also produces hormones that regulate blood sugar

29 The Liver and Gallbladder
Liver produces bile Gallbladder stores bile, and secretes it by a duct into the small intestine Bile helps break down fats

30 The Large Intestine Also called the colon
Connects to the small intestine Ends at the rectum Absorbs water from chyme Supports colonies of bacteria Compacts unused nutrients into solid waste Constipation Occurs when there is too little water in solid waste Diarrhea Occurs when there is too much water in solid waste


32 The Rectum and Anus Elimination occurs after the large intestine has compacted solid waste into feces Feces is stored in the rectum Anus is the muscle that controls release of feces


34 Section 30.1 Organization of the Body

35 Levels of Organization in the Body
Cells Are the basic unit of structure and function in an organism Tissues Are a group of cells that perform a single function

36 Levels of Organization in the Body
Four types of tissues: Epithelial Lines interior and exterior body surfaces Connective Supports and connects body parts Nervous Transmits nerve impulses Muscle Moves body parts


38 Levels of Organization in the Body
Organs Are groups of different tissue types that work together to perform a single function or several related functions Organ Systems Are groups of organs that perform closely related functions





43 Homeostasis Is the relatively constant internal physical and chemical conditions that organisms maintain despite changes in internal and external environments

44 Homeostasis Is maintained through feedback inhibition
Also called negative feedback A stimulus produces a response that opposes the original stimulus A thermostat is a good example Room gets cooler Heater turns on Room gets warmer


46 Examples of Homeostasis
Body Temperature Hypothalamus acts like a thermostat Triggers the body to shiver when cold, and to sweat when hot Blood Sugar Blood sugar (glucose) rises after a meal Too much blood sugar can damage organs Body cells absorb glucose, and the liver stores glucose as glycogen Blood sugar drops to a safe level

47 Section 30.4 The Excretory system

48 Role of the Excretory System
All cells produce waste, and it must be removed from the body, as it is toxic Excretion is the process by which metabolic wastes are eliminated to maintain homeostasis

49 Structures of the Excretory System
Skin Excretes water and salts Lungs Excrete carbon dioxide Liver Converts nitrogen waste into urea

50 Structures of the Excretory System
Kidneys Filter excess water, urea and metabolic waste from blood Ureters Transport urine from kidneys to bladder Urinary bladder Stores urine Urethra Releases urine outside the body


52 Structure and Function of the Kidneys
Filtration Is pushing a liquid or a gas through a filter to remove wastes Uses nephrons Filtering units of kidneys Removes water, urea, glucose, salts, amino acids, and some vitamins from blood Creates liquid filtrate in the nephron from material removed from blood

53 Structure and Function of the Kidneys
Reabsorption Occurs when water and dissolved substances are taken back into the blood Also uses nephrons Removes water, salts, vitamins, amino acids, fats, and glucose from the filtrate in the nephron Leaves remaining fluid as urine in the nephron

54 Structure and Function of the Kidneys
Urine Excretion Occurs when urine travels to the collecting ducts in the nephron, and then to the ureters, which connect to the urinary bladder



57 Homeostasis and the Kidneys
When waste builds up in the blood, it increases filtration by the kidneys The pituitary gland releases antidiuretic hormone (ADH) if blood fluid levels are low, causing the kidneys to reabsorb more water into the blood

58 Kidney Disorders Kidney stones Kidney damage Kidney failure
Calcium, magnesium, and other salts can crystallize in the kidney Kidney damage High blood pressure can harm the filtering mechanism of the kidney Kidney failure Occurs when kidneys can no longer filter the blood, and will lead to death if untreated

59 Kidney Disorder Treatment
Dialysis Uses a machine to filter wastes from the blood Kidney Transplant Leaves damaged kidneys in place unless they are secreting toxins Adds donor kidney below old kidney

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