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Importance of NCERT and Animal Tissues

Jun 24, 2024

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Lecture on STRUCTURAL ORGANIZATION IN ANIMALS PART-1 ( ANIMAL TISSUES)

Structural Organization in Animals

  • Covers animal tissues and structural organization.
  • Topics include Animal Tissues, Cockroach, and Frog.

Animal Tissues

  • Divided into Epithelial, Connective, Muscular, and Nervous tissues.
  • Each tissue type has distinct features and functions.

Epithelial Tissues

  • Types: Simple and Compound Epithelial tissues.
  • Simple Epithelial Tissues: Squamous, Cuboidal, Columnar, and Ciliated.
    • Simple Squamous: Flat cells, central nucleus, found in alveoli, Bowman's capsule, Glomerulus, and blood vessels (endothelium). Inner lining of blood capillaries is called endothelium
    • Simple Cuboidal: Cube-shaped, round nucleus, found in PCT of nephrons and ducts of glands, etc.
    • Simple Columnar: Tall, column-like, oval-shaped nucleus at the base, found in the stomach, intestine, and goblet cells for mucus secretion.

Special Types of Epithelial Tissues

  • Ciliated Epithelial Tissues(Only seen in cuboidal and columnar epithelium): Have cilia(hair-like structure) on the free surface for movement of particles unidirectionally, found in fallopian tubes and respiratory tract(bronchioles).
  • Brush-Bordered Epithelial Tissues: Finger-like projections on the apical part of the epithelium(seen in cuboidal and columnar epithelium) which increase the surface area of epithelium for secretion and absorption.Found in PCT(Proximal convoluted tubule),intestine,goblet cell, etc

Epithelial Tissue Functions, rest upon a connective tissue

  • Protection, absorption, secretion, sensory reception.
  • Key Points: Avascular (lacking blood vessels), compactly packed cells, supported by basement membrane.

Compound Epithelial Tissues(Limited contribution in secretion and absorption;MAJOR role in providing PROTECTION )

  • Stratified: Multiple layers, found in the skin, pharynx, esophagus, vagina, buccal cavity, duct of the gland(large duct(salivary, pancreatic)), skin.
  • Transitional: Multilayered, Stretchable, found in the urinary bladder.

###CELL JUNCTION(Found most in epithelium)

  • Provides both functional and structural linkage between individual cells. three types - 1) TIGHT JUNCTION: prevents leakage between two cells 2)GAP JUNCTION: Connects the cytoplasm of cells and helps communicate between them. 3)ADHERING JUNCTION: Helps in cementing btw cells.

Connective Tissues

  • Connective tissue elements: Cells, fibers, and ground substance.
  • Types: Loose (Areolar, Adipose), Dense (Regular, Irregular), Specialized (Bone, Cartilage, Blood, Lymph).

Loose Connective Tissues

  • Areolar: Abundant in ground substance, supports epithelia, found below the skin, contains fibroblasts, macrophages, and mast cells,etc.
  • Adipose: Stores fat, found under the skin and around organs.

Dense Connective Tissues

  • Regular: Parallel fibers, found in tendons (muscle to bone) and ligaments (bone to bone).
  • Irregular: Randomly arranged fibers, found in the dermis of the skin.

Specialized Connective Tissues

  • Bone: Solid matrix, composed of calcium salts and collagen, gives structural support.
  • Cartilage: Solid but flexible matrix, found in joints, ear, nose; lacks blood supply.
  • Blood: Fluid matrix (plasma) with cells (RBC, WBC) and platelets, main function is transport.
  • Lymph: Returns fluid from tissues to the circulatory system.

Muscular Tissues

  • Types: Skeletal, Smooth, Cardiac.
  • Skeletal Muscle: Prominently Striated, voluntary, multi-nucleated (nuclie reside on the periphery), found in limbs.
  • Smooth Muscle: Non-striated, involuntary, single nucleus(resides at the center of the cell), found in the walls of internal organs and walls of blood vessels .
  • Cardiac Muscle: Faintly Striated but involuntary, branched, single nucleus, found in the heart.

Muscle Functions

  • Movement (skeletal), peristalsis and contraction in organs (smooth), heartbeats (cardiac).

Nervous Tissues

  • Components: Neurons and Neuroglia.
  • Neurons: Structural and functional units, transmit impulses, composed of cell body, dendrites, and axon.
  • Neuroglia: Support, protect, and nourish neurons, outnumber neurons, and maintain homeostasis in the nervous system.

Function of Nervous Tissues

  • Initiate and transmit nerve impulses for coordination and control.
  • Neurons exhibit excitability and conductivity.
  • Neuroglia helps in the packaging of neurons

Structure of a Neuron

  • Cell Body with NisslтАЩs granules. Dendrites also have Nissl's granules but axon.
  • Dendrites: Receive impulses.
  • Axon: Transmits impulses away, may be myelinated (covered by myelin sheath).
  • Ends in Synaptic Knobs containing neurotransmitters.
  • Myelin Sheath produced by Schwann cells and oligodendrocytes; Nodes of Ranvier are gaps between the myelin sheaths.

Conclusions

  • Emphasis on studying NCERT thoroughly for NEET
  • Reminder to practice consistently and review notes regularly

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