Chapter 5 Study Guide PDF

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Chapter 5 Study Guide...

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Chapter 5 :Lecture Outline Introduction Tissues Groups of similar cells and extracellular material Common function E.g., providing protection Study of tissues, histology Four types of tissues Epithelial, connective, muscle, nervous Varied structure and function

5.1 Characteristics of Epithelial Tissue Epithelium, also referred to as epithelial tissue Composed of one or more layers of closely packed cells Contains little to no extracellular matrix Covers body surfaces Lines body cavities Forms majority of glands Cellularity Composed almost entirely of tightly packed cells Polarity Apical surface Exposed to external environment or internal body space Microvilli or cilia Lateral surface with intercellular junctions Basal surface Epithelium attached to connective tissue Attachment to basement membrane Barrier between epithelium and connective tissue Avascularity Epithelia lack blood vessels Nutrients obtained across apical surface or from basal surface Extensive innervation Richly innervated; detect changes in environment High regeneration capacity Continual replacement of lost cells

Characteristics of Epithelia: Figure 5.1

Physical Protection Protects from dehydration, abrasion, destruction Selective Permeability Allows passage of some substances while preventing passage of others Secretions Some cells are specialized to secrete Sensations Supply information to nervous system

Classification by number of cell layers Simple epithelium One cell layer thick; all cells contact basement membrane Filtration, absorption, or secretion is primary function

Stratified epithelium Two or more layers of epithelial cells Only basal layer in contact with basement membrane In areas subjected to mechanical stress Pseudostratified epithelium Appears layered All cells contact basement membrane, but may not reach apical surface Classification by cell shape Squamous cells Flat, wide, irregular in shape Nucleus flat

Cuboidal cells About as tall as they are wide Nucleus spherical and in center of cell

Columnar cells Slender and taller than they are wide Nucleus oval; oriented lengthwise in basal region

Figure 1 Nonciliated Simple Columnar Cell

Figure 2 simple ciliated columnar cell

Transitional cells Change shape, depending on stretch of epithelium

Classification of Epithelia: Figure 5.2

Organization and Relationship of Epithelia Types: Figure 5.3

Simple Squamous Epithelium Single layer of flat cells Spherical to oval nucleus Thinnest barrier Allows rapid movement of molecules across surface Lines air sacs of lungs (alveoli), vessel walls (endothelium), serous membranes (mesothelium)

Simple Cuboidal Epithelium Single layer of uniformly shaped cells About as tall as they are wide Centrally located spherical nucleus Designed for absorption and secretion Ideal for structural components of glands

Simple Columnar Epithelium Single layer of cells Taller than they are wide Oval nucleus, lengthwise in basal region Ideal for secretory and absorptive functions Two forms:  Nonciliated  Ciliated Nonciliated Simple Columnar Epithelium Contains microvilli Fuzzy structure—brush border Unicellular glands—goblet cells Secrete glycoprotein—mucin Forms mucus when mixed with water Lines most of digestive tract from stomach to anal canal

Ciliated Simple Columnar Epithelium cilia project from apical surface Move mucus along Goblet cells interspersed Lines Bronchioles Uterine tubes – cilia help move oocyte from ovary to uterus Pseudostratified Columnar Epithelium Appears as multiple cell layers Not really stratified All cells in direct contact with basement membrane Nuclei scattered at different distances Not all cells reach apical surface Two forms: Ciliated

Nonciliated Ciliated Pseudostratified Columnar Epithelium Contains cilia on apical surface Protective functions Goblet cells secrete mucin Traps foreign particles moved by cilia Located in large passageways of respiratory system Nonciliated Pseudostratified Columnar Epithelium Rare, lacks cilia, goblet cells Protective functions Occurs mainly in male urethra and epididymis Stratified Squamous Epithelium Multiple cell layers Only deepest in direct contact with basement membrane basal layers have a cuboidal shape apical cells with squamous shape Protects against abrasion and friction Stem cells in basal layer continuously divide Replace lost cells at surface Exists in keratinized and nonkeratinized forms Keratinized Stratified Squamous Epithelium Superficial layers of dead cells Cells lack nuclei, filled with protein keratin Cells in basal region migrate toward apical surface Fill with keratin and die Found in epidermis Nonkeratinized Stratified Squamous Epithelium All cells alive Kept moist with secretions (e.g., saliva, mucus) Lack keratin, protective protein Microscopically visible cell nuclei Lines Oral cavity, part of pharynx, esophagus, vagina, anus

