3 The Digestive and Excretory Systems What goes

#3 The Digestive and Excretory Systems What goes in, must come out…

The Digestive System 1. The food you eat contains nutrients, fats, proteins, carbohydrates, vitamins and minerals a) b) 2. Most of these molecules are too big to pass through the cell membrane… That’s where the digestive system comes in… The process of breaking food molecules into smaller molecules is called digestion.

3. Digestion a) Digestion starts out with mechanical digestion in the mouth Some chemical digestion II. saliva contains amylases that break down carbohydrates WHAT DOES –ASE MEAN? -ASE means enzyme! I. b) When you swallow, food passes into the esophagus n n moved along by wavelike contractions called peristalsis Imodium stops peristalsis!

More digestion c. Food then moves into the stomach I. II. d. Hydrochloric Acid breaks down proteins the food continues to get mixed and mechanically broken down Food passes from the stomach into the small intestine I. The small intestine is the location that most of the chemical digestion takes place

E. The small intestine I. II. Secretions from the pancreas, liver, and gall bladder enter the small intestine and complete the digestion of fats, proteins, and carbohydrates The nutrients from these molecules are absorbed by the lower parts of the small intestine

Pancreas n Pancreas releases the hormone Insulin (What diabetics don’t have enough of) which breaks down carbohydrates for storage in the liver and secretes lipases for fat digestion

Liver n Liver acts as a filter for the blood and stores sugars as glycogen and fats. Produces Bile which breaks up fat globules - a process called emulsification

Gall Bladder n Gall bladder green muscular sac attached to liver that concentrates and stores bile until it’s needed by the small intestine

F. The large intestine (Coolon) I. III. As food leaves the small intestine, most of the nutrients have been absorbed No digestion takes place in the large intestine, but water and mineral ions are absorbed The large intestine is also the place where bacteria produce vitamin K and vitamin B that you cannot easily get from the food you eat

Digestive Enzymes Amylase Pepsin Lipases Starches into sugars Large proteins into smaller proteins Fats into fatty acids and glycerol Mouth Stomach intestine

The excretory system 1. 2. Any organ that excretes wastes is part of the excretory system (skin, lungs, large intestines) However, for our purposes, we will focus most of our discussion on the elimination of urine

2. The urinary system a) b) c) d) Kidneys filter water soluble wastes from the blood and they eliminate excess water from the body…they also reabsorb water so that we don’t lose too much The urine produced then passes into the ureters…the tubes that lead to the bladder The bladder holds the urine The urine then exits the body through the urethra

The Urinary System (Excretory)

3. Other wastes a) Wastes left over from food are removed by the a) b) Colon (large intestine) Excess salt and water are removed by the kidneys and also the skin (sweat)

3. Other wastes c) d) When we take in chemicals that might be toxic (like the metabolites of alcohol), our liver filters these poisons from our blood Carbon dioxide builds up in our tissues and is removed from the cells by our blood and our bodies by lungs

Relationships 1. What other systems are dependent on our digestive system and why? All of them! The digestive system breaks down food to provide nutrients to ALL of the body systems! 2. What other systems are dependent on our excretory system? All of them! Wastes build up what goes in must come out!!! n (or we’d be full of poop and poison)

Relationships 3. What system helps our digestive system deliver nutrients and our excretory system pick up wastes? The circulatory system! 4. What system is involved in removing waste gases? The respiratory system!