Lecture 21: Abdominal Viscera I Flashcards
What is the esophagus? What cavities does it pass through?
Muscular tube 23-25 cm that travels through neck, thorax, abdomen. Connects pharynx to the stomach.
What are the muscular layers of the esophagus?
Internal circular muscles, outer longitudinal muscle
Identify the indicated structures
Where does the esophagus begin? What is it attached to?
The beginning partially blends with the pharyngeal constrictor muscles.
In which cavity is most of the esophagus located?
Thoracic
Describe esophageal position in superior mediastinum.
intermediate position between vertebral column (posterior) and trachea (anterior)
Describe esophageal position in inferior thoracic cavity.
Located in posterior mediastinum: pushed forward by the descending aorta. Passes through the diaphragm.
Through what opening does the esophagus pass through the diaphragm?
Esophageal hiatus
What is the cardiac region of the stomach?
The last 2 centimeters before the opening in the stomach.
What type of tissue is the inner layer of the esophagus composed of?
Stratified squamous non-keratinized epithelium.
How does esophagus move food to stomach.
Peristalsis - muscular contractions
What is the stomach, and its main function? What does it change food into?
A distensible organ that functions as a blender and reservoir.
It temporarily stores and digests food with strong acid and changes bolus of food into chyme
Describe location and shape of the stomach.
- J-shaped dilation distal to esophagus
- Variable shape due to ability to distend
- Has lesser curvature (concave)
- Greater curvature (convex)
What muscular strucures prevent reflux of food into the esophagus?
Voluntary muscles of diaphragm
Esophageal sphincter - smooth muscle surrounding opening to stomach
What are rugae, and their explain their function?
- Muscular folds lining the luminal surface of the stomach
- Increase surface area.
What action passes chyme into the small intestine? What controls the output of chyme?
- Peristalsis
- Pyloric sphincter - controls output of chyme
What are the 4 regions of the stomach?
- Cardia
- Fundus
- Body
- Pylorus & pyloric sphincter
Describe location of cardia, and what does it produce?
1.5-3 cm wide transition zone between the esophagus and the stomach
Its glands primarily produce mucus
Location and function of fundus and body?
histologically identical. Gastric glands releasing acidic gastric juice are located there
Location and function of pylorus.
funnel-shaped region that opens into the small intestine. Its glands primarily produce mucus
What are the 4 layers of the wall of the stomach?
- Mucosa
- Submucosa
- Muscle
- Serosa
What type of tissue is the mucosa of the stomach composed of?
Simple columnar epithelium = secretory epithelium
What protects the stomach epithelium from secreted acids?
Alkaline mucus
What are the invaginations in the stomach epithelium called?
Gastric pits
What is located at the bottom of the gastric pits?
Tubular glands, which project into lamina propria.
1-7 glands open into the bottom of each pit.
What do the gastric glands secrete?
Pepsinogen, lipase and
hydrochloric acid
What happens to pepsinogen in acidic pH?
Converted to pepsin for protein digestion.
Identify the indicated structures.
Identify the indicated structures
Where is this tissue located?
Identify the indicated structures.
The stomach
Identify indicated structures.
From what region of the stomach is the below tissue?
Identify indicated structures
From what region of stomach is tissue? Name the structures.
What region of stomach is below tissue sample? Identify structures.
Notice difference in epithelial shape between different regions.
Where is the beginning and end of the small intestine?
What are the 3 sections?
- Extends from pylorus of stomach to ileocecal junction
- Duodenum
- Jejunum
- Ileum
What are plicae circulares and their function?
Where are they most abundant?
Circular folds beginning in duodenum; composed of mucosa and submucosa.
Increase surface area for absorption
Most abundant in the jejunum and disappear in the distal ileum.