Transcript Digestive System PPT

Essentials of Human Anatomy & Physiology
Seventh Edition
Elaine N. Marieb
Chapter 14
The Digestive System and
Body Metabolism
Slides 14.1 – 14.14
Lecture Slides in PowerPoint by Jerry L. Cook
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
The Digestive System and Body
Metabolism
 Ingestion – taking in food
 Digestion
 Breakdown of food; Absorpt.of nutrients
into blood stream
 Chemically (enzymes)/Mechanically
 Metabolism
 Production of cellular energy (ATP)
 Constructive and degradative cellular
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.1
Organs of the Digestive System
 Two main groups
 Alimentary canal – continuous coiled hollow
tube
 Accessory digestive organs
 Ex. Liver, gall bladder, pancreas
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.2a
Organs of the Digestive System
Figure 14.1
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.2b
Organs of the Alimentary Canal
 Mouth
 Pharynx
 Esophagus
 Stomach
 Small intestine
 Large intestine
 Anus
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.3
Mouth (Oral Cavity) Anatomy
 Lips (labia), Cheeks
 Hard palate – forms
the anterior roof
 Soft palate – forms
the posterior roof
 Uvula – fleshy
projection of the
soft palate
Figure 14.2a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.4
Mouth (Oral Cavity) Anatomy
 Oral cavity – area
contained by the
teeth
 Tongue – attached at
hyoid and styloid
processes of the
skull, and by the
lingual frenulum
Figure 14.2a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.5
Mouth (Oral Cavity) Anatomy
 Tonsils
 Palatine tonsils
 Lingual tonsil
Figure 14.2a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.6
Processes of the Mouth
 Mastication (chewing) of food
 Mix food w/ saliva
*Salivary Amylase – Enzyme digest
Starches (bread,potato,etc)
 Tongue initiates swallowing
 Sense of taste
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.7
Esophagus
 Runs from pharynx to stomach through
the diaphragm
 Conducts food by peristalsis
(slow rhythmic squeezing)
 Passageway for food only
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.10
Stomach Anatomy
 left side of the abdominal cavity
 Food enters at the esophageal sphincter
 Holds about 1 gallon of food (Full)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.15a
Stomach Anatomy
 Rugae – internal folds of the mucosa
 External regions
 Fundus
 Pyloris
 Lesser curvature
 Greater curvature
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.16a
Stomach Anatomy
 Layers of peritoneum attached to the stomach:
 Lesser/Greater omentum – hangs like a curtain
over small/Lg. intestines - Contains fatinsulates, cushion, protect
 Mesenteries: Binds abdomin. Organs together
and attaches them to back wall of body
Slide 14.16b
Stomach Anatomy
Layers of muscles
at different angles
allow food to be
churned and
PUMMELED!
Figure 14.4a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.17
Stomach Functions
 Acts as a storage tank for food
 Some food breakdown,
 gastric glands = gastric juice
 Chem.digest. Of protein begins
(pepsinogen/pepsin)
 HCl (hydrocholoric Acid!)..
 Acidic Environ. – Activates pepsinogen
& hostile to microorganisms
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.18
Stomach Functions
• The only absorption that occurs in the
stomach is of alcohol and aspirin
• Delivers chyme (processed food) to the
small intestine…”looks like heavy cream”
Propulsion in the Stomach
 The pylorus sends out chyme to small
intestine (30 ml at a time)
 The stomach empties in four to six
hours
Figure 14.14
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.56b
Small Intestine
 *major digestive organ, only process
small amounts at a time.
 *Site of nutrient absorption into the blood
 Suspended from the posterior abdominal
wall by the mesentery
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.21
Subdivisions of the Small Intestine
 Duodenum =1st
section off stomach
 10 inches; Curves around pancreas
 Bile & pancreatic ducts enter
 Jejunum = 2nd section
 8 ft long.
 Ileum= 3rd section
ends at Lg intest. (12ft)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.22
Chemical Digestion in the Small
Intestine
 Enzymes are mixed with chyme
 From: Gall Bladder (bile=lipid digest.)
Intestinal cells
*Pancreas
 (lipid/protein enzymes)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.23a
Digestion in the Small Intestine
 Pancreatic enzymes play the major digestive
function (continued)
 Responsible for fat digestion (lipase)
 Digest nucleic acids (nucleases)
*Alkaline content neutralizes acidic
chyme
*Why is this important!?!
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.57b
Absorption in the Small Intestine
 Water is absorbed along the length of
the small intestine-90% of H20 intake
absorbed in small intest.
 End products of digestion
 Most substances are absorbed by active
transport through cell membranes
 Lipids are absorbed by diffusion
 Substances are transported to the liver
by the hepatic portal vein or lymph
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.59
Chemical Digestion in the Small
Intestine
Figure 14.6
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.23b
Small Intestine – digestion/absorption
 Villi - Fingerlike
structures give the
sm. Intest.more
surface area
 Microvilli – small
projections of
plasma membrane
on absorptive cells
Slide 14.24
Structures Involved in Absorption of
Nutrients
 Absorptive cells
 Blood capillaries
Figure 14.7b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.26
Large Intestine
Larger diameter, but
shorter length! (than
small intestines)
Slide 14.28
Functions of the Large Intestine
 Absorption of water
 Eliminates indigestible food from the
body as feces
 Does not participate in digestion of food
 Goblet cells produce mucus to act as a
lubricant
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 14.29
Rectum
• Last section of colon (large
intestines)
• eliminate feces
• undigested materials
– extracellular waste
» mainly cellulose
from plants
» roughage or fiber
• masses of bacteria