1. Digestive and Excretory Systems

2. Do Now
Section 38-1
Good Food Sense
Nutrients are molecules that provide the body with energy and materials for growth. Three kinds of nutrients you eat are called fats, proteins, and carbohydrates—terms you may have already heard. Think about what they may mean.
1. Write a brief description of what you think fats, proteins, and carbohydrates are.
2. Which of these three nutrients do you think should make up the largest part of your diet? Which should make up the smallest part? Arrange the three nutrients in order starting from the one that you should eat the most to the one that you should eat the least.
3. Why might it be unwise to eat too much of the nutrient you listed last?

3. Section Outline 38–1 Food and Nutrition A. Food and Energy
B. Nutrients
1. Water
2. Carbohydrates
3. Fats
4. Proteins
5. Vitamins
6. Minerals
C. Nutrition and a Balanced Diet

4. Food and Energy
Cells convert the chemical energy stored in food into ATP
When food is burned it releases heat energy, which is measured in calories
A calorie is the amount of heat needed to raise the temperature of 1 gram of water 1 degree Celsius
Dietary Calories refer to the energy stored in food.
One Calorie = 1000 calories
Food also supplies the raw materials used to build and repair body tissues
These raw materials are used to manufacture new biomolecules
Food also contains at least 45 substances that your body cannot manufacture

5. Concept Map Nutrients Section 38-1 include Carbohydrates Fats Minerals
Proteins
Vitamins
include
are made of
are made using
include
include
Simple
Complex
Amino acids
Calcium
Iron
Fatty Acids
Glycerol
such as
such as
Sugars
Starches
Fat-soluble
Water-soluble

6. Carbohydrates Main source of energy for the body Can be simple
Mono and disaccharides – found in honey, fruits, sugar cane
Can be complex
Polysaccharides – starches found in grains, potatoes, veggies
Broken down by the digestive system to be absorbed into the blood and carried throughout the body
If not used immediately, sugars are converted to glycogen, a complex carb and stored in the liver and muscles.
Not all carbs can be broken down
Fiber (cellulose) is used to keep your digestive system functioning properly by helping wastes to move through

7. Fats Fats (lipids) formed from fatty acids and glycerol
Needed to form cell membranes, myelin sheaths and some hormones
Extra food is stored as fat to protect body organs and insulate the body
Classified as saturated or unsaturated
Saturated fats
Solid at room temperature
Main cause of high blood pressure, heart disease, obesity and diabetes
Unsaturated fats
Liquid at room temperature
A healthier choice of fat

8. Proteins
Supply raw materials for growth and repair of skin and muscles
Have regulatory and transport functions
Ex. insulin, hemoglobin
Polymers of amino acids
The body can only synthesize 12 of the 20 amino acids
The other 8 must be ingested
Found in meat, fish, milk, eggs

9. Figure 38–8 Food Guide Pyramid
Section 38-1
Fats, Oils, and Sweets (use sparingly)
Soft drinks, candy, ice cream, mayonnaise, and other foods in this group have relatively few valuable nutrients.
Milk, Yogurt, and Cheese Group
(2-3 Servings)
Milk and other dairy products are rich in proteins, carbohydrates, vitamins, and minerals.
Meat, Poultry, Fish, Dry Beans, Eggs, and Nut Group
(2-3 servings)
These foods are high in protein. They also supply vitamins and minerals.
Vegetable Group
(3-5 servings)
Vegetables are a low-fat source of carbohydrates, fiber, vitamins, and minerals.
Fruit Group
(2-4 servings)
Fruits are good sources of carbohydrates, fiber, vitamins and water.
Bread, Cereal, Rice and Pasta Group
(6-11 servings)
The foods at the base of the pyramid are rich in complex carbohydrates and also provide proteins, fiber, vitamins, and some minerals.
Fats
Sugars

10. Section Outline 38–2 The Process of Digestion A. The Mouth 1. Teeth
2. Saliva
B. The Esophagus
C. The Stomach
1. Chemical Digestion
2. Mechanical Digestion
D. The Small Intestine
Accessory Structures of Digestion
E. Absorption in the Small Intestine
F. The Large Intestine
G. Digestive System Disorders

