From Cells to Organ Systems 4 From Cells to Organ Systems 1

Tissues Groups of cells with a common function Four primary tissues Epithelia Connective tissues Muscle Nervous

Epithelial Tissues Two basic purposes 1. Line body cavities and cover surfaces 2. Glandular epithelia Epithelial cells adapted to make up glands Exocrine glands Secrete into ducts to exterior of body Endocrine glands Secrete into the blood to carry chemical messages throughout the body

Epithelial Tissues: Classification Shape Squamous Flattened cells Line vessels, part of lungs, body surface Cuboidal Cube shaped Form lining of tubules, glandular tissue Columnar Column shaped Line respiratory, digestive, reproductive tracts

Epithelial Tissues: Classification Number of layers Simple/single-layered Adapted for diffusion across cell barriers Line glands, and respiratory, digestive, reproductive systems Stratified/multiple-layered Provide protection, as in the skin surface

Most epithelial tissues line or cover surfaces or body cavities. Figure 4.1 Simple squamous Lines blood vessels and air sacs of lungs Permits exchange of nutrients, wastes, and gases Stratified squamous Outer layer of skin, mouth, vagina Protects against abrasion, drying out, infection Stratified cuboidal Lines ducts of sweat glands Secretes water and ions Simple cuboidal Lines kidney tubules and glands Secretes and reabsorbs water and small molecules Stratified columnar Lines epididymus, mammary glands, larynx Secretes mucus Simple columnar Lines most digestive organs Absorbs nutrients, produces mucus Figure 4.1 Types of epithelial tissues. Goblet cell Basement membrane Most epithelial tissues line or cover surfaces or body cavities. Exocrine gland Endocrine gland Gland cells Gland cells Blood flow Glandular epithelia secrete a product. 6

The Basement Membrane Provides Structural Support Noncellular layer directly beneath epithelial tissue Composed of proteins secreted by epithelial cells and connective tissue Provides structural support to overlying cells Attaches epithelial layer to underlying tissues

Cell Junctions—Hold Adjacent Cells Together Tight junctions Seal plasma membranes tightly together Digestive tract lining, bladder lining Adhesion junctions/spot desmosomes Permit some movement between cells Allow tissues to stretch and bend Skin Gap junctions Protein channels enable movement of materials between cells Liver, heart

flexibility of movement. Gap junctions provide for the direct transfer Figure 4.2 Tight junction proteins Protein filaments Protein channel Figure 4.2 Examples of junctions between cells. Intercellular space Intercellular space Intercellular space Tight junctions form leak-proof seals between cells. Adhesion junctions anchor two cells together, yet allow flexibility of movement. Gap junctions provide for the direct transfer of water and ions between adjacent cells. 9

Connective Tissue General functions Supports softer organs of body Connects parts of body Stores fat Produces blood cells Contains cells embedded in nonliving extracellular matrix Matrix provides the strength Two general types Fibrous and special

Fibrous Connective Tissue Function: provides strength and elasticity Contains fibers and cells embedded in gel-like ground substance (matrix) Matrix: intercellular material giving the CT its characteristics Cells: fibroblasts, macrophages, lymphocytes, and neutrophils Fibers: collagen, elastic, and reticular

Fibrous Connective Tissue Four general types Loose: surrounds many organs, lines cavities around blood vessels Dense: forms tendons, ligaments, deeper layers of skin Elastic: surrounds stomach and bladder, maintains shape Reticular: makes up internal framework of soft organs (liver) and the lymphatic system

Mast cell Fibroblast Elastic fiber Reticular fiber Macrophage Figure 4.3 Mast cell Fibroblast Elastic fiber Reticular fiber Macrophage Nerve fiber Lymphocyte Collagen fiber Figure 4.3 Fibrous connective tissue. Neutrophil Plasma cell Ground substance Fat cell Capillary 13

Loose areolar connective tissue ( 160). In loose connective Figure 4.4 Elastin fibers Fibroblast Collagen fibers Loose areolar connective tissue ( 160). In loose connective tissue the collagen and elastin fibers are arrayed in a random pattern. Collagen fibers Figure 4.4 Examples of fibrous connective tissues. Nuclei of fibroblasts Dense connective tissue ( 160). In dense connective tissue the fibers are primarily collagen fibers. In tendons and ligaments the fibers are oriented all in the same direction, with fibroblasts occupying narrow spaces between adjacent fibers. 14

Specialized Connective Tissues Serve Special Functions Cartilage: produced by chondroblasts found in lacunae; no blood vessels; high collagen content Bone: inorganic matrix with calcium salts for hardness Blood: fluid matrix of plasma, red blood cells, white blood cells, and platelets Adipose tissue: fat cells; function in insulation, protection, and energy storage

Adipose tissue from the subcutaneous layer under the skin ( 140). Figure 4.5 Chondrocyte in lacuna Ground substance Cartilage from the trachea ( 300). Mature cartilage cells, called chondrocytes, become trapped in chambers called lacunae within the hard, rubbery ground substance. Ground substance is composed of collagen fibers, polysaccharides, proteins, and water. Vacuole containing stored fat Figure 4.5 Examples of special connective tissues. Blood vessel Nuclei of fat cells Adipose tissue from the subcutaneous layer under the skin ( 140). Adipose tissue consists almost entirely of fat cells. The fat deposit within a fat cell can become so large that the nucleus is pushed to the side. 16

