The Digestive and Excretory Systems Chapter 32

32.1 Nutrients and Homeostasis Until the 1740s, British sailors on long voyages were crippled by scurvy, an illness that produced weakness, bruising, bleeding gums, and painful joints. All the British had to do was take a note from the Dutch and Add ORANGES that are high in VITAMIN C and they had NO MORE SCURVY! Your body is AMAZING but it has 6 very different types of needs that you are responsible to know about.

6 types of Nutrients 1. WATER- your body is made up of 55-60% H2O and is a natural solvent used by nearly EVERY cell in your body. It also helps maintain your body temp, keep sin moist, and maintain blood volume. 2. Carbohydrates – a main source of energy simple carbs are made of sugars complex carbs are starches found in veggies, grains, and potatoes. Carbs are broken down into simple sugars, any extra are converted to glycogen and are stored in the LIVER and MUSSLE tissue for the future.

6 types of Nutrients Continued 3. Proteins – the raw materials used for growth and repair of the body’s cells and tissues, also make up ALL enzymes and many hormones used in the body. Your body can only MAKE 12 of the 20 needed amino acids so you MUST get them through your diet. These essential A.A. are found in meat, cheese, and eggs (Most plants lack at least one of these A.A. so vegans MUST eat a varied diet.) 4. Fats – provide energy and key components in cell membranes, myelin sheaths for neurons, and certain hormones. Consist of long chains of fatty acids hooked to glycerol molecules. Your body can only make a few fatty acids, but most MUST be obtained through your diet.

nutrients cont. 4. Fats – provide energy and key components in cell membranes, myelin sheaths for neurons, and certain hormones. Consist of long chains of fatty acids hooked to glycerol molecules. Your body can only make a few fatty acids, but most MUST be obtained through your diet. Saturated fats are solid at room temp, from animal products unsaturated fats are liquid at room temp, from plant oils or some fish Unsaturated fats are usually considered better for a person’s health

nutrients cont. 5. Minerals- are inorganic materials the body uses to carry out processes in cells and to build or repair tissues. (page973)

Nutrients cont 6. Vitamins- are inorganic molecules that work with enzymes to regulate cell functions, growth, and development. p 974 vitamins are fat-soluble and water-soluble regulate cell functions, growth, development replenished by eating variety of foods

Meeting nutritional needs supports good health During development (birth to early twenties) you need extra nutrients to be healthy. One Calorie equals one kilocalorie, or 1000 calories. 1g of protein or carbohydrate equals 4 Calories. 1g of fat equals 9 Calories.

Growth and energy Needs p 975 MALES FEMALES FEMALES Growth and energy Needs p 975 MALES FEMALES

Nutrition Labels

Chapter 32 section 2 The Digestive System

The digestive system The digestive system breaks down food into energy cells can use. After digestion is complete, nutrients are absorbed and transported to all cells. Undigested materials are eliminated as liquid and solid wastes. mouth esophagus liver gallbladder large intestine small intestine rectum/anus

Where digestion begins Digestion of carbohydrates begins in the mouth. Digestion of proteins occurs in the stomach. Digestion of fats and sugars occur in the small intestine.

Mechanical vs. Chemical Body part Mechanical fxn Chemical fxn Mouth Chewing shreds and grinds food into smaller particles. Salivary AMYLASE breaks down starches into simple sugars. Stomach Smooth muscle contractions churn food to break it down and mix it with digestive juices. HCL and PEPSIN break down proteins. Small intestine Muscular contractions break down and mix food with digestive enzymes, bile, and hormones. Enzymes, bile, and hormones finish digestion of proteins, sugars, and fats.

Most digestion takes place in the duodenum. The pancreas, liver, and gallbladder aid in digestion. liver bile gallbladder duodenum pancreas enzymes chyme stomach pancreas helps digest fat and protein bile from the liver/gallbladder helps digest fats (p 980)

Absorption of Nutrients Chapter 32.3 Absorption of Nutrients

Most absorption occurs in the sm.Intestine p 982 Three structures in the small intestine help absorb nutrients. folded lining: adds surface area, slows food villi: absorb nutrients microvilli: cover villi, absorb nutrients.

absorption cont. Water is absorbed and solids are eliminated. Duodenum, jejunum, and ileum absorb different nutrients. Nutrients enter the circulatory or lymphatic systems. Liver stores excess glucose for future use. Water is absorbed and solids are eliminated. The colon helps to maintain the body’s fluid balance. Undigested material forms the solid feces. stored in rectum eliminated through anus

The LIVER and absorption Nutrient-rich blood leaves the sm.intestine and enters the liver. Enzymes in the liver use some of the nutrients to build more complex molecules, or stores others in the liver tissue When large amounts of energy are needed, glycogen in the liver can be converted back into glucose to keep glucose levels in your blood relatively stable. Pre-meal about 83 mg/dL two hours after meal under 120 mg/dL

The large intestine. Absorbs about 1 liter of water per day with salts to help maintain fluid balance. Solid left over mass is called feces. Bile pigments from the liver give it its brown color. Contains many bacteria some synthesize important vitamins Some, like E. coli, can cause severe diarrhea if an overabundance occurs.

chapter 32.4 The Excretory System

The excretory system eliminates nonsolid wastes from the body. skin lungs kidneys ureters urinary bladder The excretory system eliminates nonsolid wastes from the body. Nonsolid wastes are eliminated through lungs, skin, and kidneys. Lungs exhale carbon dioxide and water vapor. Sweat glands in skin release excess water and salts. Kidneys filter and clean the blood to produce urine. urethra

The kidneys help to maintain homeostasis by filtering the blood. Kidneys are a pair of bean-shaped organs. two layers: medulla and cortex filtering units called nephrons renal artery and renal vein cortex medulla renal artery renal vein ureter (to bladder)

Kidneys have three basic functions in maintaining homeostasis. remove waste from blood help to maintain electrolyte, pH, and fluid balances release key hormones

Nephrons Nephrons clean the blood in a three step process. Filtration: water, electrolytes, amino acids, glucose, urea, and other small molecules diffuse out of the blood, creating the filtrate. Reabsorption: As the filtrate enters the rest of the tubule, most of the materials are reabsorbed into the blood. Materials not reabsorbed make up the urine, which flows into the loop of Henle. Excretion: In the loop of Henle, water can be reabsorbed one final time to reduce the volume of urine. the remaining urine flows into a collecting duct that leads to the ureter.

Kidney damage May occur from injury or disease like diabetes or high blood pressure by two much glucose in the blood or the elevated pressure you can live comfortably with only one healthy kidney, but you have to have at least one. patients who need kidney transplants can usually receive one from a relative like a sibling , parent, or child as long as the blood matches. Someone with one kidney must avoid heavy contact sports or activities to prevent injury to their lone kidney.

Kidney Dialysis Dialysis is a treatment in which a patient’s blood is cleaned and chemically balanced through a mechanical process outside the body. the process takes between 3 and 5 hours, depending on the patient’s size and is done 3 times a week .