2The Digestive SystemThe Digestive System is a group of organs that work together to digest food so that it can be used by the body.
3Organs of the Digestive System The digestive tract is a series of tubelike organs which food passes through.The digestive tract includes your mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum and anus.
4The Digestive System Chapter 24-1 Objectives:Compare mechanical digestions with chemical digestion.Describe the parts and functions of the digestive system.
5Other OrgansThe liver, gallbladder, pancreas and salivary glands are also part of the digestive system.Food does not pass through these organs.
6Breaking Down FoodDigestion is the process of breaking down food into a form that can pass from the digestive tract into the blood stream.
7Two Types of DigestionThere are two types of digestion : mechanical and chemical.The breaking, crushing and mashing of food is called mechanical digestion.In chemical digestion, large molecules are broken down into nutrients.Nutrients are substances in food that the body needs for growth, maintenance and repair.
8Catabolic and Anabolic Catabolic reactionsProteins from your food are made up of chains of amino acids.Catabolism refers to the breakdown of proteins into amino acids.This process releases energy in the form of ATPAnabolic reactionsAnabolism refers to the process by which simpler substances (amino acids) are combined to form more complex molecules.
9EnzymesSubstances called enzymes break some nutrients into smaller substances that the body can use.Proteins are changed into smaller molecules called amino acids.
10The Role of enzymes in Digestion 1. Enzymes break apart the long chains of amino acids that make up proteins.2. The small chains are then split by other enzymes.3. Individual amino acids are then small enough to enter the bloodstream where they will make new proteins.
12Digestion Nutrients are the usable portions of food. The six nutrients are protein, fat, carbohydrates, vitamins, minerals and water.Proteins are broken down into amino acids.Fats are broken down into fatty acids and glycerol.Carbohydrates are broken down into simple sugars.Food is pushed through the digestive system by waves of muscular contractions called peristalsis.Bacteria in the large intestine make vitamins for us.Nutrients are absorbed in the small intestine.Water and vitamins are absorbed in the large intestine.
13NutrientsChemical digestion of carbohydrates begins in the mouth and ends in the small intestine.Chemical digestion of proteins begins in the stomach and ends in the small intestine.Chemical digestion of fats begins and ends in the small intestine.Fats are broken down into fatty acids and glycerol.Proteins are broken down into amino acids.Carbohydrates are broken down into simple sugars.
14Digestion begins in the Mouth Chewing creates small, slippery pieces of food that are easier to swallow.Small pieces of food are easier to digest.
15Digestion in the MouthPalate – the “roof” of your mouth, tongue pushes against it to aid swallowing, separates the mouth and nasal cavitiesTeeth - crush food into smaller pieces to aid swallowingTongue – tastes food, mixes food with saliva, pushes food between the teeth, helps in swallowingSalivary Glands - secrete saliva into the mouth to begin carbohydrate digestion and moisten foodPharynx – where mouth and nasal passages meet, leads to the trachea and esophagusEpiglottis – flap of tissue that closes over the trachea when you swallow to prevent food or drinks from going into the trachea which prevents chokingEsophagus - connects the mouth and stomach, uses peristalsis (muscular contractions) to move food along
16Teeth Teeth break and grind food. The outermost layer of the teeth, enamel, is the hardest material in the body.Enamel protects nerves and softer material inside the tooth.
17Teeth Your teeth have different shapes. The molars are suited for grinding food.The premolars are used for mashing food.Incisors and canines are used for shredding food.
18Saliva The roof of the mouth is the palate. Saliva mixes with food in your mouth.Saliva is made in the salivary glands.It contains an enzyme that begins chemical digestion of carbohydrates by changing them into simple sugars.
19EsophagusAfter the food is very soft, the tongue pushes it into the throat, which leads to the esophagus.The esophagus squeezes the food with rhythmic muscle contractions called peristalsis, forcing the food into the stomach.
20stomachThe stomach is a muscular saclike digestive organ between the esophagus and the small intestine that breaks down the food into a liquid by the action of muscles, enzymes and acids.
21StomachThe stomach continues the mechanical digestion of your meal by squeezing food with muscular contractions.Glands in the stomach produce enzymes and acid which break food into nutrients.
22Chyme Stomach also kills bacteria that you swallow with food. After a few hours of chemical and mechanical digestion, food turns into chyme.
23Small IntestineThe stomach releases the chyme into the small intestine through a small ring of muscle that works like a valve.The valve keeps the food in the stomach until it has been mixed with digestive fluids.
24Small IntestineSince the stomach releases the chyme slowly, the small intestine has time to mix the chyme with fluids from the liver and pancreas,This help digest and stop the acids in chyme from hurting the small intestine.
25The Pancreas and Small Intestines When the chyme leaves the stomach, the chyme is very acidic so the pancreas makes fluids to protect.The pancreas is an oval organ located between the stomach and small intestine.
26Small IntestineThe small intestine is a muscular tube that is about 2.5 cm in diameter. It is about 6 m long when stretched out.The inside wall is covered with fingerlike projections called villi.The villi are covered with tine, nutrient absorbing cells.
27duodenumThe duodenum precedes the jejunum and ileum and is the shortest part of the small intestine, where most chemical digestion takes place. The name duodenum is from the Latin duodenum digitorum, or twelve fingers' breadths.
