INTRODUCTIONo Digestion is important for breaking down food into nutrients
o Food is broken down into smaller molecules
o The body uses this for energy, growth, and cell repair
ORGANS Digestive Tract (GI)-long,
twisted tube Starts at the mouth and ends
at the anuso Organs that make up the GI
tract are: mouth, esophagus, stomach, Small Intestine, Large Intestine (includes the rectum and anus)
o Digestive Organs include: liver, pancreas, and gallbladder are the solid organs of the digestive system
pancreasproduces enzymes to digest proteins & starch
stomachkills germs break up fooddigest proteinsstore food
mouthbreak up fooddigest starchkill germsmoisten food
liverproduces bile
- stored in gall bladderbreak up fats
SMALL INTESTINE Composed of three sections (duodenum,
jejunum, and ileum) Site of absorption of nutrients
types: passive absorption, facilitated absorption, active absorption, and endocytosis (phagocytosis and pinocytosis)
Huge surface area with modified structures called villi and microvilli
Villi - fingerlike projections of mucosa, contains blood capillaries and lacteals (small lymph capillaries)
Microvilli - tiny projections on cell membranes of absorptive (brush border) cells that contain enzymes (brush border enzymes) used to complete digestion
LARGE INTESTINE Function-absorbs water from the
remaining indigestible food matter and transmit the useless waste material from the body.
Three sections: ascending, transverse, and descending colon
Site of water absorption and packaging waste material
Associated with the colon is the appendix
STAGES OF DIGESTION1.Ingestiono Food is taken to the alimentary canalo Process that takes place in the mouth (chewing, grinding, and
swallowing)
- Chemical effects of saliva are released from the salivary glands
- Swallowing of food sends it to the digestive tract
2. Digestion
Process by which food is broken down in the earlier stages of the alimentary canal into a form it can be absorbed into the tissues of the body.
2 types:
Mechanical (chewing ,grinding, mixing) & Chemical (enzymes/acids)
3. Absorption/Assimilation-uptake of fluids by the tissues of the body, chemicals from food taken into the cells of the body
4. Elimination-excretion of metabolic waste products
HOMEOSTASIS Regulating pH levels Glucose regulation Absorbed into blood and taken to liver through hepatic portal vein When digestion is complete, the body is in a post-absorptive state, glucose
levels fall.
Caloric imbalance can help lose or gain weight
Hormones Gastrin
-Stomach
-Stimulates gastric acid production Secretin
- In lower small intestine
- Regulates small intestine acidity Motilin
-Lower small intestine
-Increase pepsin production
HOMEOSTASIS Affected by hormones the Endocrine system produces
-Cells secrete hormones in response to certain stimuli Ex: stomach acid from burning small intestine
Transport -Passive Transport Tea bags Dissolved nutrients move through walls of small intestine
and blood vessels using energy
-Active Transport Chewing (muscle contraction) uses energy ATP –to transport digested material across the
membrane
WHY DOES THE DIGESTIVE SYSTEM NEED ENZYMES?
Enzymes break down large food molecules into smaller ones
• Special enzyme in the mouth(amylase) helps break down starch into smaller pieces
Speed up the process of digestion by lowering the activation energy for the reaction
Work at body temperature Digestion can occur naturally at body
temperature, however this process takes a very long time as it happens at such a slow rate.
Mouth-Carbohydrates are broken down by amylase into maltose and then move down the esophagus
Duodenum- disaccharides are broken down into monosaccharides by enzymes called: maltase, sucrose, and lactase
Stomach-proteins are broken down into peptides, which are then broken down into a single amino acid
Lipids- are digested mainly in the small intestine by bile salts through (emulsification)
• Lipases divide lipids into fatty acids
HUMANS VS. EARTHWORMS DIGESTIVE SYSTEM
Earthworm (digestive system)-a simple tube of specialized tissues that can absorb nutrients
CELIAC DISEASE:DISORDER THAT OCCURS IN
THIS SYSTEM The immune reaction to eating
gluten creates an inflammation damaging the Small intestine’s lining
Symptoms: pain in the abdomen/joints, diarrhea, bloating, vomiting, heartburn, cramping
Prevent: eating a gluten-free diet
Treatments: prescription-folic acid &gluten-free diet
1% of the population
WORKS CITED "IB Guides." IB Biology Notes. N.p., n.d. Web. 25 May 2015. Mader, Sylvia S. Biology. 10th ed. New York: McGraw Hill, 2007. "Overview of the Digestive Process." Digestive Processes. N.p.,
n.d. Web. 23 May 2015. Smith, Margaret E., and Dion G. Morton. The Digestive System.
Edinburgh: Churchill Livingstone, 2001. Print. Taylor-Butler, Christine. The Digestive System. New York:
Children's, 2008. Print. "The Digestive System Diagram, Organs, Function, and More."
WebMD. WebMD, n.d. Web. 23 May 2015. Windelspecht, Michael. The Digestive System. Westport, CT:
Greenwood, 2004. Print. "Your Digestive System and How It Works." Your Digestive
System and How It Works. N.p., n.d. Web. 23 May 2015.