Creative Cuisine Notes: Proteins, Water, Carbohydrates, Fats, Digestion, Absorption.
3/31/08 Digestive System Chapter 22 – Day 4. 3/31/08 Large Intestine – Digestion Digestion of...
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Transcript of 3/31/08 Digestive System Chapter 22 – Day 4. 3/31/08 Large Intestine – Digestion Digestion of...
3/31/08
Digestive System
Chapter 22 – Day 4
3/31/08
Large Intestine – DigestionDigestion of Macromolecules Lipids (Fats):
♦Fats are broken up into smaller globules♦Emulsification requires bile♦Fats → Fatty Acids (monoglycerides): needs lipase
Nucleic Acids♦DNA (or RNA) → pentose sugars + nitrogen compounds:
needs nuclease (then they are absorbed)
Small compounds are then ready for absorption♦90% of absorption in S.I. via villi
HOW ARE THEY ABSORBED??
3/31/08
Large Intestine – Digestion Emulsified fats = Micelles
♦Micelles are absorbed into epithelial cells via simple diffusion♦Inside epithelial cells
•Recombining & repackaging takes place•Fatty acids + monoglycerides = triglycerides•All lipids combine together
◦Triglycerides + cholesterol + phospholipids = coated with a special protein
•Protein package of lipids in the epithelial cells = chylomicron•Enters lacteal (or Peyer’s patches) → lymph → veins →
heart → liver♦Inside liver – chylomicrons are broken down → lipids are released →
next step = solubilization of lipids♦Lipids are attached to Lipoproteins which are then distributed to the
body via the blood stream (HDL)♦These compounds travel through lymph via chylomicron because of
solubility issues
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Large Intestine – Digestion Remaining materials move to large intestine Structural Features
♦Ileum opens into L.I via the ileocecal pshincter → contents enter L.I.
♦First structure in L.I. = cecum (blind pouch)♦Appendix is attached to the surface of the cecum
•Contents of the intestine can enter the appendix
♦contains lymphoid tissue♦Takes care of cellulose digestion in animals
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Large Intestine – Digestion From cecum L.I. extends up = ascending colon Extends horizontally = transverse colon Extends down = descending colon
Fig. 22.22
Turns in = sigmoidal colon Tube goes towards anus =
rectum Anus = opening to release
wastes♦Guarded by a sphincter
3/31/08
Large Intestine – Digestion Folds of L.I. = haustra (pouches) Histology:
♦Inside = no villi♦Columnar cells with goblet cells
Peristalsis churns food, moves it through the L.I. Thick bands of
longitudinal muscle♦Taeniae coli
Eventually, food
moves into rectum
Fig. 22.23
3/31/08
Large Intestine – Digestion Chyme remains in L.I. for 3-10 hours Digestion is completed
♦Amino acids are broken down by bacteria♦Carbohydrates are fermented
•Gases are formed:◦ N2, CO2, methane, & H2 = flatus
Absorption is completed♦Large amount of H2O is absorbed
♦Vitamin K & B vitamins are absorbed
Gas accumulation♦= Flatulence♦Smell is due to methane gas
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Large Intestine – Digestion Material not absorbed = semi-solid at the end
♦=FECES
Contains materials that were not absorbed and waste products
Accumulates in rectum Activates pressure-sensitive receptors in rectum
♦Leads to contraction of rectum walls (muscles)♦Shortens rectum, increases pressure
Exit through anus – via sphincter Voluntary control = relaxation of sphincter
♦Aided by abdominal muscles
Fig. 22.24
3/31/08
Large Intestine – Digestion
Fig. 22.24
3/31/08
Large Intestine – Common Problems Diarrhea & Constipation Diarrhea: not enough water is absorbed in L.I. Constipation: too much water absorbed in L.I. Diarrhea:
♦Usually caused by bacteria that irritate mucosa
