Chapter 5: Tissues

Compact Bone: • Osteoblasts deposit matrix in lamellae (layers) • Lamellae occur in rings around central canals • Osteocytes + matrix + central canal form cylindrical units called osteons • Osteons are cemented together to form compact bone • Central canals contain blood vessels; bone is well-nourished, heals more quickly than cartilage

Connective Tissue Types: - Bone (Osseous Tissue) STUDY WHAT IT LOOKS LIKE.

Four main classes: - Connective tissue proper (a bunch!) - Cartilage - Bone - Blood

Connective tissue: - What are the four main classes?

• Protection - Ex. Skin • Absorption - Ex. Small intestine • Diffusion and Filtration - Ex. Lungs and kidneys • Secretion - Ex. Sweat glands • Sensory reception

What are the various functions of Epithelial Tissues?

Fibroblasts: • Most common fixed cell • Large star-shaped cell • Secrete fibers into extracellular matrix

What is the most common major cell type of Connective Tissue?

• Cells have polarity - Apical surface (upper free) exposed to exterior or cavity LUMEN • Smooth • Cilia • Microvilli Functions? - Basal surface (lower, attached) • Noncellular basal lamina • Adhesive sheet - Both surfaces differ in structure and function

What is the structure of the polarity of cells?

- In complex organisms, cells are organized into tissues - Tissues: Groups of similar cells with a common function - The study of tissues is called histology. - 4 Major types of tissues in the body= Epithelial tissue, Connective tissue, Muscle tissue, Nervous tissue (Look at table 5.2 in PPT on Slide 5).

5.1 Cells are Organized into Tissues - What is the study of tissues called? - What is the definition of tissues? - What are the four major types of tissue in the body?

• Covers organs and body surface • Lines cavities and hollow organs • Makes up glands • Have a free surface on outside, and basement membrane on inside • Usually lack blood vessels; (?!?!?!?!) • Cells readily divide; injuries heal rapidly • Cells are tightly packed • Classified according to cell shape and number of cell layers

5.2 Epithelial Tissue: - What are its general characteristics?

General characteristics: • Most abundant tissue type • Cells are farther apart than epithelial cells; contain matrix between cells • Many functions: • Bind structures together • Provide support and protection • Serve as frameworks • Fill spaces • Store fat • Produce blood cells • Protect against infections • Help repair tissue damage • Extracellular matrix consists of protein fibers and ground substance; consistency varies from fluid to semisolid to solid • Most have good blood supply, and are well-nourished, but vascularity varies among tissue types • Most cells can divide

5.3 Connective Tissue: - What are their general characteristics?

Nervous tissues: • Found in brain, spinal cord, peripheral nerves • Main cells are neurons, which are specialized for communication, via conduction of nerve impulses (sensory reception, motor control) • Neurons coordinate, integrate, and regulate body functions • Neuroglia support and nourish neurons

5.6 Nervous Tissue

- No blood vessels in epithelial tissue - How do they get nourished? Epithelial cells are nourished by substances (like?) diffusing from the underlying connective tissue. • Is supplied by nerve fibers

Avascular but Innervated

Fibrocartilage: • Very tough, due to many collagenous fibers • Shock absorber • Intervertebral discs • Pads of knee and pelvic girdle

Cartilage Types (Study what each type looks like, and be able to identify from photo).

Hyaline cartilage: • Most common type • Fine collagen fibers • Ends of bones in joints • Nose, respiratory passages • Embryonic skeleton Elastic cartilage: • Flexible, due to elastic fibers in matrix • External ear, larynx

Cartilage Types (Study what each type looks like, and be able to identify from photo).

• "...Blast"cells - Immature form; mitotically active; secrete ground substance and fibers - Fibroblasts in connective tissue proper - Chondroblasts in cartilage - Osteoblasts in bone - Hematopoietic stem cells in bone marrow (Not actually in the same tissue!) • "...Cyte"cells - Mature form; maintain matrix - Chondrocytes in cartilage - Osteocytes in bone

Cells: - What are the different types of cells of connective tissue? *Study pictures of what each of these cells look like because might be asked to identify them on the exam.

•All epithelial tissues have two names - One indicates number of cell layers • Simple epithelia = single layer of cells • Stratified epithelia = two or more layers of cells - Shape can change in different layers - One indicates shape of cells • Squamous • Cuboidal • Columnar • In stratified epithelia, epithelia classified by cell shape in apical layer

Classification of Epithelia:

Fibroblasts produce 3 types of fibers in connective tissue: Collagen Fibers: • Thick threads of collagen, the body's main structural protein • Great tensile strength and flexible, slightly elastic • Found in ligaments and tendons Elastic (Yellow) Fibers: • Composed of elastin protein; branching • Can stretch and return to original shape • Not as strong as collagen fibers • Found in vocal cords, respiratory air passages Reticular Fibers: • Thin, branching fibers of collagen • Form delicate, supporting networks • Found in spleen, liver

Connective Tissue Fibers: - What 3 types of fibers do Fibroblasts produce in Connective Tissue?

