Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple...

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Digestive System Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food vacuole, lysosomes secrete digestive enzymes to digest food. More complex animals have digestive tract and use

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Page 1: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Digestive System

Autotrophs vs. heterotrophs Intracellular digestion – digestion

inside food vacuoles – simple animals

Ex. Hydra ingests food, traps it in a food vacuole, lysosomes secrete digestive enzymes to digest food.

More complex animals have digestive tract and use extracellular digestion

Page 2: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.
Page 3: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Organs of the human digestive system

Mouth Pharynx Esophagus Stomach Small intestine Large intestine Anus

Page 4: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Mouth (oral cavity)Tongue

Esophagus

Liver

Gallbladder

Small intestineDuodenumJejunumlleum

Anus

Parotid gland

Salivary glandsSublingual glandSubmandibulargland

Pharynx

StomachPancreas(Spleen)

Large intestine

Descendingcolon

CecumSigmoid colonRectumAppendixAnal canal

Transversecolon

Ascendingcolon

Figure 14.1

Page 5: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

The mouth

Mechanical and chemical digestion Mechanical – chewing or mastication Chemical – saliva contains salivary

amylase which breaks down starch into maltose

Once chewed, the food is called a bolus

Food then moves through the pharynx into the esophagus

Food moves through involuntary muscle contractions called peristalsis

Page 6: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Figure 14.2a

(a)

Esophagus

Laryngopharynx

Epiglottis

Oropharynx

Lingual tonsil

Palatine tonsil

Uvula

Soft palate

Nasopharynx

Hardpalate

Oralcavity

Lips (labia)

Vestibule

Lingualfrenulum

Tongue

Hyoid bone

Trachea

Page 7: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Stomach Anatomy

Regions of the stomach Cardiac region—near the heart Fundus—expanded portion lateral to the

cardiac region Body—midportion Pylorus—funnel-shaped terminal end

Rugae—internal folds of the mucosa Stomach can stretch and hold 4 L (1

gallon) of food when full

Page 8: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Stomach Physiology

Temporary storage tank for food Site of food breakdown by digestive

enzymes and HCl. Chemical breakdown of protein

begins by pepsin (pepsinogen into pepsin when pH is low)

Delivers chyme (processed food) to the small intestine

Page 9: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Structure of the Stomach Mucosa

Mucosa is simple columnar epithelium Mucous neck cells—produce a sticky

alkaline mucus Gastric glands—situated in gastric pits

and secrete gastric juice Chief cells—produce protein-digesting

enzymes (pepsinogens) Parietal cells—produce hydrochloric acid Enteroendocrine cells—produce gastrin

(hormone)

Page 10: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Pyloricsphincter

Gastric pits

Surfaceepithelium

Mucousneck cells

Parietal cells

Gastricglands

Chief cells

Gastr

ic p

itG

astr

ic g

lan

d

(c)

Figure 14.4c

Page 11: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Pepsinogen PepsinHCl

Parietal cells

Chief cells

Enteroendocrinecell

(d)Figure 14.4d

Page 12: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Small Intestine

The body’s major digestive organ Site of nutrient absorption into the

blood Muscular tube extending from the

pyloric sphincter to the ileocecal valve

Page 13: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Subdivisions of the Small Intestine

Duodenum Attached to the stomach Curves around the head of the pancreas

Jejunum Attaches anteriorly to the duodenum

Ileum Extends from jejunum to large intestine

Page 14: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Chemical Digestion in the Small Intestine

Chemical digestion begins in the small intestine Enzymes are produced by▪ Intestinal cells▪ Pancreas

Pancreatic ducts carry enzymes to the small intestine

Bile, formed by the liver, enters via the bile duct

Maltase, sucrase, lactase further break down carbs.

Page 15: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Gallbladder

Duodenalpapilla

Hepatopancreaticampulla and sphincter Duodenum

Right and lefthepatic ductsfrom liver

Cystic duct

Common hepatic duct

Bile duct and sphincterAccessory pancreatic duct

Pancreas

Jejunum

Main pancreatic duct and sphincter

Figure 14.6

Page 16: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Pancreas

Produces a wide spectrum of digestive enzymes that break down all categories of food – trypsin, chymotrypsin (di-peptides), pancreatic lipase (fats), pancreatic amylase (disaccharides)

Nucleases break down nucleotides Enzymes are secreted into the duodenum Alkaline fluid introduced with enzymes

neutralizes acidic chyme coming from stomach Hormones produced by the pancreas

Insulin Glucagon

Page 17: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Liver

Largest gland in the body Located on the right side of the body

under the diaphragm

Page 18: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Bile

Produced by cells in the liver Bile leaves the liver through the

common hepatic duct Composition is

Bile salts Bile pigments (mostly bilirubin from the

breakdown of hemoglobin) Cholesterol Phospholipids Electrolytes

Page 19: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Bile

Function—emulsify fats by physically breaking large fat globules into smaller ones

Page 20: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Gallbladder

When no digestion is occurring, bile backs up the cystic duct for storage in the gallbladder

When digestion of fatty food is occurring, bile is introduced into the duodenum from the gallbladder

