Digestive System Flashcards
Herbivore
Plant-eaters. Horses, rabbits, sheep, goats. High fiber. Large flat premolars/molars for grinding. Minimum/absent canine teeth. Ruminant or non-ruminant
Carnivore
meat-eaters. Dogs and cats. small or absent cecum. Minimal fermentation, large canine teeth for ripping and tearing flesh, pointed molars for sheering/minimally chewing food
Omnivore
Plant and meat. Pigs and humans. Cecum small or absent. Teeth for ripping and grinding
Morphology
structure and function of the digestive tract
Ruminants
sheep’s and goats. Large fermentation capacity in stomach
Non-ruminants
horses and rabbits, large fermentation capacity in cecum and colon
Prehension
bringing food to mouth
Mastication
chewing
Deglutination
swallowing
Peristalsis
smooth muscle contraction to move food
Mesentary
suspends intestines from abdominal wall. Lined with blood vessels and nerves. Passage of digested nutrients from lumen of gut across mucosa into bloodstream for transport to tissues
Omentum
links stomach to abdominal wall/other organs. Less/greater omentum depending on abdomen location. Store fat, assist in insulating abdomen
Ligaments
connective tissue
Monogastric
one stomach, size/shape varies. Temporary storage of digesta
Rugae
lines interior of stomach, increases surface area for secretion of gastric juices/absorption of some nutrients
Pyloric Sphincter
band of smooth muscle. Controls movement of partially digested food and juices
Recticulum
smallest, most cranial chamber. Honeycomb to increase surface area, heavy objects get stuck here. Prevention of hardware disease
Rumen
main site of fermentation, small bumps (papillae) to increase surface area for microbial digestion. Mixes stomach content (mixing = mechanical or physical digestive process)
Omasum
muscular chamber with many folds. Important for water absorption and removal of bicarbonate buffer. Participates in absorption of energy products from digestion, microbial fermentation
Abomasum
“true stomach,” lined with glandular epithelium, secretes mucus and enzymes. Anything not digested from microbial digestion absorbed here before going to small intestine
Bile
made in liver, stored in gallbladder. Good for digestion and emulsification of fats into small lipid droplets (further digested by lipases)
Goblet Cells
Secrete mucus for lubrication of dried feces
Defecation
pooping. Feces moving into the rectum stimulates sensory receptors that initiate defecation reflex. Colon/rectum contracts/relaxes. Some animals can control it, others can’t
Cephalic Phase
1) stimulation of neurotransmitter (ACh) release
2) ACh binds to receptors that cause the release of gastric juices into the stomach (HCl and pepsinogen)
3) ACh triggers hormone histamine release which further stimulates ACh
Gastric Phase
1) formation of peptides from protein (enzymatic digestion) triggers vagal nerve (cranial nerve 10)
2) stimulation of hormone gastrin release from G cells
3) gastrin triggers more histamine and HCl stomach acid to be produced
4) stomach acidity lowers (gets more acidic for enhanced digestion)
Intestinal Phase
1) ACh triggers vagal nerve (cranial nerve 10) stimulation that increases hormones, CCK and secretin
2) most enzymatic digestion happens in duodenum of small intestine
Gastric Motility
rate of passage of digesta through stomach. Neurohormonal control
Enteroendocrine cells
dispersed in gradient fashion.
