Nutrition Digestive System Homeostasis Process by which organisms

Nutrition & Digestive System Homeostasis Process by which organisms maintain a relatively stable internal environment.

Food and Nutrition Why do we eat food? Cells convert chemical energy stored in the sugar glucose and other molecules into ATP. Energy in food is measured by the amount of heat given off by the food. We measure this in calories. One calorie is the amount of heat needed to raise the temperature of one gram of water by 1 degree Celsius. Calorie (capital C) is the energy stored in food. One Calorie is equal to 1000 calorie or 1 kilocalorie kcal.

Nutrients- Substances in food that supply the energy and raw materials your body uses for growth, repair and maintenance. The nutrients that the body needs are: Water, Carbohydrates, fats, proteins, vitamins, and minerals Water is the most important of all! Every cell in the human body needs water because of many of the body’s processes.

Nutrients continued Carbohydrates- Main source of energy for the body. Sugar found in fruit, honey and sugar can are simple carbohydrates. Monosaccharides and disaccharides Complex carbohydrates those found in pasta, potatoes and other starches Polysaccharides Fats or lipids. Fats are formed from fatty acids and glycerol. Your body cannot make all the fatty acids it needs. These can be found in vegetable oils. Fats are used to produce cell membranes

Dehydration Synthesis of a Disaccharide

Hydrolysis of a Disaccharide

Fatty Acid Structure Fatty Acid • Carboxyl group (COOH) forms the acid. • “R” group is a hydrocarbon chain Synthesis of a Fat Glycerol

Nutrients continued Proteins- supply raw materials for growth and repair of structures such as skin and muscle. Proteins have regulatory and transport functions. Insulin controls sugar levels Hemoglobin transports oxygen Another example of maintaining homeostasis! Examples of proteins? (Contains Nitrogen) Vitamins- Organic molecules that help regulate body processes, often working with enzymes. Minerals- Inorganic nutrients that the body needs, usually in small amounts. Organic vs Inorganic? Organic contains Carbon and Hydrogen

Proteins What are the building blocks of proteins? ? ? Amino Acids! Formation of a Dipeptide Dehydration synthesis Amino group Carboxyl group Alanine Serine

Organic not organic? CO 2 ______ H 2 O _______ C 6 H 12 O 6 ________ HCl _______

Process of Digestion Purpose of digestion- break food down into small molecules that can be passed to the cells that need them The digestive system includes the mouth, pharynx, esophagus, stomach, small intestine, and large intestine. Accessory structures are salivary glands, pancreas, and the liver. They add secretions to the digestive system.

Mouth Digestion starts in the mouth with mechanical digestion with chewing. Also chemical digestion happens here with digestive enzymes. Teeth – mechanical digestion cutting tearing and crushing food. Saliva- Created by salivary glands, moisten food make it easier to chew. Contains enzyme amylase. Amylase- breaks chemical bonds between the sugar monomers in starches.

How do human teeth reflect an omnivorous diet?

Esophagus Esophagus- Food tube into the stomach. The reason food can travel through the esophagus into the stomach is because of peristalsis. Food is moved along by contractions of smooth muscle surrounding the esophagus. Peristalsis- Rhythmic muscular contractions that squeeze food through the esophagus into the stomach. http: //www. nlm. nih. gov/medlineplus/ency/a natomyvideos/000097. htm

Stomach is a large muscular sac. The size enables you to eat a few large meals a day. Mechanical digestion in the stomach Contractions of its smooth muscles churn and mix the food you swallow. After churning and mixing stomach fluids and food it becomes chyme. Chemical digestion in the stomach The lining of the stomach contains millions of microscopic gastric glands that release substances. Some produce mucus others hydrochloric acid. Very acidic which activates pepsin. Pepsin is an enzyme that breaks down proteins.

More about the stomach Powerful acids released into the stomach can sometimes damage the lining producing a hole. This would be a peptic ulcer. Usually peptic ulcers caused from bacteria not stomach acid.

Pancreas and Liver As chyme is pushed from the stomach to the small intestine it first enters the duodenum. The first of three parts of the small intestine. Small intestine is the location where most of the chemical digestion happens. As chyme enters the duodenum is mixes with enzymes and digestive fluids from the pancreas and liver.

Pancreas and Liver Pancreas- Has 3 important functions (2 for digestion) 1. Produce hormones that regulate blood sugar. 2. Produces enzymes to break down carbs, proteins, lipids, and nucleic acids. 3. Produces sodium bicarbonate, a base which neutralizes stomach acid. Allows enzymes to work. Acid can change the shape. (lock and key) Liver- Produces bile, a fluid loaded with lipids and salts. Dissolves the droplets of fat found in fatty foods. Bile is stored in the gallbladder.

Small Intestine The small intestine absorbs NUTRIENTS. The folded surfaces of the small intestine are covered with projections called villi. The surfaces of the cells of the villi are covered with thousands of fingerlike projections known as microvilli. LOTS OF SURFACE AREA!! More surface area allows absorption of nutrients.

Large Intestine aka colon Is shorter, but wider, than the small intestine. The main job of the large intestine is to remove water from the undigested material that is left. Colonies of bacteria grow on the undigested material left in the colon that help with the digestive process.

The Excretory System

Excretion Every cell in the body produces metabolic wastes to maintain homeostasis the body must rid of the waste products. Excretion is the process by which metabolic wastes are eliminated. Organs: Skin, lungs, and kidneys are the main components of the excretory system.

The Kidneys Main organs involved with excretion are the 2 kidneys. A tube called the ureter leaves each kidney carrying urine to the urinary bladder where it is stored. The kidneys remove urea, excess water, and other waste produces from the blood and is collected as urine. Cleans the blood! Filtration.

Control of kidney function The kidneys play an important role in maintaining homeostasis. They regulate the water content of the blood, volume, p. H level and remove waste products from blood.