Digestive Flashcards
(42 cards)
What are the functions of the digestive system
Ingestion
Mechanical processing
Digestion
Secretion, fluid, enzymes
Absorption
Excretion
What are the major divisions of the digestive tract
Mouth, mechanical, salivary
Pharynx
Oesophagus
Stomach, chem breakdown, mechanical
Small and large intestine, enzymes and absorption
What are the accessory organs of the digestive system
Salivary glands
Liver, secretes bile
Gall bladder, bile stored
Pancreas, secrete buffers and enzymes
What is the peritoneum
Has a serous membrane
- visceral layer covers organs
- parietal layer lines cavities
Peritoneal fluid
- 7 L per day produced, provides lubrication to allow sliding
What are the mesenteries
Suspend portions of the digestive tract
Allow passage of blood vessels, nerves and lymphatic vessels
What are the functions of the digestive tract
Protect against
Digestive acids and enzymes
Mechanical stresses
Bacteria
What are the layers of the digestive tract
Mucosa - inner
Submucosa
Muscularis externa
Serosa
What are the folds in the digestive tract
Plica circulares
Allow expansion and increase SA
Explain the mucosa
Mucosal epithelium
(Replaced rapidly)
- stratified squamous in oral cavity, pharynx and oesophagus
- simple columnar with mucus cells everywhere else
Lamina propria
- areola with blood, lymphatic vessels and nerve endings
Muscularis mucosae
- inner circular layer
- outer longitudinal layer
Explain the submucosa
Layer of dense irregular connective tissue
Has large blood vessels and lymphatic vessels
May contain exocrine glands
Submucosal plexus- neural network, inner area mucosa and submucosa
Explain the Muscularis externa
Smooth muscle cells
- inner circular layer
- outer longitudinal layer
Movement connected by enteric nervous systems
- sensory neurons, interneurons, motor neurons
- mainly controlled by parasympathetic
Explain the serosa
Serous membrane covering Muscularis externa, replaced by adventia (dense collagen) in upper system and rectum to stop sliding
Explain movement of digestive materials
Rhythmic cycles of smooth activity controlled by pacesetter cells
Peristalsis - waves of muscular contraction
Segmentation- cycle of contraction, mix content
Explain the role of the oral cavity
Functions
Sensory analysis
Mechanical
Lubrication
Limited digestion, salivary enzymes, carbohydrate. Lipids
Opens to nasopharynx
Explain the salivary glands
1-1.5 L per day
Water, electrolytes, buffers, mucins, antibodies
- lubricants
- dissolving chemicals
- initial digestion
Explain the process of swallowing
Buccal phase, push to back of mouth by tongue
Pharyngeal phase, epiglottis pushed back, close trachea
Oesophagus
Stomach
Explain the oesophagus
- resting muscle tone at top prevents air going in stomach
- adventitia anchors to surrounding structures
Mucosa has thick stratified squamous epithelium for protection
Explain the functions of the stomach
- store
- mechanical
- chemical breakdown:
Pepsin - protein
Salivary amylase and lipase
Acid reduces to ph2
Production of intrinsic factor
- absorption of vit b12
Explain the structure of the stomach
Fungus - top
Body pylorus
Pyloric sphincter - ring of muscle closing off exit
Muscular layers
Oblique muscular - overlying mucosa
Circula layer
Longitudinal muscle layer
Folds, rugae
Expand
Explain the stomach lining
Simple columnar
Produces mucus
- Mucosa
Gastric pits connect gastric glands in mucosa
Mucus epithelium
Lamina propria - Submucosa
- Muscularis externa
Oblique and circular muscle
Longitudinal muscle - Serosa
Explain the stomach glands
In fundus and body of stomach
Parietal cells
- secrete intrinsic factor and HCI
Chief cells
- secrete pepsinogin
- convert to pepsin by HCI
G cells
- secrete gastrin (increase stomach activity)
Pyloric glands
In pylorus
- produce mucus
- g cells produce gastrin
- d cells release stomatostatin inhibit gastrin release
What are the regio
Duodenum- 25cm long, neutralises chyme, receives secretion from pancreas and liver - few plica circulares small villi
Jejunum- 2.5m long, most chemical digestion and nutrient absorption, prominent plica circulares and villi
Ileum - 3.5 m long, lymphoid nodules
Explain the organisation of the intestinal wall
Villi on mucosa
Muscularis mucosae
Submucosa
Muscularis externa
Serosa
Explain intestine villi
Columnar epithelium with mucus cells - brush boarder with digestive enzymes
Lacteal - lymphatic vessel in middle
Capillary network
