Gastrointestinal tract Flashcards
What is digestion?
Process of braking down macromolecules to allow absorption
What is absorption?
Process of moving nutrients and water across a membrane
What structures are located within the foregut?
Oesophagus stomach Liver Pancreas Biliary system
What structures are located in the midgut?
Intestine
What structure is located in the hind gut?
Colon and rectum
What are the four layers of the gut wall?
Mucosa
Submucosa
Muscularis
Serosa/adventitia
Which connective tissue layer is associated and in contact with the ingested food?
Lamina propria
What type of epithelial cells are located within the mouth, pharynx, oesophagus and the anal canal?
Non keratinised, stratified squamous epithelium.
Epithelial is in direct contact with the lumen (space inside the alimentary canal)
Which type of cells are intersected among the epithelial cells?
Goblet cells
What is the function of goblet cells?
Secretion of mucous and fluid into the lumen
which types of cells secrete hormones into the interstitial space between cells?
Enteroendocrine cells
Which types of cells are located within the stomach and intestine?
Simple columnar epithelial
What is located within the lamina propria?
Contains numerous blood and lymphatic vessels that transport nutrients absorbed through the alimentary canal. Serves an immune function by hosting lymphocytes
What is the term used to describe mucosa-associated lymphoid tissue?
Peyer’s patches.
What is contained within the submucosa?
Contains nerve plexus
Blood and lymphatic vessels
Submucosal glands
What two types of muscles reside within the muscularis?
Inner circular layer
Outer longitudinal layer
Contractions promote mechanical digestion and movement of substrate along canal
Constriction of bowel, food passed segmentally, enabling tie for absorption
What is the main role performed by the serosa (adventitia)?
Protective layer
What term is used to describe the enetnrace to the mouth?
Labia
Which muscle regulates the entry of substrate into the oral cavity?
Orbicularis oris muscle
What is the midline fold of mucous membrane that attaches the inner surface of each lip to the gum?
Labial frenulum
Which muscles of mastication is located between the skin and mucous membrane?
Buccinator muscle
Which muscle of mastication elevates and protrudes mandible?
Masseter muscle
What are the 3 main salivary glands?
Submandibular gland
Sublingual gland
Parotid gland
Which gland resides within the floor of the mouth?
Submandibular gland
How is saliva secreted by the submandibular gland?
Through submandibular ducts
Where are sublingual glands located?
Lie inferior to the tongue, use the lesser sublingual ducts to secrete saliva into the oral cavity
Where is the parotid gland located?
Reside between the skin and the master muscle, proximal to the ears
How does the parotid gland secrete saliva?
Secrete saliva into the mouth through the parotid duct
Where is the parotid duct located?
Second upper molar tooth
What comprises the saliva?
Water, mixture of ions, glycoproteins, enzymes and growth factors,
+ waste products
Which enzymes breaks down carbohydrates?
Salivary amylase
How is salivary amylase inactivated?
By stomach acids
Which two ions behave as chemical buffers that maintains saliva at pH 6.35/8,5?
Bicarbonate and phosphate ions
What function is performed by mucous?
Lubricates food facilitating movement in the mouth, bolus formation and swallowing
Which enzyme catalyses fat digestion?
Lingual lipase
What are the primary functions of the tongue?
Facilitates ingestion, mechanical digestion, chemical digestion (lingual lipase), sensation (taste, texture and temperature of food)
Swalloing and vocalisation
Where is the tongue attached to?
The mandible, the styloid processes of the temporal bones and hyoid bone
Tongue is positioned over the floor of the oral cavity
Medial septum extends the entire length of the tongue dividing it into symmetric halves
What are the intrinsic muscles within the tongue?
Longtudinalis inferior
Superior
Transversus linguae
Verticalis linguae
What is the function of the intrinsic tongue muscles?
Fine motor control and moving food
What is the function of extrinsic muscles?
Gross movement of tongue, assets mechanical digestion
How many teeth do humans have?
32
How many incisors?
8
How many canines?
4
How many premolars?
8
How many molars?
12
What structure connects the pharynx to the stomach?
Oesophagus
Where is the oesophagus located?
Posterior to the trachea
How does the oesophagus enter the abdomen?
Traverses through the mediastinum in order to enter, the oesophagus penetrates the diaphragm from the oesophageal hiatus
Which anatomical structure is located at the penetration of the oesophagus at the diaphragm?
Oesophageal hiatus
Where does the oesophagus begin and end?
C5-T10
What is the function of the oesophagus?
Conduit for food, drink and swallowed secretions from pharynx to stomach
What is the function of the upper oesophageal sphincter?
Controls the movement of food from the pharynx into the oesophagus
Upper 2/3 consists of both smooth and skeletal muscle fibres, with the latter transitioning out into the bottom 1/3 oesophagus
How is the bolus of food propelled towards the stomach?
Rhythmic waves of peristalsis
How is the oesophagus lubricated?
Oesophageal mucosa
What is the function of the lower oesophageal sphincter?
Relaxes to enable food to pass into the stomach, contracts to prevent stomach acids from backing up into the oesophagus.
What surrounds the LOS?
Muscular diaphragm, seals sphincter during periods of no swallowing
What is GERD?
Gastroesophageal reflux disease
Lower oesophageal sphincter does not completely close
What types of cells form the mucosa of the oesophagus?
Non-keratinised stratified squamous epithelium
Where are the mucous secreting glands located?
Mucosa lamina propria
How does the muscularis layer change along the oesophagus?
Skeletal muscle –> skeletal & smooth muscle –> smooth muscle