Cells & Tissues Anatomy & Physiology PDF

CELLS & TISSUES | ANATOMY AND PHYSIOLOGY CELLS Control center of the cell Structural units of all living things - Contains genetic material (DNA) Human body contains 50-100 trillion of ce...

CELLS & TISSUES | ANATOMY AND PHYSIOLOGY CELLS Control center of the cell Structural units of all living things - Contains genetic material (DNA) Human body contains 50-100 trillion of cells Three regions Discovered by Robert Hooke and named 1. Nuclear membrane then as “cells” Barrier of the nucleus CELL THEORY Consists of a selectively permeable, A cell is the basic structural and functional double phospholipid membrane unit of living organisms. So, when you define Contains nuclear pores that allow for cell properties, you are in fact defining the exchange of material with the rest of properties of life. the cell Cell is the smallest living unit that cannot be Inside is the nucleoplasm containing seen by naked eye the nucleoli and chromatin – fluid The activity of an organism depends on the similar to cytoplasm collective activities of its cells. 2. Nucleolus (nucleolus - singular) According to the principle of Nucleus contains one or more nucleoli complementarity, the activities of cells are Sites of ribosome production and dictated by their structure (anatomy), which partial assembly determines function (physiology). Ribosomes then migrate to the Continuity of life has a cellular basis cytoplasm through nuclear pores CELLS AND TISSUES 3. Chromatin Carry out all chemical activities needed to Composed of unwound DNA and sustain life protein – used for making proteins Cells are the building blocks of all living Scattered throughout the nucleus things Chromatin condenses to form Cells are bathed in a dilute salt water chromosomes when the cell divides solution called interstitial fluid derived from 2) PLASMA MEMBRANE the blood Tissues are groups of cells that are similar in structure and function > organs > organ systems > organism ANATOMY OF THE CELL Cells are not all the same - Size, shape, and function very different All cells share general structures Cells are organized into three main regions Barrier for cell contents Semi-permeable, Double phospholipid layer 1) THE NUCLEUS - Hydrophilic heads – water loving - Hydrophobic tails – water fearing Other materials in plasma membrane - Protein – receptors, cell recognition and communication, channels for transport - Cholesterol – keep membrane fluid and stable - Glycoproteins – receptors, cell-to-cell interactions - 1  CELLS & TISSUES | ANATOMY AND PHYSIOLOGY PLASMA MEMBRANE SPECIALIZATION Mitochondria - “Powerhouses” of the cell - Change shape continuously - Has a double membrane and had its own DNA - Carry out reactions where oxygen is used to break down food – cell respiration - ProvidesATP for cellular energy Ribosomes - Made of protein and RNA - Sites of protein synthesis Microvilli - Found at two locations - Finger-like projections that increase - Free in the cytoplasm surface area for absorption - Attached to rough endoplasmic Membrane junctions reticulum - Tight junctions – impermeable, leak Endoplasmic reticulum (ER) proof sheets - Fluid-filled tubules for carrying - Desmosomes – anchorings that prevent substances cells from being separated - Two types of ER - Gap junctions – allow communication 1. Rough Endoplasmic Reticulum between cells through connexons that Studded with ribosomes span the two cell membranes Site where building materials 3) CYTOPLASM of cellular membrane are formed Material outside the nucleus and inside 2. Smooth Endoplasmic Reticulum the plasma membrane Functions in cholesterol - Cytosol synthesis and breakdown, fat metabolism, and detoxification of - Fluid containing nutrients dissolved drugs in water that suspends other Golgi apparatus elements - Modifies and packages proteins - Organelles - Produces different types of packages - Metabolic machinery of the cell - Secretory vesicles – contain proteins - Inclusions for export - Non-functioning units – stored - Cell membrane components to be nutrients such as fat droplets, added to the plasma membrane glycogen granules, pigments, and mucus CYTOPLASMIC ORGANELLES Lysosomes - Contain hydrolytic enzymes and enzymes that digest non-usable materials within the cell such as old 2  CELLS & TISSUES | ANATOMY AND PHYSIOLOGY organelles as well as bacteria and CELLULAR PROJECTIONS viruses Cilia and Flagella Peroxisomes - Not found in all cells - Membranous sacs of oxidase enzymes - Used for movement - Detoxify harmful substances using O2 - Cilia moves materials across the cell - Break down free radicals (highly surface (usually short and many) reactive chemicals with free electrons) - Flagellum propels the cell (usually - Replicate by pinching in half long and few in number) Cytoskeleton - Network of protein structures that CELLULAR DIVERSITY extend throughout the cytoplasm - Provides the cell with an internal framework - Determines cell shape, supports organelles, provides path for intracellular transport, involved in cell movement - Three different types 1. Microfilaments – cell motility and changed in cell shape – actin and myosin 2. Intermediate filaments – help form desmosomes and internal guy wires 3. Microtubules – determine overall shape of a cell and location of organelles Centrioles - Rod-shaped bodies made of microtubules that lie at right angles to each other and near the nucleus - Direct formation of mitotic spindle during cell division 3  CELLS & TISSUES | ANATOMY AND PHYSIOLOGY concentration, or down a concentration gradient - Movement is due to kinetic energy in the molecules and affected by size and temperature - Types of diffusion 1. Simple diffusion – Passive diffusion - Unassisted process - Solutes are lipid-soluble materials or small SOLUTIONS AND TRANSFERS enough to pass Solution – homogeneous mixture of two through membrane or more components pores - Solvent – dissolving medium 2. Osmosis – simple diffusion - Solutes – components in smaller of water quantities within a solution - Highly polar water Intracellular fluid – nucleoplasm and easily crosses the cytosol plasma membrane Interstitial fluid – fluid on the exterior of - Occurs all the time the cell 3. Facilitated diffusion - Substances require CELLULAR PHYSIOLOGY: a protein carrier for MEMBRANE TRANSPORT passive transport Membranes are selectively permeable - Still moving down Membrane Transport – movement of concentration substance into and out of the cell gradient and so no Transport is by two basic methods energy is needed 1. Passive transport 4. Filtration - No energy is required - Water and solutes 2. Active transport are forced through - The cell must provide a membrane by metabolic energy fluid, or hydrostatic SELECTIVE PERMEABILITY pressure The plasma membrane allows some - A pressure gradient materials to pass while excluding must exist others - Solute-containing This permeability includes movement fluid is pushed from into and out of the cell a high pressure PASSIVE TRANSPORT PROCESSES area to a lower Diffusion pressure area - Particles tend to distribute - Not very selective themselves evenly within a on what is filtered solution out – size - Movement is from high concentration to low 4  CELLS & TISSUES | ANATOMY AND PHYSIOLOGY DIFFUSION THROUGH PLASMA - Vesicle migrates to MEMBRANE plasma membrane - Vesicle combines with plasma membrane - Material is emptied to the outside ACTIVE TRANSPORT PROCESSES Transport substances that are unable to pass by diffusion - They may be too large - They may not be able to dissolve - Endocytosis in the fat core of the membrane - Extracellular substances - They may have to move against a are engulfed by being concentration gradient enclosed in a membranous Two common forms of active transport vesicle 1. Solute Pumping - Types of endocytosis - Amino acids, some sugars Phagocytosis – cell eating and ions are transported Pinocytosis – cell drinking by solute pumps - ATP energizes protein carriers, and in most cases, moves substances against concentration gradients - Can transport different molecules different directions such as the sodium-potassium pump 2. Bulk Transport - Exocytosis - Moves materials out of the cell - Material is carried in a membranous vesicle 5  CELLS & TISSUES | ANATOMY AND PHYSIOLOGY CELL LIFE CYCLE 2. Prophase Series of changes a cell goes through from First