Lesson B11: Human Systems: Circulation

Key Ideas     Unit Checklist 

  Video Lesson

How are nutrients and wastes transported around the human body? Watch this video to learn more about the human circulatory system.

 
 

  Lesson B11: Human Systems: Circulation

Figure B.3.11.1 – Cuts and scrapes are injured skin and blood vessels.
Figure B.3.11.2– A bruise forms when capillaries break under the skin.


Figure B.3.11.3– Deep cuts require stitches to hold them closed.
Reading and Materials for This Lesson

Science in Action 8
Reading: Pages 135–140

Materials:
Mini marshmallow, toothpick, timer, 2 identical clear plastic cups, 1 large diameter straw, 1 small diameter straw, sharp knife, BBQ lighter, modelling clay, water, food colouring (optional), shallow glass pan, duct tape or packing tape, newspaper.


Figure B.3.11.4– Platelets in the blood work to stop bleeding.
Scrapes and Bruises
Cuts, scrapes, and bruises occur when blood vessels just under the skin are injured. When both skin and blood vessels are torn, bleeding occurs. When capillaries break under the skin and leak out blood, bruises form.

Blood contains tiny cells called platelets. Platelets clump together to form a clot in a torn blood vessel. The clot stops the wound from bleeding, until the blood vessels repair themselves. A clot turns into a protective scab as the injury heals.

Minor cuts and scrapes can be treated by cleaning the wound with water and applying pressure with a bandage or gauze to stop the bleeding. Deep cuts that don’t stop bleeding quickly require medical attention. Deep cuts may need stitches to close the wound.

 Watch More

Damage Control by the Circulatory System

Watch this video to learn more about blood clotting and wound healing.

 
 
 
 
Why do bruises change colour as they heal? Watch this video to learn more.

 
 
 
 
People often use band-aids to treat minor cuts and scrapes. Watch this video to learn about the invention of the band-aid.

 
 
Figure B.3.11.5– You can check your pulse along the side of your neck.
Figure B.3.11.6– You can feel your pulse on your wrist.


Figure B.3.11.7– Every time the heart beats blood is pumped throughout the body.
Beating Heart

After exercising, you might be able to feel your pulse thumping on the side of your neck. Your pulse is creating by your heart beating. When your heart squeezes blood out of the ventricles, artery muscles in your body expand, which you can feel as a pulse.

A healthy heart pumps blood at a steady rate. The normal resting heart rate of a healthy adult ranges from 60 to 100 beats per minute. Athletic people usually have lower resting heart rates. Fit people have stronger heart muscles, which means their hearts don’t need to work as hard to send blood around their bodies. Heart rate increases when a person exercises. An exercising body needs more oxygen for its cells, so the heart beats faster to send oxygen to all parts of the body.

Figure B.3.11.8– An oximeter is a machine that measures heart rate.
Figure B.3.11.9– Doctors listen to a patient’s heartbeat with a stethoscope.

 Watch More

Lub Dub. Lub Dub.

Watch this video to see what a heart looks like when it is pumping blood.

 
 

  Try It! 

See Your Pulse

Try this simple experiment to observe your pulse.

Materials: 
  • Mini marshmallow
  • Toothpick


Instructions:

  1. Stick the toothpick into one end of the marshmallow.

  2. Run on the spot until you feel your heart beating in your chest.

  3. Sit down and place one arm on a table, with your palm facing upward.

  4. Carefully place the marshmallow on your wrist, with the toothpick pointing upward. What do you observe?

  5. Watch this video to see this experiment and its results:

 
 
 

  Try It! 

Heart Rate Experiment

Try this experiment to measure your heart rate during different activities.

Materials: 
  • Timer


Download:

DOWNLOAD this document. It provides an observation table for you to record your heart rate results.

Instructions:


  1. Lie on the floor for 3 minutes.

  2. Find your pulse on your neck. Place your index finger and middle finger along the front side of your neck until you feel the bumping of your pulse.

  3. Set the timer for 10 seconds. Start the timer and count how many times you feel your pulse during 10 seconds.

  4. Record this number in the observations table, under “Beats in 10 seconds”.

  5. Multiply this number by 6 to calculate and record the number of beats per minute in the observations table.

  6. Repeat steps 1 to 5. Instead of lying down, do each of the activities listed in the table for 3 minutes . After each activity, allow your heartbeat to return to a normal rate before trying a new activity. If you are unable to do the activities listed in the table, modify the activities to suit you or only do the ones that you are able to do. Always be very careful when performing physical activity, make sure you have plenty of room and be sure the conditions around you are safe.


Observation Table:
 
Questions: 

Think about the following question very carefully. Then, type or write your answer. After you have your answer, click the question for feedback.

Activities that required the body to move around a lot had the highest heart rate. This is because muscle cells in the moving body required more oxygen when they were moving at a faster rate. The heart needed to beat faster to deliver oxygen to muscle cells around the body.
Figure B.3.11.10– A sphygmomanometer measures blood pressure.
Figure B.3.11.11– A healthy blood pressure is 120 over 80.

Blood pressure

Blood pressure describes the pressure of the fluid inside blood vessels. Doctors measure blood pressure with an inflatable cuff called a sphygmomanometer. A healthy blood pressure measurement is approximately 120 over 80.

High blood pressure is caused by factors such as stress and eating too much salt. Constant high blood pressure leads to health problems. High blood pressure weakens artery walls. This causes inflammation and can lead to blocked arteries. If the arteries leading to heart muscles are blocked, a heart attack can occur, causing muscles around the heart to die.

