Cells and Tissues PDF

ANATOMY & PHYSIOLOGY CELLS & TISSUES Lecture by: Mr. Stefan Paolo Jesalva College of Arts and Sciences Faculty Biology Department CELLS AND TISSUES Cells are the building blocks of all living beings Tissues are group of similar cell...

ANATOMY & PHYSIOLOGY CELLS & TISSUES Lecture by: Mr. Stefan Paolo Jesalva College of Arts and Sciences Faculty Biology Department CELLS AND TISSUES Cells are the building blocks of all living beings Tissues are group of similar cells from the same origin that carry out a specific function CELLS Anatomy of the Cell Cells are not all the same All cells share general structures Cells are organized into 3 main regions ▪ Nucleus ▪ Cytoplasm ▪ Plasma membrane MAIN REGIONS OF A HUMAN CELL The Nucleus Control center of the cell Contains genetic material (DNA) 3 regions Nuclear membrane Nucleolus Chromatin NUCLEUS Nuclear Membrane Barrier of nucleus Consists of a double phospholipid (bi-layer) membrane Contain nuclear pores allowing material exchange with the rest of the cell Nucleoli Nucleus contains one or more nucleoli It is a non-membrane bound organelle taking part in synthesis of ribosomes, including processing of rRNA and the assembly of them into ribosome subunits. Nucleoli The Nucleus is also involved in several other cellular processes, such as mitosis, stress response, and cell cycle regulation. After the synthesis step, ribosomes will then migrate to cytoplasm through nuclear pores Staining of nucleoli in human cell line A-431 Chromatin Composed of DNA & proteins Scattered throughout the nucleus Chromatin condenses to form chromosomes when the cell division starts Chromatin Chromatin and condensed chromosome structure Plasma Membrane Barrier for cell contents Double phospholipid layer Hydrophilic heads + Hydrophobic tails Other materials in plasma membrane Protein Cholesterol Glycoproteins Plasma Membrane Plasma Membrane: Specializations Microvilli Finger-like projections that increase surface area for absorption Plasma Membrane: Specializations Membrane junctions Tight junctions Desmosomes & hemi- desmosomes Gap junctions Cytoplasm Material outside the nucleus and inside the plasma membrane Cytosol: Fluid that contains other elements Organelles: Metabolic machinery of the cell Inclusions: Non-functioning units (Lipids …)  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 Cytoplasmic Organelles A ribosome “at work”  Cytoplasmic Organelles Endoplasmic reticulum (ER): Fluid- filled tubules for carrying substances – 2 types of ER - Rough Endoplasmic Reticulum: is studded with ribosomes and where building materials of cellular membrane are formed. - Smooth Endoplasmic Reticulum: Functions in cholesterol synthesis and breakdown, fat metabolism, and detoxification of drugs Cytoplasmic Organelles Schema of the 2 types of ER Cytoplasmic Organelles 3D of the 2 types of ER  Cytoplasmic Organelles Golgi apparatus ▪ Modifies & packages proteins ▪ Produces several types of packages Secretory vesicles Cell membrane components Lysosomes Cytoplasmic Organelles Golgi Apparatus Cytoplasmic Organelles Golgi Apparatus “at work”  Cytoplasmic Organelles Mitochondria ▪ “Power-houses” of the cell ▪ Provide ATP for cellular energy ▪ Change shape constantly ▪ Carry out reactions using oxygen break down food Cytoplasmic Organelles A mitochondrion  Cytoplasmic Organelles Lysosomes: Contain enzymes that digest non-usable materials within the cell Peroxisomes ▪ Membranous sacs of oxidase enzymes ▪ Detoxify harmful substances ▪ Break down free radicals ▪ Replicate by pinching in halves  Cytoplasmic Organelles Cytoskeleton Network of protein structures that extend throughout the cytoplasm Provides the cell with an internal framework  Cytoplasmic Organelles The cytoskeleton. The actin is stained red and the microtubules, which are composed of the protein tubulin, are stained green.  Cytoplasmic Organelles Cytoskeleton 3 different types ▪ Microfilaments ▪ Intermediate filaments ▪ Microtubules  Cytoplasmic Organelles The cytoskeleton. This organelle is the ‘skeleton’ of our cells. It maintains cell shape. We couldn’t move without the cytoskeleton’s contractions of microtubules, microfilaments, and intermediate fibers.  Cytoplasmic Organelles Centrioles ▪ Rod-shaped bodies made of microtubules ▪ Direct formation of mitotic spindle during cell division ▪ Probably involved in other cell functions that are still not very well known Cytoplasmic Organelles Centrosome Microtubule Centriole Centrioles The Cell. The basic unit of structure and function.  