Exercise 6 Classification of Tissues

 Group of cells  Similar structure & function

 Epithelial  Connective  Muscle  Nervous

 Cover surfaces  Simple or stratified? ◦ Simple ◦ Stratified ◦ Apical vs. basal Apical surface Basal surface Apical surface Basal surface Simple Stratified

Simple squamous Stratified squamous Simple cuboidal Stratified cuboidal Simple columnar Stratified columnar Squamous Cuboidal Columnar

 Simple squamous epithelium Air sacs of lung tissue Nuclei of squamous epithelial cells Photomicrograph: Simple squamous epithelium forming part of the alveolar (air sac) walls (140  ). Description: Single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm; the simplest of the epithelia. Simple squamous epithelium Function: Allows materials to pass by diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae. Location: Kidney glomeruli; air sacs of lungs; lining of heart, blood vessels, and lymphatic vessels; lining of ventral body cavity (serosae).

 Simple cuboidal epithelium Fig 4-4 Photomicrograph: Simple cuboidal epithelium in kidney tubules (430  ). Simple cuboidal epithelium Simple cuboidal epithelial cells Basement membrane Connective tissue Description: Single layer of cubelike cells with large, spherical central nuclei. Function: Secretion and absorption. Location: Kidney tubules; ducts and secretory portions of small glands; ovary surface.

 Simple columnar epithelium Photomicrograph: Simple columnar epithelium containing goblet cells from the small intestine (640  ). Simple columnar epithelium Goblet cells Mucus secretion Microvilli (brush border) Description: Single layer of tall cells with round to oval nuclei; some cells bear cilia; layer may contain mucus-secreting unicellular glands (goblet cells). Function: Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliary action. Location: Nonciliated type lines most of the digestive tract (stomach to rectum), gallbladder, and excretory ducts of some glands; ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus.

 Pseudostratified columnar epithelium Fig 4-5 Photomicrograph: Pseudostratified ciliated columnar epithelium lining the human trachea (530  ). Pseudostratified columnar epithelium Mucus of goblet cell Cilia Pseudo- stratified epithelial layer Basement membrane Description: Single layer of cells of differing heights, some not reaching the free surface; nuclei seen at different levels; may contain mucus-secreting goblet cells and bear cilia. Function: Secretes substances, particularly mucus; propulsion of mucus by ciliary action. Location: Nonciliated type in male’s sperm-carrying ducts and ducts of large glands; ciliated variety lines the trachea, most of the upper respiratory tract. Trachea

 Stratified squamous epithelium Photomicrograph: Stratified squamous epithelium lining the esophagus (280  ). Stratified squamous epithelium Nuclei Basement membrane Connective tissue Description: Thick membrane composed of several cell layers; basal cells are cuboidal or columnar and metabolically active; surface cells are flattened (squamous); in the keratinized type, the surface cells are full of keratin and dead; basal cells are active in mitosis and produce the cells of the more superficial layers. Function: Protects underlying tissues in areas subjected to abrasion. Location: Nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina; keratinized variety forms the epidermis of the skin, a dry membrane.

 Stratified cuboidal epithelium Photomicrograph: Stratified cuboidal epithelium forming a salivary gland duct (290  ). Stratified cuboidal epithelium Basement membrane Cuboidal epithelial cells Duct lumen Description: Generally two layers of cubelike cells. Function: Protection Location: Largest ducts of sweat glands, mammary glands, and salivary glands.

 Stratified columnar epithelium Fig 4-5 Photomicrograph: Stratified columnar epithelium lining of the male urethra (290  ). Stratified columnar epithelium Basement membrane Stratified columnar epithelium Connective tissue Urethra Description: Several cell layers; basal cells usually cuboidal; superficial cells elongated and columnar. Function: Protection; secretion. Location: Rare in the body; small amounts in male urethra and in large ducts of some glands.

 Transitional epithelium ◦ Stratified squamous epithelium formed of rounded cells that can slide over one another, allowing the organ to stretch: urinary system only Photomicrograph: Transitional epithelium lining the urinary bladder, relaxed state (365  ); note the bulbous, or rounded, appearance of the cells at the surface; these cells flatten and become elongated when the bladder is filled with urine. Transitional epithelium Basement membrane Connective tissue Description: Resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cells dome shaped or squamouslike, depending on degree of organ stretch. Function: Stretches readily and permits distension of urinary organ by contained urine. Location: Lines the ureters, urinary bladder, and part of the urethra.

