TRANSPORT AND DEFENSE Chapter 12 Lesson 1

Essential Questions How do nutrients enter and leave the body? How do nutrients travel through the body? How does the body defend itself from harmful invaders?

New Vocabulary Organ System Homeostasis Nutrient Calorie Lymphocyte Immunity

The Body’s Organization Your body is composed of different organ systems working together to perform specific tasks.  These provide movement, transport substances, etc.  Organ systems maintain homeostasis (steady internal conditions) when external conditions change.

Digestive System Digestion – how the human body breaks down food  Food enters the digestive system through the mouth  The esophagus connects the mouth to the stomach (a flexible baglike organ that contains enzymes that break down food into smaller parts to be used by the body).

Digestive System The small intestine has 2 functions  Digestion  Absorption of nutrients The liver makes bile and the pancreas makes enzymes  Both break down food in the small intestine

Digestive System The large intestine receives solid waste from the small intestine.  It absorbs excess water from the waste material The rectum of the large intestine stores the solid waste until it is expelled from your body (When you go to the bathroom)  Some foods like insoluble fiber, are not digested and leave the body through the rectum

Excretory System Removes liquid and gas waste from the body Organs included:  Lungs, skin, liver, kidneys, ureter, bladder, urethra Liver – breaks down proteins  Forms urea, which is toxic to the body Kidneys – remove urea from the body by making urine

Excretory System Urine then leaves the kidneys through the ureter and stored in the bladder (flexible sac)  Urine is removed from the body through the urethra