Lecture 11 (Digestive System) Flashcards
Ailmentary canal
Mouth, pharynx, esophagus, stomach, small intestine, large intestine
Accessory digestive organs
Teeth, tongue, gallbladder, salivary glands, liver, pancreas
Digestive processes (6)
- Ingestion
- Propulsion
- Mechanical breakdown
- Chemical digestion
- Absorption
- Defecation
Ingestion
Through the mouth
Propulsion
Movement of food, peristalsis
Mechanical breakdown
Prepares food for chemical digestion
Chewing, churning food in stomach, segmentation
Chemical digestion
Complex molecules broken down to chemical components
Occurs in mouth, stomach and small intestine
Absorption
Transport of digested nutrients
Mainly in small intestine
Defecation
Elimination of indigestible substances as feces
Peristalsis
Adjacent segments of alimentary tract organs alternately contract and relax, moving food along the tract distally
Segmentation
Non-adjacent segments of alimentary tract organs alternately contract and relax
Moving food forward and backwards
Food is mixed and slowly propelled
Rhythmic contractions mix food with digestive juices
Regions of the abdomen (9)
- Right hypochondriac region
- Epigastric region
- Left hypochondriac region
- Right lumbar region
- Umbilical region
- Left lumbar region
- Right iliac (inguinal) region
- Hypogastric (pubic) region
- Left iliac (inguinal) region
Right hypochondriac region
Upper (your) right
Epigastric region
Upper middle
Left hypochondriac
Upper (your) left
Right lumbar region
Middle (your) right
Umbilical region
Middle middle
Left lumbar region
Middle (your) left
Right iliac (inguinal) region
Lower (your) right
Hypogastric (public region)
Lower middle
Left iliac (inguinal) region
Lower (your) left
Mid-clavicular lines
Divide abdomen longitudinally into 3 sections
Subcostal line
Under ribs
Upper line dividing abdominal regions
Trans-tubercule line
Lower horizontal line dividing abdominal regions
Stomach divisions (3)
- Fundus
- Body
- Pyloris
Pyloric sphincter
At bottom of stomach, designates how much fluid enters the duodenum
Layers of the GI tract (4)
- Mucosa
- Submucosa
- Muscularis
- Serosa
Mucosa (3)
Innermost layer, lumen
- Epithelium
- Lamina propria
- Muscularis mucosa
Submucosa (3)
Next to mucosa
- Connective tissue
- Blood vessels
- Nerves
Muscularis Externa (2)
Between submucosa and serosa
- Inner circular layers
- Outer longitudinal layers
Serosa
Outermost layer of Gi tract
Peritoneum
Epithelium and connective tissue
Epithelium of esophagus
Stratified squamous non-keratinized
Epithelium of stomach
Simple columnar epithelium with gastric pits
Epithelium of small intestine
Simple columnar epithelium with microvilli
Large intestine
Simple columnar epithelium with numerous goblet cells
Surface mucous cell
Mucosal layer of stomach
Secretes mucous
Mucous neck cell
Mucosal layer of stomach
Secretes mucous
Parietal cell
Mucosal layer of stomach
Secretes HCl and gastric intrinsic factor
Chief cell
Mucosal layer of stomach
Secretes pepsinogen, beginning protein digestion
Enteroendocrine cell (stomach)
Mucosal layer of stomach
Secretes gastrin, which stimulates secretion from parietal cells
Enterocyte
In small intestine
Completes digestion and absorbs nutrients across microvilli
Goblet cell
In small intestine
Secretes mucus
Enteroendocrine cell (small intestine)
Secretes secretin or cholecystokinin, which stimulates the release of bile and pancreatic juices and inhibits stomach secretions
Paneth cell
In small intestine
Secretes substances that destroy bacteria
Colonocyte
In colon
Absorbs water, electrolytes and vitamins
Peptic ulcers
Caused by stomach acid
Parietal cells and mucous cells are in balance
If there is too much HCl and not enough mucus, there will be ulcers
Peritoneum
Serous membrane that forms the lining of the abdominal cavity
Peritoneal cavity
Slit like potential space between visceral and abdominal peritoneum
Mesentery
Double layer of peritoneum
Holds organs in place
Sites of fat storage
Provides a route for circulatory vessels and nerves
Dorsal mesenteries (3)
- Greater omentum
- Transverse mesocolon
- Sigmoid mesocolon
Greater omentum
Dorsal mesentery
Connects greater curvature of stomach to posterior abdominal wall
Fatty apron
Transverse mesocolon
Dorsal mesentery
Holds transverse colon in place
Sigmoidal mesocolon
Dorsal mesentery
Connects sigmoid colon to posterior pelvic wall
Retroperitoneal organs
Behind the peritoneum
Fixed to the wall
Peritoneal organs
Digestive organs that keep their mesentery
Intraperitoneal organs
Have movement
Liver
Secretes bile
Bile
Makes fat soluble in water, emulsifies
Stored in gallbladder
Hepatocyte
Functional cells of the liver
Portal triad (3)
- Bile duct tributary
- Branch of hepatic portal vein
- Branch of hepatic artery
Hepatic macrophages
Destroy bacteria
Gallbladder
Stores and concentrates bile
Expels bile into the duodenum
Cholecystokinin
Released from enteroendocrine cells in response to fatty chyme
Jaundice
Yellowish discolouration of skin and mucous membrane
Especially in sclera of the eye
Due to increased levels of bilirubin in blood
Bilirubin
Part of heme break down
Yellow in colour
Circular folds of small intestine
Transverse diges of mucosa and submucosa
Villi (small intestine)
Fingerlike projections of the mucosa and covered with simple columnar epithelium
Microvilli (small intestine)
Further increase surface area for absorption
Large intestine
Small amount of digestion by bacteria
Absorb water and electrolytes
Mass peristaltic movements force feces towards rectum
Subdivision of large intestine
Cecum, appendix, colon, rectum, anal canal
Anal canal
Lined with stratified squamous epithelium
Hemorrhoids
Varicose veins of the hemorrhoidal veins of anal canal
Straining at stool or at delivery of a baby
External hemorrhoids: itchy and painful
Internal hemorrhoids: not painful