Lecture 22 Notes 2014.pdf

11 Pages
Unlock Document

University of Toronto Scarborough
Michael Inzlicht

1Lecture 22 The Intestines Pancreas and Liver1 The Small IntestineThe stomach empties into the small intestine through the pyloric valve The small intestine itself consists of three main sections The duodenum is the small section closest to the pyloric valve about 30 cm long Chyme from the stomach enters the duodenum as do digestive enzymes from the pancreas and bile from the liver and gallbladder The jejunum follows the duodenum and is much longera little over a meter The ileum is the final section of the small intestine it is approximately 15 meters long and connects via the illeocecal valve to the large intestine The small intestine is the predominant site of nutrient absorption with the vast majority of nutrient absorption occurring within the first 20 The small intestine is anatomically designed for large rates of absorption The inner wall of the small intestine contains numerous protrusions called villi which face into the lumen of the intestine Each villus contains an artery a vein capillaries and a blindended lymphatic lacteal The villi enhance the surface area available for absorption The available surface area is increased even further as the villi themselves are covered with smaller protrusions called microvilli There can be thousands of microvilli on a single intestinal epithelial cell In between the villi are large pits called crypts of Lieberkuhn which also enhance the surface area available for absorption They contain cells that produce bicarbonate and release it into the intestinal lumen This is necessary to decrease the acidity of the stomach contents entering the small intestine Many intestinal enzymes ie from the pancreas cannot function in an acidic environment therefore the bicarbonateinduced alkalinisation of the intestinal lumen is critical for enzymatic digestion Surface epithelial cells in the intestine are replaced every 35 days meaning that millions of intestinal cells are shed each day 22 The Large IntestineThe large intestine is connected to the small intestine via the illeocecal sphincter which itself leads into a small region of the large intestine called the cecum The cecum connects to the colon the area of the intestine in which the final process of waterion absorption occursAlso attached to the cecum is the appendix a small vestigial part of the intestine It has no know function in digestion in humans The colon itself consists of the ascending colon on the right side of the body transverse colon the descending colon on the left side and the sigmoid colon which leads to the rectum Finally the rectum empties via the anus the opening of which is under the control of and external and an internal anal sphincter 3 Disorders of the Large IntestineThe appendix can become blocked by digested foodstuffs which can cause inflammation and infection This is called appendicitis and should the appendix rupture the resulting bacterial infection throughout the body cavity peritonitis is usually fatal
More Less

Related notes for RLGB10

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.