Stratified Cuboidal Epithelium Two or more layers of cells Superficial cells cuboidal in shape Forms tubes and coverings Protection and secretion Forms walls of ducts in most exocrine glands Sweat glands, parts of male urethra, periphery of ovarian follicles Stratified Columnar Epithelium Rare Two or more layers of cells Columnar cells at apical surface Protects and secretes Found in large ducts of salivary glands, parts of male urethra

Transitional Epithelium Limited to urinary tract In relaxed state Basal cells cuboidal or polyhedral; apical cells large and rounded In stretched state Apical cells flattened Binucleated cells (two nuclei) Allows for stretching as bladder fills Transitional Epithelium: Relaxed and Distended Glands Individual cells or multicellular organs composed of epithelial tissue Endocrine or exocrine Endocrine glands Lack ducts Secrete hormones into blood Exocrine glands Invaginated epithelium in connective tissue Connected with epithelial surface by duct Epithelium-lined tube for gland secretion E.g., sweat glands, mammary glands, salivary glands Unicellular exocrine glands Do not contain a duct Located close to epithelium surface Most common type is goblet cell

Multicellular exocrine glands Numerous cells Acini cells clusters that produce secretions ducts transport secretions to epithelial surface Surrounded by fibrous capsule Extensions of capsule—septa, partition gland into lobes General Structure of Multicellular Exocrine Glands: Figure 5.5

Classification of exocrine glands by anatomic form: Simple glands—a single, unbranched duct Compound glands—branched ducts Tubular glands—secretory portion and duct same diameter Acinar glands—secretory portion forms expanded sac Tubuloacinar gland—both tubules and acini

Structural Classification of Multicellular Exocrine Glands :Figure 5.6

Classification of exocrine glands by method of secretion: Merocrine glands Package secretions into vesicles, released by exocytosis E.g. Lacrimal (tear) and salivary glands Apocrine glands Apical membrane pinches off and becomes secretion E.g. mammary and ceruminous glands Holocrine glands Ruptured cell becomes secretion E.g. sebaceous (oil) glands

Methods of Exocrine Gland Secretion: Figure 5.7

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Why does an epithelium need to be highly regenerative?

because its apical surface is exposed to the environment and in order replace cells that are damaged or lost the epithelial cells undergo mitosis frequently

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Why is an epithelium considered selectively permeable?

In order to accept nutrients and reject toxic, harmful substance.

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How does simple epithelium differ from stratified epithelium?

The biggest difference between simple and stratified tissue is that simple tissue is one layer thick while stratified tissue is multi-layered

 What type of epithelial tissue lines the air sacs of the lungs? Simple Squamous What epithelial tissue contains multiple layers of cells, and the most superficial cells are squamous, dead, and filled with the protein keratin? Keratinized stratified squamous epithelium 

 What are the two basic parts of a multicellular exocrine gland? Acini and ducts 

What are the differences between holocrine and merocrine glands?

Apocrine gland secretion pinch away from the apical membrane, while holocrine glands disintegrate completely to form the secretion.

5.2 Characteristics of Connective Tissue All Connective Tissue shares three basic components: cells, protein fibers, ground substance Cells Classes of Connective Tissue have specific cell types Most cells not in direct contact with each other Two classes of cells: Resident cells Wandering cells Resident cells  Stationary, housed in Connective Tissue  Support, maintain, repair extracellular matrix Examples of resident cells: Fibroblasts Flat cells with tapered ends Most abundant resident cells in Connective Tissue proper Produce fibers and ground substance of extracellular matrix Adipocytes (fat cells) Appear in small clusters in some types of Connective Tissue proper Adipose connective tissue—dominant area of large clusters Mesenchymal cells Embryonic stem cell Divides to replace damaged cells One replaces mesenchymal cell, other becomes committed cell Fixed macrophages Relatively large, irregular-shaped cells Derived from monocytes (white blood cells) Dispersed throughout matrix Phagocytize (engulf) damaged cells or pathogens Release chemicals that stimulate immune system/attract wandering cells Wandering cells Continuously move through Connective Tissue Components of immune system Repair damaged extracellular matrix Types of leukocytes, white blood cells Protect body from harmful agents

