Human Circulatory and Respiratory System

 As promised, today is another update on the human body system. Today's guide is for the upper primary science students. 

You can download the summary on Human Circulatory and Respiratory System  by clicking on the links below. I have also compiled a set of Booklet B questions that are commonly asked on this topic, together with the answers. Please look through this carefully and remember the keywords that are required in the answers.

P5 Science - Human Circulatory and Respiratory System

P5 Science - Common Questions of Human Circulatory and Respiratory System

Let's go through some important points in this topic!

Direction and location of oxygen-rich blood

Simplified Circulatory System of Humans

This simplified diagram often appears in MCQ.  It can get tricky when you're rushing for time and confused with all the arrows in the diagram. 

To avoid this problem,  my trick for you is to first locate the arrow coming from the heart to the lungs.

The arrow coming from the heart to the lungs represents non-oxygenated blood, or blood that is oxygen-poor.

In the above diagram, arrow A represents the non-oxygenated blood.  Let's think of it as simply carrying carbon dioxide. These blood is oxygen-poor. 

Arrows that are in the same direction, A and C, (green)  are all blood that are oxygen-poor. 

Arrows that are in the same direction, B and D, (yellow)  are all blood that are oxygen-rich.

From here, it will be easier to navigate through the MCQs as now you know which arrows carry what types of blood.

Comparing circulatory system of fish and human

What is one similarity and difference  between the circulatory system of a fish and the circulatory system of a human?

First, we know that organ X in the fish represents the gills, whereas organ Y in human represents the lungs. 

Similarity: Both the gills and lungs allow for gaseous exchange to take place in the organism.

Difference: The blood flows through the heart once in the fish while the blood flows through the heart twice in the human.

Breathing rate increases when exercising

Why do our breathing rate increases when we are exercising? Why is our breathing rate higher when exercising than at rest?

When we exercise, our body needs more energy. Energy is produced during respiration, which requires oxygen and digested food. Thus, when we exercise, our body needs more oxygen and digested food. To simplify, below is the recommended answer we have for this type of question.

Our breathing rate increases during exercise because our body needs more energy. Thus, our breathing rate increases to take in more oxygen, which is pumped by the heart to all parts of the body, which is then used in the process of respiration to release more energy and carbon dioxide at a faster rate. Carbon dioxide is then transported faster away from the body to be removed and exhaled.

When comparing the heart rates during exercise and at rest, we use the same answer, but using special keywords like "faster breathing rate", "more oxygen and digested food" and "pump more blood".

These few points and other questions are covered in the summary guide and compilation of questions. I hope this benefit you during your revision. 😊