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