Hierarchy of an Organism

What is the hierarchy of organisms?

The way living things are organized, from simple to complex.

What is the correct order of organization in multicellular organisms?

Cells → Tissues → Organs → Organ systems.

What is the simplest level of organization in living things?

The cell.

How many cells do unicellular organisms have?

One.

What do cells in multicellular organisms do?

They are specialized (differentiated) to perform different functions.

What are the four types of tissue in the human body?

Epithelial, connective, nervous, and muscular.

What does epithelial tissue do?

Lines the body’s surfaces, absorbs and excretes substances, and protects the body.

How are skin cells arranged in epithelial tissue?

In an overlapping pattern to keep out invaders.

What does connective tissue do?

Supports and connects parts of the body.

What protein is found in connective tissue?

Collagen, a strong, fiber-like protein.

What does nervous tissue do?

Sends messages between the brain and the rest of the body.

What helps nerve cells send messages quickly?

They are long and connected end-to-end.

What are glial cells?

Cells that support nerve cells and help form protective myelin.

What is a nerve impulse?

A signal sent through nerves from the brain to the body or vice versa.

What does muscle tissue do?

Allows the body to expand, contract, and move.

What are voluntary muscles?

Muscles you control, like those used to move arms and legs.

What are involuntary muscles?

Muscles that work automatically, like those in your stomach or heart.

What’s special about heart muscle tissue?

It never gets tired and pumps blood for your entire life.

What is an organ?

A structure made of one or more types of tissue working together.

What is an organ system?

A group of organs that work together to do a specific job.

How many organ systems are in the human body?

11 organ systems.

What is homeostasis?

Keeping the internal environment of the body stable and balanced.

What does it mean when your body tells you it needs food or water?

It’s trying to maintain homeostasis.

What do all cells in the body have in common?

They all have the same DNA but use different parts of it depending on their function.

What is a tissue?

A group of similar cells working together to do the same job.

What is an organ?

A structure made up of different types of tissue working together.

Give an example of an organ and the tissues it may include.

The heart has muscle, connective, and nervous tissues.

What is the function of the muscular system?

Movement of the body and internal organs.

What is the function of the nervous system?

To send and receive signals to control body functions.

What is the function of the circulatory system?

To carry oxygen, nutrients, and waste throughout the body.

What is the function of the respiratory system?

To exchange oxygen and carbon dioxide with the environment.

What is the function of the digestive system?

To break down food and absorb nutrients.

What is the function of the skeletal system?

To support the body and protect internal organs.

What is the function of the immune system?

To protect the body from disease and infection.

What is the function of the excretory (urinary) system?

To remove waste from the body.

What is the function of the endocrine system?

To produce hormones that regulate body processes.

What is the function of the integumentary system?

To protect the body (includes skin, hair, and nails).

What is the function of the reproductive system?

To produce offspring and pass on genetic material.

What is the importance of organ systems working together?

They maintain homeostasis and allow the body to function properly.

What happens if one organ system fails?

It can affect the function of other systems and disrupt homeostasis.