Human Anat Chapter 5

What are tissues?

• Groups of similar cells and extracellular material​

• Common function​

• E.g., providing protection​

What are the 4 types of tissues?

• Epithelial, connective, muscle, nervous​

What is 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​

What is Cellularity?

Composed almost entirely of tightly packed cells​

What is the Apical surface?

• Exposed to external environment or internal body space​

• Microvilli or cilia​

• Lateral surface with intercellular junctions​

What is the Basal surface?

Epithelium attached to connective tissue​

What is the attachment to basement membrane?

Barrier between epithelium and connective tissue

What is Avascularity?

• Epithelia lack blood vessels​

• Nutrients obtained across apical surface or from basal surface​

What are the Characteristics of Epithelial tissue?

• Attachment to basement membrane​​

• Avascularity​​

• Extensive innervation​​

• High regeneration capacity​

What are the Functions of Epithelial Tissue?

• Physical protection​ → Protects from dehydration, abrasion, destruction​

• Selective permeability​​

• Secretions​​

• Sensations​ → Supply information to nervous system​

What is Simple epithelium?

• One cell layer thick; all cells contact basement membrane​

• Filtration, absorption, or secretion is primary function​

What is Stratified epithelium?

• Two or more layers of epithelial cells​

• Only basal layer in contact with basement membrane​

• In areas subjected to mechanical stress​

What is Pseudostratified epithelium?

• Appears layered​

• All cells contact basement membrane, but may not reach apical surface​

What are Squamous cells​?

• Flat, wide, irregular in shape​

• Nucleus flat​

What are Cuboidal cells​?

• About as tall as they are wide​

• Nucleus spherical and in center of cell​

What are Columnar cells?

• Slender and taller than they are wide​

• Nucleus oval; oriented lengthwise in basal region

What are Transitional cells?

Change shape, depending on stretch of epithelium​

What is 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)​

What is 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

What is 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

Functions of simple columnar epithelium may include:

secretion and absorption

What is 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

What is 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

What is Pseudostratified Columnar Epithelium​?

• 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​

What is 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​

What is Nonciliated Pseudostratified Columnar Epithelium?

• Rare, lacks cilia, goblet cells​

• Protective functions​

• Occurs mainly in male urethra and epididymis​

What is Stratified Squamous Epithelium?

• Multiple cell layers​ → Only deepest in direct contact with basement membrane​

• Basal layers with 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

What is Keratinized Stratified Squamous Epithelium​?

• Superficial layers of dead cells​

• Cells lack nuclei, filled with keratin​

• Cells in basal region migrate toward apical surface​

• Fill with keratin and die​

• Found in epidermis​

What are 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​

Which type of epithelium lines the oral cavity?​

stratified squamous​

What is 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​

What is 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​

What is 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:​

​
A) able to stretch​

B) lines the urethra, bladder, ureter​

C) absorbs and secretes​

D) able to convert to another epithelium​

E) A and B​

E) A and B​

What are Glands?

• Individual cells or multicellular organs composed of epithelial tissue- a structure which forms and secretes a product​

• Endocrine or exocrine​

What are Endocrine glands?

• Lack ducts​

• Secrete hormones into blood

What are 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​

What are Unicellular exocrine glands?

• Do not contain a duct​

• Located close to epithelium surface​

• Most common type is goblet cell​

What are 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​

What is a simple gland?

a single, unbranched duct​

What is a compound gland?

branched ducts​

What is a tubular gland?

secretory portion and duct same diameter​

What is an acinar gland?

secretory portion forms expanded sac​

What is a tubuloacinar gland?

both tubules and acini​

What are Merocrine glands?

• Package secretions into vesicles, released by exocytosis​

• E.g. Lacrimal (tear) and salivary glands​

What are Apocrine glands?

• Apical membrane pinches off and becomes secretion​

• E.g. mammary and ceruminous glands​

What are Holocrine glands​?