 Embryonic connective tissue ◦ mesenchyme  Loose connective tissue ◦ Areolar, adipose, reticular  Dense connective tissue ◦ Dense irregular, dense regular  Supportive connective tissue ◦ Hyaline, elastic, fibrocartilages; bone  Fluid connective tissue ◦ Blood, lymph

© 2014 Pearson Education, Inc. Figure 6.4 Areolar connective tissue: A prototype (model) connective tissue. Macrophage Fibroblast Lymphocyte Fat cell Mast cell Neutrophil Capillary Reticular fiber Elastic fiber Collagen fiber Cell types Extracellular matrix Fibers Ground substance

 Differing proportions of cells & fibers to “matrix” ◦ Matrix  noncellular, nonliving material between connective tissue cells ◦ Different proportions  strength of tissue

Fig. 4-8 Many cell types Syrupy ground substance Distinct cell types Watery matrix Less diverse cell types More fibrous matrix

 Mesenchyme ◦ Many star-shaped stem cells ◦ Gives rise to all other connective tissues ◦ Not present in adults Photomicrograph: Mesenchymal tissue, an embryonic connective tissue (627  ); the clear-appearing background is the fluid ground substance of the matrix; notice the fine, sparse fibers.) Embryonic connective tissue: Mesenchyme Fibers Ground substance Mesenchymal cell Description: Embryonic connective tissue; gel-like ground substance containing fibers; star-shaped mesenchymal cells. Function: Gives rise to all other connective tissue types. Location: Primarily in embryo.

Photomicrograph: Areolar connective tissue, a soft packaging tissue of the body (365  ). Connective tissue proper: loose connective tissue, areolar Collagen fibers Fibroblast nuclei Elastic fibers Lamina propria Epithelium Description: Gel-like matrix with all three fiber types; cells: fibroblasts, macrophages, mast cells, and some white blood cells. Function: Wraps and cushions organs; its macrophages phagocytize bacteria; plays important role in inflammation; holds and conveys tissue fluid. Location: Widely distributed under epithelia of body, e.g., forms lamina propria of mucous membranes; packages organs; surrounds capillaries.

 Adipose connective tissue ◦ (fat) ◦ Insulation for the body’s tissues ◦ Food storage ◦ Little matrix Photomicrograph: Adipose tissue from the subcutaneous layer under the skin (110  ). Connective tissue proper: loose connective tissue, adipose Vacuole containing fat droplet Nuclei of fat cells Description: Matrix as in areolar, but very sparse; closely packed adipocytes, or fat cells, have nucleus pushed to the side by large fat droplet. Function: Provides reserve fuel; insulates against heat loss; supports and protects organs. Location: Under skin; around kidneys and eyeballs; within abdomen; in breasts.

 Reticular connective tissue ◦ Reticular fibers form a soft internal skeleton for support Photomicrograph: Dark-staining network of reticular connective tissue fibers forming the internal skeleton of the spleen (350  ). Connective tissue proper: loose connective tissue, reticular White blood cell (lymphocyte) Reticular fibers Description: Network of reticular fibers in a typical loose ground substance; reticular cells lie on the network. Function: Fibers form a soft internal skeleton (stroma) that supports other cell types, including white blood cells, mast cells, and macrophages. Location: Lymphoid organs (lymph nodes, bone marrow, and spleen). Spleen

Photomicrograph: Dense irregular connective tissue from the dermis of the skin (210  ). Connective tissue proper: dense connective tissue, dense irregular Nuclei of fibroblasts Collagen fibers Fibrous joint capsule Description: Primarily irregularly arranged collagen fibers; some elastic fibers; major cell type is the fibroblast. Function: Able to withstand tension exerted in many directions; provides structural strength. Location: Fibrous capsules of organs and of joints; dermis of the skin; submucosa of digestive tract.

 Dense regular connective tissue ◦ Fibers in one direction ◦ Tendons, ligaments of body’s joints Fig Photomicrograph: Dense regular connective tissue from a tendon (590  ). Connective tissue proper: dense connective tissue, dense regular Collagen fibers Nuclei of fibroblasts Shoulder joint Ligament Tendon Description: Primarily parallel collagen fibers; a few elastic fibers; major cell type is the fibroblast. Function: Attaches muscles to bones or to muscles; attaches bones to bones; withstands great tensile stress when pulling force is applied in one direction. Location: Tendons, most ligaments, aponeuroses.

Photomicrograph: Elastic connective tissue in the wall of the aorta (250  ). Connective tissue proper: dense connective tissue, elastic Elastic fibers Heart Aorta Description: Dense regular connective tissue containing a high proportion of elastic fibers. Function: Allows recoil of tissue following stretching; maintains pulsatile flow of blood through arteries; aids passive recoil of lungs following inspiration. Location: Walls of large arteries; within certain ligaments associated with the vertebral column; within the walls of the bronchial tubes.

Photomicrograph: Hyaline cartilage from a costal cartilage of a rib (470  ). Cartilage: hyaline Chondrocyte in lacuna Matrix Costal cartilages Description: Amorphous but firm matrix; collagen fibers form an imperceptible network; chondroblasts produce the matrix and when mature (chondrocytes) lie in lacunae. Function: Supports and reinforces; serves as resilient cushion; resists compressive stress. Location: Forms most of the embryonic skeleton; covers the ends of long bones in joint cavities; forms costal cartilages of the ribs; cartilages of the nose, trachea, and larynx.

 Elastic Cartilage ◦ Maintains shape, but flexible ◦ Many elastic fibers Photomicrograph: Elastic cartilage from the human ear auricle; forms the flexible skeleton of the ear (510  ). Cartilage: elastic Chondrocyte in lacuna Matrix Description: Similar to hyaline cartilage, but more elastic fibers in matrix. Function: Maintains the shape of a structure while allowing great flexibility. Location: Supports the external ear (auricle); epiglottis.

