Pencernaan Faal
Pencernaan Faal
Pencernaan Faal
Hardian
Department of Medical Physiology Diponegoro
Topik perkuliahan
Figure 23.2
Hardian - Department of Medical Physiology Diponegoro
Gastrointestinal Tract Activities
Deglutition – swallowing
Propulsion – swallowing and peristalsis
Peristalsis – waves of contraction and relaxation of
muscles in the organ walls
Digestion:
Mechanical digestion – chewing, mixing, and
churning food
Chemical digestion – catabolic breakdown of
food
Figure 23.9a
Hardian - Department of Medical Physiology Diponegoro
Saliva: Source and Composition
Food is ingested
Mechanical digestion begins (chewing)
Propulsion is initiated by swallowing
Salivary amylase begins chemical breakdown of
starch
The pharynx and esophagus serve as conduits to
pass food from the mouth to the stomach
Tongue
Uvula
Pharynx Bolus
Epiglottis
Epiglottis
Glottis
Longitudinal muscles
contract, shortening
passageway ahead of bolus
Gastroesophageal
sphincter closed Stomach
(d) (e)
Hardian - Department of Medical Physiology Diponegoro
Stomach
Chemical
breakdown
of proteins
begins and
food is
converted to
chyme
Figure 23.19
Hardian - Department of Medical Physiology Diponegoro
Motion of Small Intestine
Myenteric reflexes
Pacesetter Cells
Located in muscularis mucosae and muscularis
externa:
Surrounding lumen of digestive tract
Peristalsis
Consists of waves of muscular contractions
Moves a bolus along the length of the digestive
tract
Peristaltic Motion
1. Circular muscles contract behind bolus:
While circular muscles ahead of bolus relax
2. Longitudinal muscles ahead of bolus contract:
Shortening adjacent segments
3. Wave of contraction in circular muscles:
Forces bolus forward
Segmentation
Cycles of contraction:
Churn and fragment the bolus
Mix contents with intestinal secretions
Does not follow a set pattern:
Does not push materials in any one direction
Figure 23.3
Hardian - Department of Medical Physiology Diponegoro
Peristaltic and segmentation Initial State
Longitudinal
muscle
Circular
muscle From To
mouth anus
Contraction
Figure 23.3
Hardian - Department of Medical Physiology Diponegoro
The Small Intestine
Duodenal Glands
Also called submucosal glands or Brunner glands
Produce copious quantities of mucus:
When chyme arrives from stomach
Figure 23.24c, d
Hardian - Department of Medical Physiology Diponegoro
Composition of Bile
Cholecystokinin causes:
The gallbladder to contract
The hepatopancreatic sphincter to relax
Figure 23.25
Hardian - Department of Medical Physiology Diponegoro
Pancreas
Location
Lies deep to the greater curvature of the stomach
The head is encircled by the duodenum and the tail
abuts the spleen
Exocrine function
Secretes pancreatic juice which breaks down all
categories of foodstuff
Acini (clusters of secretory cells) contain zymogen
granules with digestive enzymes
Figure 23.26a
Hardian - Department of Medical Physiology Diponegoro
Composition and Function of Pancreatic Juice
Examples include
Trypsinogen is activated to trypsin by
enteropeptidase (enterokinase)
Procarboxypeptidase is activated to carboxypeptidase
Active enzymes secreted
Amylase, lipases, and nucleases
These enzymes require ions or bile for optimal
activity
Figure 23.28
Hardian - Department of Medical Physiology Diponegoro
Digestion in the Stomach
The stomach:
Holds ingested food
Degrades this food both physically and chemically
Delivers chyme to the small intestine
Enzymatically digests proteins with pepsin
Secretes intrinsic factor required for absorption of
vitamin B12
Figure 23.29a
Hardian - Department of Medical Physiology Diponegoro
Large Intestine: Microscopic Anatomy
Figure 23.29b
Hardian - Department of Medical Physiology Diponegoro
Bacterial Flora
Haustral contractions
Slow segmenting movements that move the
contents of the colon
Haustra sequentially contract as they are stimulated
by distension