BIO121-Lesson-4

Lesson 4: Animal and Plant Tissues

• Characteristics of Organisms:

  • Plants: Photosynthetic, contain cell walls, specialized reproductive tissues.

  • Animals: No cell walls, capable of locomotion, possess a digestive tract.

  • Fungi: Externally digest food and absorb nutrients through cell walls.

• Multicellular Organisms:

  • Plants, animals, and fungi are multicellular.

  • Protists: Mostly unicellular and motile; can be photosynthetic or heterotrophic.

• Movement in Animals:

  • Animals generally possess mobility, but not all exhibit muscle movement.

  • Most have a mobile adult stage, while some (corals, sponges) may be sessile.

• Evolutionary History:

  • Both animal and plant multicellularity evolved from water to land, with some later re-adapting to aquatic environments (e.g., dolphins, duckweed).

• Support and Adaptations in Animals:

  • Development of skeletons (internal/external), skin for moisture retention, muscular systems for movement, nervous systems for stimulus integration, and internal digestion.

• Animal Tissues

  • Groups of specialized cells with specific functions.

  • Four main types: Epithelial, Connective, Muscle, Nervous.

• Epithelial Tissues:

  • Cover surfaces, line organs, form glands.

  • Shape variations: squamous, columnar, cuboidal, or ciliated.

• Structure of Epithelial Tissues:

  • Cells adhere tightly via junctions joined by zonulae, desmosomes, and other junctions.

  • Tight junctions seals off tissues from adjacent open spaces and prevent disease-causing microorganisms' entry.

• Classification of Epithelial Tissues:

  • By cell layers: simple, stratified, pseudostratified.

  • By shape: squamous, cuboidal, columnar.

  • By surface specializations: cilia, keratin, glands

• Functions of Epithelial Tissues:

  • Protection: e.g., skin squamous epithelium.

  • Absorption: e.g., intestinal columnar epithelium.

  • Secretion: e.g., glandular epithelium.

• Squamous Epithelium:

  • Thin, flat cells (scales).

  • Locations: blood vessels, alveoli, skin.

• Functions:

  • Diffusion

  • Filtration

  • Protection

• Simple Squamous Epithelium:

  • Located in air sacs of lungs and blood vessels.

• Function:

  • Diffusion

  • Filtration

  • Lubrication

• Cuboidal and Columnar Epithelium:

  • Cuboidal: Cube-shaped, kidneys.

  • Columnar: Rectangular, digestive tract.

• Functions:

  • Secretion

  • Absorption

• Transitional Epithelium:

  • Specialized for stretching

  • Found in the urinary bladder.

  • Allows bladder to expand and contract.

• Ciliated Epithelium:

  • Cells with cilia

  • Found in respiratory tract and female reproductive system.

• Functions:

  • Move mucus and particles.

• Stratified Keratinized Epithelium:

  • Multiple layers, outer layer contains dead keratinized cells.

  • Provides protection against abrasion.

  • Found in the skin’s epidermis (stratum corneum).

• Connective Tissues:

  • Support, protect, bind organs.

  • Types: loose connective, dense connective, cartilage, bone, fluid connective.

• Functions:

  • Structural support (bone).

  • Energy storage (adipose).

  • Transport (blood).

• Muscle Tissues:

  • Responsible for movement.

  • Three main types: Skeletal (voluntary), Cardiac (involuntary), Smooth (involuntary).

• Functions:

  • Skeletal (voluntary movement)

  • Cardiac (heart contraction)

  • Smooth: involuntary process (digestion)

Note: All three types of muscle tissue contain contractile proteins, actin and myosin, which interact to cause muscle cell contraction.

• Nervous Tissues:

  • Transmit electrical signals.

  • Consist of sensory and motor neurons.

• Functions:

  • Sensory detection

  • Motor response initiation (muscle contraction)

• Conclusion:

  • Roles of animal tissues in structure and function, including epithelial for coverage, connective tissues for support, muscle tissues for movement, and nervous for signaling for communication.

• Plant Tissues

  • Exploration of plant tissues, their origins, functions.

  • Can be categorized based on origin and structure/ function.

  • Crucial for growth, development, and adaptation.

• Classification of Plant Tissues based on origin:

  • Meristematic (embryonic): Actively dividing cells for growth.

  • Non-Meristematic (permanent): Mature tissues that have lost the ability to divide.

• Classification of Plant Tissues based on structure/function

  • Surface/dermal: epidermis and periderm.

  • Fundamental/ground: parenchyma, collenchyma, sclerenchyma.

  • Vascular: xylem and phloem.

• Meristematic Tissues:

  • Regions of dividing cells

  • Responsible for plant growth and development

• Types of Meristematic Tissues:

  • Apical: Growth in length at tips.

  • Lateral: Growth in diameter.

  • Intercalary: Lengthening internodes.

• Permanent Tissues:

  • Derived from meristematic tissues; categorized:

    • Simple: Storage, photosynthesis, support.

    • Complex: Transport (xylem, phloem).

    • Special Tissues: Protection, secretion.

• Parenchyma Tissues (permanent/ground):

  • Loosely packed with large intercellular spaces.

  • Functions: Photosynthesis (in leaves), storage of food and water, and healing the wounds.

  • Location: all parts

• Vascular Tissues:

  • Xylem: Transports water/minerals, provides structure.

  • Phloem: Transports organic nutrients from photosynthesis.

• Dermal Tissues:

  • Epidermis: Protective outer layer, regulates water loss.

  • Periderm: Replaces epidermis in older stems/roots for protection and secondary growth.

• Secretory Tissues:

  • Produce/store substances (nectar, resins, hormones).

• Conclusion:

  • Plant tissues' diversity allows for adaptation and essential functions for growth and survival.