• Ruptured cell becomes secretion​

• E.g. sebaceous (oil) glands

What type of secretion involves of the death of a cell inside a gland in order to release its products?

holocrine

All Connective Tissue shares three basic components

Cells, protein fibers, and ground substance​

What are the 2 classes of Connective tissue cells?

• Resident cells​

• Wandering cells​

What are Resident cells?

• Stationary, housed in Connective Tissue​

• Support, maintain, repair extracellular matrix​

• Fibroblasts​​

• Adipocytes (fat cells)

• Mesenchymal cells​

• Fixed macrophages​​

What are Fibroblasts?

• Flat cells with tapered ends​

• Most abundant resident cells in CT proper​

• Produce fibers and ground substance of extracellular matrix

What are Adipocytes (fat cells)?

• Appear in small clusters in some types of CT proper​

• Adipose connective tissue—dominant area of large clusters ​

What are Mesenchymal cells​?

• Embryonic stem cell​

• Divides to replace damaged cells​

• One replaces mesenchymal cell, other becomes committed cell​

What are 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​

What are 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

• Mast cells, Plasma cells, Free macrophages, other leukocytes ​

What are Mast cells?

• Small, mobile cells close to blood vessels​

• Secrete heparin to inhibit blood clotting​

• Secrete histamine to dilate blood vessels​

What are Plasma cells?

• Form when B-lymphocytes are activated when exposed to foreign material​

• Produce antibodies (proteins that immobilize foreign material)​

What are Free macrophages​?

• Mobile, phagocytic cells​

• Function like fixed macrophages, yet able to move

What are Neutrophils​?

Phagocytizes bacteria

What are T-lymphocytes?

Leukocyte that attacks foreign materials

What are the 3 types of Protein fibers?

• Collagen fibers​

• Reticular fibers​

• Elastic fibers

What are Collagen fibers?

• Unbranched, “cable-like” long fibers​

• Numerous in tendons and ligaments

What are Reticular fibers?

• Similar to collagen fibers but thinner​

• Abundant in stroma of some organs (e.g. lymph node)​

What are Elastic fibers?

• Contain protein elastin​

• Stretch and recoil easily​

• Found in skin, walls of arteries​

What is the Ground substance?

• Noncellular material produce by CT cells

• Residence of CT cells and protein fibers

• Consistency: Viscous (blood), semisolid (cartilage), solid (bone)

• Ground substance + protein fibers = ECM

What are 3 components of the Ground substance?

• Glycosaminoglycans (GAGs)​

  • Large molecule in ground substance​

  • Charge attracts cations, water follows​

• Proteoglycans​

  • Formed with GAG linked to a protein​

  • 90% carbohydrate in the form of GAGs​

• Glycoproteins​

  • Proteins with carbohydrates attached​

  • Bond CT cells and fibers to ground substance​

Which structure – function relationships of extracellular fibers is correct?

reticular – forms support meshwork for cells

These cells produce collagen fibers in connective tissues?

fibroblasts​

Which is true of the ground substance of the extracellular matrix (ECM)?​

A) loose areolar tissue has more ground substance than denseregular connective tissue.​

B) may contain large charged molecules that attract water andions. ​

C) may serve as the “glue” that holds cells together.​

D) Fibrous protein give tensile strength

E) A, B, C and D

E) A, B, C and D

Cells that ingest foreign substances, microorganisms, and dead and damaged cells:​

phagocytes​

What are the Main Functions of Connective Tissue?

1. Connection and binding: bind tissue in organs, also keep organs in place​

2. Support weight (bone, cartilage)​

3. Protection​

4. Transport (blood)​

5. Immune Protection​

What is Loose connective tissue (proper)?

• Fewer cells and protein fibers than dense CT​

• Protein fibers are sparse and irregularly arranged​

• Abundant ground substance​

• Body’s “packing material”, supports structures​

• Three types:​

  • Areolar​

  • Adipose​

  • Reticular​

What is Areolar CT?

