Transcript digestive system ppt regents

Digestive and Excretory Systems
Go to
Section:
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?
Go to
Section:
Section Outline
Section 38-1
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
Go to
Section:
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
Go to
Section:
Concept Map
Section 38-1
Nutrients
include
Carbohydrates
Fats
Proteins
Vitamins
Minerals
include
are made of
are made using
include
include
Simple
Complex
such as
such as
Amino
acids
Fatty Acids
Sugars
Go to
Section:
Starches
Calcium
Glycerol
Fat-soluble
Watersoluble
Iron
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
Go to
Section:
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
Go to
Section:
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
Go to
Section:
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.
Vegetable Group
(3-5 servings)
Vegetables are a low-fat
source of carbohydrates,
fiber, vitamins, and minerals.
Fats
Sugars
Go to
Section:
Meat, Poultry, Fish, Dry Beans, Eggs,
and Nut Group
(2-3 servings)
These foods are high in protein.
They also supply 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.
Section Outline
Section 38-2
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
Go to
Section:
Figure 38–10 The Digestive System
Section 38-2
Mouth
Pharynx
Salivary glands
Esophagus
Liver
Gallbladder
(behind liver)
Stomach
Pancreas (behind
stomach)
Large intestine
Small intestine
Rectum
Go to
Section:
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
Go to
Section:
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
Go to
Section:
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
Go to
Section:
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
Go to
Section:
Figure 38–14 The Small Intestine
Section 38-2
Villus
Small Intestine
Circular folds
Epithelial cells
Villi
Capillaries
Lacteal
Vein
Artery
Go to
Section:
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
Go to
Section:
Figure 38–13 The Liver and the Pancreas
Section 38-2
Liver
Bile duct
Gallbladder
Pancreas
Pancreatic duct
Duodenum
To rest of small intestine
Go to
Section:
The Digestive Enzymes
Section 38-2
Site
Enzyme
Role in Digestion
Mouth
Salivary amylase
Breaks down starches into
disaccharides
Stomach
Pepsin
Breaks down proteins into large
peptides
Small intestine
(from pancreas)
Amylase
Continues the breakdown of
starch
Trypsin
Continues the breakdown of
protein
Lipase
Breaks down fat
Maltase, sucrase, lactase
Breaks down remaining
disaccharides into
monosaccharides
Peptidase
Breaks down dipeptides into
amino acids.
Small intestine
Go to
Section:
Figure 38–10 The Digestive System
Section 38-2
Mouth
Pharynx
Salivary glands
Esophagus
Liver
Gallbladder
(behind liver)
Stomach
Pancreas (behind
stomach)
Large intestine
Small intestine
Rectum
Go to
Section:
Video 1
Human Digestion
Click the image to play the video segment.
Interest Grabber
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?
Go to
Section:
Section Outline
Section 38-3
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
Go to
Section:
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
Go to
Section:
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
Go to
Section:
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
Go to
Section:
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
Go to
Section:
The Urinary System
Section 38-3
Vein
Kidney (Cross Section)
Kidney
Cortex
Medulla
Ureter
Urinary bladder
Urethra
Go to
Section:
Artery
Figure 38–17 Structure of the Kidneys
Section 38-3
Kidney
Nephron
Bowman’s
capsule
Cortex
Capillaries
Glomerulus
Medulla
Renal
artery
Renal vein
Ureter
Collecting
duct
Vein
To the bladder
Artery
Loop of Henle
Go to
Section:
To the ureter
The Nephron
Section 38-3
Reabsorption
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.
Go to
Section:
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.
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.
Go to
Section:
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.
Go to
Section:
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
Go to
Section:
Figure 38–19 Kidney Dialysis
Section 38-3
Blood in tubing flows
through dialysis fluid
Blood pump
Vein
Artery
Used dialysis fluid
Shunt
Air detector
Go to
Section:
Dialysis
machine
Fresh
dialysis
fluid
Compressed
air
Video 2
Kidney Function
Click the image to play the video segment.