THE DIGESTIVE SYSTEM • INCOMPLETE DIGESTIVE TRACT
Nutrition and Digestion - Gut composed of a closed/blind sac called
gastrovascular cavity with one opening that
NUTRITION
is both the entrance and exit
- includes all those processes by which an animal
- In cnidarians, planarian
takes in, digests, absorbs, stores, and uses food
(nutrients) to meet its metabolic needs.
DIGESTION
- The chemical and/or mechanical breakdown of
food into particles that individual cells of an animal
can absorb
CATEGORIES OF NUTRIENTS
• Macronutrients
- Needed in large quantities (CHO, lipids,
proteins) • COMPLETE DIGESTIVE TRACT
- Used for energy production or as sources for - With mouth as entrance for food and anus as
the “building blocks” of life. exit for undigested food
• Micronutrients
- Needed in small quantities (organic vitamins
and inorganic minerals)
- Used in enzymatic reactions or as part of
certain proteins.
TYPES OF DIGESTION IN ANIMALS
• INTRACELLULAR DIGESTION
- Cells take in whole food particles from the PROCESSES INVOLVED IN DIGESTION
environment by diffusion, active transport, AND NUTRIENT ABSORPTION
and/or endocytosis and break them down • INGESTION
with enzymes to obtain nutrients - Eating or taking in of food – followed by
- In protozoa, sponges, cnidarians, chewing and swallowing
Platyhelminthes, rotifers, bivalve molluscs, • SECRETION
primitive chordates - The release of hormones, enzymes and
specific ions and chemicals that take part in
digestion
• DIGESTION
- The conversion of large nutrient particles or
molecules into small particles or molecules
• ABSORPTION
- The passage of usable nutrient molecules
from the small intestine into the blood
stream and lymphatic system for the final
passage to body cells
• DEFECATION
• EXTRACELLULAR DIGESTION
- The elimination from the body of undigested
- Enzymatic breakdown of large pieces of
and unabsorbed material as waste
food into constituent molecules, usually in a
special organ or cavity PROCESSES INVOLVED IN DIGESTION
- In larger animals AND NUTRIENT ABSORPTION
• PERISTALSIS
- The involuntary, sequential muscular
contractions that move ingested nutrients
along the digestive tract
, THE STORAGE REGION
STOMACH
- Muscular, distensible sac; an enlargement of
the GI (gastrointestinal) -system
- Stores partially digested food (chyme- liquid
form) involved in digestion
- Chyme meets the gastric juice secreted by
gastric glands (HCL, PEPSIN (A
PROTEASE FOR INITIAL DIGESTION
OF PROTEINS)
- ZYMOGENS-inactive form of proteases
stored in submucosa
THE MAMMALIAN DIGESTIVE SYSTEM - Activated at acid pH
• Digestive tract
THE RECEPTION REGION
1. Mouth/Oral/Buccal Cavity- receiving
chamber of food and as a ventilation
chamber of lungs
Tongue- a strong muscular organ; food tot
bolus--- pushed to pharynx (throat)
Teeth- Covered by enamel
TOUNGUE AND TEETH ARE ACCESSORY
DIGESTION WHICH IS USED FOR
MECHANICAL DIGESTION
SALIVA- secreted by 3 salivary glands;
bathes the oral cavity; moistens food into a
moist mass called bolus
STRUCTURE OF THE STOMACH
-contains salivary amylase called ptyalin for
initial enzymatic digestion of carbohydrate 3 PARTS
PHARYNX/THROAT- short tube that
1. CARDIAC REGION
serves as common passageway for food and
air - Anterior next to esophagus; regulates entry
of food in stomach (by cardiac sphincter)
2. BODY OR FUNDUS
- Middle expanded part; site for storage and
digestion
3. PYLORIC REGION OR PYLORUS
- Narrow posterior region; secretes hormone
gastrin which stimulates secretion of HCL
and permits passage of chyme into the
duodenum (by pyloric sphincter)
2. ALIMENTARY CANAL
Esophagus- short tube connecting the
pharynx to the stomach
• PERISTALSIS propel the bolus or liquid to
Nutrition and Digestion - Gut composed of a closed/blind sac called
gastrovascular cavity with one opening that
NUTRITION
is both the entrance and exit
- includes all those processes by which an animal
- In cnidarians, planarian
takes in, digests, absorbs, stores, and uses food
(nutrients) to meet its metabolic needs.
