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Tissues - Explain levels of organisation in multicellular organisms and musculoskeletal care

Grade 9CBSE

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

🔑Concepts

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Multicellular organisms exhibit a hierarchy of organization: Cells→Tissues→Organs→Organ Systems→Organism\text{Cells} \rightarrow \text{Tissues} \rightarrow \text{Organs} \rightarrow \text{Organ Systems} \rightarrow \text{Organism}.

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A tissue is a group of cells similar in structure and/or work together to achieve a particular function, providing 'division of labour'.

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Animal tissues are classified into four types: Epithelial (protection), Connective (binding/support), Muscular (movement), and Nervous (control/coordination).

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Muscular tissues include Skeletal (striated/voluntary), Smooth (unstriated/involuntary), and Cardiac (heart muscles).

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Connective tissues such as Tendons connect muscle to bone, while Ligaments connect bone to bone. Their health is vital for musculoskeletal integrity.

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Musculoskeletal care involves maintaining bone health through the intake of Calcium (Ca2+Ca^{2+}) and Vitamin D, and preserving muscle tone through regular physical activity.

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Bone matrix is hard and composed of Calcium and Phosphorus compounds, primarily Hydroxyapatite, represented as Ca10(PO4)6(OH)2Ca_{10}(PO_4)_6(OH)_2.

📐Formulae

Bone Mineral Density (BMD)=Mass of Mineral (g)Area or Volume of Bone (cm2 or cm3)\text{Bone Mineral Density (BMD)} = \frac{\text{Mass of Mineral (g)}}{\text{Area or Volume of Bone (cm}^2 \text{ or cm}^3)}

F=m×aF = m \times a

Force on Joints∝Body Weight\text{Force on Joints} \propto \text{Body Weight}

💡Examples

Problem 1:

A athlete measures their bone mineral mass in a specific section of the femur. If the initial mass was 1550 mg1550\text{ mg} and due to lack of Vitamin D, it dropped by 275 mg275\text{ mg}, calculate the final mass using vertical subtraction.

Solution:

1550−2751275\begin{array}{r} 1550 \\ - 275 \\ \hline 1275 \end{array}

Explanation:

The final bone mineral mass is 1275 mg1275\text{ mg}. Maintaining adequate Vitamin D is essential for Calcium absorption into the bone tissue matrix.

Problem 2:

If a muscle fiber generates a force of 0.005 N0.005\text{ N} and a bundle contains 10310^3 such fibers working in parallel, what is the total force exerted by the tissue?

Solution:

Total Force=103×0.005 N=5 N\text{Total Force} = 10^3 \times 0.005\text{ N} = 5\text{ N}

Explanation:

In multicellular organisms, tissues allow for a cumulative effect where individual cell actions are magnified to perform macro-level movements.