11. Figure 38–10 The Digestive System
Section 38-2
Mouth
Salivary glands
Stomach
Pancreas (behind stomach)
Large intestine
Small intestine
Rectum
Gallbladder (behind liver)
Liver
Esophagus
Pharynx

12. The Mouth Performs mechanical and chemical digestion
Mechanical – food is changed in size
Performed by the teeth
Chemical – food is changed in composition
Performed by saliva
Contains amylase (an enzyme that breaks down starch)
Also helps to moisten food so it can move easier
Contains lysozyme (an enzyme used to kill bacteria)
The chewed up clump of food is now considered a bolus

13. The Esophagus Lined with smooth (involuntary) muscle
As the bolus passes through, contractions, known as peristalsis, squeeze the food through to the stomach
The cardiac sphincter (a thick ring of muscle) closes the esophagus after food has entered the stomach to prevent the contents of the stomach from moving back up.
Is associated with heartburn
A backflow of stomach acid into your esophagus

14. Stomach A large muscular sac
Continues mechanical and chemical digestion
Mechanical – churning of bolus and stomach acids to form chyme
Chemical – stomach glands release a variety of secretions
Hydrochloric acid – activates pepsin
Pepsin – breaks down proteins
Any other chemical digestion is stopped until the food reaches the small intestine
Chyme then leaves the stomach through the pyloric valve and enters the small intestine

15. Small Intestine (SI)
Duodenum (1st part of the SI) where almost all of the digestive enzymes enter from accessory organs
Shortest part of the SI
Jejunum and Ileum
Where absorption of nutrients occurs
Villi – increase surface area to allow for greater absorption
Contain capillaries and lymph vessels
Products of carbs and proteins are absorbed into the capillaries
Undigested fats and fatty acids are absorbed by the lymph vessels
Water, cellulose and other undigestible substances leave the SI and enter the large intestine

16. Figure 38–14 The Small Intestine
Section 38-2
Small Intestine
Villus
Circular folds
Villi
Epithelial cells
Capillaries
Lacteal
Vein
Artery

17. Accessory Organs Pancreas
Produces enzymes, that break down carbs, proteins, lipids and nucleic acids
Also produces sodium bicarbonate to neutralize stomach acids so the enzymes will work
Liver
Produces bile, which dissolves and disperses droplets of fats, so that the enzymes can work on the smaller fat molecules
Gall Bladder
Stores the bile that is produced by the liver

18. Figure 38–13 The Liver and the Pancreas
Section 38-2
Liver
Gallbladder
Duodenum
Bile duct
Pancreas
Pancreatic duct
To rest of small intestine

19. The Digestive Enzymes Section 38-2 Site Mouth Stomach
Small intestine (from pancreas)
Small intestine
Enzyme
Role in Digestion
Salivary amylase
Pepsin
Amylase
Trypsin
Lipase
Maltase, sucrase, lactase
Peptidase
Breaks down starches into disaccharides
Breaks down proteins into large peptides
Continues the breakdown of starch
Continues the breakdown of protein
Breaks down fat
Breaks down remaining disaccharides into monosaccharides
Breaks down dipeptides into amino acids.

20. Figure 38–10 The Digestive System
Section 38-2
Mouth
Salivary glands
Stomach
Pancreas (behind stomach)
Large intestine
Small intestine
Rectum
Gallbladder (behind liver)
Liver
Esophagus
Pharynx

21. Click the image to play the video segment.
Human Digestion
Click the image to play the video segment.
Video 1

22. Interest Grabber Your Body’s Filter
Section 38-3
Your Body’s Filter
Have you ever seen a water-purification system attached to a faucet? This system removes impurities from the water such as arsenic or other chemicals that can be harmful to people. As water passes through the filters contained in the system, the impurities are trapped on the surface of the filters. Eventually, the water that comes out of this purifier is free of the impurities.
1. Your body has its own system for filtering blood. Why might the blood in your body need to be filtered?
2. What organ(s) do you think filters your blood?
3. How do you think the filtered materials leave your body?