DIGESTION
- The chemical and/or mechanical breakdown of
food into particles that individual cells of an animal
can absorb
CATEGORIES OF NUTRIENTS
• Macronutrients
- Needed in large quantities (CHO, lipids,
proteins) • COMPLETE DIGESTIVE TRACT
- Used for energy production or as sources for - With mouth as entrance for food and anus as
the “building blocks” of life. exit for undigested food
• Micronutrients
- Needed in small quantities (organic vitamins
and inorganic minerals)
- Used in enzymatic reactions or as part of
certain proteins.
TYPES OF DIGESTION IN ANIMALS
• INTRACELLULAR DIGESTION
- Cells take in whole food particles from the PROCESSES INVOLVED IN DIGESTION
environment by diffusion, active transport, AND NUTRIENT ABSORPTION
and/or endocytosis and break them down • INGESTION
with enzymes to obtain nutrients - Eating or taking in of food – followed by
- In protozoa, sponges, cnidarians, chewing and swallowing
Platyhelminthes, rotifers, bivalve molluscs, • SECRETION
primitive chordates - The release of hormones, enzymes and
specific ions and chemicals that take part in
digestion
• DIGESTION
- The conversion of large nutrient particles or
molecules into small particles or molecules
• ABSORPTION
- The passage of usable nutrient molecules
from the small intestine into the blood
stream and lymphatic system for the final
passage to body cells
• DEFECATION
• EXTRACELLULAR DIGESTION
- The elimination from the body of undigested
- Enzymatic breakdown of large pieces of
and unabsorbed material as waste
food into constituent molecules, usually in a
special organ or cavity PROCESSES INVOLVED IN DIGESTION
- In larger animals AND NUTRIENT ABSORPTION
• PERISTALSIS
- The involuntary, sequential muscular
contractions that move ingested nutrients
along the digestive tract
, THE STORAGE REGION
STOMACH
- Muscular, distensible sac; an enlargement of
the GI (gastrointestinal) -system
- Stores partially digested food (chyme- liquid
form) involved in digestion
- Chyme meets the gastric juice secreted by
gastric glands (HCL, PEPSIN (A
PROTEASE FOR INITIAL DIGESTION
OF PROTEINS)
- ZYMOGENS-inactive form of proteases
stored in submucosa
THE MAMMALIAN DIGESTIVE SYSTEM - Activated at acid pH
• Digestive tract
THE RECEPTION REGION
1. Mouth/Oral/Buccal Cavity- receiving
chamber of food and as a ventilation
chamber of lungs
Tongue- a strong muscular organ; food tot
bolus--- pushed to pharynx (throat)
Teeth- Covered by enamel
TOUNGUE AND TEETH ARE ACCESSORY
DIGESTION WHICH IS USED FOR
MECHANICAL DIGESTION
SALIVA- secreted by 3 salivary glands;
bathes the oral cavity; moistens food into a
moist mass called bolus
STRUCTURE OF THE STOMACH
-contains salivary amylase called ptyalin for
initial enzymatic digestion of carbohydrate 3 PARTS
PHARYNX/THROAT- short tube that
1. CARDIAC REGION
serves as common passageway for food and
air - Anterior next to esophagus; regulates entry
of food in stomach (by cardiac sphincter)
2. BODY OR FUNDUS
- Middle expanded part; site for storage and
digestion
3. PYLORIC REGION OR PYLORUS
- Narrow posterior region; secretes hormone
gastrin which stimulates secretion of HCL
and permits passage of chyme into the
duodenum (by pyloric sphincter)
2. ALIMENTARY CANAL
Esophagus- short tube connecting the
pharynx to the stomach
• PERISTALSIS propel the bolus or liquid to