 Watch More

120 Over 80

Watch this video to learn more about blood pressure and how high blood pressure causes health problems.

 
 
 
 
How do medical workers treat high blood pressure? Watch this video to learn more.

 
 
 
 
Watch this video to see an animation of a heart attack.

 
 

  Try It! 

Arteries and Blood Flow

Try this experiment to model how the diameter of arteries affects blood flow. 

Materials: 
  • 2 identical clear plastic cups
  • 1 large diameter straw
  • 1 small diameter straw
  • Sharp knife
  • BBQ lighter
  • Modelling clay
  • Water
  • Food colouring (optional)
  • Shallow glass pan
  • Duct tape or packing tape
  • Newspaper
 
Take care with the sharp knife; don’t cut yourself or anyone else!

Take care with the BBQ lighter. Use in a well-ventilated area. Beware of open flames.
Instructions:

  1. Measure a few centimetres from the bottom of each plastic cup.

  2. With the sharp knife, poke a small hole into one cup. The hole should be big enough for the small straw to fit through, without pinching the straw.

  3. With the BBQ lighter, carefully melt a larger hole into the other cup. The hole should be big enough for the large straw to fit through, without pinching the straw.

  4. Measure and cut both straws so that they are the same length (about 5 cm long).

  5. Push the small diameter straw through the hole in one cup. The end of the straw should be located well inside the cup.

  6. Secure the small straw in place with modelling clay on the inside of the cup (if necessary). The modelling clay should seal the cup from the inside so water can only escape the cup through the straw. The straw should be horizontal to the bottom of the cup.

  7. Repeat steps 4 and 5 for the large diameter straw.

  8. Place both plastic cups in the shallow glass pan. Use the tape to secure the cups to the bottom of the pan.

  9. Measure the same amount of water into each of the 2 plastic cups. Attempt to block both straws so no water leaks out yet. Use food colouring if you want to see the water level more clearly.

  10. Unblock both straws at the same time. Observe the plastic cups. Which cup drains faster?

  11. Watch this video to see this experiment and its results:

 
 

Questions: 

Think about the following questions very carefully. Then, type or write your answers. After you have your answers, click the questions for feedback.


The large diameter straw represented healthy arteries.
The water flowed quickly from the large diameter straw. Blood can flow easily through wide unblocked arteries. This allows oxygen and nutrients to move quickly to all body cells.
The small diameter straw represented unhealthy arteries.
The water flowed slower from the small diameter straw. Blood flows slower through narrower blocked arteries. This means that oxygen and nutrients do not move as quickly to all body cells, causing the heart to work harder.



Blood Transfusions

Sometimes people lose large amounts of blood from their bodies, which can be life-threatening. Blood loss can happen from severe traumatic injuries, during surgery, or from childbirth. In these situations, a blood transfusion with donated blood can save a person’s life.

To learn more about blood transfusions and blood donation,
click here to Explore with Elsie.



  Make sure you have understood everything in this lesson. Use the Self-Check below, and the Self-Check & Lesson Review Tips to guide your learning.

Unit B Lesson 11 Self-Check

Instructions


Complete the following 6 steps. Don't skip steps – if you do them in order, you will confirm your understanding of this lesson and create a study bank for the future.

  1. DOWNLOAD the self-check quiz by clicking here.

  2. ANSWER all the questions on the downloaded quiz in the spaces provided. Think carefully before typing your answers. Review this lesson if you need to. Save your quiz when you are done.

  3. COMPARE your answers with the suggested "Self-Check Quiz Answers" below. WAIT! You didn't skip step 2, did you? It's very important to carefully write out your own answers before checking the suggested answers.

  4. REVISE your quiz answers if you need to. If you answered all the questions correctly, you can skip this step. Revise means to change, fix, and add extra notes if you need to. This quiz is NOT FOR MARKS, so it is perfectly OK to correct any mistakes you made. This will make your self-check quiz an excellent study tool you can use later.

  5. SAVE your quiz to a folder on your computer, or to your Private Files. That way you will know where it is for later studying.

  6. CHECK with your teacher if you need to. If after completing all these steps you are still not sure about the questions or your answers, you should ask for more feedback from your teacher. To do this, post in the Course Questions Forum, or send your teacher an email. In either case, attach your completed quiz and ask; "Can you look at this quiz and give me some feedback please?" They will be happy to help you!

Be a Self-Check

Superhero!



Self-Check Quiz Answers

Click each of the suggested answers below, and carefully compare your answers to the suggested answers.

If you have not done the quiz yet – STOP – and go back to step 1 above. Do not look at the answers without first trying the questions.

The left ventricle pumps blood to all parts of the body. The muscle surrounding the left ventricle needs to be strong to squeeze blood out into the body.
Platelets form clots in blood vessels at the wound site, to stop the injury from bleeding. White blood cells at the injury prevent infection of the wound by harmful bacteria.
Donated blood needs to be tested for its blood type. Blood transfusion recipients can only receive specific types of blood. Blood is also tested to make sure that it doesn’t contain disease-causing bacteria and viruses.
Nicotine reduces the volume of blood vessels, which increases blood pressure. Smokers often develop chronic high blood pressure.
All body cells require oxygen to live. Blood collects oxygen from the lungs before it is sent out to deliver this oxygen the rest of the body.