BI 203 Human Anatomy & Physiology II Why do we have a digestive system? Provide nutrients to all tissues in the body What is digestion? Breakdown of organic molecules/nutrients... mechanical and chemical What tasks does your digestive system do? Ingestion, mastication, propulsion, mixing, secretion, digestion, absorption, transportation, elimination
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, mastic ation, propulsion, mixing, secretion, digestion, absorption, transportation, elimination. What is digestion ? - PowerPoint PPT Presentation
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BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Why do we have a digestive system?Provide nutrients to all tissues in the body
What is digestion?
Breakdown of organic molecules/nutrients... mechanical and chemical
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
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)
How does gastric digestion occur?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
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.
How does gastric digestion occur?
Gastric secretions and bolus form Chyme
BI 203 Human Anatomy & Physiology IIBI 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 > secretion
3) Intestinal: Dependent on pH/chemistry of chyme in duodenum. > pH 3 then stimulates, < pH 2 then inhibits.
BI 203 Human Anatomy & Physiology IIBI 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
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
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” DetoxificationPhagocytosisSynthesis
What’s the digestive role of the Liver?
What are gall stones?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Exocrine and endocrine functions
Pancreatic juice =
What’s the digestive role of the Pancreas?
Enzymatic component: enzymes essential for all food class digestion. Examples:trypsin = protein amylase = carboslipase = fatsribo and deoxyribonuclease = RNA/DNA
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Pancreatic juice = Aqueous component H2O and HCO3-ions dilute & neutralize acidic chyme.
What is a source of bicarbonate ions?
What’s the digestive role of the Pancreas?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Long segment of alimentary canal… 6 meters
3 regions:
1) Duodenum
2) Jejunum
3) Ileum
What are the regions of the small intestines?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Contains features such as:
plicae circularis (circular folds)villimicrovilli
Why?
Functions include:
Digestion/Mixing/Absorption
What’s the internal anatomy of the small intestines?
Digestive enzymes in association w/ microvilli: disaccharidases, peptidases, nucleases
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
Divided into 4 regions:1) 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
4) Sigmoid colonbegins at opening of pelvisends at rectum
RectumAnus Sphincters
What are the components of the colon?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
SecretionAbsorption(form feces)
Normal flora can produce:
Vitamins (K)Flatus
Capable of mass movements
What are the functions of the colon?
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
How does it (defecation) happen?
Diarrhea & Constipation
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
•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.
What is the big picture of digestion?
Bile
Small intestine enzymes
BI 203 Human Anatomy & Physiology IIBI 203 Human Anatomy & Physiology II
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