Digestive Systems and Nutrition – Animal Body Systems – 224.3 – Marth 15th 2023
Supplementary readings:
• Textbook (5th edition, chapter 39, pages 947-967)
• Textbook (4th edition, chapter 39, pages 1029-1049)
What is digestion
• Process of mechanical and chemical breakdown of food into molecular subunits small enough to be
absorbed into body fluids and cells (nutrients)
• Nutrients: substances essential for growth and maintaining life.
Main functions of the digestive system
• Breakdown: food into smaller molecules that can cross plasma membranes
• Food storage
• Absorption of nutrients
• Elimination of undigested food (feces, defecation)
Macro-nutrients: required in large amount
• (e.g., carbohydrate, fat, protein, macro elements)
Micro-nutrients: required in small amounts
• (e.g., vitamins, trace elements)
Essential nutrients: animals cannot synthesize themselves and must be acquired from food
• (e.g., essential amino acids, essential fatty acids vitamins & minerals)
Essential amino acids in humans: 9
• Lysine
• Histidine
• Tryptophan
• Phenylamine
• Threonine
• Valine
• Methionine
• Leucine
• Isoleucine
Essential fatty acids in humans: 2
• Linoleic acid (omega - 6)
• Linolenic acid (omega – 3)
Essential vitamins in humans: 13
• Note: humans can synthesize vitamin D
from sunlight
,Vitamins: Sources, Functions, and Effects of Deficiencies in Humans
Vitamins Common sense Main Functions Effects of Chronic
Deficiency
Fat-Soluble Vitamins
A (retinal) Yellow fruits, yellow or green Used in synthesis of visual Dry, scaly skin: lowered
leafy vegetables: also in pigments, bone, teeth, resistance to infection:
fortified milk, egg yolk, fish maintains epithelial tissues. night blindness
liver
D (calciferol) Fish liver oils, egg yolks, Promotes bone growth and Bone deformities (rickets)
fortified milk: manufactured mineralization enhances in children: bone softening
when body exposes to calcium absorption from in adults
sunshine gut
E (tocopherol) Whole grains, leafy greens Antioxidant: helps maintain Lysis of red blood cells:
vegetables, vegetable oils, cell membrane and red nerve damage
blood cells.
K (naphthoquinone) Intestinal bacteria: also in Promotes synthesis of Abnormal blood clotting,
green leafy vegetables, blood-clotting protein by severe bleeding
cabbage liver (hemorrhaging)
Water-soluble Vitamins
𝐁𝟏 (thiamine) Whole grains, green leafy Connective tissue Beriberi: water retention in
vegetables, legumes, lean formation; folate tissues; tingling sensations;
meats, eggs, nuts utilization; coenzyme heart changes; poor
forming part of enzyme in coordination
oxidative reactions
𝐁𝟐 (riboflavin) Whole grains, poultry, fish, Coenzyme Skin lesions
egg white, milk, lean meat
Niacin Green leafy vegetables, Coenzyme of oxidative Sensitive to light;
potatoes, peanuts, poultry, phosphorylation contributes to pellagra
fish, pork, beef (damage to skin, gut,
nervous system, etc.)
𝐁𝟔 (pyridoxine) Spinach, whole grains, Coenzyme in amino acid Skin, muscle and nerve
tomatoes, potatoes, meats and fatty acid metabolism damage
Pantothenic acid In many foods (meats, yeast, Coenzyme in carbohydrate Fatigue: tingling in hands.
egg yolk especially) and fat oxidation; fatty acid Headaches; nausea
and steroid synthesis
Folic Acid Dark green vegetables, whole Coenzyme in nucleic acid Anemia; inflamed tongue;
grains, yeast, lean meats; and amino acid diarrhea; impaired growth;
intestinal bacteria produce metabolism; promotes red mental disorders; neural
some folate blood cell formation tube defects and low birth
weight in newborns.
𝐁𝟏𝟐 (cobalamin) Poultry, fish, eggs, red meat, Coenzyme in nucleic acid Pernicious anemia;
dairy foods (not butter) metabolism; necessary for impaired nerve function
red blood cell formation
Biotin Legumes, egg yolk; colon Coenzyme in fat and Scaly skin (dermatitis); sore
bacteria produce some glycogen formation and tongue; brittle hair;
amino acid metabolism depression; weakness
, C (Ascorbic Acid) Fruits and vegetables, Vital for collagen synthesis; Scurvy: delayed would
especially citrus, berries, antioxidant healing; impaired immunity
cantaloupe, cabbage,
broccoli, green pepper
Supplementary readings:
• Textbook (5th edition, chapter 39, pages 947-967)
• Textbook (4th edition, chapter 39, pages 1029-1049)
What is digestion
• Process of mechanical and chemical breakdown of food into molecular subunits small enough to be
absorbed into body fluids and cells (nutrients)
• Nutrients: substances essential for growth and maintaining life.
