Download Ch. 10 Review for Test

Ch. 10 Review
 Before the food you eat can be used it must be digested.
 Your digestive system has 3 main functions-digestion, absorption, and elimination.
 Digestion- the process by which the digestive system breaks down food into molecules
that the body can use.
 Mechanical digestion- foods are physically broken apart into smaller pieces
 Chemical digestion- chemicals produced by your body break large molecules into
smaller ones that your body uses.
 Mechanical digestion allows food to be digested faster and used sooner.
 Most of the chemicals involved in digestion are enzymes, substances that speed up
chemical reactions.
 Absorption and Elimination
 Absorption- the process by which nutrients pass through the lining of your digestive
system into your blood.
 Blood transports the nutrients
 Anything not used is eliminated
 Structures of the Digestive System
 Mouth
 Pharynx
 Esophagus
 Stomach
 Small Intestine
 Large Intestine
 Liver, gallbladder, and pancreas are slightly involved in the digestion process
 Mouth
 Mechanical digestion
 Teeth tear, crush, and grind food
 Tongue pushes the food around
 Chemical digestion occurs with saliva
 Saliva moistens food so it can be swallowed
 Pharynx
 The junction between the digestive tract and the respiratory system.
 Epiglottis opens and closes to allow air into the respiratory system and food into the
digestive system.
 Esophagus
 Muscular tube that connects the pharynx to the stomach.
 Peristalsis occurs when muscle contractions push food through the esophagus, toward
the stomach.
 Stomach
 Muscular pouch located in the abdomen
 Able to contract and expand
 Can hold about one gallon of food and liquid
 Most mechanical digestion and some chemical digestion occurs here
 Mechanical digestion occurs as 3 layers of muscle produce a churning motion
 Mixes the food with fluids.
 Chemical digestion occurs as cells lining the stomach release gastric juice, which breaks
down proteins.
 Hydrochloric acid in gastric juice kills many bacteria that may be swallowed with food.
 Mucus coats the lining of the stomach and gives it protection from the acidic gastric
juice.
 Small Intestine
 Where most chemical digestion and absorption of nutrients take place.
 Liver, Gallbladder, and Pancreas also play a role in chemical digestion.
 Liver and Gall Bladder
 Liver produces Bile, a substance that physically breaks up large fat droplets that clump
together.
 Bile flows from the liver to the Gallbladder, the organ that stores bile.
 As food leaves the stomach, the gallbladder releases bile through a tube into the small
intestine.
 Pancreas
 Lies between the stomach and the first part of the small intestine.
 Secretes enzymes into the small intestine that complete the breakdown of
carbohydrates, proteins, and fats.
 After food reaches the effects of the pancreas nutrients can be absorbed.
 Nutrients are absorbed by villi, tiny finger like projections lining the small intestine.
 The Large Intestine
 Ends in a short tube called the rectum
 Feces or stool is eliminated from the body through the anus, a muscular opening at the
end of the rectum.
 Most vitamin K is produced in the large intestine.
 Avoiding Digestive Disorders
 Healthy eating habits
 Consume plenty of fiber
 Vegetables, fruits, whole grain products
 Limit fatty foods
 Digested slowly
 Can lead to heart burn
 Eat Moderately
 Overeating strains the digestive system
 Plan meals for a time when you can relax
 More likely to eat slowly and chew thoroughly
 Drink water
 During meals and throughout the day
 Get regular exercise
 Stimulates peristalsis
 Prevents constipation
 Food borne Illness
 Results from consuming a food or drink that contains either a poison or a diseasecausing micro-organism.
 Usually spread by:
 Undercooked food
 Raw food touches cooked food
 Transferring the organisms onto hands, countertops, or utensils.
 Symptoms of food borne illness include:
 Diarrhea
fever
 Vomiting
abdominal cramps
 Excretion The process by which the body collects and removes wastes.
 Includes the following organs:
 Liver, Lungs, skin, and kidneys
 Liver -Converts impurities and poisons in the body to less harmful substances.
 Forms Urea from a harmful waste product of protein breakdown.
 Urea can be safely transported to the kidneys via blood.
 Lungs and Skin
 Lungs remove carbon dioxide and water when you exhale.
 Sweat glands in the skin also serve an excretory function because water and urea are
excreted in perspiration.
 Kidneys
 Filter urea and other wastes from the blood
 Major organs in the excretory system
 Wastes are eliminated in urine
 Main organ involved in water balance
 Hormones sent from the brain signal the kidneys to release more or less water in urine
depending on the amount of water in the body.
 Your body will produce less urine on a hot day when you have sweat a lot.
 Filtration of Wastes
 Each kidney contains about a million Nephrons, tiny filtering units that remove wastes
and produce urine.
 Filtering out Wastes
 Blood enters the kidneys
 Blood enters a glomerulus, cluster of tiny blood vessels in a nephron.
 Urea, salts, glucose, and some water are filtered from the glomerulus into a thin-walled
capsule.
 Formation of Urine
 The capsule around the glomerulus is connected to a long, twisting tube.
 The tube is surrounded by tiny blood vessels.
 As filtered material flows through the tube, the glucose, most of the water, and other
needed materials pass from the tube back into the blood.
 Urea and other wastes, such as excess vitamins and harmful substances, stay in the
tube.
 The fluid that remains in the tube is urine.
 Eventually, the urine drains into a larger tube called a ureter, which carries it from a
kidney to the bladder.
 Keeping Healthy
 Proper function of your kidneys is essential for your overall health.
 To ensure your kidneys work properly it is important that you drink plenty of water.
 Drinking Water
 Much of what is filtered through you kidneys is harmful, therefore, it is important that it
is diluted with plenty of water.
 If you are not thirsty and your urine is only slightly yellow, then you are consuming
enough water.
 Treating Infections
 Common infections of the excretory system are urinary tract infection.
 Infection of the urethra or bladder
 Usually occurs when bacteria from the digestive system come in contact with the
urethra.
 Symptoms include:
 Frequent, painful urination.
 Blood in the urine.
 Preventing Kidney Stones
 Kidney stones are pebble like masses of salts, and often calcium, that form in the
kidneys.
 Often they will pass out of the kidneys through the urine.
 If the urine is blocked or the kidney is damaged a medical procedure must be done to
shatter the stone.
 Drinking plenty of water and eating a diet that is low in salt, may reduce your risk of
developing kidney stones.
 Treating Kidney Failure
 Why do kidney’s fail:
 Injury
 Diabetes
 Uncontrolled high blood pressure
 Disease
 Kidney failure can be treated by dialysis.
 Dialysis is a machine used to filter blood in place of the kidneys.
 Blood goes into the machine, is filtered, and then returned to the body.
 Must be performed three times a week and takes about 3-5 hours each time
 Kidney transplant is the best option in treating kidney failure.