Dense Irregular Connective Tissue: • Randomlyorganized, thick, interwoven collagenous fibers • Canwithstandtension exerted • from different directions • Dermis of skin • Aroundskeletalmuscles

Connective Tissue Proper: Dense

Dense Regular Connective Tissue: •Closely packed collagenous fibers •Fine network of elastic fibers •Most cells are fibroblasts •Very strong, withstands pulling •Binds body parts together •Tendons, ligaments, dermis •Poor blood supply; slow to heal

Connective Tissue Proper: Dense

Elastic Connective Tissue: • Abundant yellow elastic fibers • Some collagenous fibers • Fibroblasts • Attachments between bones of spinal column • Walls of hollow organs, such as large arteries, airways • Parts of heart • Elastic quality, stretches

Connective Tissue Proper: Dense

Adipose Tissue: • Adipocytes store fat • Push their nuclei to one side • Crowd out other cell types • Cushions and insulates • Beneath skin (subcutaneous layer) • Behind eyeballs • Around kidneys and heart • Spaces between muscles

Connective Tissue Proper: Loose

Areolar Connective Tissue: • Forms thin, delicate membranes • Cells are mainly fibroblasts • Gel-like ground substance • Collagenous & elastic fibers • In subcutaneous layer • Beneath most epithelia, where it nourishes nearby epithelial cells

Connective Tissue Proper: Loose

Reticular Connective Tissue: • Composed of thin reticular fibers • Supports walls of internal organs • Walls of liver, spleen

Connective Tissue Proper: Loose

• All are supported by connective tissue Reticular lamina - Deep to basal lamina - Network of collagen fibers • Basement membrane Basal lamina + reticular lamina - Reinforces epithelial sheet - Resists stretching and tearing - Defines epithelial boundary

Connective Tissue Support: - What are all Gap Junctions supported by, etc?

Cartilage: • A rigid, specialized connective tissue • Support, framework, attachments • Protection of underlying tissue • Models for developing bone • Matrix contains collagen in gel-like ground substance • Chondrocytes (cartilage cells) in lacunae (chambers), surrounded by matrix • Lacks blood supply; which means what? • Covered by perichondrium (connective tissue), which provides some nutrients to the cartilage • 3 types of cartilage: Hyaline, Elastic, and Fibrocartilage

Connective Tissue Types: - What are they (Study Slide 50)?

Blood: • Cells suspended in fluid matrix called _______? • Red blood cells transport gases • White blood cells defend again infection • Platelets help in blood clotting • Transports substances around body

Connective Tissue Types: - Blood STUDY WHAT IT LOOKS LIKE. *Study table 5.7 Summary of all Connective Tissues.

Bone (Osseous Tissue): • Most rigid connective tissue • Solid matrix, composed of mineral (Ca) salts & collagen • Supports structures • Protects vital structures • Produces blood cells • Stores & releases Ca, P • Attachment sites for muscles • Forms skeleton • Contain osteocytes (bone cells) in lacunae (cavities) • 2 types: compact and spongy

Connective Tissue Types: - Bone (Osseous Tissue)

Pseudostratified columnar: • Single layer, but appears layered • Nuclei at 2 or more levels • Cells vary in shape • Often has cilia, goblet cells • Protection from infection • Lines respiratory passageways

Epithelial Tissue Types (Study how they look, will have to name tissue types from photos on exam).

Simple columnar: • Single layer of elongated cells • Nuclei usually at same level, near basement membrane • Sometimes have cilia • Sometimes have microvilli • Sometimes have goblet cells (secrete mucus) • Secretion and absorption • Lines uterus, stomach, intestines

Epithelial Tissue Types (Study how they look, will have to name tissue types from photos on exam).

Simple cuboidal: • Single layer of cube-shaped cells • Secretion and absorption • Lines kidney tubules, thyroid follicles • Covers ovaries • Lines ducts of some glands

Epithelial Tissue Types (Study how they look, will have to name tissue types from photos on exam).

Simple squamous: • Single layer of thin, flat cells • Substances pass easily through • Thin & delicate, can be damaged • Found in diffusion & filtration sites • Lines air sacs (alveoli) & capillaries • Lines blood & lymphatic vessels

Epithelial Tissue Types (Study how they look, will have to name tissue types from photos on exam).

Stratified cuboidal: • 2-3 layers of cube- shaped cells • More protection than 1 layer • Lines ducts of mammary, sweat, & salivary glands, and pancreas

Epithelial Tissue Types (Study how they look, will have to name tissue types from photos on exam).

Stratified squamous: • Many cell layers; thick • Protective layer • Outermost cells are flat • Deeper cells are cuboidal • New cells form, push older cells toward free surface • Outer layer of skin (keratinized) • Lines oral cavity, vagina, anal canal

Epithelial Tissue Types (Study how they look, will have to name tissue types from photos on exam).

