Gastrointestinal Function Flashcards
What are 7 general functions of the GI tract?
- Ingestion of food
- Propulsion of food
- Secretion of mucus, water and enzymes
- Mechanical digestion of food
- Chemical digestion of food
- Absorption of digested food
- Elimination of waste products
The ____ is the innermost layer of the gastrointestinal wall and is exposed to dietary nutrients
Mucosa
In the villus, there is absorption of ___ and ___
Water and nutrients
The ____ is the next innermost layer of the GI wall; this carries the nerve plexus that innervates the mucosa and the muscle layers of the intestine
Submucosa
The ____ is the next layer of the GI wall; it contains the circular smooth muscle layer and the longitudinal muscle layer; this layer contacts to drive peristalsis to keep food moving through
Muscularis
The ____ is the outmost layer of the GI wall; it is the secretory adventitial layer; it keeps everything in place and is continuous from the mouth to the anus; it also secretes lubrication
Serosa
The autonomic nervous system controls what in the GI system?
-Direct neural stimulation
-Hormonal
-Peristalsis
-Defecation
Defecation is controlled by internal and external ____ ____
Anal sphincters
The ___ ___ ___ is a set of nerves connected to the autonomic nervous system and it is also connected to the gut; it is the third arm of the ANS (along with sympathetic and parasympathetic)
Enteric nervous system
The enteric nervous system can function ____ of the ANS and interacts with all arms of the ANS
Independently
What influence does the enteric nervous system have on GI function?
Regulates peristaltic reflex, hormones, and secretions
Stress or high fat/sugar intake triggers a response from ____ ___ that leads to increased food intake, increase fat uptake, decreased energy utilization, and decreased anxiety
Neuropeptide Y
Neuropeptide Y also blocks ____ to the CNS which releases pain
Nociceptors
Neuropeptide Y is an ____ chemical
Endogenous
What are some other examples of endocrine hormones that have an impact on the GI system?
-Gastrin
-Ghrelin
-Secretin
-Somatostatin
What are functions of the mouth?
-Mastication (physical breakdown of food in the mouth)
-In the mouth, saliva mixes with the food, and salivary amylase begins to break down carbohydrates and lingual lipases begin to break down fats
-Saliva also lubricates food to travel to the esophagus
The ____ is a passageway to the stomach; food is not being processed or absorbed here
Esophagus
____ is a neural dysfunction resulting in decreased smooth muscle movement in the middle and lower portion of the esophagus
Achalasia
What are the three sections of the stomach?
-Fundus
-Body
-Antrum
The antrum leads to the ____
Pylorus
A lot of food ____ happens in the stomach
Breakdown
The stomach rolls food around to produce ____
Chyme
In the stomach, cells secrete substances to breakdown food and protect against ____
Bacteria
What type of cells secrete gastrin?
G cells
G cells release gastrin when there is presence of ____ in the stomach
Proteins
What are the functions of gastrin?
-Increase motility
-Stimulates parietal cells to secrete HCL and chief cells to secrete pepsinogen
What type of cells secrete HCL?
Parietal cells
Parietal cells release HCL in response to…
-H2 receptors
-Parasympathetic stimulus
Functions of HCL:
-Denatures proteins
-Creates an acidic environment
What type of cells secrete ghrelin?
P/D1 cells
P/D1 cells secrete ghrelin in response to…
Low glucose levels
Functions of ghrelin:
-Hunger hormone
-Regulates appetite and motility
-Increases before meals
-Decreases after meals
What type of cells secrete somatostatin?
D cells
D cells secrete somatostatin in response to…
Low gastric pH
Roles of somatostatin:
-Decreases rates of gastric emptying and smooth muscle contraction
-Inhibits growth hormone production
-Suppresses release of gastrin, cholecystokinin, VIP, and others
What type of cells secrete Pepsinogen?
Chief cells
Chief cells secrete pepsinogen in response to…
-HCL
-Gastrin
-Vagus nerve stimulation
Roles of pepsinogen:
-Converted to pepsin if pH<5
-Protein breakdown
The mucous barrier of the stomach protects the stomach from ___
Acid
The ____ of the stomach controls gastric emptying
Pylorus
What may cause decreased gastric emptying?