Muscle Tissue Contracts to Produce Movement Skeletal muscle Moves body parts Voluntary, multinucleated Cardiac muscle Functions in the heart Involuntary, single nucleus Smooth muscle Surrounds hollow structures

Skeletal muscle ( 100). Skeletal muscle cells Figure 4.6 Nuclei Intercalated disc Width of one muscle cell Nucleus Skeletal muscle ( 100). Skeletal muscle cells are very long and have many nuclei. Cardiac muscle ( 225). Cardiac muscle cells Interconnect with each other. Smooth muscle cell Figure 4.6 Muscle tissue. Nucleus Sheet of smooth muscle ( 250). Smooth muscle cells are thin and tapered. 18

Nervous Tissues Transmit Impulses Neuron: specialized nervous system cell Function: generate and transmit electrical impulses Structural components: cell body, dendrites, axon Glial cells Function: Surround and protect neurons Provide nutrients to neurons

Axon Nuclei of glial cells Cell body Dendrites Figure 4.7 Figure 4.7 Nervous tissue: a neuron. Dendrites 20

Organs and Organ Systems Perform Complex Functions Contain two or more tissue types joined together; perform specific functions Organ systems Groups of organs that perform a common function Examples Digestive system: mouth, throat, stomach, intestines, and liver Lymphatic system: lymph nodes, tonsils, and spleen

Body Cavities Anterior cavity Posterior cavity Thoracic cavity Two pleural cavities Pericardial cavity Abdominal cavity Posterior cavity Cranial cavity Spinal cavity Tissue membranes (serous membranes) line body cavities

Cranial cavity Posterior cavity Vertebral canal Pericardial cavity Figure 4.8 Cranial cavity Posterior cavity Vertebral canal Pericardial cavity Thoracic cavity Pleural cavity Diaphram separates thoracic and abdominal cavities Anterior cavity Abdominal cavity Figure 4.8 The main body cavities. Pelvic cavity 23

Tissue Membranes Serous membranes: Mucous membranes: Line and lubricate internal body cavities Reduce friction between organs Mucous membranes: Lines airways, digestive tract, reproductive tract Lubricate surface, captures debris Synovial membranes: Line spaces in movable joints Cutaneous membranes: Outer covering (skin)

Describing Body Position or Direction Three body planes Midsagittal Divides body into left and right sides Frontal Divides body into front and back Transverse Divides body into top and bottom

Describing Body Position or Direction Terms to describe relative position Anterior: at or near the front Posterior: at or near the back Proximal: nearer to the body trunk Distal: farther away from the body trunk Superior: situated above or directed upward Inferior: situated below or directed downward

Superior Distal Proximal Inferior Posterior Anterior (closer to Figure 4.9 Superior (closer to the head or upper part of a structure) Frontal plane Distal (farther away from the trunk) Transverse plane Proximal (nearer to the trunk) Figure 4.9 Planes of symmetry and terms used to describe position or direction in the human body. Inferior (farther from the head or toward the lower part of a structure) Posterior (at or near the back) Anterior (at or near the front) Midsagittal plane 27

The Skin As an Organ System The proper name is integumentary system Includes skin, hair, nails, glands Functions Protection from dehydration Protects from injury Serves as defense against microorganisms Regulates body temperature Makes vitamin D Provides sensation

Epidermis Dermis Hypodermis Free nerve endings Hair follicle Figure 4.10 Free nerve endings Hair follicle Hair shaft Hair root Small blood vessels Epidermis Sebaceous gland Dermis Vein Artery Smooth muscle Figure 4.10 The skin. Adipose tissue Hypodermis Sweat gland Nerve Receptors 29

Skin Consists of Epidermis and Dermis Outer layer Stratified squamous epithelial cells No blood vessels Two major cell types Keratinocytes: provide a tough waterproof protein (keratin) Melanocytes: provide dark pigment (melanin)

Melanocyte containing melanin granules Figure 4.11 Dead cells of epidermis Keratinocyte containing melanin Living cells of epidermis Melanocyte containing melanin granules Dividing keratinocyte (basal cell) Figure 4.11 The epidermis. Basement membrane Blood vessel Dermis with blood vessel 31

Skin Consists of Epidermis and Dermis Lies underneath the epidermis Supports tissues Fibers Collagen Elastic Cells Fibroblasts (most abundant) Mast cells White blood cells Fat cells

Accessory Structures of Dermis Hair Shaft Follicle Smooth muscle Attached to hair follicle, raises hair to upright position Oil glands/sebaceous glands Secretion moistens and softens skin Sweat glands Blood vessels Sensory nerve endings

Accessory Structures of Dermis Sweat glands Secrete sweat, help in temperature regulation Sebaceous glands Secrete oil to moisten and soften hair and skin Blood vessels Supply nutrients, remove waste, assist in temperature regulation Sensory nerve endings Detect heat, cold, touch, deep pressure, vibration

Negative Feedback Helps Maintain Core Body Temperature Controlled variable: body temperature Sensors: temperature sensors in skin and internal organs Control center: hypothalamus Effectors Blood vessels Sweat glands Skeletal muscles