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

Chapter 30 Section 30.2 Food and Nutrition

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

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

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

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

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

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

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)

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

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

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

Chapter 30 Section 30.3 The Digestive System

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

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

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

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

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

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

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

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

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

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

Section 30.1 Organization of the Body

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

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

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

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

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

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

Section 30.4 The Excretory system

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

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

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

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

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

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

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

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

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