 Fibrocartilage ◦ Strength, shock absorption ◦ Dense network of collagen fibers Photomicrograph: Fibrocartilage of an intervertebral disc (160  ). Special staining produced the blue color seen. Cartilage: fibrocartilage Chondrocytes in lacunae Collagen fiber Intervertebral discs Description: Matrix similar to but less firm than that in hyaline cartilage; thick collagen fibers predominate. Function: Tensile strength with the ability to absorb compressive shock. Location: Intervertebral discs; pubic symphysis; discs of knee joint.

 Osseous Connective Tissue (Bone) ◦ Support, protection Photomicrograph: Cross-sectional view of bone (175  ). Bones (osseous tissue) Central canal Lacunae Lamella Description: Hard, calcified matrix containing many collagen fibers; osteocytes lie in lacunae. Very well vascularized. Function: Bone supports and protects (by enclosing); provides levers for the muscles to act on; stores calcium and other minerals and fat; marrow inside bones is the site for blood cell formation (hematopoiesis). Location: Bones

Photomicrograph: Smear of human blood (1000  ); two white blood cells (neutrophil and lymphocyte) are seen surrounded by red blood cells. Blood Plasma Neutrophil Red blood cells Lymphocyte Description: Red and white blood cells in a fluid matrix (plasma). Function: Transport of respiratory gases, nutrients, wastes, and other substances. Location: Contained within blood vessels.

 Lymph ◦ Fluid of the lymphatic system ◦ Like plasma without the big proteins ◦ Immune defense

 Skeletal  Cardiac  Smooth

Photomicrograph: Skeletal muscle (approx. 550  ). Notice the obvious banding pattern and the fact that these large cells are multinucleate. Skeletal muscle Part of muscle fiber (cell) Nuclei Striations Description: Long, cylindrical, multinucleate cells; obvious striations. Function: Voluntary movement; locomotion; manipulation of the environment; facial expression; voluntary control. Location: In skeletal muscles attached to bones or occasionally to skin.

 Only in the heart  Striated tissue  Under involuntary control  Branching, uninucleate cells with intercalated discs Photomicrograph: Cardiac muscle (775  ); notice the striations, branching of cells, and the intercalated discs. Cardiac muscle Nucleus Intercalated discs Striations Description: Branching, striated, generally uninucleate cells that interdigitate at specialized junctions called intercalated discs. Function: As it contracts, it propels blood into the circulation; involuntary control. Location: The walls of the heart.

 Found in the walls of hollow organs (digestive, urinary tracts; blood vessels)  2 layers at right angles for contraction/dilation of the organ cavity  Not striated tissue  Uninucleate, spindle-shaped cells Photomicrograph: Smooth muscle cells (265  ). Smooth muscle Smooth muscle cell Nucleus Description: Spindle-shaped cells with central nuclei; no striations; cells arranged closely to form sheets. Function: Propels substances or objects (foodstuffs, urine, a baby) along internal passageways; involuntary control. Location: Mostly in the walls of hollow organs.

Muscle typeCellsstriationsVoluntary? Cardiacbranched Uninucleate Intercalated discs yesno SkeletalLong fibers multinucleate yes SmoothSpindle shaped 1 nucleus no

 Brain, spinal cord, nerves  2 basic cell types: ◦ Neuroglia cells  Protect, support, insulate neurons ◦ Neurons  Receive stimuli & conduct nerve impulses

Photomicrograph: Neurons (370  ) Nervous tissue Nuclei of supporting cells Cell body of a neuron Neuron processes AxonDendrites Cell body Description: Neurons are branching cells; cell processes that may be quite long extend from the nucleus-containing cell body; also contributing to nervous tissue are nonexcitable supporting cells. Function: Neurons transmit electrical signals from sensory receptors and to effectors (muscles and glands); supporting cells support and protect neurons. Location: Brain, spinal cord, and nerves.

© 2014 Pearson Education, Inc. Review Figure 6.1 (1 of 2)

© 2014 Pearson Education, Inc. Review Figure 6.1 (2 of 2)

© 2014 Pearson Education, Inc. Review Figure 6.1a

© 2014 Pearson Education, Inc. Review Figure 6.1b

© 2014 Pearson Education, Inc. Review Figure 6.1c

© 2014 Pearson Education, Inc. Review Figure 6.1d

© 2014 Pearson Education, Inc. Review Figure 6.1e

© 2014 Pearson Education, Inc. Review Figure 6.1f

© 2014 Pearson Education, Inc. Review Figure 6.1g

© 2014 Pearson Education, Inc. Review Figure 6.1h

© 2014 Pearson Education, Inc. Review Figure 6.1i

© 2014 Pearson Education, Inc. Review Figure 6.1j

© 2014 Pearson Education, Inc. Review Figure 6.1k

© 2014 Pearson Education, Inc. Review Figure 6.1l