23. Section Outline 38–3 The Excretory System
A. Functions of the Excretory System
B. The Kidneys
1. Kidney Structure
2. Filtration
3. Reabsorption
4. Kidney Stones
C. Control of Kidney Function
D. Homeostasis by Machine

24. Functions of the Excretory System
Every cell in the body produces metabolic wastes as a result of maintaining homeostasis
Wastes such as urea, excess salts and carbon dioxide must be removed from the body
The skin, lungs and liver are three organs that assist in excretion
The skin excretes excess salts, water and a small amount of urea
The lungs excrete carbon dioxide
The liver takes excess amino acids from the blood stream and converts them to useful compounds
In the process of conversion, poisonous nitrogen compounds are created, which are turned into urea
Urea is then removed from the bloodstream by the body’s principal organs of excretion – the kidneys

25. Kidneys The kidneys have many roles
Remove waste products from the blood
Maintain blood pH
Regulate the water content of the blood and therefore blood volume
As waste-laden blood enters the kidney from the renal artery, it removes urea, excess water and other wastes and passes them to the ureter
The clean, filtered blood leaves the kidney through the renal vein and returns to circulation

26. Kidney Structure Two distinct regions Renal cortex – outer part
Contains nephrons – the functional units of the kidney
Each one is a small, independent unit
One part of a nephron, the loop of Henle, descend into the inner part of the kidney
Renal medulla – inner part

27. Nephron Each nephron has its own blood supply
An arteriole, a venule and a network of capillaries
Each nephron releases fluid into a collecting duct, which leads to the ureters
Blood purification involves two distinct processes: filtration & reabsorption
Filtration – takes place in the glomerulus, a small network of capillaries encased in Bowman’s capsule
Reabsorption – most of the material (water, amino acids, glucose) removed from Bowman’s capsule is taken back into the blood
The material that remains is urine (urea, salts, water) and is concentrated in the loop of Henle, where water is conserved and the volume of urine is minimized.
Urine is then stored in the bladder until it is released from the body through the urethra

28. The Urinary System Section 38-3 Artery Vein Kidney (Cross Section)
Cortex
Medulla
Ureter
Urinary bladder
Urethra

29. Figure 38–17 Structure of the Kidneys
Section 38-3
Kidney
Nephron
Cortex
Medulla
Renal artery
Renal vein
Ureter
To the bladder
Bowman’s capsule
Glomerulus
Capillaries
Collecting duct
To the ureter
Loop of Henle
Artery
Vein

30. The Nephron Reabsorption Filtration Section 38-3
As the filtrate flows through the renal tubule, most of the water and nutrients are reabsorbed into the blood. The concentrated fluid that remains is called urine.
Filtration
Most filtration occurs in the glomerulus. Blood pressure forces water, salt, glucose, amino acids, and urea into Bowman’s capsule. Proteins and blood cells are too large to cross the membrane; they remain in the blood. The fluid that enters the renal tubules is called the filtrate.

31. Control of Kidney Function
The activity of the kidneys is controlled by the blood itself.
Water is absorbed into the blood from the digestive system.
The concentration of water in the blood increases.
Without your kidneys, the increase in water conc. would force water into cells and tissues, causing your body to swell
As the amount of water in the blood increases, the rate of water reabsorption in the kidneys decreases.
Less water is returned to the blood and the excess water is sent to the bladder.
With an increase in salt, your kidneys return less salt to the blood, and send the excess salt to the bladder.

32. Disease
Kidney Stones
Substances such as calcium, magnesium or salts in the urine crystallize and form stones
These stones may block the ureter, causing great pain
Often treated using ultrasound waves
The stones gets pulverized into smaller fragments, which are then excreted in the urine.

33. Homeostasis by Machine
Dialysis
Blood is removed from the body through a tube and pumped through special tubing that acts like nephrons
Wastes diffuse out of the blood and into a fluid-filled chamber
The purified blood is then returned to the body

34. Figure 38–19 Kidney Dialysis
Section 38-3
Blood in tubing flows through dialysis fluid
Blood pump
Vein
Artery
Shunt
Used dialysis fluid
Air detector
Dialysis machine
Fresh dialysis fluid
Compressed air

35. Click the image to play the video segment.
Kidney Function
Click the image to play the video segment.
Video 2