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Structural Organisation in Animals and Plants - Animal Tissues (Epithelial, Connective, Muscular, Nervous)

Grade 11ICSEBiology

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

🔑Concepts

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Epithelial Tissue: Provides covering or lining for some parts of the body. Cells are compactly packed with little intercellular matrix. It is divided into Simple (single layer) and Compound (multi-layered).

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Specialized Epithelium: Ciliated epithelium possesses ciliacilia to move particles or mucus in a specific direction (e.g., bronchioles and fallopian tubes). Glandular epithelium is specialized for secretion (Unicellular like Goblet cells or Multicellular like Salivary glands).

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Cell Junctions: Three types occur in epithelia: Tight junctions (prevent leakage), Adhering junctions (cementing cells together), and Gap junctions (facilitate communication by allowing ion and small molecule transfer).

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Connective Tissue: Most abundant and widely distributed. It includes loose connective tissue (Areolar, Adipose), dense connective tissue (Tendons, Ligaments), and specialized connective tissue (Cartilage, Bone, Blood).

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Connective Tissue Matrix: Contains structural proteins called collagencollagen or elastinelastin fibers, except in blood. The ground substance is a modified polysaccharide.

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Muscular Tissue: Composed of many long, cylindrical fibers arranged in parallel arrays called myofibrilsmyofibrils. It includes Skeletal (striated, voluntary), Smooth (non-striated, involuntary), and Cardiac (striated, involuntary with intercalated discs).

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Nervous Tissue: Consists of Neurons (excitable units) and Neuroglial cells (supportive and protective units). Neuroglia make up more than half the volume of neural tissue in our body.

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Bone Structure: Characterized by a hard, non-pliable ground substance rich in calciumcalcium salts and collagencollagen fibers, providing structural strength. Osteocytes are located in spaces called lacunaelacunae.

📐Formulae

Bone Mineral (Hydroxyapatite)=Ca10(PO4)6(OH)2\text{Bone Mineral (Hydroxyapatite)} = Ca_{10}(PO_{4})_{6}(OH)_{2}

Surface Area to Volume Ratio=AV\text{Surface Area to Volume Ratio} = \frac{A}{V}

Blood Composition=Plasma (55%)+Formed Elements (45%) (RBCs, WBCs, Platelets)\text{Blood Composition} = \text{Plasma (55\%)} + \text{Formed Elements (45\%) (RBCs, WBCs, Platelets)}

Nerve Impulse Velocity∝Diameter of Axon×Myelination\text{Nerve Impulse Velocity} \propto \text{Diameter of Axon} \times \text{Myelination}

💡Examples

Problem 1:

A tissue sample shows cells with a single nucleus located at the center, spindle-shaped morphology, and no striations. Identify the tissue and its primary function.

Solution:

Smooth Muscle Tissue.

Explanation:

Smooth muscle fibers are fusiform (spindle-shaped) and do not show striations (non-striated). They are involuntary and found in the walls of internal organs like blood vessels, stomach, and intestine to facilitate peristalsis and vasoconstrictionvasoconstriction.

Problem 2:

Explain the role of Ca2+Ca^{2+} in the functionality of specialized connective tissue like bone.

Solution:

Bone is a specialized connective tissue with a hard matrix.

Explanation:

The matrix is rich in calciumcalcium salts (Ca2+Ca^{2+}) and collagencollagen fibers which give the bone its strength. The Ca2+Ca^{2+} ions are primarily stored in the form of hydroxyapatite crystals, which allow the bone to support weight and protect softer tissues.

Problem 3:

How do Gap Junctions assist in the synchronized contraction of the heart?

Solution:

Gap junctions allow for rapid ion transfer.

Explanation:

In cardiac muscle tissue, communication junctions (intercalated discs) at some fusion points allow the cells to contract as a unit. When one cell receives a signal to contract, Na+Na^{+} and Ca2+Ca^{2+} ions flow through gap junctions, triggering neighboring cells to contract simultaneously.

Animal Tissues (Epithelial, Connective, Muscular, Nervous) Revision - Class 11 Biology ICSE