Digestion

1
Digestion Nutrition

• Chapter 41

2
Introductory Question 2

1. From pg. 845, name the four types of feeders and
   the organism example shown.
2. How is an essential nutrient different from any
   other nutrient? (pg. 849) Give three examples of
   a fat-soluble and three examples of a water
   soluble vitamin.
3. Name the four stages of food processing. (see
   pg. 853).
4. How are the alimentary canals different in an
   earthworm, grasshopper, a bird, and a cow
   (ruminant animal).
5. Explain what peristalsis is and what causes it to
   occur.

3
Vegetarians must be sure to obtain all eight
essential amino acids

• The eight essential amino acids that adults
  require must be obtained from food
• They are easily obtained from animal protein
• They can also be obtained from the proper
  combination of plant foods

ESSENTIALAMINO ACIDS
Methionine
Valine
(Histidine)
Threonine
Phenylalanine
Leucine
Corn
Isoleucine
Beans andotherlegumes
Tryptophan
Lysine
Figure 21.16
4
Table 21.17 (Water-soluble vitamins)
5
Table 21.17 (Fat-soluble vitamins)
6
Overview Food processing occurs in four stages
Smallmolecules
Piecesof food
Nutrientmoleculesenter body cells
Chemical breakdown(enzymatic hydrolysis)
Mechanicalbreakdown
Undigestedmaterial
Food
1
3
4
2
INGESTION
DIGESTION
ELIMINATION
ABSORPTION
Figure 21.2
7
Digestion occurs in specialized compartments

• Food is digested in compartments housing
  hydrolytic enzymes
• Most animals have a specialized digestive tract

8

• Relatively simple animals have a sac with a
  single opening

• This is called a gastrovascular cavity
• Example hydra

Mouth
Tentacle
Hydrolyticenzymes
Flagella
Foodparticle
Engulfmentof foodparticle
Food(Daphnia,a waterflea)
Gastro-vascularcavity
Digestion infood vacuole
Figure 21.3A
9

• In most animals, the digestive compartment is an
  alimentary canal

• This is a tube running from mouth to anus
• This tube is divided into specialized regions
  that process food sequentially

Crop
Gizzard
Esophagus
Intestine
Pharynx
Anus
Mouth
EARTHWORM
Wall of intestine
Interior of intestine
Figure 21.3B
10
Esophagus
Stomach
Gizzard
Anus
Esophagus
Stomach
Gizzard
Intestine
Crop
Intestine
Gastric pouches
Mouth
Mouth
GRASSHOPPER
Crop
Anus
BIRD
Figure 21.3B (cont)
11
Oral cavity
Mouth
Tongue
Pharynx
Salivaryglands
Esophagus
Liver
Stomach
Pyloricsphincter
Stomach
Gall-bladder
Smallintestine
Pancreas
Smallintestine
Largeintestine
Rectum
Figure 21.4
Anus
12
Small intestine
Smallintestine
Stomach
Cecum
Colon(largeintestine)
Figure 21.12A
CARNIVORE
HERBIVORE
13

• Ruminants such as cows process cellulose in a
  four-chambered stomach

Intestine
3
1
Omasum
Rumen
Esophagus
2
Rumen
Reticulum
4
Abomasum
Figure 21.12B
14
The human digestive system consists of an
alimentary canal and accessory glands

• When food is swallowed, it is moved through the
  alimentary canal by peristalsis
• Peristalsis is rhythmic muscle contraction in the
  walls of the digestive tract
• Ringlike sphincter muscles regulate the passage
  of food

15
The esophagus squeezes food along to the stomach

• Peristalsis in the esophagus moves food boluses
  into the stomach

Relaxedmuscles
Circularmuscle layer
Circularmusclescontract,constrictingpassageway
and pushingbolus down
Relaxedmuscles
Bolus offood
Longitudinalmusclescontract,shorteningpassagew
ayahead of bolus
Stomach
Longitudinalmuscle layer
Figure 21.7
16
Interior surfaceof stomach
Pits
Gastric juice(mucus, HCI,and pepsinogen)
Food particle
3
Epithelium
Gastricjuice
Pepsinogen
Pepsin (activeenzyme)
2
Mucouscells
HCI
Pyloricsphincter
1
Gastricgland
STOMACH
Chief cells
Parietal cells
Figure 21.8
17
Bile
Liver
Stomach
Gall-bladder
Acid chyme
Bile
Duodenum ofsmall intestine
Pancreas
Figure 21.10A
18

