Digestion & Nutrition

Chapter 41

Introductory Question #21) 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.

• 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

Vegetarians must be sure to obtain all eight essential amino acids

Figure 21.16

ESSENTIALAMINO ACIDS

Methionine

Valine

(Histidine)

Threonine

Phenylalanine

Leucine

Isoleucine

Tryptophan

Lysine

Beans andotherlegumes

Corn

Table 21.17 (Water-soluble vitamins)

Table 21.17 (Fat-soluble vitamins)

Overview: Food processing occurs in four stages

Figure 21.2

1 INGESTION 2 DIGESTION 3 ABSORPTION 4 ELIMINATION

Food

Mechanicalbreakdown

Piecesof food

Chemical breakdown(enzymatic hydrolysis)

Smallmolecules

Nutrientmoleculesenter bodycells Undigested

material

• Food is digested in compartments housing hydrolytic enzymes

• Most animals have a specialized digestive tract

Digestion occurs in specialized compartments

• Relatively simple animals have a sac with a single opening– This is called a gastrovascular cavity– Example: hydra

Figure 21.3A

Tentacle

Mouth

Food(Daphnia,a waterflea)

Gastro-vascularcavity

Foodparticle

Engulfmentof foodparticle

Digestion infood vacuole

FlagellaHydrolyticenzymes

• 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

Figure 21.3B

EARTHWORM

Pharynx

EsophagusCrop

Mouth

Gizzard

Intestine

Anus

Wall of intestine

Interior of intestine

Figure 21.3B (cont)

GRASSHOPPER

Mouth

Esophagus

Gizzard

Crop

Gastric pouches

Intestine

StomachAnus

BIRD

Mouth

Esophagus

StomachGizzard

Crop

Intestine

Anus

Figure 21.4

Mouth

Tongue

Salivaryglands

Oral cavity

Pharynx

Esophagus

Stomach

Liver

Gall-bladder

PancreasSmallintestine

Largeintestine

Smallintestine

Stomach

Pyloricsphincter

Anus

Rectum

Figure 21.12ACARNIVORE HERBIVORE

Smallintestine Stomach

Cecum

Colon(largeintestine)

Small intestine

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

Figure 21.12B

Intestine 3 Omasum 1 Rumen

4 AbomasumRumen

Esophagus

2 Reticulum

• 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

The human digestive system consists of an alimentary

canal and accessory glands

• Peristalsis in the esophagus moves food boluses into the stomach

The esophagus squeezes food along to the stomach

Figure 21.7

Circularmuscle layer

Longitudinalmuscle layer

Bolus offood

Longitudinalmusclescontract,shorteningpassagewayahead of bolus

Stomach

Relaxedmuscles

Circularmusclescontract,constrictingpassagewayand pushingbolus down

Relaxedmuscles

Figure 21.8

Food particle

Pyloricsphincter

STOMACH

Gastricjuice

Interior surfaceof stomach

Gastricgland

Pits

Gastric juice(mucus, HCI,and pepsinogen)

Epithelium

Chief cells

Parietal cells

Pepsinogen

1

2

3

HCI

Pepsin (activeenzyme)Mucous

cells

Figure 21.10A

LiverBile

Gall-bladder

Bile

Duodenum ofsmall intestine

Acid chyme

Stomach

Pancreas

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

Table 21.10

Figure 21.10B

Musclelayers

Circular folds

Villi

INTESTINAL WALL

Blood vesselwith blooden route tothe liver

INTERIOR OF INTESTINE

Nutrientabsorption

Epithelialcells

Lumen

Bloodcapillaries

Lymphvessel

Nutrientabsorption

VILLI

Nutrientabsorption

Microvilli

EPITHELIALCELLS

• Undigested material passes to the large intestine, or colon– Water is

absorbed – Feces are

produced

Large Intestine Reclaims Water

Figure 21.11

Largeintestine(colon)

Endof smallintestine

Nutrientflow

Appendix

Cecum

Anus

Rectum

Smallintestine

Ch. 44 & 45 - Digestion & Fluid Balance1. 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)

2. How is a complete digestive system different from an incomplete one? What function does each segment (region) of the digestive system have?

3. 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.

Video: Nutrition & Digestion

Write 10 statements

• The teeth break up food

• Saliva moistens it

• Salivary enzymes begin the hydrolysis of starch

• The tongue pushes the chewed food into the pharynx

Digestion begins in the oral cavity

Figure 21.5

TEETH

Incisors

Canine

Premolars

Molars

“Wisdom”tooth

Tongue

Salivaryglands

Opening of asalivary gland duct

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

The food and breathing passages both open into the pharynx

Figure 21.6

Sphincter contracted

Pharynx

Larynx

Trachea(windpipe)

Tongue

Sphincter relaxed

Larynxup

Epiglottisdown

Esophagus

Sphincter contracted

Larynxdown

Bolus of food

Epiglottisup

Esophagealsphincter

Esophagus

• The stomach mixes food with gastric juice– The gastric juice contains pepsin, which begins

the hydrolysis of protein

The stomach stores food and breaks it down with acid and

enzymes

• New evidence suggests that a spiral-shaped prokaryote causes gastric ulcers – Helicobacter pylori growth erodes protective

mucus and damages the stomach lining

Bacterial Infections can cause Ulcers

• 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

The small intestine is the major organ of chemical digestion

and nutrient absorption

• 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

• 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

Adaptations of vertebrate digestive systems reflect diet

• 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

• An animal’s diet provides– fuel for its activities– raw materials for making the body’s own

molecules– essential nutrients that the body cannot make

A healthful diet satisfies three needs

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

Chemical energy powers the body

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

Figure 21.14

• More energy is required for an active life

– Excess energy is stored as glycogen or fat

Table 21.14

• The human body tends to store excess fat molecules instead of using them for fuel

• A balanced diet includes adequate amounts of all nutrients

Body Fat and Fad Diets

• Fad diets are often ineffective and can be harmful

Table 21.15

• Most of these vitamins function as coenzymes

A healthful diet includes 13 vitamins

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

Essential minerals are required for many body functions

Table 21.18

• Food labels provide important nutritional information about packaged foods

What do food labels tell us?

Figure 21.19

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

Diet can influence cardiovascular disease and cancer

Figure 21.20

BEHAVIORALRISK FACTORS

UNAVOIDABLERISK FACTORS

Fatty diet

Lack ofexercise

Smoking

Highblood

cholesterol

Highblood

pressure

CARDIOVASCULARDISEASE

Aging

Family history

Being male

Table 21.20

Figure 21.10A

LiverBile

Gall-bladder

Bile

Duodenum ofsmall intestine

Acid chyme

Stomach

Pancreas

Video: Laparoscopic Cholecystectomy

*Write 10 Statements from the video

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

• IQ’s (x4) -Chapter 39 (2)-Chapter 40 (1)-Chapter 41 (1)

• Classification of Animal Phyla• Drosophila Lab• Extra credit: 12 AP Labs from Website

• 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

• 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”

Getting Their Fill of Krill

• 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

• In a typical day, a humpback whale’s 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

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

and other animals

Animals ingest their food in a variety of ways

Figure 21.1A

• Most animals ingest chunks of food

Figure 21.1E

– Some animals are suspension feeders, consuming particles from water

Figure 21.1B, C

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

– Some are fluid feeders, sucking liquids

Figure 21.1D