Module 9 Flashcards
Name the four main layers or tunics of the gut wall:
1) mucosa 2) submucosa 3) muscularis externa 4) serosa or adventitia
Name the individual components that comprise innermost Layer A:
Epithelium lamina propria muscularis mucosa
In the basic plan of the gut, muscularis externa has two components. Identify them:
Inner circular layer Outer longitudinal layer
Where in the digestive tract is muscularis externa composed of skeletal muscle i.e. under somatic control?
Pharynx, upper third of oesophagus, external anal sphincter
Where in the digestive tract does muscularis externa have an extra component? In which organ is it located and why is it required?
Stomach – for mixing and churning
For each of the following peritoneal folds state the specific organs that they are connected to or support. 1) greater omentum 2) lesser omentum 3) falciform ligmament 4) mesentery 5) mesocolon
1) Connects transverse colon and greater curvature of stomach 2)Connects stomach and duodenum to liver 3)Connects liver to anterior abdominal wall 4)Connects small intestine to posterior abdominal wall 5)Connects large intestine to posterior abdominal wall
What does retroperitoneal mean?
What does retroperitoneal mean?
What is peritonitis?
Inflammation of the peritoneum
What type of epithelium is found on the surface of the tongue? Why?
stratified squamous, keratinised in parts (on the filiform papillae) permits wear & tear
The tongue is a muscular structure; explain the difference between intrinsic and extrinsic muscles of the tongue?
Intrinsic lie entirely within tongue, extrinsic have attachments to bones of skull
The palate forms the roof of the oral cavity, identify the parts of the palate labelled:
Hard palate, Soft palate, Uvula
What is the function of structure 8?
Closes off nasopharynx during swallowing
The salivary glands contain serous secretory cells, mucous secretory cells or a combination of both. What is the difference in the composition of the secretions produced by these cells?
Serous: water and amylase Mucus: mucin, water
How may pairs of salivary glands are there?
Three
What type of muscle (skeletal, smooth or cardiac) is found in the posterior walls of the pharynx? Why is this?
Skeletal, for voluntary control of food bolus
What role does the epiglottis play in swallowing? What type of tissue is made from?
Prevents food entering the larynx; elastic cartilage
Does the oesophagus lie anterior or posterior to the trachea?
Posterior
Which muscular structure must the oesophagus pass through to enter the abdominal cavity?
diaphragm
What is the hole or opening in this muscle called?
oesophageal hiatus
What type of epithelium lines the oesophagus and what is its function?
Non-keratinised stratified squamous – allows wear and tear
There are numerous glands in the submucosa - they may not be visible. What are their secretions made of and what purpose do they serve?
Mucus, for lubricating passage of food
Can you think of a reason for this?
Upper 2/3s has skeletal muscle for voluntary control
The outermost layer of the thoracic oesophagus consists of connective tissue that anchors it to surrounding structures (there is no serous membrane present). What is this layer called?
adventitia
What role do the sphincters play?
Isolate acidic stomach environment from oesophagus and duodenum, regulate flow
Are rugae permanent structures?
No ; permit the stomach to distend
Name the two folds of peritoneum that are attached to the stomach:
To liver: lesser omentum greater omentum
What type of epithelium is found here (stomach)?
Simple columnar
Entero-endocrine cells (G cells) are also found in the glands but their secretions pass through the lamina propria into the blood, rather than going into the lumen of the stomach. What products do these cells secrete?
Gastrin
What role do the secretions from G cells play in the digestive process?
Stimulates gastric activity
Name the three layers of muscle that are found in the muscularis externa of the stomach.
Oblique, circular, longitudinal
What purpose does the extra layer serve in the stomach?
Mixing and churning
What MACROSCOPIC (visible to the naked eye) structures, found within the wall of the small intestine, increase its surface area?
Plicae circulares
What other function do these structures perform?
Help to spiral chyme along length of intestine
There are two more features of the epithelium that help to increase surface area, name them
Villi and microvilli
One of these gives the internal surface of the small intestine a velvety appearance. Which one?
Villi (0.5-1.5mm, just visible to naked eye)
Which structure/serous membrane attaches the small intestine to the posterior abdominal wall? (Hint: check your Prelab)
Mesentery