Grand Tour of The Alimentary Systems Flashcards
What are the functions of the digestive system?
- Digestion
- Secretion
- Absorption
- Motility
What are the three salivary glands?
Parotid
Sublingual
Submandibular
What happens in the stomach?
Digestion of proteins, foodstuffs reduced to liquid form, sterilisation
What are the digestive enzymes in the pancreas used for?
Digestion of fats, proteins and carbohydrates
What is the function of the liver?
Bile salts for digestion/absorption of fats in small intestine
What is the function of the gallbladder?Stores and concentrates bile
Stores and concentrates bile
What is the function of the small intestine?
Final stages of chemical digestion and nutrient absorption
What is the function of the large intestine?
Water absorption, bacterial fermentation and formation of faeces
What are the different layers of the alimentary canal?
Mucosa
Submucosa
Muscularis externa
Serosa/adventita
What is the mucosa composed of?
Epithelium
Lamina propria
Muscularis mucosae (no significant function)
What is the function of the muscularis externa?
Where all the motility comes from
When is the serosa called the adventita?
The shiny connective tissue sheath is known as the serosa below the diaphrafm, but above it is known as the adventitia
What is the inner layer of the musculris externa?
Inner layer is the circular muscle layer
Outside that is the longitudinal muscle layer
Where in the digestive tract can you find stratified squamous epithelium?
Mouth, oesophagus, anal canal (entry and exit)
Where can you find simple columnar epithelium?
Stomach, small & large intestine
What is the function of the epithelium in the digestive tract?
- Barrier separating lumen of alimentary canal from body
- Synthesis and secretion of digestive enzymes, hormones, mucus
- Absorbs products of digestion
What is the lamina propria?
•Loose connective tissue (glands, blood/lymph vessels)
What is the muscularis mucosae?
Thin smooth muscle layer
What type of the tissue is the submucosa?
Thick irregular connective tissue
What is the function of the submucosa?
Supports the mucosa
What is contained within the submucosa?
Blood vessels, neurones, lymphatic vessels.
The neurones form an extensive network, submucosal plexus (Meissner’s) (parasympathetic)
What is the function of the submucosal glands in the oesophagus and the duodenum?
Oesophagus - mucus secretion
Duodenum - bicarbonate secretion to neutralise stomach acid
What are the function of the lymphatic vessels in the submucosa?
Take away the products of fat digestion
What is the serosa / adventita described as?
A connective tissue sheath surrounding the alimentary canal.
Adventita attaches the oesophagus and rectum to surrounding structures
Serosa surrounds the stomach, small intestine and the large intestine
What comprises the enteric nervous system?
The submucosal plexuses and the myenteric plexuses
Where can you find myenteric plexus’?
•Myenteric (Auerbach’s) plexus between circular and longitudinal muscle
Which parasympathetic nerves are responsible for alimentary nervous control?
Vagus nerve (cranial nerve 10) apart from salivation which is controlled by facial (VII) and glossopharyngeal (IX)
What is the effect of the parasympathetic nervous system on the alimentary function?
Stimulatory - an increase in secretion and motility
Which sympathetic nerves are responsible for alimentary nervous control?
Splanchnic nerve
What is the effect of the sympathetic nervous system on the alimentary function?
Inhibatory (except salivation)
There is a decrease in ecretion and motility
What do the following arteries supply?
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How does blood from the stomach reach the inferior vena cava?
Gastric veins - Hepatic portal vein - Hepatic vein - Inferior Vena Cava
How does blood from the pancreas reach the inferior vena cava?
Splenic vein - Hepatic portal vein - Hepatic vein - Inferior Vena Cava
How does blood from the small intestine, caecum, ascending colon and the transverse colon reach the inferior vena cava?
Superior mesenteric vein - hepatic portal vein - hepatic vein - IVC
How does blood from the descending colon, sigmoid colon and the rectum reach the IVC?
Inferior mesenteric vein - Hepatic portal vein - hepatic vein - IVC
Which organs send blood to the liver?
The heart for oxygen supply - hepatic artery
Those which supply the hepatic portal vein (digestive tract arteries) - these include the stomach, intestines, pancreas and spleen
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