Term
| What is the difference between the stomach and the small intestines? |
|
Definition
| The small intestines is where most chemical digestion takes place. Enzymes are not produced by mucosa, but are provided by the pancreas |
|
|
Term
| How does the pancreas get enzymes to the small intestines? |
|
Definition
|
|
Term
| What are the sections of the small intestine? |
|
Definition
- Duodenum - Receives chyme, neutralizes acid. Secretion of mucus from Brunner's glands (more than goblet cells). Controls rate of emptying
- Jejunum - chemical digestion and nutrient absorption. LARGE surface area
- Ileum - absorption of water, immune protection due to Peyer's patches. Absorption of B12, bile salts, and nutrients. |
|
|
Term
| From the small intestines, where are nutrients absorbed to? |
|
Definition
| Into the superior mesenteric vein |
|
|
Term
| What increases the surface area of the small intestine? |
|
Definition
Plicae, Villi, and microvilli.
Contain goblet cells and enterocytes |
|
|
Term
| What is important about the brush border of the small intestine? |
|
Definition
- Increases surface area
- Contains the enzyme enterokinase: converts the inactive enzymes trypsinogen, chymotrypsinogen, and procarboxypeptidase from the PANCREASE into active enzymes. |
|
|
Term
| What are the functions of cells in the small intestine? |
|
Definition
- Enterocytes - absorption of water and other substances
- Goblet cells - production of mucus
- Enteric endocrine cells - produce Enterogastrones
- Stem cells - for cell turnover
- Paneth cells - Antibacterial, release lysozyme |
|
|
Term
| What are Peyer's patches? |
|
Definition
| Lymphoid follicles in the lamina propria of the mucus layer. Aggregates form in the ILEUM. |
|
|
Term
| What is the difference between the fed motor pattern and fasting motor pattern? |
|
Definition
- Fed motor pattern - Segmentation (mixing) and peristalsis controlled by gastroenteric and gastroileal reflexes.
** Enterogastric reflex is inhibitory, allows for stomach and small intestine to work longer
- Fasting motor pattern - during interdigestive period, every 90-120 min. Release of motilin increases MMC, which is peristalsis of indigestible material. |
|
|
Term
| What is the mechanism of water secretion in the small intestines? |
|
Definition
- Exchange of 3Na for 2K creates a negative charge inside the cell.
- K/Na/2Cl pumps into the cell, building up chloride ions.
- Chloride is then actively pumped out using the TYPE 2 CHLORINE CHANNEL, water moves paracellularly at the same time |
|
|
Term
| Where does Amitiza/lubiprostone work? |
|
Definition
At the type 2 chlorine channel in the small intestine for relief of constipation - brings in more water.
Tx of IBS and iodiopathic constipation. |
|
|
Term
| What sites/conditions are associated with initiation of the vomiting reflex? |
|
Definition
- GI tract irritation or overdistention - Serotonin, Ach, Histamine, Sub P
- Labrythin disorders of the inner ear - ALCOHOL - M and H1
- Endocrine - PREGNANCY - HCG, T4, serotonin
- Post-op due to anesthesia or analgesia - DA2, serotonin, NK1
- Infection in GI or inner ear
- Increased intercranial pressure
- CNS - smells, memories
- Drugs - cancer therapy, opiates |
|
|
Term
|
Definition
The chemoreceptor trigger zone, outside the BBB, contains receptors that induce vomiting:
- 5-HT3 - Serotonin
- H1 - Histamine
- M - Ach
- DA2 - Dopamine
- NK1 - Sub P
- Opioid - Apomorphine
- Digoxin, cancer drugs, mustard |
|
|
Term
| What is the mechanism of induction of vomiting? |
|
Definition
- Local irritants such as drugs or an infection can cause the stomach/intestines to produce Sub P or Serotonin --> Vagal/SNS afferents --> Nucleus tractus solitarius has same receptors as CTZ --> Response in the vomiting center!
