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7.1: Planning

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

  • Blood pressure is an important indicator of how hard the heart is working to circulate blood, through the body. High blood pressure can lead to health problems.
  • Friction builds up resistance in blood vessels, contributing to an elevation of blood pressure.
  • The endocrine and the nervous systems provide feedback that regulates basic functions, such as breathing, heart rate, and blood pressure.


In Section 5 students investigated how veins control the direction of blood flow with valves. In this section students explore the question of how the body controls the amount of blood passing through the blood vessels. They investigate how a control system of the body regulates pressure and resistance, and complete an activity introducing the concept of negative feedback. These systems control basic body functions, such as breathing, heart rate, and blood pressure. Students then measure their own blood pressures using a sphygmomanometer and cuff or a blood pressure meter.



explain the idea of pressure, resistance, and flow of blood through the heart and the blood vessels

demonstrate chat narrower tubes have more resistance than wider tubes, thus decreasing rate of flow, and relate this finding to vessels in the human circulatory system.

compare “systolic” and “diastolic” blood pressure readings.

identify the effects of a specific change on the regulation of a system.

graph the results of the activity dealing with negative feedback.

explain how a control system can regulate a body function.


blood pressure, controllers, endocrine system, friction, hypertension, negative feedback, nervous system, pressure head, resistance, sensors

Student Materials

Activity 6-1: Pressure, Resistance, and Flow

  • Activity Report
  • 2 large containers or beakers; 2 equal lengths of flexible tubing of different inside diameters; Clamp; Metric ruler; Plastic bottle; Tape; Large nail; Water; Sink or container to collect water

Activity 6-2: How a Controller Works

  • Activity Report
  • Resources 1,2, and 3
  • Water bath (1,000ml beaker); Thermometer; Crushed ice in container; Hot plate or other heat source; Paper towels

Teacher Materials

Activity 6-1: Pressure, Resistance, and Flow

  • Activity Report Answer Key
  • Materials for cleanup

Activity 6-2: How a Controller Works

  • Activity Report Answer Key
  • Additional supply of water, ice, and towels; Examples of other controllers, such as a thermostat (demonstration); Extension cords; Hot pads
  • Diagram of the brain showing hypothalamus, pons, and medulla

Advance Preparation

See Activities 6-1 and 6-2 in the Student Edition.

Part A: Find tubing with differing diameters. The diameters must be different enough to clearly demonstrate a difference in the rate of flow.

Part B: Collect plastic gallon milk bottles ahead of time.

Activity 6-2: How a Controller Works

Be sure to have a custodian confirm that the electrical outlets will handle electrical load.

Prepare containers of ice water in advance.

Position hot plates so the cords are not a hazard.

Interdisciplinary Connections

Language Arts/Arts or Health Education Create a poster describing high blood pressure as a cardiovascular risk factor.

Math Develop and solve math problems connecting pressure and resistance.

Social Studies Contact the American Heart Association for demographic data on vascular disease which can be used to construct graphs.

Enrichment Activity

Enrichment 6-1: Your Blood Pressure

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