29 terms

Science Notes: Chapter 15 Lesson 2-3


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Steps to Processing Food:
*Food enters mouth-breakdown begins
*The mechanical and chemical breakdown of food into smaller particles and molecules that your body can absorb
*When the cells of the digestive system take in small molecules of digested food
*Removal of undigested food and other wastes from the body
Two Types of Digestion:
*Food is physically broken into smaller pieces-chew, mash, and grind
*Chemical reactions break down pieces of food into smaller molecules
*Proteins that help break down large molecules into smaller molecules
*Speed up the rate of chemical reactions
*Do not change in the reaction
Parts of the Digestive System:
Accessory Organs
*Food does not pass through these organs(liver, gallbladder, pancreas, tongue, salivary glands)
*Important in mechanical and chemical digestion—food passes through these organs
Digestive Tract
A) Mouth
*Mechanical digestion begins (chew)
*Chemical digestion begins (saliva)
*Slippery substance makes food easier to swallow
B) Esophagus
*Muscular tube that moves food from the mouth to the stomach using peristalsis (wave-like muscle contractions)
C) Stomach
*A large, hollow organ that stores food and aids in chemical digestion
*Contains gastric juices that break down food
*Food becomes chyme(thin, watery, liquid)
D) Small Intestine
*Long tube connected to the stomach
*Chemical digestion takes place in the duodenum
*Folds of the small intestine are covered with villi
*The pancreas, liver and gall bladder produce substances that enter the small intestine to help with chemical digestion
E) Large Intestine
*As more water is absorbed, the waste products become more solid
*Peristalsis continues
*Rectum(last section of large intestines)and anus control release of solid(poop)
Excretory System
*collects and eliminates wastes from the body
*if not eliminated, waste could become toxic and damage organs
*regulates level of fluid in the body
*ensuring that neither too little nor too much water is lost
Digestive System
collects and removes undigested solids from the foods you eat
Urinary System
processes, transports, collects, and removes liquid waste from the body
Respiratory System
removes carbon dioxide and water vapor from the body
Integumentary System
secretes excess salt and water through sweat glands
Organs of the Urinary System:
1. bean-shaped organ that filters wastes from blood
*contain blood vessels and nephrons (about 1 million)
*produce urine (pee)
2. networks of capillaries and small tubes where filtration of blood occurs
3. a fluid produced when blood is filtered
4. a tube through which urine leaves each kidney
*connects kidneys to the bladder
5. a muscular sac that holds urine
6. a tube through which urine leaves the bladder
*contains sphincters (circular muscles) that control the release of urine