• Enzymes from the walls of the small intestine
  complete the digestion of many nutrients

Table 21.10
19
INTERIOR OF INTESTINE
Blood vesselwith blooden route tothe liver
Nutrientabsorption
Nutrientabsorption
Microvilli
Epithelialcells
Lumen
Musclelayers
Bloodcapillaries
Circular folds
Villi
Lymphvessel
EPITHELIALCELLS
Nutrientabsorption
VILLI
INTESTINAL WALL
Figure 21.10B
20
Large Intestine Reclaims Water

• Undigested material passes to the large
  intestine, or colon
• Water is absorbed
• Feces are produced

Largeintestine(colon)
Endof smallintestine
Small intestine
Rectum
Anus
Nutrientflow
Appendix
Cecum
Figure 21.11
21
Ch. 44 45 - Digestion Fluid Balance

• What organism is used by Dr. Carol Beuchat to
  illustrate how fluid is regulated and the role
  played by the urinary tract in maintaining
  homeostasis? (1st segment)
• How is a complete digestive system different from
  an incomplete one? What function does each
  segment (region) of the digestive system have?
• Name two enzymes mentioned by Dr. Sokolowski that
  play a role in the digestive system. How is the
  diet of a dog different from a cat? What are the
  nutritional needs for a cat and dog? What is the
  name of the café mentioned in the video?
• 4. The final segment discusses the role the
  kidneys play in maintaining homeostasis. What
  kind of machine is the patient connected to?
  Write the title for each segment and FIVE
  statements for each segment.

22
Video Nutrition Digestion

• Write 10 statements

23
Digestion begins in the oral cavity

• The teeth break up food
• Saliva moistens it
• Salivary enzymes begin the hydrolysis of starch
• The tongue pushes the chewed food into the pharynx

24
TEETH
Incisors
Canine
Premolars
Molars
Wisdomtooth
Tongue
Salivaryglands
Opening of asalivary gland duct
Figure 21.5
25
The food and breathing passages both open into
the pharynx

• The swallowing reflex moves food from the pharynx
  into the esophagus
• At the same time, food is kept out of the trachea

26
Bolus of food
Tongue
Epiglottisdown
Epiglottisup
Pharynx
Larynx
Larynxdown
Esophagealsphincter
Larynxup
Trachea(windpipe)
Esophagus
Esophagus
Sphincter relaxed
Sphincter contracted
Sphincter contracted
Figure 21.6
27
The stomach stores food and breaks it down with
acid and enzymes

• The stomach mixes food with gastric juice
• The gastric juice contains pepsin, which begins
  the hydrolysis of protein

28
Bacterial Infections can cause Ulcers

• New evidence suggests that a spiral-shaped
  prokaryote causes gastric ulcers
• Helicobacter pylori growth erodes protective
  mucus and damages the stomach lining

29
The small intestine is the major organ of
chemical digestion and nutrient absorption

• Alkaline pancreatic juice neutralizes stomach
  acids
• Its enzymes digest polysaccharides, proteins,
  nucleic acids, and fats
• Bile emulsifies fat droplets for attack by
  pancreatic enzymes
• It is made in the liver and stored in the gall
  bladder

30

• The lining of the small intestine is folded and
  covered with tiny, fingerlike villi

• Villi increase the absorptive surface
• Nutrients pass through the epithelium of the
  villi and into the blood
• The blood flows to the liver
• The liver can store nutrients and convert them to
  other substances the body can use

31
Adaptations of vertebrate digestive systems
reflect diet

• Herbivores and omnivores generally have longer
  alimentary canals than carnivores
• Plant matter is more difficult to digest than
  meat
• Nutrients in vegetation are less concentrated
  than in meat

