BI 203 Human Anatomy

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BI 203 Human Anatomy Physiology II
Why do we have a digestive system? Provide
nutrients to all tissues in the body
What tasks does your digestive system
do? Ingestion, mastication, propulsion, mixing,
secretion, digestion, absorption, transportation,
elimination
What is digestion? Breakdown of organic
molecules/nutrients... mechanical and chemical
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BI 203 Human Anatomy Physiology II
See Table 24.1
What happens between my mouth and anus?
Organ Function Time
ingestion/mastication 10-20
sec.secretion/mixing/digestion
Oral cavity Pharynx Esophagus Stomach Small
intestines Pancreas Liver Large
intestines Rectum Anus
transportation 1-2 sec.
transportation/propulsion 5-8 sec.
digestion/secretion 3-4 hrs.mixing
digestion/secretion/mixing 3-5 hrs.absorption/pro
pulsion
absorption/propulsion 18-36 hrs.elimination
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BI 203 Human Anatomy Physiology II
What structures exist between mouth and anus?
Graphic overview of alimentary canal
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BI 203 Human Anatomy Physiology II
What is the oral cavity and what does it do?
Graphic overview of
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BI 203 Human Anatomy Physiology II
What is the oral cavity and what does it do?
Vestibule space between cheeks, lips and
gums Oral cavity properspace within floor of
mouth and roof (palate)
permanent
deciduous
Ingestion (alternate routes) Mastication
chewingWhich type of digestion?
Why?Accomplished via cheeks, lips, tongue,
teeth, jaws
Types of teethIncisorsCaninesPremolarsMolars
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BI 203 Human Anatomy Physiology II
How do you masticate?
Teeth embedded inAlveoli in the Maxilla(upper
jaw) Mandible (lower jaw) Closing jaw
massetertemporalismedial pterygoids Opening
jaw lateral pterygoids
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BI 203 Human Anatomy Physiology II
How do you salivate?
3 paired glandsParotidSubmandibularSublingual
Scattered small tubular glands
Secrete mucus, serous fluid and enzymes Endocrine
or Exocrine?
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BI 203 Human Anatomy Physiology II
What can your palate do for you ?
Hard and Soft palates Cleft lip/palatecongenital
defect where embryonic tissues fail to
fuse Because I was different by Don Bartlette
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BI 203 Human Anatomy Physiology II
How does food get from oral cavity to esophagus?
Food formed into a bolus Pushed against hard
palate by tongue Initiates swallowing
reflex Pharyngeal muscles aid in pushing into
esophagus Swallowing (deglutition) divided into 3
phases1) voluntary2) pharyngeal3) esophageal
Which of the pharynxes usually conduct food?
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BI 203 Human Anatomy Physiology II
What is the role of the esophagus?
Conducting Tube 12 in length 2
sphinctersupper esophageal lower esophageal or
cardiac Generalized layers of alimentary canal
4
1
2
3
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BI 203 Human Anatomy Physiology II
What is the role of the enteric plexus?
Nerve plexus allows local reflexes to be
integrated independent of the CNS. Sensory
neurons Motor neurons Interneurons
4
1
2
3
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BI 203 Human Anatomy Physiology II
Whats unique about the stomique?
Varies in size Rugae (wrinkles) allow
distention Entrance gastroesophageal opening
(cardiac) Exit pyloric opening Muscularis
different because 3 layers of muscle
DisordersHiatal hernia Hypertrophic pyloric
stenosis
Endoscopy
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BI 203 Human Anatomy Physiology II
How does gastric digestion occur?
5 types of cells 1) Surface mucous cells mucus
(1-1.5 mm, alkaline) 2) Mucous neck cells
mucus 3) Parietal cells HCl, Intrinsic factor
(B12)
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BI 203 Human Anatomy Physiology II
How does gastric digestion occur?
5 types of cells 4) Chief cells pepsinogen,
becomes pepsin in low pH, breaks covalent protein
bonds, making peptides 5) Endocrine cells
hormones (gastrin), which stimulates secretory
activity of parietal cells.
Gastric secretions and bolus form Chyme
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BI 203 Human Anatomy Physiology II
How is gastric secretion regulated?
Gastric secretion is divided into 3 phases 1)
Cephalic Stimuli from head region initiate
gastric secretion 2) Gastric Stimuli from w/n
stomach cause gt secretion
3) Intestinal Dependent on pH/chemistry of chyme
in duodenum. gt pH 3 then stimulates, lt pH 2
then inhibits.
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BI 203 Human Anatomy Physiology II
What is important about Liver anatomy?
Largest internal organ, 2 major, 2 minor lobes
Connective tissue capsule invades at hepatic
portal, form membrane bound lobules (6-sided),
portal triads in corners
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BI 203 Human Anatomy Physiology II
Whats the digestive role of the Liver?
Bile production formed in lobules, drains out
hepatic ducts, secreted and/or stored in gall
bladder.Storage can store nutrients (glycogen,
vitamins, fats)Nutrient interconversion
metabolically swapped DetoxificationPhagocytosi
sSynthesis
What are gall stones?
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BI 203 Human Anatomy Physiology II
Whats the digestive role of the Pancreas?
Exocrine and endocrine functions Pancreatic juice

