The Human Body35-1

Body Organization

Body Tissues

• 1) Connective – provides body support and connections

• 2) Epithelial – line exterior body and internal glands and organs

• 3) Nervous – transmits electrical impulses

• 4) Muscle – allows the body to move inside and out

Human Body Systems

Homeostasis

This is a classic example of feedback inhibition/negative feedback. Can you think of another?

Digestion and Excretion

38-1 to 38-3

By the end of this digestion lesson you should be able to:

1) Explain why your body needs food

2) Explain how the digestive system allows you to use your food

3) Describe the path that food takes through your digestive system

4) Explain the functions of the major structures in the digestive system

Why is eating such a vital part of your day?

• Your body needs the fuel (energy) that is can extract from your food

• Your body cells convert the chemical energy stored in your food (calories) into ATP

So why not just eat these all day???

Your balanced diet should include….

The New Food Labels…

• Why not this?

Our body needs nutrients like

• Water

• Carbohydrates

• Fats

• Proteins

• Vitamins

• Minerals

Vitamins:

• Organic molecules that work with enzymes to regulate body processes

• Diets lacking certain vitamins can have serious consequences

• 2 Types: Fat-soluble - A, D, E & K; can be stored for

future use Water-soluble - B varieties, C, Niacin,

Pantothenic acid; can’t be stored in the body

Minerals:

• Inorganic nutrients needed by the body in small amounts

• Ex: Calcium, Iron, Magnesium, Sodium, Potassium

• What are they needed for?

Digestion

• Breaks down food into small molecules that can be used by our cells

• Includes the mouth, pharynx, esophagus, stomach, small intestine, large intestine

• Other helpful structures are the salivary glands, pancreas, and the liver

The Mouth

• Mechanical digestion - the teeth tear and crush food

• Chemical digestion - enzymes break down carbohydrates (amylase) and microorganisms (lysozyme)

THINK ABOUT IT: Where do the enzymes come from?

The Esophagus

• The food tube that the bolus travels through to reach the stomach

• Peristalsis draws the food down

• The cardiac sphincter prevents food from leaving the stomach

The Stomach

• Large muscular sac • Mechanical Digestion - muscle

contractions produce a fluid and food mixture called chyme

• Chemical Digestion - gastric glands release lubricating mucus, hydrochloric acid, and pepsin

• What does pepsin do?

The Small Intestine

• Food enters through the pyloric valve • Most chemical digestion and absorption

occur here• Enzymes from the pancreas, liver and

intestine lining continue to break down food

• Divided into three parts: Duodenum, jejunum, and the ileum

The Small Intestine

Digestion in the Small Intestine

1) Liver - produces bile to digest fats

2) Pancreas -1) Produces enzymes that break down

carbohydrates (amylase), proteins(trypsin), nucleic acids and fats (lipase)

2) Produces the base, sodium bicarbonate that allows the other enzymes to be effective

3) What else does it do?

Absorption in the Small Intestine

• Made of folded surfaces covered with villi that increase the surface area for absorption

• Capillaries line the villi in order to absorb small carbohydrates and proteins

• Lymph vessels absorb some fats• Water, cellulose and undigestible

substances leave the small intestine

The Large Intestine

• Colon

• Removes the water by absorbing it from the remaining chyme

• Bacterial colonies produce compounds for the body like vitamin K

• Wastes are eliminated through the rectum

Food for thought….

1) Write down on a scrap piece of paper the complete meal you ate for dinner last night. List out each part of your meal.

2) Did you consume a balanced diet? Show what nutrients, vitamins and minerals you ate by writing them next to the food they came from. Use pgs. 974-975

3) What enzymes were hard at work in your stomach???

Tonight’s Assignment