Flashcards in Lecture 13- Digestive Tract Deck (75):
What makes up the Gastrointestinal system?
- digestive tract
- associated glands
What makes up the digestive tract? (7)
1) oral cavity
4) small intestine
5) large intestine
What makes up the associated glands? (3)
- salivary glands
What is the general layout of the layers in the GI tract?
- serosa or adventitia
What makes up the mucosa in the GI tract?
- epithelial layer
- CT lamina propria
- muscularis mucosa
What makes up the submucosa?
What makes up the muscularis?
Smooth muscle, exception is skeletal muscle in esophagus
What makes up the serous or adventitia?
- Epithelial layer (only in serous layers)
What type of tissue is on the hard palate and gingiva made for abrasion and chewing food?
Stratified squamous epithelium, keratinized
What type of epithelial layer is found in the cheek, floor of mouth, lips, and soft palate?
Stratified squamous epithelium, non-keratinized
What underlies the epithelial layer in the hard palate and gingiva?
Lamina propria goes into the periosteum of bone
What underlies the lips, cheek, soft palate, and floor of mouth?
Lamina propria, submucosa, striated or skeletal muscle
What contributes to linea alba or thickening of the buccal mucosa?
keratinization of the epithelium- abrasion can cause keratinization
What types of papillae make up the anterior or dorsal surface of the tongue?
Filiform and fungiform
What are filiform papillae?
- most abundant
- rough, keratinized surface to help with food movement
- like "file"
Where are taste buds found?
Everywhere but filiform. Fungiform, vallate, foliate
Where are the vallate papillae found?
The V of the terminal sulcus
What is the purpose of the serous fluid that is excreted by the papillae?
Helps wash away substances that cause taste so the next taste can be recognized.
What is the purpose of the gustatory cell?
- contains taste receptors that are lined with microvilli to increase surface area
- transduction pathways send impulses to afferent sensory neuron
- Stem cells regenerate gustatory cells and support cells
Where are taste buds found?
Inside the papillae
What connects the nasal cavity to the larynx and the oral cavity to the esophagus?
What type of epithelial tissue lines the nasopharynx?
Ciliated pseudostratified columnar
What type of epithelial tissue lines the hypopharynx?
Stratified squamous, non-keratinized
A disease in which layer of tissue would lead to the loss of peristalsis?
What type of tissue makes up the mucosa of the esophagus?
Stratified squamous epithelium, non- keratinized
What makes up the submucosa of the esophagus?
- Lamina propria (loose CT)
- Muscularis mucosa- smooth and skeletal
- Mucous glands
How is the muscle tissue in the esophagus divided?
- Top 1/3- striated muscle
- middle 1/3 mixed striated/smooth
- bottom 1/3 smooth muscle
What are some of the functions of the stomach? (6)
1) accepts food from the esophagus
2 ) mixes food
3) makes gastric acid
4) starts protein, lipid digestion
5) absorbs very few substances from food
6) moves food (chime) into the intestine
What are the four layers of the stomach?
1) mucosa- simple columnar epithelial
2) submucosa- CT
3) muscularis- 3 layers in different directions
4) serosa with an outer mesothelium layer
How can you tell if a stomach is full or empty?
Evidence of folds or rugae.
What type of cells are the surface mucous cells?
Simple columnar epithelial cells
Why don't gastric contents normally injure the stomach mucosa?
Stomach mucosa is covered with mucus and bicarbonate that will neutralize acid
What happens at the apical cup of mucinogen granules?
Mucus and bicarbonate are secreted
What is the pH at the surface of mucosa and inside the stomach?
- Mucosa pH=7
- Stomach pH= 1
What affect can aspirin have on the stomach?
It can deteriorate the surface mucosa leading to stomach ulcers.
What are the for anatomical regions of the stomach?
What are the three histological regions of the stomach?
* differences in mucosa
Describe the cardiac region of the stomach
- simple columnar epithelium
- cardiac glands present that secrete mucus
What types of glands are present in the fundus/body?
What are the three parts of gastric glands and how does their size compare to cardiac glands?
-much larger than cardiac glands
What do surface mucus cells in gastric pit secrete?
Alkaline mucous and bicarbonate
What do mucous neck cells secrete?
more neutral mucous
What do parietal cells in the isthmus/neck secrete?
HCl and intrinsic factor
What do chief cells in the base secrete?
Pepsinogen and gastric lipase
How do parietal cells secrete acid?
They use a Hydrogen-Potassium ATPase pump
What organelles have proton pumps in parietal cells?
- Canaliculi with microvilli
What is the role of mitochondria in the parietal cells?
- Lots of ATP is needed to run the proton pump
What happens when food is digested?
Tubulovesicles with the proton pump fuse with the canaliculi membrane
Why is there acid in the stomach? (3)
- helps kill bacteria
- acid and intrinsic factor important for Vitamin B12 absorption
- acid converts pepsinogen to pepsin
Where are the pyloric glands found?
What types of cells are found in the plylorous?
- surface mucous cells
- mucous neck cells
- G cells
- Enteroendocrine cells
What are the distinct features of pyloric glands?
- deeper pits
- shorter coiled pyloric glands
What stimulates the release of gastrin?
What do enterochromaffin-like cells do?
Release histamine that releases acid
What cells bind to enterochromaffin-like cells?
Gastrin and ACh from parasympathetic response
Blocking the secretions of what kinds of cells would potentially treat gastroesophageal reflux disease?
- G cells (gastrin)
- Parietal cells (acid)
- enterochromaffin-like cells (histamine)
What makes up the pyloric sphincter?
- Smooth muscles thickening the middle layers of the stomach muscularis
Do the circular folds of the small intestine change shape during digestion?
What is the main role of the small intestine?
Absorb nutrients and minerals from food
What types of cells are found inside the lamina propria of the small intestine?
Where do new intestinal cells come from?
What types of cells to stem cells from the intestinal crypt differentiate into?
- Enteroendochrine cells
- paneth cells
What is the function of paneth cells and where are they found?
- secrete antimicrobial peptide to protect against bacteria
- found at the bottom of the intestinal crypt
What does not increase the surface area for absorption in the small intestine?
- intestinal crypts ( crypts of Lieberkuhn)
Intestinal inflammation associated with inflammatory bowel disease would be associated with dysfunction in which type of cell?
Where can peptic ulcers occur?
Stomach and duodenum
How is the duodenum protected from gastric acid?
Brunner's or duodenal glands in produce alkaline mucus
What helps with absorption of nutrients?
The rhythmic movement of villi mixes and facilitates absorption
What helps with the absorption of amino acids and monosaccharides?
- venules, capillaries, and arterioles
Where are the fatty acids and monoglyerides absorbed?
The lymphatic cappilaries of the lacteal
What controls the activity of the gut?
Enteric nervous system
What two plexus make up the enteric nervous system?
- submucosal (Meissner plexus)
- myenteric (Auerbach plexus) between smooth muscle layers
What is the funtion of the large intestine? (3)
- absorption of water and electrolytes
- microbial fermentation
- storage of fecal materia
What is unique about the muscularis externa layer of the large intestine?
- circular layer of muscularis externa
- 3 thin bands of longitudinal muscle making up the Tenia coli from cecum to rectum