- Blood borne emetics act in the stomach/SI or through the CTZ to produce a response, may or may not go through NTS. |
|
|
Term
| What are the phases of vomiting? |
|
Definition
- Nausea/pre-ejection phase - cold sweat, pallor, salivation
- Retching - contraction of abdominal muscles, chest wall and diaphragm w/o expulsion. Generates a pressure gradient.
- Vomiting - sustained contraction w/ closure of the pyloric valve. |
|
|
Term
| What is the function of the pancreas? |
|
Definition
EXOCRINE, secretion of pancreatic enzymes, buffers, and water to aid in digestion
**Exit controlled by the sphincter of Oddi. Common bile duct (from liver and gall bladder) merges w/ pancreatic duct to the Sphincter of Oddi |
|
|
Term
| What are the main exocrine cells in the pancreas? |
|
Definition
The acinar cells - produce the enzymes found in zymogen granules
- Has receptors: Strong response to CCK (CCKa receptor) and Ach (M3) receptor to release granules
- GRP, VIP, and Secretin are weak responses.
** Also tubular cells - release of bicarb in response to secretin |
|
|
Term
| What phases are pancreatic secretions found? |
|
Definition
- Cephalic - neural control via Ach - 20%
- Gastric - gastrin via vagus - 10%
- Intestinal - CCK and Secretin into duodenum, 70% |
|
|
Term
|
Definition
| Gall stones can block the sphincter of oddi, backing up enzymes and causing infection |
|
|
Term
| What is the function of the liver? |
|
Definition
- Produce bile for the duodenum and for storage in the gall bladder.
- Bile - emulsification of fat, extraction of nutrients
- Kupffer cells remove foreign material |
|
|
Term
| What is the anatomy of the liver? |
|
Definition
4 major lobes. Blood enters through portal vein, leaves through hepatic vein
Functional unit - lobules. Arterial and venous blood mixes in sinusoids.
Hepatocytes produce bile, leaves via bile ducts. |
|
|
Term
| What is enterohepatic circulation? |
|
Definition
How bile acids are recirculated. Most of what is used is reabsorbed.
A small about is concentrated and stored in the gall bladder - gall bladder becomes acidic to reduce chance of gall stones.
- Reabsorption in the ILEUM at ASBT pump
- Fatty acids in duodenum stimulate release of SECRETIN from S cells --> synthesis and release of bile. |
|
|
Term
| What are the different forms of bilirubin? |
|
Definition
- In the ileum, oxidated to stercobilin, which is brown
- In the urethra, oxidated to urobilin, which is yellow
- Lack of bilirubin = jaundice |
|
|
Term
| What are the stages of liver cirrhosis? |
|
Definition
- Fatty liver - deposits of fat enlarge liver
- Liver fibrosis - Scar tissue
- Cirrhosis - Connective tissue growth is irreversible. |
|
|
Term
What is the function of the gall bladder?
What stimulates release? |
|
Definition
Concentration and storage of bile during interdigestive period
**CCK - contraction of the gall bladder and relaxation of sphincter of oddi |
|
|
Term
| How do secretin and CCK affect bile? |
|
Definition
- CCK - Inhibits motility in the stomach. Stimulates Pancreas to release enzymes, relaxes sphincter of oddi, and contracts gall bladder
- Secretin - Inhibits stomach motility. Stimulates Pancreas to release enzymes, relaxes sphincter of oddi, and increases bile secretion from the LIVER |
|
|
Term
| What are gall stones made of? |
|
Definition
|
|
Term
| What are important enzymes in the stomach/intestines? |
|
Definition
- Amylase - starts breakdown of carbs. NOT in the stomach
- Lactase - in the small intestine
- Pepsin - in the stomach
- Lipase - in the small intestine |
|
|
Term
| How does Xenical/Orlistat work? |
|
Definition
| Inhibits pancreatic lipases, preventing the absorption of fats |
|
|
