DIGESTIVE SYSTEM

Lilian Gonzalez

Sean-Paul Gouw

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.