The Digestive System

Nutrition Nutrition is the study of how food affects

the function of living organisms. Food contains nutrients. If cells don’t have nutrients, they don’t

function correctly. Poor diet = poor cells. There are six general categories of

nutrients.

Six Nutrient CategoriesEnergy

SuppliersCarbohydratesLipidsProteins

Regulatory Nutrients

WaterVitaminsMinerals

2 Factors leading to Nutritional Problems

1) too little physical activity(sedentary lifestyle)

2) Over consumption of foodLeads to obesity

The Digestive System System is responsible for breaking down food

so that it can be absorbed by the bloodstream.

The “alimentary canal” is the pathway which food travels through the digestive system.

The Alimentary Canal Mouth Esophagus Stomach Small intestine Large intestine Rectum

* The liver, pancreas, and gallbladder are parts of the digestive system but are not parts of the alimentary canal.

26 ft long!!!!!!!

The Mouth Chemical (saliva) and mechanical

(chewing) digestion occur in the mouth. Salivary glands produce saliva. Saliva lubricates food. Saliva contains enzyme amylase (starch

digestion).

Esophagus 9.8 in Muscular tube. Leads from back of throat

(pharynx) to the stomach. Opening to trachea (tube)

and esophagus (soft) are right next to each other.

Epiglottis prevents food from going down the wrong tube.

Muscular contractions (peristalsis) pushes food down the esophagus.

Stomach 4 hours Responsible for protein digestion. Chemical and mechanical digestion. Hydrochloric acid and pepsin

(enzyme) break down proteins into amino acids. (pH 1.5-2.5)

Stomach lining contains mucus. Mucus protects stomach from acid. Ulcers Sphincter muscles (cardiac and

pyloric) control what enters and leaves the stomach.

Small Intestine 20 ft. long. The first part of the small

intestine is called the “duodenum.”

Remaining carbo’s and proteins are broken down.

All lipids are digested in S.I.

Gall bladder. (stores bile from the liver & delivers to the S.I.)

Duodenum connects to liver and pancreas.

Liver and PancreasSecrete Digestive Enzymes

LIVER JOBS Detoxifies drugs and

alcohol Secretes bile into

duodenum. Bile breaks down

lipids. Bile is stored in the

gall bladder.

PANCREAS JOBS Regulates blood

sugar. Releases digestive

enzymes into duodenum.

Neutralizes stomach acid before it enters S.I.

Small Intestine (cont.) After all nutrients are

digested from food, they are absorbed into the blood.

S.I. contains lots of capillaries.

Mesentary.

Large Intestine All proteins, carbos, and

lipids have been removed from food by the time it gets here.

Water in food is absorbed into the blood.

Vitamins are absorbed into the blood.

Whatever food is left is “fecal” matter and passes out the rectum and anus.

Feces is undigested food.

Excretory System Kidney

Clean the blood Vital role in maintaining homeostasis Removes waste Regulate amount of water in blood

Nephrons- blood cleaning units Forms urine Urine contains nitrogenous waste

products, excess amounts of water and solutes.

~1 Liter of urine produced each day.

Reabsorption Returns important substances to the

blood.Second process of urine formation

Kidney Disorders & Treatment ~ 13 million people suffer form kidney

disorders in the US. Kidney stones-

Uric or oxalic acid, calcium salts, etc. collect outside of kidneys

Hemodialysis- Filtering of blood. Receive 2x’s a week