Types of wandering cells Mast cells Small, mobile cells close to blood vessels Secrete heparin to inhibit blood clotting Secrete histamine to dilate blood vessels Plasma cells Form when B-lymphocytes are activated when exposed to foreign material Produce antibodies (proteins that immobilize foreign material) Free macrophages Mobile, phagocytic cells Function like fixed macrophages, yet able to move Other leukocytes Neutrophils Phagocytizes bacteria T-lymphocytes Leukocyte that attacks foreign materials Protein fibers Collagen fibers Unbranched, “cable-like” long fibers Numerous in tendons and ligaments Reticular fibers Similar to collagen fibers but thinner Abundant in stroma of some organs (e.g. lymph node) Elastic fibers Contain protein elastin Stretch and recoil easily Found in skin, walls of arteries Ground substance Noncellular material produced by Connective Tissue cells Residence of CT cells and protein fibers Consistency: Viscous (e.g., blood) semisolid (e.g., cartilage) Solid (e.g., bone) Ground substance + protein fibers = extracellular matrix

Functions of Connective Tissue: Physical protection Support and structural framework Binding of structures Storage Transport Immune protection Embryonic Connective Tissue Source of all other Connective Tissue cells Adult Connective Tissue often has mesenchymal stem cells Connective Tissue Classification: Figure 5.9

Connective Tissue proper  Loose Connective Tissue Fewer cells and protein fibers than dense connective tissue Protein fibers are sparse and irregularly arranged Abundant ground substance Body’s “packing material”, supports structures Three types:  Areolar  Adipose  Reticular Areolar connective tissue Loose organization of collagen and elastic fibers Highly vascularized Contains all fixed and wandering cells of connective tissue proper Ground substance is abundant and viscous Found in the papillary layer of dermis, subcutaneous layer, and surrounding organs, nerve and muscle cells, and blood vessels

Adipose connective tissue Commonly referred to as fat Composed mostly of adipocytes Two types White (stores energy, acts as insulator, cushions) Brown (found in newborns, generates heat, lost as we age) Adipose gain/loss due to adipocytes enlarging or shrinking Reticular connective tissue Meshwork of reticular fibers, fibroblasts, leukocytes Structural framework of many lymphatic organs (e.g. spleen, thymus, lymph nodes, bone marrow) Connective Tissue proper  Dense connective tissue Mostly protein fibers Less ground substance than loose CT Collagen fibers predominate Three categories: o Dense regular o Dense irregular o Elastic Dense regular connective tissue Tightly packed, parallel collagen fibers Resemble stacked lasagna noodles In tendons and ligaments Stress typically applied in a single direction Few blood vessels Takes a long time to heal Dense irregular connective tissue Clumps of collagen fibers extend in all directions Provides support and resistance to stress in multiple directions Found in most of the dermis of skin, periosteum of bone, perichondrium of cartilage, capsules around internal organs Supporting connective tissue Two types: cartilage, bone Cartilage Firm, semisolid extracellular matrix Collage and elastic protein fibers Chondrocytes - mature cells

Occupy small spaces called lacunae Surrounded by a dense irregular connective tissue covering Perichondrium Outer fibrous layer and inner cellular layer Stronger and more resilient than other connective tissue More flexible than bone In areas of body that need support and must withstand deformation (e.g., tip of nose) Avascular in mature state Three types o Hyaline cartilage o Fibrocartilage o Elastic cartilage. Hyaline Cartilage Most common type Clear, glassy appearance under microscope Surrounded by perichondrium Located in Nose, trachea, and larynx Costal cartilage Articular ends of long bones Most of fetal skeleton Fibrocartilage Weight-bearing cartilage, resists compression Protein fibers in irregular bundles between chondrocytes Sparse ground substance; no perichondrium Located in Intervertebral discs Pubic symphysis Menisci of knee joint Elastic Cartilage Flexible, springy cartilage Numerous densely packed elastic fibers Ensure tissue is resilient and flexible Chondrocytes closely packed Surrounded by a perichondrium Located in external ear and epiglottis

