Zoology Lecture Module 2 PDF

Republic of the Philippines CAVITE STATE UNIVERSITY Bacoor City Campus Soldiers Hills IV, Molino VI, City of Bacoor, Cavite...

Republic of the Philippines CAVITE STATE UNIVERSITY Bacoor City Campus Soldiers Hills IV, Molino VI, City of Bacoor, Cavite  (046) 476 - 5029 www.cvsu.edu.ph ZOOL 1 – General Zoology Cells and Tissues  Carry out all chemical activities needed to sustain life  Cells are the building blocks of all living things  Tissues are groups of cells that are similar in structure and function Anatomy of the Cell  Cells are not all the same  All cells share general structures  Cells are organized into three main regions  Nucleus o Control center of the cell o Contains genetic material (DNA) Three regions o Nuclear membrane o Nucleolus o Chromatin  Cytoplasm  Plasma membrane Chromatin  Composed of DNA and protein  Scattered throughout the nucleus  Chromatin condenses to form chromosomes when the cell divides Plasma Membrane  Barrier for cell contents  Double phospholipid layer  Hydrophilic heads  Hydrophobic tails  Other materials in plasma membrane  Protein  Cholesterol  Glycoproteins Cytoplasm  Material outside the nucleus and inside the plasma membrane  Cytosol  Fluid that suspends other elements  Organelles  Metabolic machinery of the cell  Inclusions  Non-functioning units Cytoplasmic Organelles  Ribosomes  Made of protein and RNA  Sites of protein synthesis  Found at two locations  Free in the cytoplasm   Attached to rough endoplasmic reticulum  Endoplasmic reticulum (ER)  Fluid-filled tubules for carrying substances  Two types of ER  Rough Endoplasmic Reticulum  Studded with ribosomes  Site where building materials of cellular membrane are formed  Smooth Endoplasmic Reticulum  Functions in cholesterol synthesis and breakdown, fat metabolism, and detoxification of drugs  Golgi apparatus  Modifies and packages proteins  Produces different types of packages  Secretory vesicles  Cell membrane components  Lysosomes  Lysosomes  Contain enzymes that digest non usable materials within the cell  Peroxisomes  Membranous sacs of oxidase enzymes  Detoxify harmful substances  Break down free radicals (highly reactive chemicals)  Replicate by pinching in half  Mitochondria  “Powerhouses” of the cell  Change shape continuously  Carry out reactions where oxygen is used to break down food   Provides ATP for cellular energy  Cytoskeleton o Network of protein structures that extend throughout the cytoplasm o Provides the cell with an internal framework  Centrioles o Rod-shaped bodies made of microtubules o Direct formation of mitotic spindle during cell division Cell Life Cycle  Cells have two major periods  Interphase  Cell grows  Cell carries on metabolic processes  Cell division  Cell replicates itself  Function is to produce more cells for growth and repair processes Body Tissues  Cells are specialized for functions  Tissues  Groups of cells with similar structure and function  Four primary types  Epithelium  Connective tissue  Nervous tissue  Muscle 1. Epithelium Characteristics  Cells fit closely together  Tissue layer always has one free surface  The lower surface is bound by a basement membrane   Avascular (have no blood supply)  Regenerate easily if well nourished Classification of Epithelium  Number of cell layers  Simple – one layer  Stratified – more than one layer  Shape of cells  Squamous – flattened  Cuboidal – cube-shaped  Columnar – column-like  Simple squamous  Single layer of flat cells   Usually forms membranes  Lines body cavities  Lines lungs and capillaries  Simple cuboidal  Single layer of cube-like cells  Common in glands and their ducts  Forms walls of kidney tubules  Covers the ovaries  Simple columnar  Single layer of tall cells  Often includes goblet cells, which produce mucus  Lines digestive tract  Pseudostratified  Single layer, but some cells are shorter than others   Often looks like a double cell layer  Sometimes ciliated, such as in the respiratory tract  May function in absorption or secretion  Stratified squamous  Cells at the free edge are flattened  Found as a protective