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3.1: Planning

Difficulty Level: At Grade Created by: CK-12
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Key Ideas

  • The heart is divided into four chambers—two “pumps” with two chambers each. One pump sends blood to the lungs for oxygen and back to the heart. The other pump sends the oxygenated blood throughout the body.
  • The cardiac (heart) cycle is made up of two parts—squeeze and fill. The fill part of the cycle is called diastole. The squeeze part of the cycle is called systole. In systole the heart contracts, forcing blood out. In diastole the heart expands or relaxes, filling the heart with blood. So the heart is always following this cycle-fill, squeeze, fill, squeeze or diastole, systole, diastole, systole.
  • The pacemaker is a specialized region of the heart which, in combination with the nervous system and the endocrine system, helps to maintain homeostasis.


Students explore how the heart pumps blood by building on their initial exploration of the circulatory system in Section 1. They dissect a mammalian heart, which is similar in structure to their own. Then they use a siphon pump to investigate how the heart functions as a double pump. Both of these activities help students learn that the heart is divided into four chambers—actually two “pumps” with two chambers each. One pump takes in blood from the body and sends it to the lungs for oxygen. The other pump takes in blood from the lungs and sends it throughout the body. Students discover that their heart pumps cyclically in a cardiac cycle. In other words, the heart pumps in a cardiac cycle from the time the blood enters the heart until it leaves the heart. The cardiac cycle is made up of a fill part (diastole) and a squeeze part (systole). The cardiac cycle is constant—fill-squeeze-fill-squeeze—or—diastole-systole-diastole-systole.



\begin{align*}\checkmark\end{align*} describe the structure of the \begin{align*}4-\end{align*}chambered heart.

\begin{align*}\checkmark\end{align*} describe the function of the \begin{align*}4-\end{align*}chambered heart.

\begin{align*}\checkmark\end{align*} explain how the heart works as a double pump.

\begin{align*}\checkmark\end{align*} demonstrate the path blood takes through the heart.

\begin{align*}\checkmark\end{align*} describe the cardiac cycle.


aorta, aortic valve, arteries, atrium, bicuspid valve, cardiac output, coronary arteries, diastole, heart rate, inferior vena cava, pacemaker, pericardium, pulmonary artery, pulmonary valve, pulmonary vein, siphon pump, stroke volume, superior vena cava, systole, tricuspid valve, veins, ventricle

Student Materials

Activity 2-1: Exploring the Heart

  • Activity Reports 1, 2, and 3
  • Animal heart (sheep, cow, or pig); Tweezers; Scalpel; Scissors; Probes; Apron or smock; Plastic disposable gloves; Dissection pan; Paper towels; Plastic bag

Activity 2-2: Siphon Pump

  • Activity Report
  • Siphon pump (available at Marine Stores—Tempco fuel pump); Siphon pump, split lengthwise; \begin{align*}2\end{align*} large containers (i.e., buckets, dishpans, etc.), filled \begin{align*}\frac{3}{4}\end{align*} with water; Inlet and outlet hoses—supplied with pump; Siphon hose with bulb

Teacher Materials

Activity 2-1: Exploring the Heart

  • Activity Reports Answer Keys
  • Newspaper to protect working surface.
  • Container for used heart specimens
  • Soap and paper towels
  • Charts and other visuals showing the heart and circulation of blood

Activity 2-2: Siphon Pump

  • Activity Report Answer Key
  • A pump split lengthwise so that the valves are visible; Towels or sponges to clean up water spills; Models students produced in Activity 1-1

Advance Preparation

See Activities 2-1 and 2-2 in the Student Edition

Activity 2-1: Exploring the Heart

Purchase disposable gloves or obtain gloves donated by a local hospital, clinic, or doctor/dentist office.

Order mammalian hearts such as cow, pig, or sheep. Contact a local butcher to make sure you can obtain hearts. Or you can order prepared dissection materials from the following.

Carolina Biological Supply Company, 2700 York Rd., Burlington, NC 27215. Call 1-800-334-5551.

Activity 2-2: Siphon Pump

Order the siphon pumps. Purchase siphon pumps from a marine store or from Tempco Products. Cut convenient lengths of plastic tubing to be used for siphons. The pumps are the ones used to pump fuel on boats. Using a saw or sharp knife, split one pump lengthwise so students can observe the valves inside. Collect \begin{align*}2\end{align*} buckets or dishpans for each lab station.

Display constructed models from Activities 1-1 and 1-2 and a siphon pump (Activity 2-2).

Interdisciplinary Connections

Music Compare the rhythm of a heartbeat to a piece of music. Explain similarities and differences.

Language Arts Describe in writing the sequence of events that must happen to pump blood through the heart.

Art Draw a diagram or paint a picture of a mammalian heart. Label the parts of the heart.

Drama Pantomime the circulation of blood through the heart by walking through a large heart diagram marked on the floor with masking tape.

Enrichment Activity

Enrichment 2-1: What Makes the Heart Beat Faster?

Students observe the effects of the hormone epinephrine (adrenaline) on the beating heart of a brine shrimp by counting the number of times the brine shrimp legs pulse per minute.

Obtain the adult brine shrimp from an aquarium store. (The pulsating blood is not noticeable in newly hatched shrimp.) They can be stored in a container in the refrigerator for a few days without food or a water change. Daphnia, or water fleas, can be used in place of brine shrimp. They need to be ordered from a science supply house. Since they need to be kept alive with special food, the specified delivery date must be close to the date of the activity. It is difficult to keep these critters alive for long periods of time. Also order epinephrine.

Carolina Biological Supply Company, 2700 York Rd., Burlington, NC 27215. Call 1-800-334-5551.

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