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Respiration and Transportation in Organisms - Human Circulatory System: Blood, Vessels, and Heart

Grade 7CBSE

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

🔑Concepts

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Blood is a fluid tissue that consists of Plasma (liquid part), Red Blood Cells (RBCsRBCs), White Blood Cells (WBCsWBCs), and Platelets.

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Red Blood Cells contain a red pigment called Hemoglobin (HbHb), which binds with oxygen to form Oxyhemoglobin (HbO2HbO_2) for transport.

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Arteries have thick, elastic walls to withstand high pressure as they carry oxygen-rich (O2O_2) blood away from the heart (except the Pulmonary Artery).

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Veins have thinner walls and possess valves to ensure blood flows in only one direction, carrying carbon dioxide-rich (CO2CO_2) blood towards the heart (except the Pulmonary Vein).

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The human heart is a four-chambered muscular organ: two upper chambers (Atria) and two lower chambers (Ventricles). This structure prevents the mixing of oxygenated and deoxygenated blood.

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Capillaries are extremely thin-walled vessels that connect arteries to veins, allowing the exchange of O2O_2, CO2CO_2, nutrients, and waste products between blood and tissues.

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Pulse rate is the number of heartbeats per minute. For a resting healthy adult, it typically ranges between 7272 and 8080 beats per minute.

📐Formulae

ightarrow HbO_2 \text{ (Oxyhemoglobin)}$$

Pulse Rate=Total Number of HeartbeatsTime in Minutes\text{Pulse Rate} = \frac{\text{Total Number of Heartbeats}}{\text{Time in Minutes}}

Blood=Plasma+Blood Cells (RBCs, WBCs, Platelets)\text{Blood} = \text{Plasma} + \text{Blood Cells (RBCs, WBCs, Platelets)}

💡Examples

Problem 1:

A student measures their pulse and counts 1515 beats in 1010 seconds. Calculate the pulse rate per minute and determine if it falls within the normal resting range of 72−8072 - 80 beats per minute.

Solution:

Step 1: Convert 1010 seconds to minutes: 10 seconds=1060 minutes=16 minutes10 \text{ seconds} = \frac{10}{60} \text{ minutes} = \frac{1}{6} \text{ minutes}. Step 2: Calculate Pulse Rate: Pulse Rate=15÷16=15×6=90 beats per minute\text{Pulse Rate} = 15 \div \frac{1}{6} = 15 \times 6 = 90 \text{ beats per minute}.

Explanation:

The calculated pulse rate is 9090 beats per minute, which is higher than the normal resting range of 72−8072 - 80 beats per minute. This could be due to recent physical activity or excitement.

Problem 2:

Explain the role of Hemoglobin (HbHb) in the blood using scientific notation.

Solution:

Hemoglobin (HbHb) binds with Oxygen (O2O_2) in the lungs to form Oxyhemoglobin (HbO2HbO_2). The reaction can be represented as: Hb+O2→HbO2Hb + O_2 \rightarrow HbO_2.

Explanation:

Hemoglobin acts as a carrier molecule. When blood reaches the tissues where O2O_2 concentration is low, the HbO2HbO_2 dissociates to release O2O_2 for cellular respiration.