Enzymatic component enzymes essential for all
food class digestion. Examplestrypsin
protein amylase carboslipase fats
ribo and deoxyribonuclease RNA/DNA
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BI 203 Human Anatomy Physiology II
Whats the digestive role of the Pancreas?
Pancreatic juice Aqueous component H2O and
HCO3-ions dilute neutralize acidic chyme. What
is a source of bicarbonate ions?
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BI 203 Human Anatomy Physiology II
What are the regions of the small intestines?
Long segment of alimentary canal 6 meters 3
regions 1) Duodenum 2) Jejunum 3) Ileum
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BI 203 Human Anatomy Physiology II
Whats the internal anatomy of the small
intestines?
Contains features such as plicae circularis
(circular folds)villimicrovilli Why? Functions
include Digestion/Mixing/Absorption
Digestive enzymes in association w/ microvilli
disaccharidases, peptidases, nucleases
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BI 203 Human Anatomy Physiology II
What are the components of the colon?
Divided into 4 regions1) Ascending colonbegins
at ileocecal valveends at hepatic flexure
2) Transverse colonbegins at hepatic
flexureends at spleenic flexure
3) Descending colonbegins at spleenic
flexureends at opening of pelvis
Rectum
4) Sigmoid colonbegins at opening of pelvisends
at rectum
Sphincters
Anus
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BI 203 Human Anatomy Physiology II
What are the functions of the colon?
SecretionAbsorption(form feces) Normal flora
can produce Vitamins (K)Flatus Capable of mass
movements
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BI 203 Human Anatomy Physiology II
How does it (defecation) happen?

• Mass movements
• Colic distension results in defecation reflex
  w/c is a contraction of rectal tunica muscularis
  and relaxation of internal anal sphincter.
• If ignored reflex is extinguished.
• If acted upon, voluntary actions result in
  defecation.

Diarrhea Constipation
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BI 203 Human Anatomy Physiology II
What is the big picture of digestion?
To understand Digestion and then absorption You
need to know the component pieces molecules of
each major nutrient group. Water
H2O Vitamins/Minerals B12, Ascorbic acid (C)
etc. Salts Positive ion (Ca2) and negative ion
(Cl-) CaCl2 Carbohydrates Polysaccharides
?Disaccharides ? Monosac. Lipids triglycerides
? 3 fatty acids gylcerol Proteins
Polypeptides ? Dipeptides ? amino acids
Bile
Small intestine enzymes
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BI 203 Human Anatomy Physiology II
What is the big picture of carbohydrate digestion?

• Goal Convert complex carbs (polysaccharides) and
  disacchrides into monosaccharides
• Absorbed via 2ndary active transport
• Facilitated diffusion to blood
• Monosac. to liver to be converted to glucose and
  or glycogen

Bile
Small intestine enzymes
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BI 203 Human Anatomy Physiology II
What is the big picture of lipid digestion?

• Goal Convert to fatty acids, glycerol
• Micelles formed
• Attach to plasma membrane, lipid components
  diffuse into epithelium
• Changed back into triglycerides and coated with
  proteins. Chylomicrons excreted
• Chylomicrons move to lacteal, then blood stream

Bile
Small intestine enzymes
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BI 203 Human Anatomy Physiology II
What is the big picture of lipid digestion?
What is the most dense? Water Lipids Proteins
Bile
Small intestine enzymes
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BI 203 Human Anatomy Physiology II
What is the big picture of lipid digestion?
Bile
Small intestine enzymes
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BI 203 Human Anatomy Physiology II
What is the big picture of protein digestion?

• Goal Form amino acids
• Amino acids absorbed via 2ndary active transport
  and/or diffusion
• A.a. moved out via active transport
• Enter blood stream and move to liver

Bile
Small intestine enzymes
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BI 203 Human Anatomy Physiology II
What is the big picture of protein digestion?
Pepsin
polypeptides
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BI 203 Human Anatomy Physiology II
What is the big picture of protein digestion?
oligopeptides
Trypsin Chymotrypsin Carboxypeptidase
oligopeptides
amino acids
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BI 203 Human Anatomy Physiology II
What is the big picture of protein digestion?
amino acids
Carboxypeptidase Aminopeptidase
Dipeptidase
amino acids
amino acids
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BI 203 Human Anatomy Physiology II
What is the big picture of digestion?
Carbos
Proteins
Lipids
Saliva
amylase
Gastric juice
pepsin
Bile
bile salts
Pancreatic juice
trypsin
amylase
lipase, esterase
Small intestine enzymes
SucraseLactase
peptidase
lipase