Human Anatomy & Physiology, Sixth Edition

4Tissue: The Living Fabric

Tissues Groups of cells similar in structure and function

Four major types Epithelial

Lining & secretory functions

Connective Structural and dispersal functions

Muscle movement

Nerve Rapid coordination of muscles, cognitive and homeostatic

functions

Epithelial Tissue Tightly connected by cell-cell adhesions – desomosomes, tight

junctions & adherins junctions

Form continuous sheets

Adherent to and supported by underlying basal laminae

Cells are polarized – apical and basal surfaces

Avascular but innervated

Regenerative

Classification of Epithelia

Layering Shape

Epithelia: Tissues composed of epithelial cells

Lining Skin

Digestive tract

Exocrine glands

Epithelial organs Lung

kidney

Epithelia: Simple Squamous

Figure 4.2a

Epithelia: Stratified Squamous

Figure 4.2e

Thick membrane composed of several layers of cells

Function in protection of underlying areas subjected to abrasion

Forms the external part of the skin’s epidermis (keratinized cells), and linings of the esophagus, mouth, and vagina (nonkeratinized cells)

Epithelia: Simple Cuboidal

Figure 4.2b

Single layer of cubelike cells with large, spherical central nuclei

Function in secretion and absorption

Present in kidney tubules, ducts and secretory portions of small glands, and ovary surface

Epithelia: Transitional

Figure 4.2f

Several cell layers, basal cells are cuboidal, surface cells are dome shaped

Stretches to permit the distension of the urinary bladder

Lines the urinary bladder, ureters, and part of the urethra

Epithelia: Simple Columnar

Figure 4.2c

Epithelia: Pseudostratified Columnar

Figure 4.2d

Single layer of cells with different heights; some do not reach the free surface

Nuclei are seen at different layers

Function in secretion and propulsion of mucus

Present in the male sperm-carrying ducts (nonciliated) and trachea (ciliated)

Glands 1 or more cells that makes and secretes an aqueous fluid

Endocrine Release material into blood stream

Secretions include amino acids, proteins, glycoproteins, and steroids (hormones)

Exocrine Secrete products into a duct of epithelial cells or directly into

target organ (stomach, intestine etc…)

mucous, sweat, oil, and salivary glands

Exocrine Glands Unicellular gland

goblet cells in stomach

Multicellular composed of a duct and secretory unit

Classified according to: Simple or compound duct type

Structure of their secretory units

Figure 4.3a-d

Multicellular Exocrine Glands

Modes of SecretionMerocrine - exocytosis

(e.g., pancreas, sweat, and salivary glands)

Holocrine – fragmentation of cells

(e.g., sebaceous glands)

Connective Tissue 4 subcategories

Fibrous

Cartilagenous

Osseous

Hematopoietic

Extracellular matrix Proteins secreted by connective tissue cells

Fluid

Connective Tissue Types & Derivation

Figure 4.5

Fibrous

Extracellular Matrices Ground substance – unstructured material

between cells Proteins

proteoglycans – protein core with glycosaminoglycans (GAGs) attached

GAGs – chondroitin sulfate, keratin sulfate, heparin, hyaluronic acid

fibronectin, laminin – attachement network for cells

Fluid

Structural protein fibers – collagen, elastin

Connective Tissue: Loose

Figure 4.8b

Connective Tissue: Loose

Figure 4.8c

Connective Tissue: Loose

Figure 4.8d

Connective Tissue: Dense Regular

Figure 4.8e

Connective Tissue: Dense Irregular

Figure 4.8f

Connective Tissue: Hyaline Cartilage

Figure 4.8g

Connective Tissue: Fibrocartilage

Figure 4.8i

Matrix similar to hyaline cartilage but less firm with thick collagen fibers

Provides tensile strength and absorbs compression shock

Found in intervertebral discs, the pubic symphysis, and in discs of the knee joint

Connective Tissue: Elastic Cartilage

Figure 4.8h

Similar to hyaline cartilage but with more elastic fibers

Maintains shape and structure while allowing flexibility

Supports external ear (pinna) and the epiglottis

Connective Tissue: Bone (Osseous Tissue)

Figure 4.8j

Connective Tissue: Blood

Figure 4.8k

Blood Extracellular Matrix Components H2O

Proteins Serum albumin

Apolipoproteins, HDL, & LDL

Complement proteins

Immunoglobulins (antibodies)

Clotting factors

Neural Tissue Neurons

Conductive cells

Soma, Axon, Dentrites

Schwann cells Insulating cells

Glia Supporting cells

Nervous (Neural) Tissue

Figure 4.10

glial cells

Muscle Tissue Striated (skeletal)

Long, cylindrical, multinucleate cells

Striations due to alignment of contractile proteins

Cardiac Branching, striated, uninucleate cells that interlock

Smooth Sheets of spindle-shaped, uninucleate cells without visible

striations

Muscle Tissue: Skeletal

Figure 4.11a

Long, cylindrical, multinucleate cells with obvious striations

Initiates and controls voluntary movement

Found in skeletal muscles that attach to bones or skin

Muscle Tissue: Cardiac

Figure 4.11b

Branching, striated, uninucleate cells interdigitating at intercalated discs

Propels blood into the circulation

Found in the walls of the heart

Muscle Tissue: Smooth

Figure 4.11c

Developmental Aspects Cellular differentiation

Primary germ layers ectoderm

mesoderm

endoderm

Primary cell types interact - induction 1st Ectoderm + Endoderm mesoderm

2nd Mesoderm + Ectoderm neural tissue

Subsequent inductions give rise to all other tissue types

Developmental Aspects

Figure 4.13

Ectoderm

Mesoderm

Endoderm

& Endothelium