Digestive system Notes Flashcards
The Peritoneum
Covers the internal space (Lines) including organs. Helps hold these organs in place.
Mesentery
A Peritoneal extension for organ support, contains vessels that transport nutrients to Cardiovascular system.
Parts and functions of the Mucosa
Epithelium- Simple columnar & Stratified Squamous
Lamina Propria- Capillaries and WBC
Mucosa Pits- Can be glandular (Gastric glands). These are mitosis sanctuaries.
Extromural gland
EG Pancreus
Muscularus
Mostly smooth muscle. Has a inner circular layer and an outer longitudinal layer.
Promotes gut motility like peristalsis
Peristalsis
Wave of contraction that moves digestra analward as a Bolus.
Parts of the Alimentary Canal
Oral Cavity Salivary glands Teeth Esophagus Stomach Intestines Rectum and Anus
Oral Cavity
In most verts a tonuge is possessed for food manipulation
Salvatory glands
In tetrapods- Dissolve flavorants with saliva, lubricates, and produce enzymes.
These are modified as Venum glands in some reptiles.
Teeth (or equivalent)
There are Keratin equivalents- Composed of dead Keratinocytes. (Example being the Balegn whales filter-feeding apparatus Balegn in the Agnathans.
The vast majority of teeth are made of bone.
Parts of a human tooth
Crown Root Enamel Dentin Pulp Cavity Root Canal Peridontal Ligument
Enamel
The matrix- Mostly Hydroxyapatite, the hardest surface in the body
Made by cells called Amyloblasts.
Dentin
Bone-like matrix. Made by Odontoblast cells.
Pulp Cavity
Vascular and Innerved. Lined with odontoblasts that help monitor Denton quality and make secondary Denton to accommodate for wear.
Periodontal Ligament
Bioliogen holding the tooth in place.
The Esophagus
Does the Peristalsus of swallowing and transfer of muscularous for skeletal muscle to smooth muscle. There is an abundance of mucus glands.
Special adaptations of the Esophagus
A birds crop- food storage in fore-gut fermentors the esophagus portion.
The Rumin
In a bird’s CROP! It is a chamber for microbial digestion of cellulose.
The Stomach
Functions as food storage and has mucosal folds (Rugae to permit stretch).
Has three muscle layers that permit mixing
Gastric pits/glands secrete gastric juice (hydrochloric acid to protect, digest, and break down proteins.
It also secretes mucus to protect itself from digestion!
Bird Stomach
2 stomachs- Secrotory and Gizzard
Gizzards
Have Keritin like internal covering for grinding and can ingest rocks to assist.
Digestive Product in Birds
Chyme- Acidic liquid that enters the duedeum of the small intestine
Duodeum
Receives Chyme from stomach, enzymes from pancreas, bile from the liver, and alkaline (to neutralize) mucus from Brunners Gland.
The Small Intestine
Lined with collumnar cells called enterocytes. Nature favors large SA of enterocytes. Enterocytes have apical “brush border” enzymes that finish digestion. Enterocytes perform all absorption
How enterocyte surface is maximized
Great intestinal length Spiral valve in some fishes e.g. sharks Circular internal folds Villi: finger-like mucosa projections Microvilli of enterocytes
All of these together increase the SA by 600x
Large Intestine
It absorbs H2O and feces, and helps control the animals’ water budget.
Cecum
section joined with the small intestine (in the large intestine
Has an appendix in humans Thin extension; lymphatic organ Hindgut Fermenters e.g. horses and rabbits Cecum large; houses microbial digestion of cellulose
How does water enter and leave an animal?
In- Drinking, food, metabolic H2O
Out- Urine, feces, evaporation
