Digestive system Flashcards
What are the stages of digestion and explain them
- DIGESTION: taking food into body (mouth)
- DIGESTION: breaking food into small chemical units (stomach, SI)
3: ABSORPTION: passing chemical units into blood (SI)
4: METABOLISM: conversion of chemical units into energy for organs to use (liver)
5: Excretion: removal of indigestible material (LI)
Whats the difference between mechanical and chemical digestion?
Mechanical involves movements of teeth of GI tract to physically break up food, Chemical involves reactions that breaks down bonds holding macromolecules together
What are the components of the Digestive system
- Oral cavity (tongue, teeth, saliva)
- Pharynx
- Oesophagus
- Stomach
- Small intestine
- Pancreas
- Liver
- Large intestine
What is the tempomandibular joint
Connection between condylar process of mandible and mandibular fossa of temporal bone.
-Does flexion, extension and translation
What are the functions of the tongue
-Aids mechanical food digestion
-Helps form food bolus
-Involved in thermoregulation
-Has taste receptors
Where is the tooth crown
it projects over gingiva and is covered in enamel
What is the root tip
the apex where blood vessels and nerves enter the tooth
What is the pulp cavity
The blood and nerve supply
Brachydont teeth
-Small crowns
-Developed roots
-Stops growing
-is in dogs, cats, humans, etc
Hypsodont teeth
-Deep crowns
-Short roots
-Continuously grows
-is in rabbits, rodents, horses, etc.
two types of hypsodont teeth
Radicular: root apices are open for ages but close eventually
Aradicular: No true root so grow forever
Types and functions of teeth
-INCISOR: in incisive bone and maxilla (used for fine nibbling)
-CANINE: one on each corner of maxilla and mandible (for holding prey)
-PREMOLAR: flat cheek teeth (for shearing flesh)
-MOLAR: bigger cheek teeth (for shearing/grinding flesh)
-CARNASSIALS: first lower molar and last upper (only in carnivores)
What are the functions of saliva
-Lubricates
-Thermoregulates
-pH regulates
-Anti bacterial
What are the 3 salivary glands
-Parotid: goes into mouth opposite 4th premolar
-Mandibular: runs along mouth floor and produces mucoid saliva.
-Sublingual: found under tongue and produces mixed saliva.
what is the dog dental formula
I3/3 C1/1 P4/4 M2/3
what is the cat dental formula
I3/3 C1/1 P3/2 M1/1
what is the horse dental formula
I3/3 C1/1 P3-4/3 M3/3
what is the cow dental formula
I0/3 C0/3 P3/3 M3/3
what is the puppy dental formula
i3/3 c1/1 p3/3
Function of the pharynx
-Part of GI and Resp tract
-Tonsils in pharynx protect animal from disease
What is the passage of food through the oral cavity and pharynx
- Food in mouth is broken down by mastication
- Mixes with saliva which softens and lubricates
- In omni/herbivores, carb digestion starts
- Food goes from oral cavity to stomach in three stages
3 stages from oral cav. to stomach
- Voluntary: tongue moves bolus to pharynx
- Pharyngeal: bolus causes all openings to close (except oesophagus)
- Oesophageal: peristalsis begins
What is the function of the oesophagus
-Connects pharynx to stomach
What is peristalsis
a pattern of muscle contractions that propel food through GI tract
What is connecting peritoneum
connects organs to each other of to parietal peritoneum
-mesentary suspends organs from abdominal wall
-omentum connects stomach to wall and other organs
Functions of the stomach
-Stores ingested food
-Breaks down food
-Controls release of food into SI (pyloric sphincter)
-Produces HCL to kill bacteria
Parts of the Monogastric stomach
- Cardia: where oesphagus enters stomach
- Fundus: Dome shaped
- Body: Mixing chamber that links fundus with pylorus
- Pylorus: Opens into duodenum through pyloric sphincter.
- Rugae: folds that allow stomach to expand and increase surface area for absorption
What cells are in the stomach
-Parietal cells: produce HCL
-Mucous neck cells
-Chief cells: produce pepsinogen
What are the gastric function phases
(CGI)
1. Cephalic phase: brain perceives sight/smell of food and informs stomach to prep.
2. Gastric phase: food enters stomach
3. Intestinal phase: food is liquified in stomach and enters SI.
Movements/Contractions in the stomach
- Mixing wave starts in stomach body and goes to pyloric sphincter
- Fluid of chyme goes to pyloric sphincter and solid part is squeezed back towards body.
- Stronger peristaltic waves move in same direction as mixing waves.
- Step 2 repeats.
- Peristaltic contractions push fluid chyme into duodenum and the rest of chyme goes back to the stomach body
Types of Chemical digestion in the stomach
- Luminal digestion: bonds are broken by insertion of water molecules
- Membranous digestion: molecules are broken down into their most basic components
where does protein digestion begin
It begins in the stomach as pepsinogen is converted to pepsin by HCL
