Digestive System 3 Flashcards
Where is the pancreas located?
Below the curvature of the stomach
3 Pancreas Parts?
Head, body, tapering tail
Pancreas functions?
99% Exocrine (duct), 1% Endocrine
How many ducts of pancreas?
2 - hepatopancreatic (shared) and accessory duct
6 Components of pancreatic juice?
Sodium bicarbonate, lipase, amylase, trypsin group (proteins), nucleases (nucleic acids), H2O
What is the function of sodium bicarbonate?
Neutralizes stomach’s acidic chyme
What is the function of pancreatic lipase?
Digest fats into glycerol and fatty acids
What is the function of pancreatic amylase?
Break carbs (polysaccharides) into oligosaccharides and disaccharides
Functions of Trypsin?
Digest proteins (polypeptides) into peptides and inactive as trypsinogen until contact with brush-border enzymes
What is the hepatopancreatic ampulla?
Shared duct between pancreas, liver, gall bladder that leads into duodenum regulated by sphincter
What is the process of pancreatic secretions?
- As chyme moves into duodenum, CCK & secretin released into bloodstream. 2. CCK stimulate pancreatic enzymes & secretin stimulates HCO3 juices.
- Bile salts & secretin delivered to liver induce faster bile production.
- CCK induce gallbladder contracts and relaxation of hepatopancreatic sphincter causing bile to enter duodenum.
What digests carbs & where?
Salivary amylase, pancreatic amylase and brush-border enzymes in small intestine
What are carbs made of?
Polysaccharides
How are carbs broken up?
Salivary amylase breaks carbs into smaller components, pancreatic amylase breaks carbs into disaccharides, brush border enzymes sucrose, lactose and maltose into monosaccharides
What is maltose broken into?
Glucose + glucose
What is sucrose broken into?
Fructose + glucose
What is lactose broken into?
Galactose + glucose
What digest proteins & where?
Pepsin - stomach, proteases - pancreas, brush border enzymes - small intestion
What are proteins made of?
Polypeptides
How are proteins broken?
Stomach pepsin breaks polypeptides into peptides, proteases continue fragmentation of peptides, brush-border enzymes split them into tri/dipeptides
What digests fats & where?
Lingual & stomach lipases, pancreatic lipase, bile - SI
What are fats made of?
Fatty acids & Triglycerides
How are carbs absorbed?
Active transport or facilitated diffusion into absorptive epithelial cells of villus and by facilitated diffusion into blood capillary of villus
How are proteins absorbed?
Active transport into absorptive epithelial cells of villus, and by diffusion into blood capillary of villus
How are lipids absorbed?
Preliminary fat digestion begins in the stomach where in the SI pancreatic enzymes and bile separate and stabilize fat into monoglycerides & fatty acids, encased in bile salts salts called micelles and transported by diffusion into epithelium cells by simple diffusion, and once through form into triglycerides again and encased in proteins called chylomicron and exocytosed into lacteals.
4 Sections of large intestine?
Ascending, transverse, descending & sigmoid colon.
Connection with SI?
Joins with ileum at the ileocecal valve which leads into the caecum which attaches at its bottom a twisted tube called the appendix in the lower right corner of abdomen
The LI is lined with what type of epithelium?
Simple columnar & goblet cells
What are Teniae coli?
Group of tri-bands along the entire length of the LI, due to thickened longitudinal muscle forming serial pouches called haustra across the colon
What are 3 Functions of LI?
Absorbing water, electrolytes from indigestible produce, Absorbing vitamins K and B from intestinal bacteria, and producing and eliminating feces
What is the cecum?
Opening from the ileocecal valve that leads to colon
How does the transverse colon move?
Right to left
What is the Sigmoid colon?
S-shaped structure that leads to pelvis
What are the two structures in the anus?
Internal (involuntary sphincter) and external (voluntary sphincter)
What is the mesentry?
Bilayer of peritoneum serosa that attaches the digestive organs to the body wall, hold organs in place and houses the blood vessels of small intestines
What is the mesocolon?
Fixes the colon to the wall of the digestive system
What chemical & mechanical functions occur in the LI?
Mechanically, haustral churning, peristalsis and mass peristalsis breakdown and pass chyme into the rectum, Chemically, bilirubin is broken down and excreted, while gut bacteria ferment carbs, and further digest proteins and amino acids and absorb Vit. K & B.
How are feces formed?
Chyme in the large intestine forms into solid clumps and masses called feces
What is the composition of feces?
Water, inorganic salts, sloughed-off epithelial cells and bacteria
How does the defecation reflex work?
Stretching of anal walls cause stretch receptors to signal the spinal cord which stimulates the contraction of longitudinal rectum muscles and causes the relaxation of the internal involuntary sphincter, and signals brain to to gain consciousness of situation. If defecation is wanted, the external sphincter is also relaxed voluntarily causing defecation, if not feces travel to sigmoid and wait until open.
