Digestive System Flashcards
What is physical digestion?
Using teeth and muscle action to break down food into smaller pieces to increase its surface area for absorption
What is chemical digestion?
Breaking down large, insoluble molecules into smaller, soluble molecules using hydrolysis by enzymes
What are the 2 main functions of the digestive system?
- To break down food into nutrients needed for metabolic processes
- Remove waste products
What are the 5 main constituents/ nutrients of food?
- Carbohydrates
- Protein
- Fats
- Vitamins and Minerals
- Dairy
What are the 2 parts of the digestive system?
- Alimentary Canal (GI Tract)
2. Accessory Organs
What are the 6 parts of the alimentary canal?
- Mouth
- Pharynx
- Oesophagus
- Stomach
- Small Intestine
- Large Intestine
What are the 5 accessory organs?
- Teeth
- Salivary Glands
- Pancreas
- Liver
- Gall Bladder
What is another name for the mouth and what is it lined with?
Oral cavity, lined with a mucous membrane
What forms the lateral walls of the oral cavity?
Cheeks
What forms the anterior and posterior roof of the oral cavity?
Anterior = hard palate Posterior = soft palate
What is the uvula?
A fleshy finger-like projection of the soft palate which extends downwards
What is the vestibule?
The space between the lips and cheeks externally and the teeth and gums internally
Describe the tongue
Muscular and has several bony attachments such as the hyoid bone and styloid processes of the skull
What is the lingual frenulum?
A fold of mucous membrane which secures the tongue to the floor of the mouth
What is the name of the situation in which the lingual frenulum is very short?
Tongue-tie
What are the 3 types of salivary gland?
- Parotid gland
- Sublingual gland
- Submandibular gland
What are tonsils?
Collections of lymphatic tissue located at the posterior end of the oral cavity
What are the 4 main types of tonsils?
- Palatine
- Pharyngeal
- Lingual
- Tubal
What is tonsillitis?
An illness in which the pharyngeal tonsil becomes inflamed and swollen and obstructs the nasopharynx, forcing the person to breathe through their mouth and making swallowing difficult and painful
What are the 3 sections of the pharynx?
- Nasopharynx
- Oropharynx
- Laryngopharynx (continuous with the oesophagus)
Where is the oesophagus located?
Runs from the mouth to the stomach passing through the diaphragm
What are the 4 layers of the oesophagus wall?
- Mucosa (inner)
- Submucosa
- Muscularis Externa
- Serosa (outer)
What are the 2 nerve plexuses in the alimentary canal and what is their function?
- Submucosal nerve plexus
- Myenteric nerve plexus
To regulate mobility and secretory activity
Where is the stomach located?
On the left side of the abdominal cavity, hidden mostly by the liver and diaphragm
What is the small intestine and where is it located?
- The major digestive organ
- Muscular tube extending from the pyloric sphincter to the large intestine
- The longest section of the alimentary tube
What is the average length of the small intestine?
2.5 - 7m
What are the 3 subdivisions of the small intestine and what percentage do they account for?
- Duodenum (5%)
- Jejunum (<40%)
- Ileum (<60%)
What is significant about the walls of the small intestine?
They have microvilli in the absorptive cells that increase surface area and the plasma membrane bears enzymes that complete the digestion of proteins and carbohydrates
What 3 accessory organs are associated with the small intestine?
- Pancreas
- Liver
- Gall Bladder
What is the pancreas and what is its function?
- A triangular gland that extends across the abdomen to the spleen and duodenum
- Produces enzymes that break down digestible foods by secreting them into the duodenum
What is the liver and what is its function?
- Largest gland in the body
- Located under the diaphragm on the right side of the body
- Has 4 lobes
- Produces bile, a yellow-to-green watery fluid that leaves the liver via the common hepatic duct
What is the gall bladder and what is its function?
- Thin-walled, green organ
- Stores bile when food digestion is not occurring
What is mastication?
Chewing
Outline the 5 steps of ingestion
- Food is placed in mouth, triggering large amounts of saliva to be produced
- Tongue mixes the food and saliva
- Mastication occurs, breaking down food into smaller pieces
- A bolus is created ready for swallowing
- Salivary amylase begins chemical digestion of starch to maltose
What is propulsion and what are the 2 phases?
- Swallowing and peristalsis
- 1st phase = buccal phase = voluntary
- 2nd phase = pharyngeal-oesophageal phase = involuntary
What is the name for the process of swallowing?
Deglutition