Main functions of the digestive system
• Breakdown: food into smaller molecules that can cross plasma membranes
• Food storage
• Absorption of nutrients
• Elimination of undigested food (feces, defecation)
Macro-nutrients: required in large amount
• (e.g., carbohydrate, fat, protein, macro elements)
Micro-nutrients: required in small amounts
• (e.g., vitamins, trace elements)
Essential nutrients: animals cannot synthesize themselves and must be acquired from food
• (e.g., essential amino acids, essential fatty acids vitamins & minerals)
Essential amino acids in humans: 9
• Lysine
• Histidine
• Tryptophan
• Phenylamine
• Threonine
• Valine
• Methionine
• Leucine
• Isoleucine
Essential fatty acids in humans: 2
• Linoleic acid (omega - 6)
• Linolenic acid (omega – 3)
Essential vitamins in humans: 13
• Note: humans can synthesize vitamin D
from sunlight
,Vitamins: Sources, Functions, and Effects of Deficiencies in Humans
Vitamins Common sense Main Functions Effects of Chronic
Deficiency
Fat-Soluble Vitamins
A (retinal) Yellow fruits, yellow or green Used in synthesis of visual Dry, scaly skin: lowered
leafy vegetables: also in pigments, bone, teeth, resistance to infection:
fortified milk, egg yolk, fish maintains epithelial tissues. night blindness
liver
D (calciferol) Fish liver oils, egg yolks, Promotes bone growth and Bone deformities (rickets)
fortified milk: manufactured mineralization enhances in children: bone softening
when body exposes to calcium absorption from in adults
sunshine gut
E (tocopherol) Whole grains, leafy greens Antioxidant: helps maintain Lysis of red blood cells:
vegetables, vegetable oils, cell membrane and red nerve damage
blood cells.
K (naphthoquinone) Intestinal bacteria: also in Promotes synthesis of Abnormal blood clotting,
green leafy vegetables, blood-clotting protein by severe bleeding
cabbage liver (hemorrhaging)
Water-soluble Vitamins
𝐁𝟏 (thiamine) Whole grains, green leafy Connective tissue Beriberi: water retention in
vegetables, legumes, lean formation; folate tissues; tingling sensations;
meats, eggs, nuts utilization; coenzyme heart changes; poor
forming part of enzyme in coordination
oxidative reactions
𝐁𝟐 (riboflavin) Whole grains, poultry, fish, Coenzyme Skin lesions
egg white, milk, lean meat
Niacin Green leafy vegetables, Coenzyme of oxidative Sensitive to light;
potatoes, peanuts, poultry, phosphorylation contributes to pellagra
fish, pork, beef (damage to skin, gut,
nervous system, etc.)
𝐁𝟔 (pyridoxine) Spinach, whole grains, Coenzyme in amino acid Skin, muscle and nerve
tomatoes, potatoes, meats and fatty acid metabolism damage
Pantothenic acid In many foods (meats, yeast, Coenzyme in carbohydrate Fatigue: tingling in hands.
egg yolk especially) and fat oxidation; fatty acid Headaches; nausea
and steroid synthesis
Folic Acid Dark green vegetables, whole Coenzyme in nucleic acid Anemia; inflamed tongue;
grains, yeast, lean meats; and amino acid diarrhea; impaired growth;
intestinal bacteria produce metabolism; promotes red mental disorders; neural
some folate blood cell formation tube defects and low birth
weight in newborns.
𝐁𝟏𝟐 (cobalamin) Poultry, fish, eggs, red meat, Coenzyme in nucleic acid Pernicious anemia;
dairy foods (not butter) metabolism; necessary for impaired nerve function
red blood cell formation
Biotin Legumes, egg yolk; colon Coenzyme in fat and Scaly skin (dermatitis); sore
bacteria produce some glycogen formation and tongue; brittle hair;
amino acid metabolism depression; weakness
, C (Ascorbic Acid) Fruits and vegetables, Vital for collagen synthesis; Scurvy: delayed would
especially citrus, berries, antioxidant healing; impaired immunity
cantaloupe, cabbage,
broccoli, green pepper
