Physiology - grand tour of alimentary canal Flashcards
4 functions of the digestive system
Digestion
Secretion
Absorption
Motility
Oesophagus function
Connects mouth and stomach
Stomach function (4)
Digest proteins;
Food reduced to liquid form;
storage;
sterilisation
Pancreas function
Contains digestive enzymes for digestion of fats, carbohydrates and proteins
Liver function
Contains bile salts for digesting/absorbing fats in small intestine
Gallbladder function
Stores and concentrates bile
Small intestine function
Final stages of chemical digestion and nutrient absorption
Large intestine function
Water absorption, bacterial fermentation and formation of faeces
Alimentary canal is a continuous … tube of varying …
Hollow tube of varying diameter
Oesophagus to rectum length
8m
4 distinctive layers of the alimentary tube wall (inside to outside)
Mucosa
Submucosa
Muscularis externa
Serosa/adventitia
3 layers that make up the mucosa
Epithelium
Lamina propria
Muscularis mucosae
What kind of epithelium does the mouth, oesophagus and anal canal have
Stratified squamous
What kind of epithelium does the stomach, small and large intestine have
Simple columnar
Functions of the epithelium (of mucosa)
Synthesises and secretes digestive enzymes, hormones, mucus
Absorbs products of digestion
Epithelium changes along alimentary canal because…
It’s adapting for function
Lamina propria made up of…
Loose connective tissue (glands, blood/lymph vessels)
Muscularis mucosae made up of…
Thin smooth muscle layer
Submucosa made of what kind of tissue
Thick, irregular connective tissue
What does the submucosa contain
Neurones, blood vessels, lymphatic vessels
Where in the alimentary tube are submucosal glands found
Oesophagus and duodenum
What is the serosa/adventitia
Connective tissue layer of alimentary canal
How is the serosa/adventitia (outer layer) differentiated
Serosa is inside peritoneal cavity
Adventitia is outside peritoneal cavity
Adventitia function (outside peritoneal cavity)
Adventitia attaches oesophagus and rectum to surrounding structures
Serosa function (inside peritoneal cavity)
Serosa surrounds stomach, small intestine and large intestine
What is the muscularis externa
Two concentric thick layers of smooth muscle
What type of muscle makes the inner layer of muscularis externa and what is its function to the lumen
Circular muscle (to constrict lumen)
What type of muscle makes the outer layer of muscularis externa and what is its function to the tube
Longitudinal muscle (shortens tube)
Muscularis externa produces motility which helps with
Peristalsis
Segmentation
What plexus is located between the circular and longitudinal muscle
Myenteric (Auerbach’s)
Submucosal + myenteric plexuses=
Enteric nervous sytem (ENS)
Autonomic control of alimentary function
Long (parasympathetic) and short (enteric nervous system) reflexes
Parasympathetic control of alimentary function is via what nerve + what exception
Vagus nerve (X) Except salivation which is controlled via facial (VII) and glossopharyngeal (IX)) nerves
Effect of parasympathetic nervous system on secretion and motility
Stimulatory so increases secretion + motility
Effect of sympathetic nervous system on secretion and motility + what exception
Inhibitory so decreases secretion + motility Except salivation (doesn't inhibit salivation)
Sympathetic control of alimentary function is via what kind of nerves
Splanchnic nerves (nerves that innervate organs, they arise from thoracic, lumbar or sacral parts of spinal cord) -carry visceral efferent fibres to the organs
Arterial supply to the stomach, small intestine, pancreas and liver is via … which originates from the …
Celiac trunk from descending abdominal aorta
Arterial supply to the stomach, small intestine, caecum ascending colon and transverse colon is via … which originates from the …
Superior mesenteric artery from descending abdominal aorta
Arterial supply to the descending colon, sigmoid colon and rectum is via … which originates from the …
Inferior mesenteric artery from descending abdominal aorta
Celiac trunk supplies what part of gut + what other abdo organs (4)
Abdominal part of oesophagus to proximal half duodenum
Liver, spleen, liver, gallbladder, pancreas
Superior mesenteric artery supplies…
distal half duodenum to proximal 2/3 transverse colon
Inferior mesenteric artery supplies…
distal 1/3 transverse colon to rectum
Blood from stomach drains into what veins…
Gastric veins
Blood from pancreas drains into what vein…
Splenic vein
Blood from Small intestine, Caecum, Ascending colon, Transverse colon drains into what vein…
Superior mesenteric vein
Blood from Descending colon, Sigmoid colon and Rectum drains into what vein…
Inferior mesenteric vein
All of these veins (gastric, splenic, superior mesenteric and inferior mesenteric) drain into what vein…
Hepatic portal vein
Hepatic portal vein drains into what vein…
Hepatic vein
Hepatic vein drains into what vein…
IVC