Gallstones are crystallized cholesterol which can cause blockages

Page 21: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Small Intestine Anatomy

Three structural modifications that increase surface area Microvilli—tiny projections of the plasma

membrane (create a brush border appearance)

Villi—fingerlike structures formed by the mucosa

Lacteals – part of the lymphatic system – absorb fatty acids

Page 22: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Absorptivecells

Lacteal

Bloodcapillaries

(b) Villi

Lymphoidtissue

Intestinalcrypt

Muscularismucosae

Villus

Venule

Lymphatic vessel

Submucosa

Figure 14.7b

Page 23: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Figure 14.7c

(c) Absorptive cells

Microvilli(brush border)

Page 24: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Digestive Hormones

Gastrin – stimulates stomach to make gastric juices

Secretin – stimulates pancreas to produce bicarbonate and digestive enzymes

Cholecystokinin – stimulates the secretion of pancreatic enzymes and the release of bile

Page 25: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Large intestine

Reabsorbes water and salt Bacteria live here that are useful for

digestion. They break down food and extract vitamins like vitamin K

Feces is undigested food that moves through the rectum.

Page 26: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Right colic(hepatic) flexure

Transverse colon

Haustrum

Ascending colon

IIeum (cut)

IIeocecal valve

Cecum

Appendix Rectum

Alan canal External anal sphincter

Sigmoid colon

Teniae coli

Cut edge ofmesentery

Descending colon

Left colic(splenic) flexure

Transversemesocolon

Figure 14.8

Page 27: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Regulation of Pancreatic Juice Secretion

Secretin causes the liver to increase bile output

CCK causes the gallbladder to release stored bile Bile is necessary for fat absorption and

absorption of fat-soluble vitamins (K, D, A)

Page 28: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Upon reaching thepancreas, CCKinduces secretion ofenzyme-rich pancreaticjuice; secretin causessecretion of bicarbonate-rich pancreatic juice.

Stimulation by vagal nervefibers causes release ofpancreatic juice and weakcontractions of the gallbladder.

Secretin causes the liver tosecrete more bile; CCK stimulatesthe gallbladder to release storedbile and the hepatopancreaticsphincter to relax (allows bile toenter the duodenum).

Chyme enteringduodenum causes theenteroendocrine cellsof the duodenum torelease secretin andcholecystokinin (CCK).

CCK (red dots)and secretin (bluedots) enterbloodstream.

2

1

3

45

Figure 14.16

Page 29: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Accessory Digestive Organs

Teeth Salivary glands Pancreas Liver Gallbladder

Page 30: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Teeth

Function is to masticate (chew) food Humans have two sets of teeth

Deciduous (baby or “milk”) teeth A baby has 20 teeth by age two First teeth to appear are the lower

central incisors

Page 31: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Teeth

Permanent teeth Replace deciduous teeth between the

ages of 6 and 12 A full set is 32 teeth, but some people do

not have wisdom teeth (third molars) If they do emerge, the wisdom teeth

appear between ages of 17 and 25

Page 32: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Classification of Teeth

Incisors—cutting Canines (eyeteeth)—tearing or

piercing Premolars (bicuspids)—grinding Molars—grinding

Page 33: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

IncisorsCentral(6–8 mo)

Lateral(8–10 mo)

Canine (eyetooth)(16–20 mo)MolarsFirst molar(10–15 mo)Second molar(about 2 yr)

IncisorsCentral (7 yr)

Lateral (8 yr)Canine (eyetooth)(11 yr)Premolars(bicuspids)First premolar(11 yr)Second premolar(12–13 yr)MolarsFirst molar(6–7 yr)

Second molar(12–13 yr)Third molar(wisdom tooth)(17–25 yr)

Deciduous(milk) teeth

Permanentteeth

Figure 14.9

Page 34: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Figure 14.13 (1 of 3)

Page 35: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Figure 14.13 (2 of 3)

Page 36: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Figure 14.13 (3 of 3)

Page 37: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Nutrition Nutrient—substance used by the

body for growth, maintenance, and repair

Major nutrients Carbohydrates Lipids Proteins Water

Minor nutrients Vitamins Minerals

Page 38: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Figure 14.17

Page 39: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Dietary Sources of Major Nutrients

Carbohydrates Most are derived from plants Exceptions: lactose from milk and small

amounts of glycogens from meats Lipids

Saturated fats from animal products Unsaturated fats from nuts, seeds, and

vegetable oils Cholesterol from egg yolk, meats, and

milk products

Page 40: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Dietary Sources of Major Nutrients

Proteins Complete proteins—contain all essential

amino acids▪ Most are from animal products▪ Essential amino acids are ones that our

bodies cannot make▪ We must obtain essential amino acids

through our diet Legumes and beans also have proteins,

but are incomplete

Page 41: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Dietary Sources of Major Nutrients

Vitamins Most vitamins are used as coenzymes Found in all major food groups

Page 42: Autotrophs vs. heterotrophs Intracellular digestion – digestion inside food vacuoles – simple animals Ex. Hydra ingests food, traps it in a food.

Dietary Sources of Major Nutrients

Minerals Play many roles in the body Most mineral-rich foods are vegetables,

legumes, milk, and some meats


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