Section 1A Flashcards
Peristalsis is dependent on what type of contractions?
on involuntary contractions of smooth muscle
Describe how Peristalsis works
It propels contents forward through the GI tract at varying speeds
How does Segmentation work?
It promotes mechanical digestion of food. It takes large pieces of food and breaks it into smaller pieces
How does segmentation facilitate absorption?
By exposing all portions of the intestinal contents to the absorbing surfaces of the GI tract
What type of contractions is segmentation dependent on?
Involuntary contractions of smooth muscle
What are the 4 types of segmentation motility?
Regularly spaced
Isolated
Irregularly spaced
Weak regularly spaced
What are the two basic functions of the GI tract?
- Separate food into essential nutrients and unnecessary waste
- Absorb the essential nutrients while getting rid of the waste
Relaxation of sphincters is mediated by what?
Reflexes
Name the 6 sphincters within the Gi tract
Upper Esophageal Sphincter (UES) Lower Esophageal Sphincter (LES) Pyloric Sphincter Ileocecal Sphincter Internal Anal Sphincter External Anal Sphincter
What is the sphincter that controls movement of things Into the GI Tract?
Sphincter of Oddi
What does the Sphincter of Oddi do?
Regulates movement of contents of the common bile duct into the duodenum
Sphincters are dependent on what type of contractions?
Involuntary contractions of smooth muscle
How do sphincters function to be a mode of motility
Tonic contractions of sphincters with intermittant relaxation serve to regulate movement of luminal contents
What are the 3 basic types of motility?
- Propulsive movements or PERISTALSIS
- Mixing movements or SEGMENTATION
- TONIC CONTRACTIONS of sphincters or valves
What are the two things in the GI tract under voluntary control?
- At the mouth through the early portion of the esophagus (including the UES), chewing muscles, swallowing, etc.
- At the external anal sphincter (skeletal muscle)
What three acts of the GI tract have voluntary components involving skeletal muscle?
- Chewing
- Swallowing
- Defecation
How much of the following is made of each per day:
Saliva, Gastric Juice, Bile, Pancreatic juice, Intestinal secretions, Mucus
Saliva: 1.5 L Gastric Juice: 2.5 L Bile: 0.5 L Pancreatic Juice: 1.5 L Intestinal Secretions: 1.0 L Mucus: 2.0 L
Define Digestion:
Breakdown process whereby the structurally complex foodstuffs of the diet are converted into smaller absorbable units
What two ways can digestion occur and by what means?
Mechanically –> aforementioned motility
Chemically –> Enzymes
The enzymes for chemical digestion come from where?
Pancreas and Stomach
Where does digestion mainly occur?
In the small intestine and stomach
Absorption solves what two problems?
- How to reclaim the enormous volume of fluid (approx. 9.0 L)
- How to recognize specific nutrients, vitamins, electrolytes and to absorb them effectively and efficiently.
Approximately how much of the daily input of fluid ends up in stool daily?
100 mL
What four mechanisms has the GI tract developed to carry out its functions?
- Motility
- Secretion
- Digestion
- Absorption
Name the 4 basic quadrants
- Right Upper Quadrant
- Left Upper Quadrant
- Right Lower Quadrant
- Left Lower Quadrant
Below the diaphragm, the GI organs reside in what cavity?
Abdominopelvic cavity
What is the Peritoneum?
A slick serous membrane of the abdominopelvic cavity
What is the visceral peritoneum?
It covers the external surfaces of most digestive organs and is continuous with the parietal peritoneum
What is the parietal peritoneum?
It lines the walls the Abdominopelvic cavity
T or F, Peritoneal fluid secreted by the two membranes
True
What does the peritoneal fluid do?
The serous fluid lubricates the mobile digestive organs allowing them to glide easily across one another as they carry out their activities.
What is peritonitis? What 3 things can cause it?
Inflammation of the peritoneum, may occur when one:
1) suffers a piercing wound of the abdomen
2) a perforating ulcer
3) a ruptured appendix
What is Ascites?
The condition characterized by the accumulation of peritoneal fluid
What are the peritoneal folds?
Located in the peritoneum. They are large folds that weave between the viscera. They are unlike pericardium and pleurae which smoothly cover the heart and lungs
What is the example of a peritoneal fold?
Greater Omentum which hangs loosely from the transverse colon and small intestine.
What is the mesentery?
Another example of a peritoneal fold which is found in between the small intestine and anchors it to the posterior abdominal wall.
What are the accessory digestive organs?
Salivary glands Pancreas Biliary System (Gallbladder & Liver)
Smooth muscle in GI tract walls maintain constant low level of contractions known as what?
Tone
Tone is important for what 2 things?
- Maintaining a steady pressure on the contents of the GI tract
- Preventing walls from remaining permanently stretched following distention.