part of cell division the time it is formed until it divides Centromeres migrate to the poles and Cells have two major periods direct the assembly of the mitotic 1. Interphase – metabolic phase spindle - Longest phase where the cell grows Chromosomes form - Cell carries on metabolic processes 3. Metaphase 2. Cell division Spindle from centromeres are - Cell replicates itself attached to chromosomes that are - Function is to produce more cells for aligned in the center of the cell growth and repair processes 4. Anaphase Daughter chromosomes are pulled DNA REPLICATION toward the poles Genetic material duplicated and readies a The cell begins to elongate cell for division into two cells 5. Telophase Occurs toward the end of interphase Daughter nuclei begin forming DNA uncoils and each side serves as a A cleavage furrow (for cell division) template begins to form and finished dividing the cell into two by the end of cytokinesis Everything from prophase is reversed 2. Cytokinesis Division of the cytoplasm Begins when mitosis is near completion Results in the formation of two daughter EVENTS OF CELL DIVISION cells 1. Mitosis Division of the nucleus PROTEIN SYNTHESIS Results in the formation of two daughter Gene – DNA segment that carries a blueprint nuclei for building one protein STAGES OF MITOSIS Proteins have many functions 1. Interphase - Building materials for cells No cell division occurs - Act as enzymes (biological catalysts) The cell carries out normal metabolic RNA is essential for protein synthesis activity and growth 6  CELLS & TISSUES | ANATOMY AND PHYSIOLOGY ROLE OF RNA BODY TISSUES 1. Transfer RNA (tRNA) Cells are specialized for particular functions Transfers appropriate amino acids to Tissues the ribosome for building the protein Groups of cells with similar structure and 2. Ribosomal RNA (rRNA) function Helps form the ribosomes along with Four primary types proteins where proteins are built 1. Epithelium (covering) 3. Messenger (mRNA) Found in different areas Carries the instructions for building a - Body coverings protein from the nucleus to the - Body linings ribosome - Glandular tissue Functions - Protection - Absorption - Filtration - Secretion Characteristics - Cells fit closely together - Tissue layer always has one free surface – unattached, the apical surface - The lower surface is bound by a basement membrane – structureless material secreted by the cells - Avascular (have no blood supply) TRANSCRIPTION AND TRANSLATION – depend on diffusion Transcription - Regenerate easily if well Transfer of information from DNA’s nourished base sequence to the complimentary Classification of Epithelium base sequence of mRNA – switching T Number of cell layers for U - Simple – one layer Translation - Stratified – more than one layer Base sequence of mRNA is translated Shape of cells to an amino acid sequence based on - Squamous – flattened codon/anticodon complements - Cuboidal – cube-shaped - Amino acids are the building - Columnar – column-like blocks of proteins Simple Epithelium 1. Simple Squamous Single layer of flat cells Usually forms membranes where filtration or exchange occurs Lines body cavities – serous membranes Lines lungs and capillaries 7  CELLS & TISSUES | ANATOMY AND PHYSIOLOGY 2. Stratified cuboidal 2. Simple Cuboidal Two layers of cuboidal cells Single layer 3. Stratified columnar of cubelike Surface cells are columnar, cells cells underneath vary in size and shape Common in 4. Stratified cuboidal and columnar glands and Rare in human body their ducts Found mainly in ducts of large glands Forms walls of kidney tubules 5. Transitional epithelium Covers the ovaries Shape of cells 3. Simple Columnar depends upon Single layer of the amount of tall cells that stretching fit closely Cells of the basal together layer are Often includes cuboidal or columnar while those at the goblet cells, free surface vary which produce mucus Lines organs of the urinary system Lines digestive tract Mucosae – mucous membranes line 2. Connective tissue (support) body cavities open to the body exterior Found everywhere in the body 4. Pseudostratified Columnar Includes the most abundant and widely Single layer, distributed tissues