Digestive System 1 Flashcards
What does the digestive system do
Functions to break down food into consumable parts and extract valuable nutrients and water
Creation and removal of waste products
What does the creation and removal of waste products allow
1) to make nutrients available
2) to allow mass processing of low nutrient value food
3) to deal with potentially toxic compounds
Name the Basic human structures
Oral cavity-> pharynx-> oesophagus-> stomach-> duodenum-> jejunum -> ileum-> caecum-> ascending colon -> transverse colon -> descending colon-> rectum -> anal canal
What is the roof of the buccal cavity called
Palate
What does the palate separate
Oral and nasal cavities
What is the primary palate called
In most fishes is a Low vault with no openings. Basic design where nasal passage opens into bucal cavity (salamanders)
What is the Choanae
Opening into nasal cavity (tetrapods)
What is the second palate
Palatal folds form a second horizontal shelf that separates the nose and mouth
What are palate folds
Creates secondary palate
What does the soft palate often do
It hangs from the bony hard palate and pushes the internal nares (opening to the nasal cavity) further back in the buccal cavity
Hat is the function of the tongue in humans
To move food around mouth and push food to the back of the mouth for swalllowing
Describe the tongue in snakes and nectar feeding bats
Flexible and mobile
Describe the tongue in jawed fish, turtles, crocs and some birds
Immobile
What are the modifications of a frog tongue
Allow tongue to protrude quickly and be drawn back, glands to create sticky fluid
What is the function of the buccal cavity
Create secretions and release into buccal cavity
What does labial mean
Near the lips
What does palatal mean
Near the palate
Where is the pharynx seen
In all tetrapods
What is the pharynx subdivided into
Nasopharynx (air passage)
Oropharynx (food)
What is the eustacian tube
Opening to the oesophagus, opening to larynx
What is the eustacian tube covered by
The epiglottis
Describe the stages of swallowing
Bolus of food pushed from the buccal cavity to the oesophagus then to the stomach
How do snakes continue breathing whilst swallowing their food
The snakes trachea slips down and forwards beneath prey
What is the oesophagus
A muscular tube connecting pharynx to stomach
Some species have __________ epithelium, others _______ to allow ingestion of abrasive ______
Stratified, keratinised, food
What is the oesophagus site of
Large amounts of food if swallowed at one time
What is the difference with a birds oesophagus
It posses a crop
What is a crop
Outgrowth of oesophagus used to store food prior to digestion or regurgitation
In pigeons what does the crop do
It secretes a nutritional fluid to feed hatchlings for several days - pigeon milk
What is the stomach
Muscular sac to receive, churn food and process it using gastric juices
Some carnivores use the stomach for what
When intake is irregular and large quantities of food are eaten
What is secreted from the stomach to prevent food decay by bacteria whilst food was stored prior to digestion
Acid secretion
What are examples or gastric juices
HCL plus some enzyme and mucus
What are the inner folds called in the stomach
Rugae
Mucosal histology splits the stomach into what
Glandular and non-glandular epithelium
What is the cardiac gland within stomach
Only found in mammals and marks the transition for oesophagus to stomach (mostly mucus secreting)
What is the funds/gastric glands
Mucus cells, parietal cells (HCL) and chief cells (proteolytic enzymes)
What is the pyloric gland
Contains pyloric glands that create mucous that helps to neutralise acidic chyme prior to release into the intestine
In rodents the loss of gastric glands leads to what
Smooth muscle stomach that uses contractions to churn and mix food
Rodent epithelial may also be what to resist mechanical abrasion from insect exoskeletons, grasses and seeds
Keratinised
What animals contain a gizzard
Crocs and alligators
What is a gizzard
A region of the stomach with very thick muscular walls
What does the gizzard do
Grinds food against ingested stones
What lies before the gizzard
Glandular part
What breaks down the food in the gizzard
Gastric juices from the glandular part and the mechanical grinding in the gizzard
What two things do birds posses in the stomach
Crop and gizzard
In birds where does the oesophagus join
To the proventriculus
What does the proventriculus do in birds
Secretes gastric fluid to digest the food bolus
In ruminants and camels how many chambers are there in the stomach
4
What are the 4 chambers of the stomach in camels and ruminants
Rumen
Reticulum
Omasum
Abomasum
What is the rumen
Large and serves to receive the food from the oesophagus
What follows the rumen
The reticulum
Both the rumen and reticulum are lined with what
Oesophageal epithelium
What is the omasum
The third chamber
What is the omasum lined with
Oesophageal epithelium but folded into overlapping leaves
What is the abomasum
The final chamber
What does the abomasum contain tht the other chambers don’t
Possesses a cardia, fundus and pylorus
What does the liver do
Detoxification of blood and production of bile
What animals is the gall bladder present
Bony fish, amphibians, reptiles, some birds and most mammals
What type of functions does the pancreas have
Endocrine and exocrine
