Organ Systems

Organ Systems

Middle School

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Learning Objectives

• Describe the levels of organization in the human body, from cells to systems.

• Define homeostasis and explain its role in keeping the body’s environment stable.

• Identify the major organ systems that make up the human body.

• Describe the main functions of organ systems and how they cooperate.

Key Vocabulary

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Cell

The most basic structural and functional unit of all living organisms.

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Tissue

A cluster of similar cells that group together to perform a specialized function.

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Organ

A distinct structure made of two or more tissue types working for a common function.

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Organ System

A group of organs that work together to perform major functions in the body.

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Homeostasis

The process by which the body maintains a stable, constant internal environment or condition.

Levels of Organization

• The cell is the most basic unit of life in the human body.

• Similar cells work together to form tissues.

• Tissues form organs, and organs create organ systems.

Multiple Choice

What is formed when two or more different types of tissues work together?

• A cell

• An organ

• An organ system

• An organism

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The Four Basic Types of Tissues

Structure & Movement

• ​Connective tissue connects and supports different body parts to provide the body's overall structure.

• ​​Muscle tissue has the unique ability to contract, which allows our bones and body to move.

• ​Connective tissue includes a wide variety of types, from bones and cartilage to blood.

Protection & Communication

• ​Epithelial tissue covers body surfaces to protect organs, and aids in secretion and absorption.

• ​​Nervous tissue acts as the body's command center, carrying signals between the brain and nerves.

• ​It allows the brain to communicate with other parts of the body for coordinated function.

Multiple Choice

Which type of tissue is responsible for carrying electrical signals throughout the body?

• Connective tissue

• Epithelial tissue

• Muscle tissue

• Nervous tissue

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What Is Homeostasis?

• Homeostasis keeps your body's internal environment stable and balanced.

• All organ systems work together to maintain this crucial internal balance.

• Hormones and the endocrine system play a very large role in regulation.

• If homeostasis fails, an organism can get sick or even die.

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Multiple Choice

What is the primary consequence if the body fails to maintain homeostasis?

• The body will grow stronger.

• The person may get sick and die.

• The endocrine system will shut down.

• The body will no longer need hormones.

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Digestive & Circulatory Systems

Digestive System

• Takes in and breaks down food, and absorbs the nutrients your body needs.

• It is responsible for removing and eliminating all the solid waste from the body.

• Includes the mouth, stomach, liver, pancreas, and small and large intestines.

Circulatory System

• Transports nutrients, gases like oxygen and carbon dioxide, and wastes through the blood.

• Blood is circulated to and from the heart to all parts of the body.

• Consists of the heart, arteries, veins, and capillaries that carry the blood.

Multiple Choice

Which system is primarily responsible for breaking down food and absorbing its nutrients?

• Circulatory System

• Respiratory System

• Digestive System

• Nervous System

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Nervous & Respiratory Systems

Nervous System

• This system is the body's command center, controlling thought, movement, and sensation.

• It consists of the brain, spinal cord, nerves, and various sense organs.

• It detects environmental changes and signals the body on how to properly respond.

Respiratory System

• This system's primary function is to control breathing and exchange gases in the lungs.

• The main parts include the nasal cavity, the trachea, and the lungs.

• It works to take in oxygen and release waste gases from the body.

Multiple Choice

Which system acts as the body's command center to control thought, movement, and other activities?

• Respiratory System

• Nervous System

• Digestive System

• Circulatory System

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Musculoskeletal & Excretory Systems

Musculoskeletal System

• ​This system provides the body’s frame, giving it shape and support.

• ​​It is also responsible for protecting our internal organs and enabling movement.

• ​It consists of bones, muscles, cartilage, tendons, ligaments, and our joints.

Excretory System

• ​The main function of this system is to remove waste from the body.

• ​​This process helps the body maintain a stable internal balance called homeostasis.

• ​It includes the kidneys, bladder, lungs, sweat glands, and the liver.

Multiple Choice

What is the primary function of the musculoskeletal system?

• To remove waste from the body

• To transport nutrients and gases

• To provide shape, support, and movement

• To control sensation and thought

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Reproductive & Immune Systems

Reproductive System

• This system is responsible for producing specialized cells, specifically egg cells in females and sperm cells in males.

• It transports and sustains these cells and provides a nurturing environment for any developing offspring before birth.

• This system also produces hormones, which are the body's chemical messengers that regulate growth and development.

Immune System

• This system's primary function is to defend and protect the body against diseases and harmful foreign infections.

• It is composed of a complex network that includes white blood cells, antibodies, and the lymphatic system.

• Other major components of this system include the spleen, tonsils, and bone marrow, which produce blood cells.

Multiple Choice

Which system is responsible for producing hormones and creating egg and sperm cells?

• Immune System

• Reproductive System

• Excretory System

• Musculoskeletal System

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Common Misconceptions

Misconception	Correction
Organs are made of only one type of tissue.	Organs are made of two or more different types of tissues.
Organ systems work independently of each other.	Organ systems work together to maintain homeostasis.
Homeostasis is only about maintaining body temperature.	Homeostasis includes temperature, blood sugar, water balance, and waste removal.

Multiple Choice

After a meal, the digestive system absorbs nutrients into the bloodstream. Which system is then responsible for transporting these nutrients to all the cells in the body?

• The nervous system

• The respiratory system

• The circulatory system

• The excretory system

Multiple Choice

Why is the partnership between the nervous system and the musculoskeletal system essential for an action like kicking a ball?

• The nervous system provides the energy, and the muscles provide the structure.

• The nervous system sends the signal to move, and the muscles contract to create the movement.

• The muscles decide when to move, and the nervous system provides the support.

• The nervous system removes waste, and the muscles absorb nutrients for the action.

Multiple Choice

A person is exercising heavily, causing their body to heat up and produce waste products like CO₂ more quickly. Analyze how at least two organ systems would work together to restore homeostasis.

• The digestive system absorbs more nutrients while the immune system fights off infection.

• The reproductive system produces hormones while the musculoskeletal system provides support.

• The nervous system signals the digestive system to slow down and the circulatory system to speed up.

• The excretory system releases heat through sweat, and the respiratory system expels more CO₂.

Multiple Choice

If a person's kidneys (part of the excretory system) were to fail, predict the most likely immediate consequence for the circulatory system.

• The circulatory system would transport more oxygen to compensate.

• The circulatory system would become overloaded with waste products that can't be filtered out.

• The circulatory system would stop transporting nutrients to other cells.

• The circulatory system would direct more blood to the lungs to be cleaned.

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Summary

• The body is organized in a hierarchy from cells to organisms.

• All systems work together to maintain homeostasis, a stable internal balance.

• Key systems handle digestion, circulation, breathing, and nervous control.

• Other systems provide movement, remove waste, fight disease, and allow reproduction.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

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• 3

• 4