Opening

LAUNCH · SCIENCE · Lesson 3 of 7

Can you design a route with no wrong turn?

Learning intention

Explain how heart structure supports double circulation and calculate cardiac output from supplied data.

Mission: follow blood through two linked circuits.

A correct route needs both destination and direction.

Success looks like

Trace the body–heart–lungs–heart–body route with named chambers and vessels.
Explain valves and the thicker left-ventricle wall using function.
Calculate output with correct units and state a limitation of the constructed data.

Retrieval

LAUNCH · SCIENCE · Lesson 3 of 7

Direction, exchange and rate

R1. Where does blood gain oxygen from air?

R2. What does a per-minute rate include?

R3. Does a larger pressure mean the same thing as a larger volume?

I do

LAUNCH · SCIENCE · Lesson 3 of 7

Trace the full double circuit

Body → right heart → lungs → left heart → body.

Arteries go away; veins return towards the heart.

Two linked circuits, one continuous route

Diagram description

Schematic double circulation: body→right heart→lungs→left heart→body. Blue-labelled paths carry relatively oxygen-poor blood; red-labelled paths carry relatively oxygen-rich blood. Colour is accompanied by text. The positions are not anatomical.

I do

LAUNCH · SCIENCE · Lesson 3 of 7

Explain structure using its job

Atria receive; ventricles pump out.

The septum separates the two sides.

The left ventricle generates higher systemic pressure.

Atria receive; ventricles pump out

Diagram description

Simplified four-chamber map. The body’s right side is shown on the left of the image. Blood passes from each atrium to its ventricle, with a septum separating sides. The thicker left-ventricle outline represents a thicker muscular wall, not a larger volume per beat.

I do

LAUNCH · SCIENCE · Lesson 3 of 7

Separate the pump from the valve

Muscle contraction changes pressure.

Valves open or close as pressure differences change.

They help prevent backflow.

A valve permits forward flow and limits backflow

Diagram description

Two-panel simplified valve model. Left: a forward pressure difference opens leaflets, permitting flow. Right: reverse pressure closes leaflets, opposing backflow. Valves do not provide the pumping energy.

We do

LAUNCH · SCIENCE · Lesson 3 of 7

Route engineering desk

Go to interactive investigation

W1. Match the four named vessels to their routes.

Add the missing atrium→ventricle steps.

Schematic adult double-circulation route.
Journey segment	Major vessel
Body → right atrium	Vena cava
Right ventricle → lungs	Pulmonary artery
Lungs → left atrium	Pulmonary veins
Left ventricle → body	Aorta

My response — say it, sketch on paper or type

Route engineering: trace, calculate, challenge

Original flow models and constructed pump records.

Decision 1 of 3

Where does right-ventricle blood go next?

Choose, test, then explain together. Evidence diagrams appear only after your test. Diagram transitions explain the model; they do not represent real elapsed time. Use Pause model to stop transitions and model controls, or your device’s reduced-motion setting. The printed We do activity provides the paper route.

We do

LAUNCH · SCIENCE · Lesson 3 of 7

Pump data challenge

W2. Calculate output for P and Q.

Check both heart rate and stroke volume.

Constructed pump records; not pupil measurements.
Record	Beats/min	mL/beat
P	80	55
Q	100	70

My response — say it, sketch on paper or type

We do

LAUNCH · SCIENCE · Lesson 3 of 7

Repair the wall claim

W3. “The thicker left ventricle proves it always pumps more blood than the right.”

Replace volume with the relevant mechanism.

My response — say it, sketch on paper or type

Hinge

LAUNCH · SCIENCE · Lesson 3 of 7

Which definition survives the lung route?

Choose the accurate statement.

You do

LAUNCH · SCIENCE · Lesson 3 of 7

Produce a route-and-pump brief

Choose your response route.

Show the route, a structural reason and one calculation.

My response — say it, sketch on paper or type

You do

LAUNCH · SCIENCE · Lesson 3 of 7

Make every arrow explain something

Name the vessel and direction.

Keep pressure, volume and rate distinct.

My response — say it, sketch on paper or type

Review

LAUNCH · SCIENCE · Lesson 3 of 7

Audience checks the exception

L1. Share one vessel claim.

Audience asks: “Would it still work for the pulmonary vessels?”

My response — say it, sketch on paper or type

Review

LAUNCH · SCIENCE · Lesson 3 of 7

A route and a calculation need units

A correct name tells us where blood goes.

A correct unit tells us what the number measures.

My response — say it, sketch on paper or type

Exit

LAUNCH · SCIENCE · Lesson 3 of 7

Three useful checks

E1. Which chamber pumps blood to the lungs?

E2. Why is the left-ventricle wall thicker?

E3. Calculate 60 mL/beat × 90 beats/min.

My response — say it, sketch on paper or type

Exit

LAUNCH · SCIENCE · Lesson 3 of 7

Next useful step

Vessel direction • chamber route • pressure • output units.

My response — say it, sketch on paper or type

Continue within this stage’s shared time.

My science task sheets

Choose one route with your teacher. Shared evidence and the exit sheet appear in every route. Your work stays here while the page is open; save it before closing.

Shared evidence | Route and pump records

The route is a simplified adult circulation map. Pump numbers are constructed for learning.

Journey segment	Major vessel
Body → right atrium	Vena cava
Right ventricle → lungs	Pulmonary artery
Lungs → left atrium	Pulmonary veins
Left ventricle → body	Aorta

Pump record	Heart rate (beats/min)	Stroke volume (mL/beat)
P	80	55
Q	100	70

Cardiac output = heart rate × stroke volume. 1 L = 1000 mL. Atria receive blood; ventricles pump blood out. The two sides are separated by the septum.

W1. Trace the route. W2. Calculate both outputs. W3. Repair: “The thicker left ventricle proves it always pumps more blood than the right.”

Supported route | Follow the blood

Use the vessel table and calculator if needed.

S1. Complete a full route from body back to body, including lungs and the four chambers.S2. Explain why the pulmonary artery is an artery even though its blood is relatively oxygen-poor.S3. Calculate output for P and Q. Give one result in both mL/min and L/min.S4. Explain one valve action and why the left-ventricle wall is thicker.

Standard route | Route-and-pump explanation

Use scientific names, mechanisms and units.

M1. Trace body→lungs→body through the named vessels and chambers. Explain the septum’s role.M2. Explain how chamber-wall thickness and valves support the circulation, separating pressure from output.M3. Calculate both constructed outputs and their difference, with units.M4. Evaluate: “The faster pulse alone proves more blood is pumped each minute.” State what else is needed.

Stretch route | Test the pump interpretation

Optional transfer. A constructed record R has 120 beats/min and 35 mL/beat. A record S has 70 beats/min and 70 mL/beat.

T1. Calculate both outputs. Which is greater? Explain why heart rate alone misleads.T2. A faulty valve permits some backflow. Why might total chamber movement overestimate useful forward output?T3. Explain why long-term unequal left/right outputs would be a problem for a linked circulation.T4. A technician reports “5400 beats/min output”. Correct the quantity/unit error without diagnosing a person.

Exit and reflection | A direction and a quantity

Keep pressure, volume and time distinct.

E1. Which chamber pumps to the lungs?E2. Explain the thicker left-ventricle wall using pressure.E3. 60 mL/beat × 90 beats/min: show output and units.L1. What did your audience ask? Improve one route or calculation label.

Next useful step Define vessels by direction. Trace all four chambers. Explain pressure and valves. Calculate output with units.