covering where friction is common  Locations  Skin  Mouth  Esophagus  Stratified cuboidal  Two layers of cuboidal cells  Stratified columnar  Surface cells are columnar, cells underneath vary in size and shape  Stratified cuboidal and columnar  Rare in human body  Found mainly in ducts of large glands  Transitional epithelium  Shape of cells depends upon the amount of stretching  Lines organs of the urinary system Glandular Epithelium   Gland – one or more cells that secretes a particular product  Two major gland types  Endocrine gland  Ductless  Secretions are hormones  Exocrine gland  Empty through ducts to the epithelial surface  Include sweat and oil glands 2. Connective Tissue o Found everywhere in the body o Includes the most abundant and widely distributed tissues Functions a. Binds body tissues together b. Supports the body c. Provides protection Connective Tissue Characteristics  Variations in blood supply  Some tissue types are well vascularized  Some have poor blood supply or are avascular  Extracellular matrix  Non-living material that surrounds living cells  Two main elements  Ground substance – mostly water along with adhesion proteins and polysaccharide molecules  Fibers  Produced by the cells  Three types  Collagen fibers  Elastic fibers  Reticular fibers  Bone (osseous tissue)  Composed of:  Bone cells in lacunae (cavities)  Hard matrix of calcium salts  Large numbers of collagen fibers  Used to protect and support the body  Hyaline cartilage  Most common cartilage  Composed of:  Abundant collagen fibers  Rubbery matrix  Entire fetal skeleton is hyaline cartilage  Elastic cartilage  Provides elasticity  Example: supports the external ear  Fibrocartilage  Highly compressible  Example: forms cushion-like discs between vertebrae  Dense connective tissue  Main matrix element is collagen fibers  Cells are fibroblasts  Examples  Tendon – attach muscle to bone  Ligaments – attach bone to bone  Areolar connective tissue  Most widely distributed connective tissue  Soft, pliable tissue   Contains all fiber types  Can soak up excess fluid  Adipose tissue  Matrix is an areolar tissue in which fat globules predominate  Many cells contain large lipid deposits  Functions  Insulates the body  Protects some organs  Serves as a site of fuel storage  Blood  Blood cells surrounded by fluid matrix  Fibers are visible during clotting  Functions as the transport vehicle for materials 3. Muscle Tissue  Function is to produce movement Three types a. Skeletal muscle b. Cardiac muscle c. Smooth muscle Muscle Tissue Types  Skeletal muscle  Can be controlled voluntarily  Cells attach to connective tissue  Cells are striated  Cells have more than one nucleus  Cardiac muscle  Found only in the heart  Function is to pump blood (involuntary)  Cells attached to other cardiac muscle cells at intercalated disks  Cells are striated  One nucleus per cell  Smooth muscle  Involuntary muscle  Surrounds hollow organs  Attached to other smooth muscle cells  No visible striations  One nucleus per cell  4. Nervous Tissue o Neurons and nerve support cells o Function is to send impulses to other areas of the body a. Irritability b. Conductivity Tissue Repair  Regeneration  Replacement of destroyed tissue by the same kind of cells  Fibrosis  Repair by dense fibrous connective tissue (scar tissue)  Determination of method  Type of tissue damaged  Severity of the injury Events in Tissue Repair  Capillaries become very permeable  Introduce clotting proteins  Wall off injured area  Formation of granulation tissue  Regeneration of surface epithelium Regeneration of Tissues  Tissues that regenerate easily  Epithelial tissue  Fibrous connective tissue and bone  Tissues that regenerate poorly  Skeletal muscle  Tissues that are replaced largely with scar tissue  Cardiac muscle  Nervous tissue within the brain and spinal cord Developmental Aspects of Tissue  Epithelial tissue arises from all three primary germ layers  Muscle and connective tissue arise from the mesoderm  Nervous tissue arises from the ectoderm  With old age there is a decrease in mass and viability in most tissues