-High-fat meals
-Diabetic neuropathy
-Eating in the evening
-Drugs like anesthesia
-Traum
____ is the forceful expulsion of gastric or intestinal contents
Vomiting
The vomiting center of the brain is called the ____ ____
Area postremia
The area postremia has no ___-___ barrier
Blood-brain
The area postremia can be stimulated by…
-Chemicals: opioids, high levels of toxins in the blood
-Mechanical: high pressure in the brain, myocardial infarction, gag reflect, infection
-Vestibular: rollercoasters
Consequences of vomiting:
-Acid-base imbalances
-Aspiration pneumonia
-Ruptured esophagus or the vessels that line the esophagus
-Tearing of the stomach lining
Most digestion and absorption of nutrients occurs in the ___ ___
Small intestine
What are the three regions of the small intestine?
-Duodenum
-Jejunum
-Ileum
Chyme moves from the pylorus to the ____ ___
Ileocecal valve
The small intestine contains villi with microvilli (brush borders) which break down ____
Polysaccharides
The ileocecal valve controls flow to the ____ ____
Large intestine
The duodenum secretes ____ in the presence of chyme in the duodenum
Secretin
In the intestines, secretin has what functions?
-Increases water and bicarb release
-Increases pancreatic and gallbladder contractions
I cells in the small intestine secrete _____ in the presence of chyme in the duodenum
Cholecystokinin
Roles of cholecystokinin in the intestine:
-Stimulates pancreatic enzymes
-Stimulates gallbladder contraction
-Increases gastric motility
-Suppresses hunger
-Induces anxiety
The duodenum and jejunum release ____ ____ ____ in response to hyperosmolarity of glucose in the duodenum
Gastric inhibitory peptide
Role of gastric inhibitory peptide in the intestine:
Induces insulin secretion
The small intestine and the Delta cells of the pancreas release ____ in response to low gastric pH
Somatostatin
Roles of somatostatin in the intestines:
-Decreases gastric emptying and smooth muscle contractions
-Suppresses other gastric secretions and pancreatic hormones
-Inhibits glucagon and insulin release from the pancreas
The intestine and hypothalamus release ____ ____ ____
Vasoactive Intestinal Polypeptide (VIP)
Roles of vasoactive intestinal polypeptide in the intestine:
-Increase GI motility and vasodilation
-Promotes H2O/lyte secretion
-Inhibits gastric acid and pepsinogen
-Variety of non-GI effects
VIP is released when the stomach is ____ and ____, but can also be secreted from the hypothalamus, can regulate sleep, increase vaginal lubrication, etc.
Distended and full
Gastric inhibitory peptide (GIP) can neutralize ____
HCl
The large intestine is also known as the ____
Colon
The large intestine lacks ____
Villi
The large intestine does not do much ____ (but has many glands)
Absorption
In the large intestine, we have a _____ that provides beneficial things for our body and helps to ferment food
Microbiome
The large intestine absorbs ____, ____, and some ____
Water, vitamins, electrolytes
When you have _____, things are moving through the large intestine too fast which leads to increased frequency and fluidity of bowel movements
Diarrhea
When you have _____, you have decreased amount of bowel movements and decreased fluidity
Constipation
The ____ is controlled by internal (autonomic NS) and external (consciously controlled) sphincters
Rectum
In the GI system, more fluids are ___/___ than lost (7000 mL)
Absorbed/reabsorbed
50-200 mL of fluid is lost through the ____ each day
Stool
Where are carbohydrates broken down (3)?
-Mouth: some carbs broken down by salivary amylase
-Stomach: some carbs broken down with HCl in stomach
-Small intestine: most carbs are broken down at the brush border of the small intestine
Where are proteins broken down (2)?
-Stomach: HCl and pepsin
-Small intestine: most enzymes here from the pancreas work to breakdown/reabsorb protein
Where are fats broken down (1)?
-Small intestine: pancreatic enzymes and gallbladder enzymes break down fats and most pass through the large intestine
GI ____ affects 50-150 of 100,000 people
Bleeding