• Glandular Epithelium: Composed of cells that produce and secrete substances into ducts or body fluids • There are 2 types of glands: • Endocrine glands secrete into tissue fluid or blood • Exocrine glands secrete into ducts that open onto surface 2 structural types of exocrine glands: • Unicellular: Composed of one cell, such as a goblet cell (secretes mucus) • Multicellular: • Composed of many cells • Sweat glands, salivary glands, etc. • Simple or compound Structural Types of Exocrine Glands: Simple: duct does not branch Compound: duct branches before it reaches secretory portion Tubular: consist of epithelial-lined tubes Alveolar: terminal portions form saclike dilations

Glandular Epithelium: - What is this and what are the two types of glands? - What are the two types of exocrine glands? *Study slide with structural types of Exocrine Glands (What are all of them?).

Mast Cells: • Large, fixed cells • Release heparin to prevent blood clotting • Release histamine, which causes inflammatory response Macrophages: • Usually attached to fibers, but can detach and wander • Conduct phagocytosis • Defend against infection

Major Cell Types of Connective Tissue:

General Characteristics: • Muscle cells are also called muscle fibers • Contractile; can shorten and thicken • 3 types of muscle tissue: skeletal, cardiac, and smooth Skeletal muscle tissue: • Attached to bones • Striated • Voluntary • Multinucleated cells • Long cylindrical cells • Stimulated by nerve cells

Muscle Tissues: - MUST BE ABLE TO IDENTIFY IT FROM PHOTO

Smooth muscle tissue: • Non-striated • Spindle-shaped fibers • Walls of hollow organs, and blood vessels • Involuntary Cardiac muscle tissue: • Only in wall of heart • Branching cells • Involuntary • Striated • Intercalated discs

Muscle Tissues: - MUST BE ABLE TO IDENTIFY IT FROM PHOTO

• Covering and lining epithelial tissues fit closely together - Form continuous sheets • Specialized contacts bind adjacent cells - Lateral contacts - ????

Specialized Contacts: Tissues

• High regenerative capacity • Stimulated by loss of apical-basal polarity and lateral contacts - Some exposed to friction (too much friction?) - Some exposed to hostile substances • If adequate nutrients can replace lost cells by cell division

Regeneration

• Simple epithelium - containsonelayerofcells - named by shape of cells - all cells touch the basement membrane • Stratified epithelium - contains more than one layer - named by shape of apical cells - some cells rest on top of others and do not touch basement membrane

Simple vs. Stratified Epithelia (Study shape of different nuclei)

- 50 trillion cells of 200 different cell types - Tissue= Group of similar cells serving a function - Organ= structure with discrete boundaries that is compose of two or more tissue types. Ex. Heart *How many Tissues are there in an organ? There are 4 types: muscle tissue, nervous tissue, connective tissue, and epithelial tissue

The Study of Tissues

- Individual body cells specialized - Each type performs specific functions that maintain homeostasis - Tissues - Group of cells similar in structure that perform common or related function - Histology - Study of tissues - How do we look at tissues?

Tissue: The Living Fabric

Merocrine Glands: - Secrete fluid products by exocytosis; salivary & sweat glands, pancreas Apocrine Glands: - Lose small part of cell during secretion; mammary & ceruminous glands Holocrine Glands: - Release entire cells filled with product; sebaceous glands

Types of Glandular Secretion: * Look at the summary of epithelial tissues on slide 34.

Connective tissues can be classified in 2 major categories: Connective Tissue Proper: • Loose connective tissues: - Areolar - Adipose - Reticular • Dense connective tissues: - Dense Regular - Dense Irregular - Elastic Specialized connective tissues: • Cartilage • Bone • Blood

What 2 major categories can Connective tissues be classified in?

• Three characteristics make connective tissues different from other primary tissues - Have mesenchyme (an embryonic tissue) as their common tissue of origin - Have extracellular matrix • Connective tissue not composed mainly of cells • Largely nonliving extracellular matrix separates cells - So can bear weight, withstand tension, endure abuse - Cells embedded in a non-living matrix, (ground substance mixed with fibers)

What are the characteristics of Connective Tissue?

Tight junctions: - Membranes between cells merge and fuse - Located among cells that form linings, sheetlike layers - Blood-brain barrier • Desmosomes: - Form "spot welds" between cells - Structural reinforcement - Located among outer skin cells Gap junctions: - Tubular channels between cells - Molecules can move between cells - Located in cardiac muscle cells

What are the different types of Intercellular Junctions and what is each one's function?

ALL epithelial tissue has in common: 1. Polarity 2. Specialized contacts 3. Supported by connective tissues 4. Avascular, but innervated 5. Can regenerate

What are the five characteristics of Epithelial Tissues?

- Nervous tissue: Internal communication - Found in brain, spinal cord, and nerves - Muscle tissue: Contracts to cause movement - Muscles attached to bones (skeletal) - Muscles of heart (cardiac) - Muscles of walls of hollow organs (smooth) - Epithelial tissue: Forms boundaries between different environments, protects, secretes, absorbs, filters - Found in lining of digestive tract organs and other hollow organs - Skin surface (epidermis) - Connective tissue: Supports, protects, binds other tissues together - Bones - Tendons - Fat and other soft padding tissue

Where are the four different types of tissues located and what is each one's primary function? - Nervous Tissue - Muscle Tissue - Epithelial Tissue - Connective Tissue