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Chapter 4 Tissues,

Glands, and

Membranes

Simple Columnar Epithelium

Tissues and Histology

• Tissues

– collections of similar cells + surrounding extracellular

matrix

• Histology

– study of tissues

• 4 primary tissue types

– Epithelial

– Connective

– Muscle

– Nervous

Embryonic Tissue

• Primary tissue types derived from embryonic germ layers

– Endoderm • Forms lining of digestive tract and its derivatives

– Mesoderm • Forms muscle, bone, blood vessels

– Ectoderm • Forms outermost layer of skin and nervous system

• Gives rise to all tissues of body

Epithelial Tissue

• Covers surfaces

• little extracellular material

• Usually has basement membrane

• Has no blood vessels

Epithelial Cells

• free apical surface

– not attached to other cells

• lateral surface

– attached to other cells

• basal surface

– attached to basement membrane

Fig. 4.1

5 Main Epithelial Tissue Functions

1. Protect underlying structures

- outer layer of skin, oral mucosa

2. Act as barrier

- skin

3. Permit passage of substances

- epithelium in lungs

4. Secrete substances

- mucous glands, sweat glands

5. Absorb substances

- intestine

Epithelial Tissue Classification

• # of cell layers & shape of cells

– Cell layers

• Simple epithelium: 1 layer of cells

• Stratified epithelium: >1 cell layer

• Pseudostratified epithelium: 1 layer, but appears to

have 2 or more layers

• Transitional epithelium: stratified epithelium that can

be greatly stretched

– Cell shape

• Squamous - flat and thin

• Cuboidal - cubelike

• Columnar - tall and thin

Tab. 4.1a

Tab. 4.1b

Tab. 4.1c

Tab. 4.1d

Tab. 4.2a

Tab. 4.2b

Tab. 4.2c

Tab. 4.2d

Epithelial Tissue

Structural and Functional Relationships

• Cell Layers & Cell Shapes

– Simple epithelium

• Diffusion

• Secretion

• Absorption

– Stratified epithelium - protective role

– Squamous cells

• Diffusion

• Filtration

– Cuboidal or columnar cells

• Secrete

• Absorb

• Free Cell Surfaces

– smooth, free surface reduces friction

• Lining of blood vessels

– Microvilli- cylindrical extensions of cell

membrane, increase surface area

(absorption/secretion)

• Lining of small intestines

– Cilia propel materials over cell surface

• Lining of nasal cavity, trachea

Epithelial Tissue

Structural and Functional Relationships

•Cell connections – Tight junctions

• bind adjacent cells together,

form permeability barrier

– Gap junctions

• intercellular communication

– Desmosomes

• mechanically bind cells

together

– Hemidesmosomes

• mechanically bind cells to

basement membrane

Fig. 4.2

Epithelial Tissue

Structural and Functional Relationships

Epithelial Tissue Glands

• GLAND:

– single cell or multicellular structure that secretes

– Endocrine glands do not have ducts

• Secrete hormones directly into blood

– Exocrine glands have ducts

• Secretions released onto a surface or into a

cavity

– Sweat glands, mammary glands

• Classified by

– Structure

– How products leave cell

Structure of Exocrine Glands

Fig. 4.3

– Simple: 1 duct

– Compound: ducts that branch repeatedly

– Tubules: ducts end in small tubes

– Acini: ducts end in saclike structures

– Alveoli: ducts end in hollow sacs

Exocrine Glands and Secretion Types

Fig. 4.4

– Merocrine – no loss of

cellular material

– sweat glands

– Apocrine – part of cell

pinches off

– mammary glands

– Holocrine – entire cell is

shed

– sebaceous glands

Connective Tissue

• cells separated from each other by abundant

extracellular matrix

• Functions

1. Enclosing and separating

2. Connecting tissues to one another (Ligaments,

Tendons)

