Grade 7 · Body Systems · Digestive and Circulatory Systems
Body Systems Working Together
How cells, tissues, organs and systems build one working body.
Learning objectives
- Order the levels of organisation from cell to organism.
- Describe the main function of six body systems.
- Explain how two systems depend on each other.
NGSS alignment
MS-LS1-3
Use argument supported by evidence for how the body is a system of interacting subsystems composed of groups of cells.
HS-LS1-2
Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms.
MYP criteria
- Criterion A — Knowing and Understanding
- Criterion D — Reflecting on the Impacts of Science
ENGAGE
Running up the stairs
Run up two flights of stairs and your breathing rate, heart rate and skin temperature all change within seconds, without you deciding to change them.
Think about it
- Which body systems just responded?
- Why must these systems communicate with each other?
EXPLAIN
Levels of organisation
- Cell — the basic unit, e.g. a muscle cell
- Tissue — similar cells working together, e.g. muscle tissue
- Organ — several tissues with one main job, e.g. the heart
- Organ system — organs cooperating, e.g. the circulatory system
- Organism — all systems together
| System | Main function | Depends on |
|---|---|---|
| Digestive | Breaks food into absorbable nutrients | Circulatory to carry nutrients away |
| Respiratory | Exchanges oxygen and carbon dioxide | Circulatory to transport gases |
| Circulatory | Transports gases, nutrients and wastes | Respiratory and digestive |
| Nervous | Detects change and coordinates responses | Muscular to produce the response |
| Muscular and skeletal | Support and movement | Nervous for signals, circulatory for fuel |
| Excretory | Removes wastes and balances water | Circulatory to deliver blood to kidneys |
Systems thinking
No system works alone. If one fails, others are quickly affected, which is why doctors treat the whole body and not one organ.
Watch
Human Body Systems Overview
Amoeba Sisters · 10 min
Connects all the major systems into one working body.
Before you watch: Which two systems do you think cooperate most closely?
- Give one example of two systems depending on each other.
- Which system coordinates all the others?
Interactive simulation · PhET
Neuron
Stimulate the neuron and watch ions move across the membrane to create a signal.
While you explore
- What moves to create the signal?
- How does this connect the nervous system to the muscular system?
Key vocabulary
- Tissue
- A group of similar cells doing the same job.
- Organ system
- A group of organs that work together on one big job.
Practice questions
0/2 correct
Level 1 · Criterion A
Place these in order from smallest to largest.
Level 2 · Criterion A
Which pair of systems works together to deliver oxygen to muscle cells?
MYP criterion tasks
Level 3 · Criterion D
A person with severe kidney failure also develops problems with their heart and bones. Explain how this shows that body systems are interdependent.
Reflect & track
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