Human Anatomy Ch 23 Flashcards
(27 cards)
Digestive organs
Mouth to anus -mouth -tongue -salivary glands: parotid gland, sublingual gland, submandibular gland -esophagus -pharynx -stomach -gall bladder -small intestine -large intestine -anal canal, anus -liver and pancreas accessory organs -
Digestive processes
-Ingestion: food intake
•Propulsion: smooth muscle relaxation and contraction moves food through system
•Mechanical digestion: chewing and breaking down food
•Chemical digestion: enzymes, acids
•Absorption: become nutrients/molecules, body takes these and uses them
•Defecation: waste out of body
Peristalsis
-Major means of propulsion
-contraction, relaxation, contraction
•Adjacent segments of the alimentary canal relax and contract
Segmentation
Rhythmic local contractions of the intestine
•Mixes food with digestive juices
Abdominal regions
Review ch 1
Peritoneum
- a serous membrane
–Visceral peritoneum: surrounds digestive organs
–Parietal peritoneum: lines the body wall
Peritoneal cavity
A slit-like potential space
Inside abdominal cavity
Mesentery
.a double layer of peritoneum
–Holds organs in place
–Sites of fat storage
–Provides a route for circulatory vessels and nerves
Histology of the alimentary canal wall
.Same four layers from esophagus to anus –The mucosa: innermost layer •Consists of: –Mucosa –submucosa –Muscularis –Serosa
The salivary glands
Produce saliva (breaks down carbs only)
•Compound tubuloalveolar glands
–Parotid, submandibular, and sublingual glands
The pharynx
.Oropharynx and laryngopharynx: passages for air and food
–The pharynx opens into the larynx and the esophagus.
–Lined with stratified squamous epithelium(internal)
–External muscle layer
•Consists of superior, middle, and inferior pharyngeal constrictors
The esophagus
.Gross anatomy: muscular tube
–Begins as a continuation of the pharynx
–Joins the stomach inferior to the diaphragm
The stomach
.Site where food is churned into chyme
•Protein digestion begins
•Secretes pepsin
–Functions under acidic conditions
-duodenum connects to pylorus
-muscularis externa: longitudinal, circular, and oblique layerThe small intestine gross anatomy
Longest portion of the alimentary canal
•Site of most enzymatic digestion and absorption
•Three subdivisions
–Duodenum, jejunum, and ileum
Duodenum: receives digestive enzymes (pancreas) and bile(gallbladder). Fat digestion
–Main pancreatic duct and common bile duct
The small intestine microscopic anatomy
.Modifications for absorption
–Circular folds (plicae circulares)
•Transverse ridges of mucosa and submucosa
–Villi: finger-like projections of the mucosa
•Covered with simple columnar epithelium
–Microvilli: further increase surface area for absorption
Histology of the intestinal wall
Absorptive cells: uptake digested nutrients
•Goblet cells: secrete mucin that lubricates chyme
•Enteroendocrine cells: secrete hormones
•Intestinal crypts: epithelial cells secrete intestinal juice
The large intestine gross anatomy
.Digested residue contains few nutrients
•Small amount of digestion by bacteria
•Main functions: absorb water and electrolytes
•Mass peristaltic movements force feces toward the rectum
Subdivided into:
–Cecum, vermiform appendix, colon, rectum, anal canal
Cecum
A blind pouch
Vermiform appendix
Contains lymphoid tissue
Neutralizes pathogens
Colon
Divided into distinct segments
-ascending, transverse, descending, and sigmoid colon
Rectum
Descends along the inferior half of the sacrum
Anal canal
The last subdivision of the large intestine
Microscopic anatomy of the large intestine
-Villi are absent
•Contains numerous goblet cells
•Intestinal crypts: simple tubular glands
•Lined with simple columnar epithelial tissue
•Epithelium changes at anal canal
–Becomes stratified squamous epithelium
The liver
-digestive accessory organ
-Largest gland in the body
•Performs over 500 functions
•Digestive function: bile production
•Performs many metabolic functions
-liver is the chemical factory