but some Functions cells are - Binds body tissues together shorter than - Supports the body others - Provides protection Often looks Connective Tissue Characteristics like a double cell layer Variations in blood supply Sometimes ciliated, such as in the - Some tissue types are well respiratory tract vascularized May function in absorption or secretion - Some have poor blood supply or STRATIFIED EPITHELIUM (+2 layers) are avascular such as tendons, 1. Stratified Squamous ligaments, and cartilage Cells at the free edge are flattened Extracellular matrix while cells close to the basement Non-living material that surrounds membrane are cuboidal or columnar living cells Found as a protective covering where Two main elements friction is common - Ground substance – mostly Locations water along with adhesion - Skin proteins and polysaccharide - Mouth molecules - Esophagus - Fibers - Produced by the cells - Three types 1. Collagen fibers 2. Elastic fibers 3. Reticular fibers 8  CELLS & TISSUES | ANATOMY AND PHYSIOLOGY Connective Tissues Type 5. Dense connective tissue 1. Bone (osseous tissue) Main matrix Composed of: element is - Bone cells in lacunae (cavities) collagen fibers - Hard matrix of calcium salts Crowed between - Large numbers of collagen fibers the collagen fibers Used to protect and support the body are rows of cells called fibroblasts Examples - Tendon – attach muscle to bone - Ligaments – attach bone to bone 6. Adipose tissue Matrix is an areolar tissue in which fat 2. Hyaline Cartilage globules Most common cartilage predominate - Abundant collagen fibers Many cells - Rubbery matrix contain large Entire fetal skeleton is hyaline cartilage lipid deposits Functions - Insulates the body - Protects some organs - Serves as a site of fuel storage 7. Reticular connective tissue Delicate network of interwoven fibers 3. Fibrocartilage Forms stroma Highly compressible (internal supporting Example: forms cushion-like discs network) of between vertebrae lymphoid organs - Lymph nodes - Spleen - Bone marrow 8. Blood Blood cells surrounded by fluid matrix Fibers are visible 4. Elastic cartilage during clotting Provides elasticity Functions as the Example: supports the external ear transport vehicle for materials 9  CELLS & TISSUES | ANATOMY AND PHYSIOLOGY Loose Connective Tissue Types 4. Nervous Tissue (control) 1. Areolar connective tissue Neurons and nerve supporting cells Most widely (those that insulate, support, and distributed protect neurons) connective Function is to receive and send tissue impulses to other areas of the body Soft, pliable - Irritability tissue - Conductivity Functions as universal packing tissue and connective tissue glue Contains all fiber types Can soak up excess fluid 3. Muscle tissue (movement) Function is to produce movement by contracting or shortening Three types 1. Skeletal muscle Can be Tissue Repair (wound Healing) controlled Regeneration voluntarily - Replacement of destroyed tissue Cells attach to by the same kind of cells connective Fibrosis tissue - Repair by dense fibrous Cells are connective tissue (scar tissue) striated Determination of method Cells have more than one nucleus - Type of tissue damaged 2. Cardiac Muscle - Severity of the injury Found only in the heart Events in Tissue Repair Function is to Capillaries become very permeable pump blood - Introduce clotting proteins to (involuntary) make clot Cells - Wall off injured area to prevent attached to other cardiac muscle cells at blood loss and infection intercalated disks Formation of granulation tissue Cells are striated - Contains capillaries and One nucleus per cell phagocytes 3. Smooth muscle – visceral muscle Regeneration of surface epithelium just Involuntary below the scab muscle Surrounds hollow organs Attached to other smooth muscle cells No visible striations One nucleus per cell Spindle shaped 10  CELLS & TISSUES | ANATOMY AND PHYSIOLOGY Regeneration of Tissues Tissues that regenerate easily 1. Epithelial tissue 2. Fibrous connective tissue and bone Tissues that regenerate poorly 1. Skeletal muscle Tissues that are replaced largely with scar tissue 1. Cardiac muscle 2. 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 11