• Loose organization of collagen and elastic fibers​

• Highly vascularized​

• Contains all fixed and wandering cells of CT 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​

What is Adipose CT?

• 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​

What is Reticular CT?

• Meshwork of reticular fibers, fibroblasts, leukocytes​

• Structural framework of many lymphatic organs (e.g. spleen, thymus, lymph nodes, bone marrow)​

What is Dense connective tissue?

• Mostly protein fibers​

• Less ground substance than loose CT​

• Collagen fibers predominate​

• Three categories:​

  • Dense regular ​

  • Dense irregular ​

  • Elastic​

What is Dense Regular CT?

• 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​

What is Dense Irregular CT?

• Clumps of collagen fibers extend in all directions​

• Provides support and resistance to stress in multiple directions​

• Found in dermis of skin, periosteum of bone, perichondrium of cartilage, capsules around internal organs​

What is Elastic CT?

• Branching, densely packed elastic fibers​

• Able to stretch and recoil​

• Found in walls of large arteries, trachea, vocal cords​

What are the 2 types of Supporting CT?

Cartilage and bone​

What is Cartilage?

• Firm, semisolid extracellular matrix​

• Collage and elastic protein fibers​

• Chondrocytes: mature cells​ → Occupy small spaces called lacunae​

• Surrounded by a dense irregular CT covering​

• Perichondrium​ → Outer fibrous layer and inner cellular layer​

• Stronger and more resilient than other CT​​

• In areas of body that need support and must withstand deformation (e.g., tip of nose)​

• Avascular in mature state​

What is 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​

What is 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​

What is 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​

Which of the following is constructed from elastic cartilage?

external ear​

Tendons are composed of:​

dense regular connective tissue​

What are Osteoblasts?

Bone building cells at the edges​

What are Osteocytes?

Mature osteoblasts now trapped in the rings of bone matrix

What are Osteoclasts?

Resorb and destroy at the edges​

What is 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

What is Plasma?

• Dissolved proteins​

• Transports nutrients, wastes, hormones​

What is Lymph- fluid CT?

• Derived from blood plasma ​

• No cellular components or fragments​

• Ultimately returned to bloodstream​

What is the Mucous membrane?

• Mucosa​

• Lines compartments that open to external environment​

• Includes: digestive, respiratory, urinary, and reproductive tracts​

• Performs absorptive, protective, and secretory functions​

• Formed from epithelium and underlying CT

• lamina propria​

What is Cutaneous membrane​?

• Skin​

• Covers external surface of body​

• Composed of​: Keratinized stratified squamous epithelium ​ & Underlying CT​

• Protects internal organs and prevents water loss​

Synovial membranes:​

line the cavities surrounding freely movable joints. ​

Which term describes the serous membrane that covers the intestine inside its cavity?​

visceral peritoneum

What are the Stages of tissue development?

1. Oocyte fertilized by a sperm​ → Forms diploid cell, zygote​

2. After multiple cell divisions, becomes blastocyst​

3. Cells forming embryo, embryoblast​

4. Three primary germ layers formed by 3rd week ​

5. Ectoderm, mesoderm, endoderm​

6. Growing structure now an embryo​

What is an Ectoderm?

• Initially located on dorsal and external embryo surfaces​

• Responsible for forming many external structures​ → epidermis of skin, hair, nails, exocrine glands​

• Some, but not all, epithelial tissues derived from ectoderm​

• Tooth enamel, eye lens, adrenal medulla, all nervous tissue​

What is a Mesoderm?

• Middle primary germ layer​

• Forms all muscle tissue​

• Forms epithelial lining of vessels and serous membranes​

• Becomes mesenchyme​ → Later forms all CT in body​

• Dermis, adrenal cortex, heart, spleen, kidneys and ureters, internal reproductive structures​