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The Human Body - External and Internal organs

Grade 3ICSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

External Organs: These are the body parts located on the outside that we can see and touch, such as hands, legs, and the 55 sense organs.

Internal Organs: These are the organs located inside the body, such as the brain, heart, lungs, stomach, and kidneys. They are protected by the skeletal system.

The Brain: It is the 'Control Center' of the body. It helps us think, learn, and remember. It requires a constant supply of oxygen (O2O_2) to work efficiently.

The Heart: A muscular organ that pumps blood throughout the body. The average human heart beats approximately 7272 times per minute.

The Lungs: We have a pair of lungs that help us breathe. They take in oxygen (O2O_2) and release carbon dioxide (CO2CO_2).

The Stomach: A J-shaped bag that helps in the digestion of food by breaking it down into simpler forms.

The Kidneys: A pair of bean-shaped organs that filter waste products from the blood to form urine.

Sense Organs: These include the eyes (sight), ears (hearing), nose (smell), tongue (taste), and skin (touch). The skin is the largest organ of the human body.

📐Formulae

Total Sense Organs=5\text{Total Sense Organs} = 5

InhalationO2 (Oxygen)\text{Inhalation} \rightarrow O_2 \text{ (Oxygen)}

ExhalationCO2 (Carbon Dioxide)\text{Exhalation} \rightarrow CO_2 \text{ (Carbon Dioxide)}

Average Heart Rate72 beats per minute\text{Average Heart Rate} \approx 72 \text{ beats per minute}

💡Examples

Problem 1:

Which organ is responsible for pumping blood to all parts of the body?

Solution:

The Heart

Explanation:

The heart acts as a pump that circulates blood, carrying nutrients and O2O_2 to different cells.

Problem 2:

Identify whether the following are Internal or External organs: (a) Lungs, (b) Eyes.

Solution:

(a) Internal, (b) External

Explanation:

Lungs are located inside the chest cavity and cannot be seen from the outside, while eyes are visible on the face.

Problem 3:

What gas do the lungs remove from our body during exhalation?

Solution:

CO2CO_2 (Carbon Dioxide)

Explanation:

During the process of respiration, the lungs exchange gases, taking in O2O_2 and expelling CO2CO_2 as a waste product.

External and Internal organs - Revision Notes & Key Formulas | ICSE Class 3 Science