Cellular Projections Not found in all types of cells Used for movement: ▪ Cilia move materials across the cell surface ▪ Flagellum propels the whole cell (e.g. sperm cell)  Cellular Projections Flagella and cilia differ in the way they move. Flagella use an undulating, propeller-like motion to propel a cell. Cilia beat back and forth, perpendicular to the cilium, bending & sweeping sideways.  Cellular Projections Flagella and cilia. Movement and structure. Cell Diversity Cell Diversity Cell Diversity Cell Diversity Cellular Physiology: Membrane Transport Membrane Transport – movement of substance in and out of the cells Transport is by 2 basic methods: ▪ Passive transport: No energy is required ▪ Active transport: Metabolic energy required Solutions and Transport Solution: homogeneous mixture of 2 or more components ▪ Solvent: dissolving medium (e.g. Water) ▪ Solutes: components in smaller quantities within a solution Intracellular fluid: nucleoplasm & cytosol Interstitial fluid: fluid on the exterior of the cell (Extracellular fluid) Selective Permeability The plasma membrane allows some materials to pass while excluding others This permeability includes movement in and out of the cells Passive Transport Processes Diffusion Particles tend to distribute themselves evenly within a solution Movement is from high concentration to low concentration, or down a concentration gradient Passive Transport Processes Diffusion. Passive Transport Processes Types of diffusion Simple diffusion: Unassisted process. Solutes are lipid-soluble materials or small enough to pass through membrane pores. Osmosis – simple diffusion of water: Highly polar water easily crosses the plasma membrane. Facilitated diffusion: Substances require a protein carrier for passive transport. Diffusion through Plasma Membrane Passive Transport Processes Filtration: Water and solutes are forced through a membrane by fluid, or hydrostatic pressure. ▪ A pressure gradient must exist ▪ Solute-containing fluid is pushed from high pressure area to lower pressure one Active Transport Processes Transport of substances that are not able to pass by diffusion because they: ▪ May be too large ▪ May be unable to dissolve in the fat of membranes ▪ May have to move against a concentration gradient 2 common forms of active transport: Solute pumping & Bulk transport Active Transport Processes Solute pumping ▪ Amino acids, some sugars and ions are transported by solute pumping ▪ ATP energizes protein carriers, & in most cases, moves substances against concentration gradients Solute Pumping Active Transport Processes Bulk transport Exocytosis: Moves materials out of the cell. Material is carried in a membranous vesicle. STEPS: ▪ Vesicle migrates to plasma membrane ▪ Vesicle combines with plasma membrane ▪ Material is emptied to the outside Exocytosis Active Transport Processes Bulk transport Endocytosis: Extracellular substances are engulfed by being enclosed in a membrane vesicle. TYPES OF ENDOCYTOSIS: Phagocytosis: cell eating Pinocytosis: cell drinking Endocytosis Cell Life Cycle Cells have 2 major periods Interphase: Cell grows and carries on metabolic processes Cell division: Cell replicates itself to produce more cells for growth and repair processes DNA Replication Genetic material duplicated and readies a cell for division into two cells Occurs toward the end of interphase DNA uncoils and each side serves as a template Cell Division Steps Mitosis: Division of the nucleus. Results in the formation of 2 nuclei. Cytokinesis: Division of the cytoplasm. Begins when mitosis is near completion. Results in the formation of 2 new cells. Stages of Mitosis Interphase: No cell division occurs. The cell carries out normal metabolic activity & growth. Prophase: First part of cell division. Centromeres migrate to the poles Stages of Mitosis Metaphase: Spindle from centromeres are attached to chromosomes that are aligned in the center of the cell Stages of Mitosis Anaphase: Daughter chromosomes are pulled toward the poles. The cell begins to elongate. Telophase: Daughter nuclei begin forming. A cleavage furrow (for cell division) begins to form Stages of Mitosis Stages of Mitosis  Protein Synthesis Gene: DNA segment that carries a ‘blueprint‘ for building one protein Proteins have many functions ▪ Building materials for cells ▪ Act as enzymes (biological catalysts) RNA is essential for protein synthesis Role of RNA Transfer RNA (tRNA): Transfers appropriate amino acids to the ribosome for building the protein Ribosomal