Transcript Basic Digestion

Body Cells
Form tissues
Tissues form Organs
Organs form Systems (e.g., digestive)
Turnover
Require energy, adenosine triphosphate
Require nutrients
Cell Membrane
Double layers of lipid, CHO, and protein
Controls passage of substances
Distinct identification structures
Organelles
Cytoplasm
Mitochondria—Power plant
Major site for energy production
Nucleus
DNA
Endoplasmic reticulum - communication network
Rough endoplasmic reticulum - protein synthesis
Smooth endoplasmic reticulum -fat synthesis
Organelles
Golgi Complex
Packaging site for protein
Lysosomes
Cell’s digestive system
Peroxisomes
Detoxify harmful chemicals
Four Types of Tissues
Epithelial
Lines the outside surfaces and external passages
Connective
Holds structures together
Muscle
Able to contract
Nervous
Transport nerve impulses
Circulatory System
Heart and blood vessels
Systemic circuit
Pulmonary circulation
Lymphatic system
Blood
Blood Circulation
Cardiovascular System
Heart to the lungs
Arteries
Capillaries
Veins
Portal Circulation
Transports nutrients
From the small intestine
Delivers to the liver
Allow liver to process nutrients before returning it to
the bloodstream
Exchange of Nutrients
Insert Fig. 3-4
Exchange of Nutrients
Insert Fig. 3-4
The Digestive System
Digestive System
Mouth to anus
Epithelium lines the lumen
Barrier to invaders
Submucosal layer
Muscularis
Taste and smell
The Mouth
Mastication
Saliva
Enzymes to help breakdown simple sugars
Mucus to lubricate the food for easier swallowing
Lysozyme to kill bacteria
Tongue
Taste receptors
Enzymes to help breakdown fatty acids
The Esophagus
Long tube
Connects pharynx to the stomach
Epiglottis prevents choking
Peristalsis, muscle contraction
Lower esophageal sphincter
Heartburn
The Stomach
Lower esophageal sphincter and pyloric sphincter
Capacity of ~4 cups
Secretion of acid, enzymes, and intrinsic factor
Holds food for 2-4 hours
Formation of chyme
Mucus layer prevents autodigestion
Physiology of the Stomach
Stomach Acid
Destroys activity of protein
Activates digestive enzymes
Partially digests dietary protein
Assists in calcium absorption
Makes dietary minerals soluble for absorption
The Small Intestine
The walls are folded
Villi projections are located on the folds
Absorptive cells are located on the villi
Increases intestinal surface area by 600x
Rapid cell turnover
The Small Intestine
Nutrient Absorption
Passive diffusion
Active absorption
Phagocytosis and pinocytosis
Nutrient Absorption
The Large Intestine
~3 1/2 feet in length
No villi or enzymes present
Little digestion occurs
Indigestible food stuff
Absorption of water, some minerals, vitamins
Contains bacteria
Formation of feces for elimination
Rectum
Stool remains
Stimulates elimination
Muscle contraction
Anal sphincters
Movement Along the Intestine
Peristalsis
A ring of contraction propelling material along the
GI tract
Mass movement
Peristaltic wave that contracts over a large area of
the large intestine to help eliminate waste
Movement
Site of Absorption
Accessory Organs
Pancreas
Gallbladder
Liver
The Liver
Produces bile
Enterohepatic circulation
The Pancreas
Manufactures digestive enzymes
Produces glucagon and insulin
Secretes pancreatic juices
Bicarbonate needed to neutralize chyme
Storage Capabilities
System of maintaining reserves
Adipose tissue
Glucose
Amino acids in the blood
Vitamins and minerals in the liver
Calcium in bones