Integuementary System
This organ is the largest in the human body and serves as the primary barrier of the integumentary system to protect internal tissues from pathogens and injury.
What is the skin?
This hard internal framework provides structural support for the body and protects vital internal organs like the brain, heart, and lungs.
What is the skeletal system (or skeleton)?
This body system consists of specialized tissues that contract and relax to enable body movement, maintain posture, and circulate fluids.
What is the muscular system?
Recognized as the fundamental building block of life, this is the smallest structural and functional unit capable of carrying out all life processes independently.
What is a cell?
Along with the skin, these two structures made of keratin form accessory organs of the integumentary system to protect fingers, toes, and insulate the head.
What are hair and nails?
These tough, flexible bands of connective tissue attach bones directly to other bones at joints to allow controlled movement.
What are ligaments?
These tough, cord-like bands of connective tissue attach skeletal muscles directly to bones to pull on them during movement.
What are tendons?
When a group of similar cells work together to perform a specific function—such as muscle, connective, or epithelial—they form this next level of organization.
What is a tissue?
When body temperature rises, sweat glands release fluid that cools the body through evaporation to maintain this internal state of balance.
What is homeostasis (or thermoregulation)?
Found inside the cavity of major bones, this soft tissue is responsible for producing red blood cells, white blood cells, and platelets.
What is bone marrow?
Unlike skeletal muscle, which is under voluntary control, these two specialized types of muscle operate involuntarily to pump blood and move materials through internal organs.
What are cardiac muscle and smooth muscle?
Composed of two or more different types of tissues working together to execute a complex job, examples of this level include the heart, stomach, skin, and leaf.
What is an organ?
Specialized sensory receptors located in the skin interact directly with this other body system to receive and respond to stimuli like touch, pressure, and pain.
What is the nervous system?
The skeletal system interacts directly with this system to allow movement, providing rigid leverage points for tissues to pull against when contracting.
What is the muscular system?
Smooth muscle rhythmically contracts through a process called peristalsis to move broken-down food through organs in this other body system.
What is the digestive system?
A group of organs working together to perform major body functions—such as breaking down food or transporting oxygen throughout the body—is known as this.
What is an organ system?
When exposed to sunlight, the skin synthesizes Vitamin D, which allows the digestive system to absorb this essential mineral needed by the skeletal system.
What is calcium?
To maintain chemical homeostasis, the skeleton stores and releases this critical mineral required for nerve signal transmission and heart contractions.
What is calcium?
To maintain homeostatic internal body temperature when exposed to cold, skeletal muscles undergo rapid, involuntary contractions to generate heat through this process.
What is shivering?
At the highest level of this hierarchy, multiple organ systems work together in unison to create a single, complete living individual capable of maintaining homeostasis.
What is an organism?