Digestive System Flashcards

Flashcards about the digestive system, covering anatomy, function, and variations between species.

Functions of the Muscular System

Movement, posture, support/protection, thermoregulation.

Muscle Tissue Types

Cardiac, smooth, skeletal.

Muscle Structure

Origin, insertion, belly.

Sliding Filament Theory

Myosin and actin, requires ATP, Ca and innervation.

Types of Digestion

Carnivore, herbivore, omnivore.

Digestive System Types

Monogastric (cat, dog, human), Ruminant (cow, sheep), Hind gut fermenter (rabbit, guinea pig, horse).

Physical (mechanical) Digestion

Chewing & grinding (teeth), churning food (stomach).

Chemical Digestion

Enzymes, acids.

Elimination

Removal of wastes, bacteria, and other undigestible substances.

Storage

Glycogen, iron (liver).

Sense of Taste

Receptors (tongue).

Ingestion

Food into body (mouth).

Digestion

Food broken down into small units (mouth, stomach, small intestine); mechanical and chemical methods.

Absorption

Passes from GI to blood, goes to liver (small intestine).

Metabolism

Converted to energy (liver).

Excretion

Indigestible material removed.

The Digestive System

Oral cavity, pharynx, oesophagus, stomach, small intestine, large intestine, accessory glands.

Small Intestine

Duodenum, jejunum, ilium.

Large Intestine

Caecum, colon, rectum, anus.

Accessory Glands

Salivary glands, liver, gall bladder, pancreas.

Monogastric

Mono = one, gastric = stomach.

Hind-gut Fermenter

Enlarged caecum.

Ruminant

4-chambered stomach; modified = 3 chambered (camelids).

Oral Cavity Contents

Hard palate, soft palate, teeth, tongue, pharynx, tonsils, epiglottis, oesophagus.

Prehension

Pick up food.

Mastication

Break down food by chewing.

Lubrication

Mucus and saliva.

Digestion in Oral Cavity

Mechanical (teeth) and chemical (amylase).

Deglutination

Swallowing food.

Incisors

Bite, gnaw.

Canines

Pierce tissue, hold, stab and kill prey (carnivores).

Premolars and Molars

Grind and crunch.

Carnassial Tooth

Special large tooth for shearing flesh and bone.

Brachydont

Short crown.

Hypsodont

Long crown.

Tongue

Attached to hyoid bones and mandible.

Functions of Saliva

Moisten food for tasting, lubricate food for swallowing (bolus), begin starch digestion (amylase), kill bacteria.

Peristalsis

Peristalsis - waves of muscular contraction that move food bolus along oesophagus to stomach (vagus nerve control).

Four Layers of the Oesophagus

Outer connective tissue layer – serosa, muscle layer (inner circular and outer longitudinal layers), submucosa, mucosa (stratified squamous epithelium).

Four Parts of the Monogastric Stomach

Cardia (entry from oesophagus), fundus (top), body (biggest part), pylorus (exit to duodenum).

Smooth Muscle Layers of Stomach

Longitudinal, circular, oblique.

Mucus Secretion in Stomach

From goblet cells in cardia and pylorus.

Pepsinogen

Converted to pepsin, digests proteins.

Hydrochloric Acid (HCl)

Inactivate microorganisms.

Gastrin Hormone

Secreted by stomach into bloodstream to stimulate HCl production.

Digestion in Stomach

Contraction of muscle layers; gastric acid (HCl, lipase and pepsin).

4 Chambers of Ruminant Stomach

Rumen, reticulum, omasum, abomasum.

Function of Ruminant Stomach Microbes

Microbes/bacteria to ferment/break down food and produce volatile fatty acids (energy source).

Hind Gut Fermenter Characteristics

Smaller tract with enlarged caecum; symbiotic bacteria in caecum ferment cellulose; microorganisms synthesise Vit B and K.

Caecotrophs

Soft faeces that are ingested (usually at night).

Crop

Pouch of oesophagus.

Proventriculus

True stomach, HCl and enzymes.

Gizzard (Ventriculus)

Grinding food, muscular, may contain small stones/grit.

Duodenum

Enzymes from pancreatic duct and bile from bile duct with villi to increase surface area.

Jejunum

Very long and coiled.

Ilium

Mucosa lacks villi.

Caecum

Blind ending sac, size depends on species.

Colon

Ascending, transverse and descending colon in dog & cat; water resorption, passage of wastes.

Rectum

Dorsal to reproductive and urinary tract; storage of faeces until defaecation.

Anal Sphincter

Controls faecal movement from rectum.

Internal Anal Sphincter

Involuntary (smooth muscle).

External Anal Sphincter

Voluntary control in some species (skeletal muscle).

Anal Sacs

Pair of glands just inside anus with glandular epithelium lining that secretes fluid for scent marking.

Microbial Digestion in Large Intestine

Breakdown of fibre, produce essential amino acids, produce B vitamins, resorb water and electrolytes.

Salivary Glands

Parotid, zygomatic (carnivores only), mandibular, sublingual (under tongue).

Saliva Initiation

Contact with mouth, the odour, or even the thought of food.

Functions of the Liver

Metabolise carbohydrates, protein and fat (from GI tract); produce bile; neutralize and destroy drugs and toxins; produce, destroy and regulate hormones; make enzymes and proteins (e.g., albumin); remove old red blood cells from circulation; store iron and vitamins A, D, E & K; generate heat.

Gall Bladder

Stores bile until required for digestion.

Digestive Function of Pancreas

Produces bicarbonate to neutralise HCl; produces digestive enzymes (trypsin, lipase, amylase).

Endocrine Function of Pancreas

Produces insulin and glucagon.

Pepsin and Trypsin Function

Proteins broken down to amino acids.

Fats Breakdown

Fats emulsified in stomach, broken down in SI by lipase. Bile acids emulsify fats for digestion.

Carbohydrates Breakdown

Broken down to simple sugars by enzymes – amylase.

Absorption

Nutrients enter blood stream; fats enter lymphatic ducts, then blood stream.

Blood Vessel Transporting Nutrients from GI Tract to Liver

Hepatic portal vein (hepatic portal system).

Excretion/Elimination

Solid waste (undigested food) exits body from rectum via anal sphincter as faeces due to relaxation of sphincter and contraction of abdominal muscles.

Proteins Breakdown

Break down to amino acids.

Lipids Breakdown

Break down to fatty acids.

Carbohydrates Breakdown

Break down to simple sugars.