3. Supporting and moving (Bones, cartilage)

4. Storing (Adipose tissue, Bones)

5. Cushioning and insulating (Adipose tissue)

6. Transporting (Blood)

7. Protecting (Blood, Bones)

Connective Tissue Cells

• Specialized cells of various connective

tissues produce extracellular matrix

– suffixes identify cell functions

• Blast (germ) cells form matrix

• Cyte (cell) cells maintain it

• Clast (break) cells break it down

Connective Tissue

• Extracellular matrix contains

– Protein fibers

• Collagen fibers flexible but resist stretching

• Reticular fibers form a fiber network

• Elastic fibers recoil

– Ground substance

• Proteoglycans in ground substance hold

water, enabling connective tissues to return to

their original shape after being compressed

– Fluid

Connective Tissue Classification

• Mesenchyme:

– embryonic

– gives rise to 6 major

categories of conn tissue

Connective Tissue Classification

• Loose areolar is “loose packing” material of body – Fills spaces between organs

– Holds organs in place

• Adipose tissue (fat) – Stores energy

– Pads and protects body parts

– thermal insulator

• Dense connective tissue - matrix w/densely packed fibers – Collagen fibers (tendons, ligaments, dermis of skin)

– Elastic fibers (elastic ligaments and in walls of arteries)

Connective Tissue Classification

• Cartilage - support – Hyaline cartilage (covers ends of bones, forms costal

cartilages)

– Fibrocartilage (disks between vertebrae)

– Elastic cartilage (external ear)

• Bone - mineralized matrix – forms most of skeleton

• Compact bone - more matrix than spaces

• Cancellous bone - more spaces than matrix

• Blood - liquid matrix – in blood vessels

– Produced in hemopoietic tissue (red bone marrow)

Tab. 4.4

Tab.

4.5a

Tab.

4.5b

Tab. 4.5c

Tab.

4.5d

Tab.

4.6a

Tab.

4.6b

Tab.

4.7a

Tab.

4.7b

Tab. 4.7c

Tab. 4.8

Tab. 4.9

Muscle Tissue

• Specialized to contract (shorten) making movement possible – Length of muscle cells greater than diameter

– called muscle fibers because resemble tiny threads

• 3 types – Skeletal

• Meat of animals

• ~40% of person’s body weight

• Attaches to skeleton, allows for movement

• Voluntary, multinucleated; striated (banded)

– Cardiac • Muscle of heart

• Connected to one another by intercalated disks (w/gap junctions)

• Involuntary, striated; usually 1 nucleus per cell

– Smooth • Forms walls of hollow organs (except heart); also found in skin, eyes

• Involuntary, not striated; single nucleus

Tab.

4.10a

Tab.

4.10b

Tab.

4.10c

Nervous Tissue

• Specialized to conduct action potentials

(electrical signals)

• Neurons conduct action potentials

• Neuroglia support neurons

Tab.

4.11

Membranes

• Mucous memb: line cavities that open to outside

of body

– Digestive, respiratory, urinary, reproductive tracts

– Contain glands

– Secrete mucus

• Serous memb: line trunk cavities that do not

open to outside of body

– pleural, pericardial, peritoneal cavities

– Do Not contain glands

– Secrete serous fluid

• Synovial memb: line freely movable joints

Fig. 4.5

Inflammation

• Inflammatory response functions to isolate and destroy harmful agents

• 5 symptoms – Redness

– Heat

– Swelling

– Pain

– Disturbance of function

• Chronic inflammation – agent causing injury is not removed or something else

interferes with healing process

Fig. 4.6

Tissue Repair

• substitution of viable cells for dead cells – Labile cells divide throughout life, can undergo

regeneration

– Stable cells do not ordinarily divide but can regenerate if necessary

– Permanent cells have little or no ability to divide • If killed, repair is by replacement

• involves – Clot formation

– Inflammation

– Formation of granulation tissue

– Regeneration or replacement of tissues

Fig. 4.7

Tissues and Aging

• Cells divide more slowly

• Injuries heal more slowly

• Extracellular matrix containing collagen and elastic fibers becomes less flexible and less elastic

• Consequently...

– Skin wrinkles

– Elasticity in arteries is reduced

– Bones break more easily