Gastrointestinal System Flashcards
What are the 3 main components of the digestive system?
- digestive tracts
- accessory organs
- cell lining and tissue components
What are the functions of the GIT?
- ingestion
- mechanical digestion and processing
- chemical digestions
- secretion (e.g. enzymes, acids, salts) by glandular organs
- absorption of vitamins, nutrients, water and minerals
- defecation (waste elimination through the anus)
- defence
What are the 7 components of the oral cavity?
- lips
- front 2/3 of tongue
- floor of the mouth
- buccal mucosa
- upper and lower gingiva
- retromolar trigone
- hard palate
What is the hard and soft palate respectively?
- hard = front part of roof of mouth
- soft = back part
What are functions of the oral cavity?
- mastication and lubrication to produce a bolus
- gustation (taste)
- limited chemical digestion of glucose and lipdis
What are functions of the uvula?
- secrete saliva to moisten the mouth and throat
- prevents food and liquid from going up the nose (along with soft palate)
What are functions of the tongue?
- mechanical digestion
- manipulation of food
- sensory taste and temperature
- lubrication via mucin, water and lingual lipase
What are teeth required for?
tearing and grasping food (mastication)
What do the major salivary glands do?
work together to keep the mouth moist and help with digestion
What are the 3 major salivary glands?
- parotid glands
- submandibular glands
- sublingual glands
Where are the parotid glands and what do they produce?
near the back of the jaw just in front of the ears and produce serous secretion to help with chewing and swallowing
Where are the submandibular glands and what do they produce?
under the jaw and produce a mix of mucus and saliva
Where are the sublingual glands and what do they produce?
under the tongue and produce saliva that is mostly mucus
What do minor salivary glands secrete?
mucous
What is the difference between serous and mucous cells?
- serous cells have spherical and vesicular nuclei and secrete a more watery substance
- mucous cells cytoplasm and nuclei are pushed against the basal cell membrane and secrete mucin
What are functions of saliva?
- lubricate and moisten the bolus
- dissolve chemicals for gustation
- act as a buffer
- control oral bacteria population via antibodies and lysozymes
- salivary reflex
What is the pharynx (throat)?
the muscle-lined space that connects the nose and mouth to the larynx and oesophagus
What is the larynx?
the upper opening into the trachea (windpipe)
What are the 4 phases of swallowing?
- buccal phase - voluntary phase where the tongue pushes the bolus to the back of the mouth towards the pharynx
- pharyngeal phase - involuntary phase begins when the bolus reaches the back of the throat which triggers a reflex that closes off the airway and moves the bolus down through the pharynx to the oesophagus
- oesophageal phase – involuntary phase where the bolus is pushed down the oesophagus towards the stomach by peristalsis
- bolus enters the stomach by triggering the opening of the lower oesophageal sphincter
What is mucosa?
the moist, inner linings of organs and body cavities
What are the 3 layers of mucosa?
- mucosal epithelium
- lamina propria
- muscularis mucosae (deepest and most active)
What parts of the digestive system have stratified squamous epithelium?
- oral cavity
- pharynx
- oesophagus
- anal canal
What parts of the digestive system have simple columnar epithelium?
- stomach
- small intestine
- large intestine
What is the muscularis mucosae made up of?
smooth muscle and elastic fibres that regulate contraction of the lumen