Chapter 1: Cells and Tissues

Chapter 1: Cells and Tissues

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

Cells: General Structure Three main regions: Nucleus Cytoplasm Plasma membrane

Recall the structure and function of the following organelles from Biology Nucleus Ribosome Golgi apparatus Endoplasmic Reticulum (smooth and rough) Mitochondrion Cytoplasm/cytosol Cytoskeleton Lysosome Cell Membrane

Specializations of the Plasma Membrane Microvilli Tiny fingerlike projections that greatly increase the cell s surface area Membrane junctions: Tight junctions: bind cells together into leakproof sheets that prevent substances from passing through the spaces between cells Gap junctions: allow communication between cells, nutrients or ions can pass directly from one cell to another

Cellular Diversity 1. Cells that connect body parts:

Cellular Diversity 2. Cells that cover and line body organs:

Cellular Diversity 3. Cells that move organs and body parts:

Cellular Diversity 4. Cell that stores nutrients:

Cellular Diversity 5. Cell that fights disease:

Cellular Diversity 6. Cell that gathers information and controls body functions:

Cellular Diversity 7. Cells of reproduction:

Body Tissues Tissues Groups of cells with similar structure and function Four primary types: Epithelium Connective tissue Nervous tissue Muscle

Epithelial Tissues Found: Body coverings Body linings Glandular tissue Function: Protection Absorption Filtration Secretion Structure: Tightly packed cells Tissue layer always has one free surface Lower surface always has a basement membrane Avascular (there is no blood supply) Regenerates easily

Classification of Epithelium Number of cell layers: Simple: 1 layer Stratified: layered Shape of cells: Squamous: scale-like Cuboidal: cube shaped Columnar: column-like

Simple epithelium: 4 types: Simple squamous Simple cuboidal Simple columnar Pseudostratified

1. Simple Squamous Single layer of flat cells Typically forms membranes: Lines body cavities Lines lungs and capillaries

2. Simple Cuboidal Single layer of cubelike cells Common in glands and their ducts Forms walls of kidney tubules Covers the ovaries

3. Simple Columnar Single layer of tall cells Often includes goblet cells, which produce mucus Lines digestive tract

4. Pseudostratified Single layer, but some cells are shorter than others Looks like a double cell layer Sometimes ciliated (respiratory tract) Functions in absorption and secretion

Stratified epithelium: 5 types: Stratified squamous Stratified cuboidal Stratified columnar Stratified cuboidal and columnar Transitional epithelium Don t need to know details on these three

Stratified squamous Cells at the free edge are flattened Found as a protective covering where friction is common Located: Skin Mouth Esophagus

Transitional Epithelium Shape of cells depends on the amount of stretching Lines organs of the urinary system

Glandular Epithelium A gland consists of one or more cells that makes and secretes a product (goblet cell) 2 types: Endocrine glands have no ducts their secretions (hormones) diffuses directly into the blood Ex. thyroid, adrenal and pituitary glands Exocrine glands have ducts and the secretions empty through the ducts to the epithelial surface Ex. sweat and oil glands in skin

Connective tissues Found Everywhere, most abundant and widely distributed tissues Function Binds body tissues together Supports the body Provides protection Structure Blood supply: can be well vascularized or avascular A main component of connective tissues includes the Extracellular Matrix which is mon-living material that surrounds living cells

More about the Extracellular Matrix 2 main elements A ground substance: mostly water along with adhesion proteins and polysaccharide molecules Fibers Produced by cells Three types: Collagen fibers Elastic fibers Reticular fibers

Types of Connective Tissues Bone Cartilage Dense connective tissue Loose connective tissue Areolar tissue Adipose tissue Reticular connective tissue Blood

Bone (osseous tissue) Structure Bone cells in lacunae (cavities) Hard matrix of calcium and salts Large numbers of collagen fibers Function: Used to protect and support the body

Hyaline cartilage Structure Abundant collagen fibers Rubbery matrix Function Covers ends of bones where joints are formed Fetal skeleton Most abundant type of cartilage

Elastic cartilage and Fibrocartilage Elastic cartilage Provides elasticity Ex. External ear Fibrocartilage Highly compressible Ex. Discs between vertebrae

Dense connective tissue Structure: Collagen fibers Fibroblast cells Function: Ropelike structures such as: Tendons (attach skeletal muscle to bone) Ligaments (connect bones to bones at joints)

Areolar connective tissue Structure: Soft, pliable Contains all fiber types (collagen, elastic, and reticular) Function Can soak up excess fluid Underlies all mucous membranes Reservoir of water and salts for surrounding tissues

Adipose tissue Structure: Matrix is areolar tissue where fat cells are most common Many cells contain large lipid deposits Functions: Insulation Protection of organs Fuel storage

Reticular connective tissue Structure: Delicate network of interwoven fibers Function: Forms internal supporting network (stroma) of lymphoid organs: Lymph nodes Spleen Bone marrow

Blood Structure: Blood cells surrounded by fluid matrix Fibers are visible during clotting Function: Transport vehicle for materials

Muscle Tissue Function: to produce movement through contraction or shortening Structure: Cells are elongated to provide a long axis for contraction Types: Skeletal Cardiac Smooth

Skeletal Muscle Structure: Attach to connective tissue Cells are striated (striped) Cells have multiple nuclei Function: Voluntary movement

Cardiac Muscle Structure: Cells attached to other cardiac muscle cells at intercalated discs (tight cell junctions) Cells are striated (striped) One nucleus per cell Function: Pump blood (involuntary) Found only in the heart

Smooth Muscle Structure: Attached to other smooth muscle cells No striations (stripes) One nucleus per cell Function: Involuntary muscle movement Surrounds hollow organs

Nervous Tissue Structure: Neurons and nerve support cells Function: Send impulses to other parts of the body Irritability (receive) Conductivity (conduct)

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 damaged tissue Severity of damage

Events in Tissue Repair Capillaries become very permeable (allow materials to pass through) Introduce clotting proteins which wall off the injured area Angiogenesis or the formation of granulation tissue: pink tissue composed of new capillaries that grow into the damaged area 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 chord

Unless otherwise noted content taken from Essentials of human anatomy and physiology seventh edition