28The LiverThe Liver is a large, reddish brown organ that help with digestion. I human liver can be as big as a football.It is located toward your right side, slightly higher than you stomach.The functions of the liver are:Store nutrientsMake bile to break up fatBreak down toxins
29GallbladderBile is stored in a saclike organ called the gallbladder, which squeezes the bile into the small intestine where the breaking down of fats take place.The bloodstream absorbs nutrients that have been broken down.
31The End of the LIneMaterial that can’t be absorbed into the blood is pushed into the large intestine.The large intestine absorbs most of the water in undigested material and changes the liquid into semisolid waste material called feces, or stool.Feces are stored in the rectum until they can be expelled.
32Rectum and AnusFeces pass to the outside of the body through an opening called the anus.It has taken each of your meals about 24 hours to make this journey through your digestive system.
33Summary of Functions of parts of the Digestive System Teeth – crush food into smaller pieces to aid swallowingLiver – secretes bile which breaks fat into smaller piecesGall bladder – stores bile until needed in the small intestineLarge Intestine – absorbs water and vitamins (made by bacteria living in the large intestine), stores waste, releases wasteSmall Intestine – all digestion is completed here (no nutrients are broken down past this point), nutrients are absorbed through the villi into the blood streamRectum – end of large intestine, stores solid wastes until they leave the body
34Digestion Summary Anus – opening to let out wastes Mouth – allows food to enter the body, contains teeth and tongue, carbohydrate digestion begins here due to the action of the enzymes in salivaSalivary glands – secrete saliva into the mouth to begin carbohydrate digestion and moisten foodEsophagus – connects the mouth and stomach, uses peristalsis (muscular contractions) to move food alongStomach – churns food into a thick liquid called chyme, protein digestion begins here due to the action of gastric juice (enzymes and hydrochloric acid)Pancreas – secretes pancreatic juice into the small intestine to neutralize the acid from the stomach and to digest all types of food
35The urinary System Chapter 24-2 Objectives: To describe the path and function of the urinary systemTo explain how kidneys filter bloodTo describe three disorders of the urinary system
36Excretion Excretion is the process of removing waste from the body. Three of the body systems have a role in excretion.The integumentary system releases waste products and water when you sweat.The respiratory system releases carbon dioxide and water when you exhale.The urinary system contains the organs that remove waste products from your blood.
37Urinary SystemAs the body performs the chemical activities to keep the body alive, waste products, such as carbon dioxide and ammonia are produced.The body has to get rid of these wastes to stay healthy.
38Kidneys The kidneys act as filters. They filter about 2000L of blood a day. (You body can only hold about 5.6 L).Inside each kidney is over 1 million nephrons.
39NephronsNephrons are microscopic filters. They remove harmful substances, such as urea.Urea is formed when cells use protein for energy. It contains nitrogen.
40How the Kidneys Filter Blood 1. A large artery, called the renal artery, brings blood into each kidney.2. Tiny blood vessels branch off the main artery and pass through part of each nephron.
41How the Kidneys Filter Blood 3. Water and other substances are forced out of the blood vessels and into the nephrons.4. The nephrons filter the wastes out of the blood and water, and allow the filtered blood and water to move back into the blood vessels.
42How the Kidneys Filter Blood 5. As filtered blood and water go back into the blood vessels, waste materials are left in the nephrons.6. Cleaned blood leaves each kidney in the renal vein to recirculate in the body.7. The yellow fluid that remains in the nephrons is called urine.
43How the Kidneys Filter Blood 8. Urine leaves each kidney through a slender tube called the ureter and flows into the urinary bladder.9. Urine leaves the body through another tube called the urethra.10. Urination is the process of expelling urine from the body.
45Water Balance in BodyYou drink water everyday but you lose water in sweat and urine. You need to get rid of as much water as you drink or your body will swell up.When you are too warm, you sweat. The evaporation of water cools down the body.As the water content of the body drops when you sweat, the salivary glands will produce less saliva and you will feel thirsty.When you get thirsty a hormone, called antidiuretic hormone or ADH will be released.
46ADHADH will signal the kidneys to take water from the nephrons. The nephrons will return the water to the blood stream and the kidneys will make less urine.When your blood has too much water, small amount of ADH are released. The kidneys will react by allowing more water to stay in the nephrons and leave the body as urine.
47DiureticsSome beverages contain caffeine, which is a diuretic. Diuretics cause the kidney to make more urine, which decreases the amount of water in the blood.When you drink a beverage that contains water and caffeine, the caffeine increases fluid loss. So your body will get less of the water from a glass of a caffeinated beverage than from a glass of water.
48Urinary System Problems Since the job of the urinary system is to remove wastes and regulate body fluids, any problems with water regulation can become dangerous for your body.
49Bacterial InfectionsBacteria can get into the bladder and ureters through the uretha. If not treated, it can spread to the kidneys. Infections in the kidneys can permanently damage the nephrons.
50Kidney StonesSometimes salts and other wastes will collect inside the kidney and form stones. Some interfere with urine flow.If the body does not pass them, they must be removed.
51Kidney diseaseDamage to nephrons can prevent normal kidney functioning. If the kidneys do not function properly, a machine must be used to filter waste from the blood.
52Urinary System Summary The Urinary SystemKidney – filters blood, controls water levelsUreter – carries urine from the kidneys to the bladderUrethra – carries urine out of the bodyBladder – stores urine until it leaves the bodyBlood vessels – carries blood to the kidneys to be cleaned and carries cleaned blood to the bodyNephrons – filter the blood, microscopicCortex – contains the nephrons