Download The Digestive System

The Digestive System
Marki, Anastasia, and Pritch
What’s The Point?
• Breaks down food in order to gain three
essential things: chemical energy,
organic molecules and essential
nutrients
Chemical Energy
• Energy that is in the form of molecular
bonds created during photosynthesis
• Chemical energy in the form of starches
is used in cellular respiration to create
ATP
Organic Molecules
• Organic molecules are used as building
blocks within the organism
Essential Nutrients
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Four different types:
amino acids
fatty acids
vitamins
minerals
Amino Acids
• Eight essential to humans and a ninth
one Histidine is needed by babies
• Complete proteins such as meat have
all eight
• Incomplete proteins such as corn or
beans do not have all eight unless
eaten together
Essential amino acids for adults
Methionine
Valine
Threonine
Phenylalanine
Leucine
Corn (maize)
and other grains
Isoleucine
Tryptophan
Lysine
Beans
and other
legumes
Fatty Acids
• Few that animals cannot synthesize
themselves:
• linoleic acid is necessary to make
membrane phospholipids
Vitamins
• Organic molecules that perform various
functions but cannot be synthesized
within the body
• Vitamin B2 is FAD+
• Water soluble are B and C, work as
coenzymes
• Fat soluble A, K, and D work as building
blocks
Minerals
• Inorganic elements
• Calcium and phosphorus used in
building bones
• Iodine in hormones
Nourishment
• Under-nourishment- body does not
have enough chemical energy
• Mal-nourishment- body does not have
enough of a specific essential nutrient
Steps of Eating
Small
molecules
Pieces
of food
Mechanical
digestion
Chemical digestion
Nutrient
(enzymatic hydrolysis) molecules
enter body
cells
Undigested
material
Food
1 Ingestion
2 Digestion
3 Absorption
4 Elimination
Types of Digestive
Compartments
• Intracellular digestion versus
extracellular digestion
Intracellular Digestion
• By phago or pino cytosis, food is
ingested by cells and made into food
vacuoles where they can be digested
• Occurs in sponges (filter feeders) and
single-celled organisms
Extracellular Digestion
• Gastrovascular cavity: only a mouth
• Alimentary canal: mouth and anus
Fig. 41-10
Humans have extracellular digestion and an alimentary canal
Tongue
Sphincter
Salivary
glands
Oral cavity
Salivary glands
Mouth
Pharynx
Esophagus
Esophagus
Sphincter
Liver
Stomach
Ascending
portion of
large intestine
Gallbladder
Gallbladder
Duodenum of
small intestine
Pancreas
Liver
Small
intestine
Small
intestine
Large
intestine
Rectum
Anus
Appendix
Cecum
Pancreas
Stomach
Small
intestine
Large
intestine
Rectum
Anus
A schematic diagram of the
human digestive system
Cnidaria- exhibit a
gastrovascular cavity
Main Organs
Layers of Tissue
Linear Path
Salivary
glands
Mouth
Esophagus
Gallbladder
Liver
Pancreas
Stomach
Small
intestine
Large
intestine
Rectum
Anus
A schematic diagram of the
human digestive system
Whole Body
Ingestion
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Mouth
Salivary glands that secrete saliva
Amylase hydrolyzes starch and glycogen
Muchin lubricates mouth and food to avoid abrasion
Buffer neutralizes acids
Tongue regulates what goes into mouth by taste
Bolus, a ball of food, is created and shoved back to
the pharynx
• Pharynx: (fork between trachea and esophagus)
• epiglottis covers glottis opening to trachea
Pharynx
Ingestion
• Esophagus: muscles lining it
• Peristalsis- wave-like contractions that
push food down in 5-10 seconds
• Sphincter- muscular rings in the
esophagus that close off parts of the
alimentary canal
Stomach
QuickTime™ and a
decompressor
are needed to see this picture.
Digestion
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Stomach:
Gastric Juice : HCL + pepsin
Chyme: gastric juice + food
Mucus
Muscle
Digestion
• Small intestine (duodenum)
• - secretions from pancreas and gall
bladder
Blood Sugar Homeostasis
Stimulus:
Blood glucose
level rises
after eating.
Homeostasis:
90 mg glucose/
100 mL blood
Stimulus:
Blood glucose
level drops
below set point.
Cecum
Small intestine
Stomach
Small
intestine
Cecum
Colon
(large
intestine)
Carnivore
Herbivore
Large Intestine
• 90% water is recollected
• Includes the colon
Linear Flow Total
Bloodstream
Veins to heart
Lymphatic
system
Hepatic portal vein
Liver
Lipids
Stomach
Mouth
Esophagus
Secretions from
the gastric glands
of the stomach
Absorbed food Absorbed
(except lipids) water
Small intestine
Anus
Large Rectum
intestine
Secretions from the
pancreas and the liver
Final Table
Carbohydrate digestion
Oral cavity,
pharynx,
esophagus
Protein digestion
Nucleic acid digestion
Fat digestion
Polysaccharides Disaccharides
(starch, glycogen)
(sucrose, lactose)
Salivary amylase
Smaller polysaccharides,
maltose
Stomach
Proteins
Pepsin
Small polypeptides
Lumen of
small intestine
Polysaccharides
Pancreatic amylases
Polypeptides
Pancreatic trypsin and
chymotrypsin
DNA, RNA
Fat globules
Pancreatic
nucleases
Bile salts
Maltose and other
disaccharides
Nucleotides
Fat droplets
Smaller
polypeptides
Pancreatic lipase
Pancreatic carboxypeptidase
Glycerol, fatty
acids, monoglycerides
Amino acids
Epithelium
of small
intestine
(brush
border)
Small peptides
Disaccharidases
Monosaccharides
Nucleotidases
Nucleosides
Dipeptidases, carboxypeptidase,
and aminopeptidase
Amino acids
Nucleosidases
and
phosphatases
Nitrogenous bases,
sugars, phosphates
Diseases
• Crohn’s Disease
• Acid Reflux Disease
• Celiac Disease
Crohn’s Disease
• an inflammatory autoimmune disease
• Symptoms: primarily abdominal pain,
diarrhea (usually with blood), vomiting or
weight loss
• The immune system attacking the
gastrointestinal tract and producing
inflammation in the gastrointestinal tract
• No cure, but stem cell research is promising
• medication to control symptoms, maintain
remission and prevent relapses
Crohn’s Disease
• Affects the ileum and the large intestine or
both most commonly
• Structuring: narrowing of the bowel which can
lead to bowel obstruction or changes in the
caliber of feces
• Penetrating: creates abnormal passageways
between the bowel and other structures like
the skin
• Inflammatory: inflammation without causing
strictures or fistula
Celiac Disease
• an autoimmune disorder of the small
intestine that occurs in genetically
predisposed people.
• Symptoms: chronic diarrhea, failure to
thrive in children, fatigue. There are
asymptomatic cases
• Treatment: a gluten free diet
Acid Reflux
Acid is regurgitated and burns the
esophagus
Symptoms: Heartburn, Nausea, Chronic
Salivation, Damage to esophagus
Treatments are usually lifestyle (foods,
positional therapy) changes along with
medications and possibly surgery
Acid Reflux
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Reflux esophagitis
Esophageal strictures
Barrett's esophagus
Esophageal adenocarcinoma—a rare
form of cancer.
• http://www.youtube.com/watch?v=o4uln
K5mK-A&feature=related