32

• Some mammals house cellulose-digesting microbes
  in the colon or cecum

• The cecum is a pouch where the large and small
  intestines connect
• Examples horses and elephants
• Other mammals re-ingest their feces to recover
  nutrients
• Examples rabbits and some rodents

33
A healthful diet satisfies three needs

• An animals diet provides
• fuel for its activities
• raw materials for making the bodys own molecules
• essential nutrients that the body cannot make

34
Chemical energy powers the body

• Once nutrients are inside cells, they can be
  oxidized by cellular metabolism to generate
  energy
• This energy is in the form of ATP

35

• The energy a resting animal requires each day to
  stay alive is its basal metabolic rate (BMR)

Figure 21.14
36

• More energy is required for an active life

• Excess energy is stored as glycogen or fat

Table 21.14
37
Body Fat and Fad Diets

• The human body tends to store excess fat
  molecules instead of using them for fuel
• A balanced diet includes adequate amounts of all
  nutrients

38

• Fad diets are often ineffective and can be harmful

Table 21.15
39
A healthful diet includes 13 vitamins

• Most of these vitamins function as coenzymes

40
Essential minerals are required for many body
functions

• Minerals are elements other than carbon,
  hydrogen, oxygen, and nitrogen
• They play a variety of roles in the body

41
Table 21.18
42
What do food labels tell us?

• Food labels provide important nutritional
  information about packaged foods

Figure 21.19
43
Diet can influence cardiovascular disease and
cancer

• Choice of diet may reduce the risk of
  cardiovascular disease and cancer

BEHAVIORALRISK FACTORS
UNAVOIDABLERISK FACTORS
Highbloodcholesterol
Highbloodpressure
Fatty diet
Aging
Lack ofexercise
Family history
CARDIOVASCULARDISEASE
Smoking
Being male
Figure 21.20
44
Table 21.20
45
Bile
Liver
Stomach
Gall-bladder
Acid chyme
Bile
Duodenum ofsmall intestine
Pancreas
Figure 21.10A
46
Video Laparoscopic Cholecystectomy

• Write 10 Statements from the video

47
Assignments Packet

• Bold list of Terms from Chapter 42
• Print out of Quizzes Online (x3)
• Ch. 39, 40, and 41
• AP Test MC Questions (2) Essays
• IB Syllabus Review (13 topics w/three areas)
• IB Test (3) Sections-paper 1, 2, and 3
• Videos (x5)
• -Digestive Nutrition
• -Heart Attack
• -Immune Lymphatic
• -Endocrine Homeostasis
• -Laparoscopic Cholecystectomy
• -Bacteria, Protists, Viruses
• IQs (x4)
• -Chapter 39 (2)
• -Chapter 40 (1)
• -Chapter 41 (1)
• Classification of Animal Phyla
• Drosophila Lab

48

• A sound diet supplies

• enough raw materials to make all the
  macromolecules we need
• the proper amounts of prefabricated essential
  nutrients
• enough kilocalories to satisfy our energy needs

49
Getting Their Fill of Krill

• Animals obtain and process nutrients in a variety
  of ways
• Humpback whales eat small fishes and crustaceans
  called krill
• This painting shows how the whales corral their
  food using bubble nets

50

• Humpback whales strain their food from seawater
  using large, brushlike plates called baleen

• When they feed, they take in large amounts of
  seawater in which the fish and krill live
• They must filter out the water in order to get a
  meal

51

• In a typical day, a humpback whales digestive
  system will process as much as 2 tons of fish and
  krill

• They store the excess energy they harvest in the
  form of blubber
• In about 4 months, a humpback whale eats,
  digests, and stores as fat enough food for an
  entire year

52
Animals ingest their food in a variety of ways

• Animal diets are highly varied
• Herbivores are plant-eaters
• Carnivores are meat-eaters
• Omnivores eat both plants and other animals

Figure 21.1A
53

• Most animals ingest chunks of food

Figure 21.1E
54

• Some animals are suspension feeders, consuming
  particles from water

• Some are substrate feeders, living in or on their
  food source

Figure 21.1B, C
55

• Some are fluid feeders, sucking liquids

Figure 21.1D