Lecture 23: Digestive System Anatomy Flashcards
(23 cards)
What are the six steps involved in the digestive system?
- Ingestion
- Mechanical breakdown
- Propulsion
- Chemical digestion
- Absorption
- Defecation
What is the parietal and visceral peritoneum?
Parietal: Lines the wall of the abdominopelvic cavity/
Visceral: Covers most of the organs and make up their outer layer. Between the visceral and parietal is serous fluid.
What is a mesentery?
It is a fold of tissue that holds intestines in place inside your belly. It also provides route for blood vessels, lymphatic vessels and nerves to the organs.
What are the layers to the GI Tract? (From superficial to deep)
- Serosa
- Muscularis externa
- Submucosa
- Mucosa
What is the function of muscularis externa and submucosa?
Muscularis externa: (Smooth muscle) Responsible for mechanical breakdown and propulsion.
Submucosa: (Areolar connective tissue) Contains blood and lymphatic vessels. Also has elastic fibers for stretch and recoil.
What is the function of mucosa?
Lines the lumen of the GI tract. absorbs nutrients, secrete mucus and enzymes and protect against infectious disease.
What is the passageway for food from mouth to anus?
- Mouth
- Pharynx
- Esophagus
- Stomach
- Small intestines
- Large intestines
- Anus
What is the difference between hard and soft palate?
Hard palate: Helps create friction against the tongue.
Soft palate: Closes off the nasal cavity during swallowing.
Which type of cells line the pharynx?
Stratified squamous epithelium
Where are sphincters found in the GI tract?
- Pharynx and esophagus
- Esophagus and stomach
- Stomach and duodenum
- Small intestines and large intestines
- Anus and external environment
(Prevents backward movement; give food enough time to digest)
Know the structures that block the bolus from moving back into the mouth, the nasopharynx and trachea.
Mouth: Tongue
Nasopharynx: Uvula and soft palate
Trachea: Epiglottis
What is the epithelial lining of stomach?
Simple columnar epithelium
What are the four regions of the stomach?
- Cardia
- Fundus
- Body
- Pylorus with pyloric sphincter
(Folding of the mucosa - rugae)
How is the muscularis externa unique to the stomach?
It has three layers if smooth muscle running in different directions (oblique, circular and longitudinal) which allows stomach to mechanically break down food. Surface exposed to stomach has deep gas pits.
Which are the four gastric juices?
- Hydrochloric Acid (Breaks down cell wall of plant foods, activates pepsin and kills microbes)
- Intrinsic factor (Absorption of vitamin B12)
- Pepsinogen (Inactive form of protein digestive enzyme pepsin)
- Hormones
How does the stomach stay intact when HCL and protein digesting enzyme pepsin are within it?
Mucous helps to protect the stomach against the acidic environment.
What are the three parts to the small intestine?
- Duodenum
- Jejunum
- Ileum
What is the function of the duodenum?
Primary site of chemical digestion. Acidic chyme is neutralized with alkaline mucous produced by the mucosa of the duodenum as well as bicarbonate ions released from the pancreas.
What is the function of jejunum and ileum?
Ileum is the last and longest section of the small intestine. It connects to the large intestine at ileocecal valve. (Most absorption of food, nutrients and water).
What is the function of villi?
Surface of villi lined with enterocytes (absorptive cells). Each villus contains blood capillaries which will take up most absorbed nutrients. This blood will go to the hepatic portal vein to be delivered to the liver.
Each villus also contains a wide lymph capillary (lacteal). Most lipids are transported this way.
What are the subdivisions of the large intestine?
- Cecum
- Appendix
- Colon (Ascending, Transverse, Descending and Sigmoid)
- Rectum (storage of feces)
- Anus
what is the function of the large intestines?
Resident good bacteria (flora) metabolize some of the remaining nutrients and also make vitamins K and B.
What is the defecation reflex?
- Stretching of the rectum causes the internal anal sphincter to relax.
- Feces moves into the anal canal.
- External sphincter is under voluntary control.