RNA (rRNA): Helps form the ribosomes where proteins are built Messenger RNA (mRNA): Carries the instructions for building a protein from the nucleus to the ribosome Transcription and Translation Transcription: Transfer of information from DNA’s base sequence to the complimentary base sequence of mRNA. Translation: Base sequence of nucleic acid is translated to an amino acid sequence. Remember? Amino acids are the building blocks of proteins Proteins Synthesis TISSUES Body Tissues Cells are specialized for particular functions Tissues: Groups of cells with similar origin, structure and function Body Tissues 4 primary types of tissues: Epithelium Connective tissue Nervous tissue Muscle Epithelial Tissues Found in different areas ▪ Body coverings ▪ Body linings ▪ Glandular tissue Functions ▪ Protection ▪ Absorption ▪ Filtration ▪ Secretion 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 1-Number of cell layers: Simple: one layer Stratified: more than one layer 2- Shape of cells: Squamous: flattened Cuboidal: cube-shaped Columnar : column-like Simple Epithelium Simple squamous Single layer of flat cells Usually forms membranes (Lines body cavities, Lines lungs and capillaries) Simple Epithelium Simple cuboidal Single layer of cube- like cells Common in glands and their ducts Forms walls of kidney tubules Covers the ovaries Simple Epithelium Simple columnar Single layer of tall cells Often includes goblet cells, which produce mucus Lines digestive tract Simple Epithelium 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 Epithelium Stratified squamous Cells at the free edge are flattened Found as a protective covering where friction is common Locations: Skin, Mouth, Esophagus. Stratified Epithelium 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. Stratified Epithelium 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 2 major gland types: ▪ Endocrine gland: Ductless, Secretions are hormones. ▪ Exocrine gland: Empty through ducts to the epithelial surface. Include sweat & oil glands. Connective Tissue Found everywhere in the body Includes the most abundant and widely distributed tissues Functions: ▪ Binds body tissues together ▪ Supports the body ▪ 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 Extracellular Matrix 2 main elements: Ground substance: mostly water along with adhesion proteins and polysaccharide molecules Fibers: ▪ Produced by the cells ▪ 3 types Collagen fibers Elastic fibers Reticular fibers Connective Tissue Types Bone (osseous tissue): Used to protect and support the body. Composed of: Bone cells in lacunae (cavities) Hard matrix of calcium salts Large numbers of collagen fibers Connective Tissue Types Hyaline cartilage: Most common cartilage. The entire fetal skeleton is hyaline cartilage. Composed of: ▪ Abundant collagen fibers ▪ Rubbery matrix Connective Tissue Types Elastic cartilage Provides elasticity Example: supports the external ear Connective Tissue Types Fibrocartilage Highly compressible Example: forms cushion-like discs between vertebrae Connective Tissue Types Dense connective tissue Main matrix element is collagen fibers Cells are fibroblasts Examples: Tendon – attach muscle to bone Ligaments – attach bone to bone Connective Tissue Types Areolar connective tissue Most widely distributed connective tissue Soft, pliable tissue Contains all fiber types Can soak up excess fluid Connective Tissue Types Adipose tissue (Fat) 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 Connective Tissue Types Reticular connective tissue Delicate network of interwoven fibers Forms stroma (internal supporting network) of lymphoid organs ▪ Lymph nodes ▪ Spleen ▪ Bone marrow Connective Tissue Types Blood Blood cells surrounded by fluid matrix Fibers are visible during clotting Functions as the transport vehicle for materials Muscle Tissue Function is to produce movement 3 types ▪ Skeletal muscle ▪ Cardiac muscle ▪ 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 Muscle Tissue Types 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 Muscle Tissue Types Smooth muscle Involuntary muscle Surrounds hollow organs Attached to other smooth muscle cells No visible striations One nucleus per cell Nervous Tissue Neurons and nerve support cells Function is to send impulses to other areas of the body Irritability 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 Development aspects of Tissues Epithelial tissue arises from all 3 primary germ layers Muscle & 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 THANK YOU FOR LISTENING!