Presentation is loading. Please wait.

Presentation is loading. Please wait.

Digestive Physiology The primary function of the digestive system is move nutrients from the external environment into the body.

Similar presentations


Presentation on theme: "Digestive Physiology The primary function of the digestive system is move nutrients from the external environment into the body."— Presentation transcript:

1 Digestive Physiology The primary function of the digestive system is move nutrients from the external environment into the body

2 Outline Digestion & Absorption of nutrients
Secretion of digestive chemicals Regulation of Digestion Regulation of Metabolism

3 Digestion & Absorption of Protiens
Proteins digested in stomach & small intestine Proteins are broken into smaller peptides & amino acids by: 1) Pepsin: Stomach 2) Trypsin & chymotrypsin: SI 3) Exopeptidases: SI 3) Peptides/Amino Acids are absorbed in SI by: 1) Cotransport then Antiport with H+ 2) Cotransport then Antiport with Na+ 3) Transcytosis via vesicles

4 Digestion & Absorption of Fats
Emulsified fats are digested by Lipase & Colipase End products move into SI wall 1) Monoglycerides & fatty acids: simple diffusion 2) Cholesterol: NPC1L1 transporter 5) End products are re-comined in absoptive cells to form Chylomicrons 6) Chylomicrons travels through lymph to body

5 Digestion & Absorption of Carbohydrates
Carbs digested in mouth & SI Complex Carbs are digested into Disaccharides by amalyase & alpha-amylase Maltose, Sucrose, Lactose 3) Disaccharides are digested into Monosacch. By: 1) Maltose by Maltase to glucose 2) Sucrose by Sucrase to glucose + fructose 3) Lactose to Lactase to glucose + galactose 4) Monosaccharides can FINALLY! be absorbed 1) Glucose & Galactose via Na+-glucose Symporter 2) Fructose via Glut5 & Glut2 transporter Na+-Glucose Symporter Glut5 Glut2

6 Absorption of Vitamins, Ions, Minerals, Water
Vitamins: Fat-Soluble (A, D, E, K) – transported with fats Water-Soluble (C, B) – mediated transport Minerals: Ca2+ (hormonally controlled ion channels/Active transport) – used everywhere Iron (???)- needed for RBC Ions: Na+ - active transport, symport, antiport Water: Follows Na+ & other absorbed solutes by Osmosis

7 Secretion: Salivary Glands
Parotid, Sublingual, & Submandibular glands secrete Saliva Saliva contains Alpha-amylase (carbs), lingual lipase (fats)

8 Secretion: Stomach * * Acid Secretion
1) Protein in food activates enteric nervous system 2) Gastric enzymes activate a variety of pathways 3) Secretion of H+ & Pepsinogen Pepsinogen converted to Pepsin by H+ Surface Mucosa Gastric Glands Vasculature * Muscle * Drugs for heartburn & ulcers (Zantac, Pepcid) block Histamine receptors in stomach!

9 Secretion: Pancreas Pancreas secretes Trypsin & Trypsinogen
Pancreatic Duct Small Intestine Pancreas Pancreas secretes Trypsin & Trypsinogen Exopeptidases Amylase Lipase Bicarbonate Ions (raise pH) Pancreatic Enzymes work best at higher pH Acini Cells Islet Cells

10 Secretion: Small Intestine
Villi Crypts with glands Vasculature Small Intestine Muscle Glands with crypts secrete: Amylase, Maltase, Lactase, Sucrase Peptidase Enterokinase (activates trypsin!)

11 Secretion: Bile Bile is secreted by the LIVER Stored in Gall Bladder
Without Bile….fat digestion is very slow

12 Why doesn’t the digestive system digest itself?
Digestive tract is made of cells that can be digested by enzymes! Mucus forms a protective barrier between intestinal walls & acids/bases, enzymes Mucous Cells in Stomach Goblet Cells in Small Intestine Goblet Cell

13 Outline Digestion & Absorption of nutrients
Secretion of digestive chemicals Regulation of Digestion Regulation of Metabolism

14 Regulation of Digestion: Thinking with your stomach
Long Reflexes – CNS Parasympathetic- Increase Digestion Sympathetic – Slow Digestion 2) Short Reflexes – Enteric Nervous System Ingested food and pH trigger self-regulating changes in digestive system Neurons located in walls of digestive system 3) Digestive Peptide (Hormones) Digestive system release several hormones to regulate itself and communicate with brain Autonomics work with the Enteric System to coordinate Digestive Function Digestive Peptides: CCK, Gastrin, Secretin, GIP, Motilin, GLP-1

15 The Liver Bile Production: Fat Emulsification
Processes & Detoxifies Absorbed Products Hepatic Portal System carries products to and from liver 3) Storage: Liver is a major storage site of glucose & some vitamins

16

17 Cholesterol Metabolism
VLDL = Very Low Density Lipoprotien LDL = Low ‘’ IDL = Intermediate ‘’ HDL = High ‘’ LPL = Lipoprotien Lipase (Endothelial Enzyme) CE = Cholesteryl Esters

18 Cholesterol Synthesis
‘Statins’ = Inhibit HMG CoA reductase Reduce Total Cholesterol *

19 Bile Acid Sequestrants
Bile Acids with Fats REMAIN in Digestive Tract Acids + Cholesterol + Triglycerides are Excreted via Feces!

20 Amino Acid Metabolism -Some AA are used by body
-Excess is metabolized by the liver -End product is NH3 or NH4 = TOXIC -NH3 and NH4 repackaged for transport and excretion 1) Urea Cycle 2) Glutamate-Glutamine Transport Kidney excretes urea and NH4 via urine

21 Amino Acid Metabolism Urea, Glutamate and Glutamine carry Ammonia(ium) (NH3, NH4+) to kidney for excretion Glutamine


Download ppt "Digestive Physiology The primary function of the digestive system is move nutrients from the external environment into the body."

Similar presentations


Ads by Google