Bone More solid than cartilage Greater support, but less flexible Organic components (collagen and glycoproteins) Inorganic components (calcium salts) Bone cells are called osteocytes Housed within spaces in extracellular matrix called lacunae Two types: o Compact bone  Perforated by neurovascular canals  Cylindrical structures—osteons  Display concentric rings of bone CT called lamellae  Lamellae encircle central canal, location of blood vessels and nerves o Spongy bone  Located in interior of bone  Latticework structure, strong and lightweight Bone functions Levers for movement Supports tissues Protects vital organs Stores minerals, e.g., calcium and phosphorus Houses hemopoietic cells, which make blood cells Fluid Connective Tissue Blood Fluid connective tissue with formed elements Erythrocytes transport respiratory gases Leukocytes protect against infectious agents Cellular fragments, called platelets, help clot blood Liquid ground substance is called plasma Dissolved proteins Transports nutrients, wastes, hormones Lymph Derived from blood plasma No cellular components or fragments Ultimately returned to bloodstream

What did you learn?      

What are the basic functional differences between resident cells and wandering cells in connective tissue? What is the function of GAGs in ground substance? What are some of the general functions of connective tissue? What is the composition of mesenchyme, and what is its function? Compare loose connective tissue to dense connective tissue with respect to fiber density, fiber distribution, and the amount of ground substance. Describe the composition and location of fibrocartilage.

 Why is blood considered a connective tissue? Blood is considered a connective tissue for two basic reasons: (1) embryologically, it has the same origin (mesodermal) as do the other connective tissue types and (2) blood connects the body systems together bringing the needed oxygen, nutrients, hormones and other signaling molecules, and removing the wastes.

5.3 Muscle Tissue: Movement 5.3 Muscle Tissue: Movement 1 Muscle tissue Cells contract when stimulated Contraction causes movement Voluntary motion of body parts Contraction of heart Propulsion of material through digestive and urinary tracts Three types  Skeletal o Striated or voluntary muscle tissue o Moves skeleton o Does not contract unless stimulated by somatic nervous system o Voluntary  Cardiac o Confined to middle layer of heart wall, myocardium o Responsible for heart contraction to pump blood o Involuntary - Cannot be controlled by voluntary nervous system  Pacemaker cells initiate contraction  Smooth o Visceral or involuntary muscle tissue

o Found in walls of intestines, stomach, airways, bladder, uterus, blood vessels o Helps propel movement through these organs o No voluntary control over the muscle

5.4 Nervous Tissue: Nervous tissue Located in the brain, spinal cord, and nerves Cells called neurons Receive, transmit, and process nerve impulses Larger number of glial cells Do not transmit nerve impulses Instead, are responsible for protection, nourishment, and support of neurons Neurons are longest cells in the body

5.5 Organs Organs two or more tissue types Work together to perform specific complex functions Different structures must work in concert E.g., stomach, contains all four tissue types Example: The stomach Lined by epithelium Secretes substances for chemical digestion of nutrients Areolar and dense CT in walls Blood vessels and nerves Provides shape and support Three layers of smooth muscle in walls Contract and relax to mix stomach contents Abundant nervous tissue Responsible for regulating muscle contraction and gland secretion Body membranes Formed from epithelial layer bound to underlying CT Line body cavities Cover viscera Cover body’s external surface Four types:  Mucous  Mucosa  Lines compartments that open to external environment  Includes: digestive, respiratory, urinary, and reproductive tracts

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Performs absorptive, protective, and secretory functions Formed from epithelium and underlying CT o Connective tissue component, lamina propria o Covered with a layer of mucus derived from goblet cells, multicellular glands, or both Serous o Lines body cavities that do not open to external environment o Simple squamous epithelium (mesothelium) o Produces thin, watery serous fluid o Derived from blood plasma o Reduces friction between opposing surfaces o Forms parietal and visceral layers o Serous cavity is in between Cutaneous o Skin o Covers external surface of body o Composed of  Keratinized stratified squamous epithelium  Underlying CT o Protects internal organs and prevents water loss Synovial o Reduces friction among moving bone parts and distributes nutrients to the cartilage on articular surfaces of bone

What did you learn?  Describe why the stomach is considered an organ. It is part of the digestive system, has a specific and complex physiological function, composed of two or more tissues, consists of a mass of similar cells that form a specific secretion and it is physically interconnected with other organs What are the differences between the parietal and visceral layers of the serous membrane? The parietal layers of the membranes line the walls of the body cavity (pariet- refers to a cavity wall). The visceral layer of the membrane covers the organs (the viscera). Between the parietal and visceral layers is a very thin, fluid-filled serous space, or cavity. ...