Body Basics
Circulatory
Systems & Functions
Structures
Systems Working Together
100

This is the basic unit of life that makes up the human body.

Cell

100

This organ pumps blood throughout the body.

Heart

100

This system breaks down food and absorbs nutrients.

Digestive

100

These tiny blood vessels allow exchange of materials between blood and tissues.

Capillaries

100

The respiratory system brings this gas into the body for cells to use.

Oxygen

200

Cells working together form this level of organization.

Tissue

200

These vessels carry blood away from the heart.

Arteries

200

This system uses hormones as chemical messengers.

Endocrine

200

This structure is the main site of gas exchange in the lungs.

Alveoli

200

The digestive system provides these two things to the circulatory system for transport to cells.

Nutrients and water (especially nutrients absorbed during digestion)

300

Tissues working together form these structures.

Organs

300

These vessels return blood to the heart.

Veins

300

This system removes wastes and helps maintain the body's internal balance.

Excretory

300

The bone marrow found inside bones performs this important function.

Blood cell production (hematopoiesis)

300

Muscles need oxygen and nutrients delivered by this system to support their activity.

Circulatory system

400

These structures are made of different types of organs working together.

Organ systems

400

Name the four chambers of the human heart.

Right atrium, right ventricle, left atrium, left ventricle

400

This system includes the skin and helps protect the body while also contributing to temperature regulation.

Intergumentary

400

The trachea, lungs, and alveoli are associated with this system.

Respiratory system

400

The nervous and endocrine systems both help coordinate the body, but one primarily uses electrical signals while the other uses these chemical messengers.

Hormones

500

Put these in order from simplest to most complex: organ, cell, organ system, tissue.

Cell → tissue → organ → organ system

500

Explain how arteries, veins, and capillaries differ in their roles.

Arteries carry blood away from the heart; veins return blood toward the heart; capillaries are tiny vessels where exchange occurs.

500

Identify the system responsible for defense against pathogens and explain why the lymphatic system is important to it.

The lymphatic and immune systems help defend the body against pathogens; the lymphatic system is involved in immune defense and fluid balance.

500

This system provides support, protects organs, produces blood cells, and works with muscles to allow movement.

Skeletal system

500

Explain why the body's organ systems cannot be considered completely independent of one another.

Because the systems depend on one another to accomplish functions such as obtaining nutrients and oxygen, transporting materials, removing wastes, coordinating activities, protecting the body, and maintaining the body's overall functioning. Organ Systems work as an interconnected team rather than in isolation.

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