digest Flashcards
Introduction: specialized for? consists of? located?
- specialized for digestion and absorption of food
- consists of digestive tract and accessory digestive glands
- located predominantly in the abdominopelvic cavity
Introduction: walls/organs lined with? cavity?
- walls of cavity lined with parietal peritoneum
- organs covered with layer of visceral peritoneum
- peritoneal cavity is space between the two layers
Functions (6)
- Ingestion: food and liquid taken in
- Secretion: acids, buffers, enzymes
- Motility: mixes and moves food along digestive tract
- Digestion: Mechanical and Chemical
- Absorption: materials move acroos digestive epithelium
- Elimination: waste is compacted and excreted
Digestion: chemical vs mechanical?
- mechanical: teeth and tongue break food into smaller particles
- chemical: food broken down by acid and enzymes
Tongue - composed of _ muscle? orientation? allows?
- composed of multiple layers of skeletal muscle
- oriented at different angles
- allow movement in multiple directions
Tongue - functions? (3)
- positions food within oral cavity
- sensory organ - temperature and taste (sweet, salty, sour, bitter, umami)
- organ of speech
Gastrointestinal Tract - oral cavity? pharynx? esophagus?
- OC: teeth, tongue and salivary glands fragment and hydrate food
- P: initiates swallowing
- E: muscular tube that conducts food from pharynx to stomach
GI Tract: stomach? small intestine? large?
- S: muscular sac that stores food and initiates digestion
- SI: digestion and absorption
- LI: compaction and storage of feces
Teeth - decidous? permanent? replacement? function?
- deciduous aka temporary aka baby dentition: 20 teeth
- permanent dentition: 32 teeth
- replacement occurs between 6 and 17
- function in mechanical breakdown of food aka mastication
Esophagus - what? size? where? lined with?
- muscular tube extending from pharynx to stomach
- 25 cm long, 2cm in diameter
- passes along posterior mediastinum through diaphragm, into adominal cavity
- lined with stratified squamous non-keratinized epithelium
Muscules of the esophageal wall- upper and lower?
- Upper portion: skeletal aka voluntary
- can decide to continue swallowing or bring food back up
- lower portion: smooth aka involuntary
- committed to finish swallowing
Stomach - what? does what? mechanically? chemically? mixes?
Gastric Cland Cells (5)
- surface mucus cells
- mucus neck cells
- parietal cells
- chief cells
- enteroendocrine cells
Enteroendocrine Cells
- secrete hormones
- G cells secrete gastrin
- gastrin stimulates secretion of parietal and chief cells
Gastric Gland Cells - surface mucus and mucus neck?
- SM: secrete alkaline mucus to protect epithelium from acid
- mucus neck: secrete protective mucus
GG Cells - parietal? chief?
- P: secrete HCl and intrinsic factor (vit B12 absorption)
- C: secrete pepsinogen - converted into pepsin by stomach acid
Small intestine - 3 regions?
- duodenum
- jejenum
- ilieum
Duodenum - size? shape? recieves?
- short, 25 cm or 10 in
- C shaped segment
- receives chyme from stomach
- receives secretions of pancreas and gall bladder
Jejenum - size? function?
- 2.5 m or 8 ft
- majority of digestion and absorption
Ilieum - size? function?
- final segment, 2.5 m or 12 ft long
- digestion and absorption completed
- empties into large intestine
Neutralization of Chyme
- pH of chyme in stomac is acidic, but digestive enzymes in SI have alkaline pH optimum
- chyme is released slowly from the stomach by the pyloric sphincter
- as it enters duodenum, rapidly neutralized by: alkaline secretions from pancreas and alkaline mucus secreted by subjucosal glands of the duodenum (Brunner’s)
Duodenum position
Surface Area of Small Intestine
- 6m/20 ft length, 2.5
Large Intestine - shape and size? functions?
- horseshoe shaped tube
- 1.5 m/ 5 ft long
- 7.5 cm / 3 in in diameter
- reabsorbs water and electrolytes
- absorbs important vitamins produced by colonic bacteria - K and B 12
- compacts and stores feces
Duodenum Position
Intenstinal Wall - mesentery? plicae circulares? villi?
Specializations of Intestinal Wall: d vs. J vs. I
- duodenum: plicae, glands and villi
- jejenum: most numerous plicaie and villi
- ileum: reduced in height villi, peters patches: permanent lymphoid nodules
Digestive Tract Epithelium Comparison
