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Fish
Teeth
Oral Glands
Modifications
Pancreas
- t: polyphodont and homodont
- OG: few
- M: many fish, instead of plicae, have a spiral arrangement called the spiral valve in the ileum
- P: dorsal and ventral (two)
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Amphibians Teeth
Oral Glands
Modifications
Pancreas
- i. Polyphodont and homodont
- ii. Oral glands
- iii. Villi in intestines
- iv. Single pancreas
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Reptiles
TeethOral GlandsModificationsPancreas
- i. Polyphodont and homodont teeth
- ii. Oral glands
- iii. Villi in intestines
- iv. Single pancreas
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Birds
Teeth
GI Tract
- i. Edentate—have beaks and bills
- ii. GI tract of grain-eating birds
- 1. Esophagus- crop
- a. Store grain before digestion (storage area)
- 2. Stomach—FUNDUS (chemical digestion) and gizzard (mechanical digestion; seeds thrown back and forth; helps pulverize and grind down seeds)
- 3. No gall bladderin grain-eating birds
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Humans
Oral Cavity
- 1. Salivary glands
- a. Mammals have three major sets of salivary glands
- i. Parotid
- 1. Under ear
- ii. Sublingual
- 1. Under tongue
- iii. Submandibular
- 1. Around mandible
- b. Saliva and salivary amylase
- i. Salivary amylase is the enzyme that begins digestion of carbohydrates
- ii. Just think about food to salivate!
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Humans
Stomach Parts
- 1. Main part is the fundus
- 2. Narrow part is the pylorus, where the pyloric sphincter is
- 3. Flattened mucosa has holes, openings into gastric glands, called gastric pits (beneath lumen)
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Gastric Pits of Human Stomach contain
- chief cells, which secrete pepsinogen
- a. Contain parietal cells, which secrete hydrocholoric acid
- b. cells that release the hormone, gastrin
- mucus
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Pepsinogen
- i. Pepsinogen generally is called a zygomen
- 1. Inactive form of an enzyme
- a. Not active; won’t digest anything
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HCl
- i. HCl is needed to activate pepsinogen to pepsin which is a protein-splitting enzyme that begins the digestion of protein
- ii. Because of acidity, chyme has an acidity of 2
- 1. Needs to be acidic to activate pepsinogen
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Gastrin
- i. Hormone that increases gastric motility (enhances churning and peristalsis) and also increases gastric juice release
- 1. Gastrin and parasympathetic do the same thing and work at the same time
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Small intestine adn enzymes
- 1. All of the enzymes present in the small intestine come from the small intestinal gland, pancreas, have bile
- a. They won’t function in acidic environment
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What must happen to acid chyme?
- i. Acid chyme has to be neutralized
- 1. It’s the sodium bicarbonate salts from the pancreas that neutralize the acid chyme when it comes in the small intestines
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Small Intestine Modifications in Humans
- 1. The small intestine projects the villi and sends a small part below the villus
- a. The portion of the mucosa that dips below the luminal surface are the intestinal glands
- i. Called Krypts of Lieberkuhn
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Krypts of Lieberkuhn
- 1. Name of small intestinal glands
- 2. Secrete lots of enzymes
- a. Lipases, nucleases, peptidases
- 3. Also secretes some hormones
- a. One is secretin
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What does secretin do?
- i. An intestinal hormone which is released when acid chyme enters the small intestines
- ii. Goes out and affects pancreas, causing pancreas to secrete sodium bicarbonate salts
- iii. Secretin controls sodium bicarbonate salt release (acts when acid chyme enters the small intestine)
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