Pancreas, Liver, GB and Small and Large Intestine

Pancreas Only gland to produce enzymes to digest: Amylase – carbs Lipase – fats Proteinase – proteins When chyme enters the duodenum the hormone cholecystokinin is released to signal the release of pancreatic juice Hormones also produced by the pancreas Insulin Glucagon

Gallbladder Bile made by liver is stored in gallbladder Bile storage sac (bile produced in liver) Cholecystokinin signals the gallbladder to release bile Gallstones are crystallized cholesterol which can cause blockages

Liver Largest gland in the body Connected to the gallbladder via the common hepatic duct Can regenerate if part of it is damaged or removed

Metabolic Functions of the Liver Store glycogen Convert glycogen to glucose Create new glucose Metabolise: proteins, carbs & lipids Detoxifies drugs and alcohol Decomposes red blood cells Makes bile

Bile Produced by cells in the liver Composition is Yellow/green color – not an enzyme Salt Cholesterol Electrolytes Function— emulsify fats by physically breaking large fat globules into smaller ones Breakdown Red Blood cells

Small Intestine The body’s major digestive organ Site of nutrient absorption into the blood Muscular tube extending from the pyloric sphincter to the ileocecal valve Suspended from the posterior abdominal wall by the mesentery

Subdivisions of the Small Intestine Duodenum Attached to the stomach Curves around the head of the pancreas Finishes digestion – pancreas and GB attached

Subdivisions of the Small Intestine Jejunum Attaches anteriorly to the duodenum 2/5ths of absorption Ileum Extends from jejunum to large intestine 3/5ths of absorption

Small Intestine Anatomy Villi – increase surface area Villi—fingerlike structures formed by the mucosa Microvilli—tiny projections of the plasma membrane (create a brush border appearance) Circular folds (plicae circulares)—deep folds of mucosa and submucosa

Small Intestine Physiology All about absorption and transporting the nutrients to the blood stream Peristalsis moves the chyme through the SI to the LI through the ileocecal sphincter

Small Intestine Physiology Mucus – secreted by cells for easy passage and to help absorption Peptidase – breaks down protein Sucrase – breaks down sugars Lipase – splits fats

Large Intestine Larger in diameter, but shorter in length, than the small intestine Frames the internal abdomen Reabsorption of water and electrolytes

Large Intestine Anatomy Cecum—saclike first part of the large intestine – attached to SI by ileocecal valve Appendix No digestive purpose lymphatic tissue that sometimes becomes inflamed (appendicitis) Hangs from the cecum

Large Intestine Anatomy Colon Ascending—travels up right side of abdomen Transverse—travels across the abdominal cavity Descending—travels down the left side Sigmoid—enters the pelvis (S shaped) Rectum and anal canal —also in pelvis

Large Intestine Anatomy Anus—opening of the large intestine External anal sphincter—formed by skeletal muscle and under voluntary control Internal involuntary sphincter—formed by smooth muscle These sphincters are normally closed except during defecation

Large Intestine Anatomy No villi present Banded muscles Mucus – lubricate for feces passage Haustra (pocketlike sacs) – pouches for holding fecal material

Large Intestine Physiology Little to no digestive function Vitamin B and K – bacteria living in LI produce these vitamins Reabsorb water, vitamins and minerals

Large Intestine Physiology Peristalsis and mixing occur 2-3 times a day Mass Movement – movement of material happens in large sections that constrict at once Defecation reflex – forces out rectum when sphincter relaxes