♦Chyme moves too quickly for adequate H2O absorption
Constipation:♦Less H2O or fiber in diet
♦Water is limited so larger % absorbed compared to remaining in feces
♦Need more fluid and fiber in diet
3/31/08
Large Intestine – Common Problems Diarrhea & Constipation Diarrhea: not enough water is absorbed in L.I. Constipation: too much water absorbed in L.I. Diarrhea:
♦Usually caused by bacteria that irritate mucosa
♦Chyme moves too quickly for adequate H2O absorption
Constipation:♦Less H2O or fiber in diet
♦Water is limited so larger % absorbed compared to remaining in feces
♦Need more fluid and fiber in diet
3/31/08
Problems in Digestive System Hemorrhoids, Appendicitis, Colon cancer, Ulcers,
Liver problems (hepatitis & cirrhosis) Hemorrhoids:
♦Affects rectum & anus♦Varicose veins in rectal walls♦Damaged valves in veins♦Accumulation of blood – causes blood vessel to protrude♦Damage to valves is caused by pressure against veins:
•Pushing during delivery or during pregnancy (or constipation)
•Can be surgically removed
Fig. 22.22
3/31/08
Problems in Digestive System Appendicitis:
♦Inflammation of the appendix♦Usually caused by obstruction:
•Foreign body, feces, tumor
♦If not removed it can burst & cause other problems♦Symptoms:
•Waves of abdominal pain on right, then becomes steady
•May experience:◦ Vomiting◦ low-grade fever◦ Increase in WBC count
Fig. 22.22
3/31/08
Problems in Digestive SystemUlcers Erosion of epithelial lining in the GI tract Forms a lesion → eats through tissue layers Causes
♦Excess acid production•i.e. hypersecretion of gastric juices
♦Reduced mucus secretion•i.e. hyposecretion of alkaline mucus
♦Bacteria or stress•Which enhance hyper- or hyposecretion
Commonly occur in the duodenum or stomach (=gastric ulcer)
Fig. 22.22
3/31/08
Problems in Digestive SystemUlcers Symptoms
♦Severe pain, usually 1-4 hours after eating♦Weight loss♦Bleeding
Treatment♦Antacids♦Zantac (aluminum coat)♦Surgery♦Lifestyle changes
Fig. 22.22
3/31/08
Problems in Digestive SystemLiver Problems Cirrhosis
♦Liver cells become inflamed or sever damage, then destroyed
♦Cells cannot regenerate to full extent♦Hepatocyte tissue gets replaced by fibrous tissue♦Causes:
•Damage by:◦ Toxins, Inflammation, Metabolic problems
•Hepatitis can lead to cirrhosis•Most common cause = alcoholism•Bile duct problems
♦Treatment•Depends on cause•Prevent further damage
Fig. 22.22
3/31/08
Problems in Digestive SystemLiver Problems Hepatitis
♦Caused by a virus – Hepatitis A or Hepatitis B, C & D, E♦Contaminated water with Feces♦Sexual transmission♦Food
Symptoms♦Fever♦Tiredness♦Sore muscles♦Yellowing of the skin = accumulation of bilirubin
Fig. 22.22
3/31/08
MetabolismColon Cancer Common cancer of the G.I. tract Tumor formation in the large intestine = polyps Polyps may be benign or malignant Usually in the rectum or sigmoidal colon Polyps must be removed and analyzed for cancer
cells – biopsy Symptoms of polyps:
♦Pain, cramps, blood in stool
Detected by colonoscopy♦http://www.mayoclinic.com/health/colonoscopy/MM00010
Fig. 22.22
3/31/08
Metabolism After digestion & absorption: glucose, lipids etc. Chemical reactions take place in cells
♦Process of cellular metabolism Nutrients in the cell
♦Can either be broken down further by the process of catabolism♦Or they can be joined together to form new larger molecules by the
process of anabolism Catabolic processes – release energy
♦Mitochondria = location for numerous catabolic activities Energy
♦40% ATP, 60% heat (released back into environment) ATP: helps to maintain cellular activities & governs
anabolism (anabolic processes require energy) Big picture: process of metabolism is essential for
homeostasis
Fig. 22.22
3/31/08
Metabolism
Fig. 23.1
3/31/08
Metabolism
Fig. 23.2