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Chapter 5

Tissues

Tissues

• Tissues - groups of cells that are

similar in structure & function

– RBC, WBC, & platelets are a group

of cells working together to form BLOOD tissue

• Histology –

• Pathohistology – study of diseased

tissues

4 Types of Body Tissues

• Tissues are groups of cells with similar structure & function

• 4 primary types

• Epithelium –

• Connective tissue –

• Muscle –

• Nervous tissue –

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Epithelial Tissues• Found in different areas

• Body coverings

• Body linings

• Glandular tissue

• Functions

• Protection

• Absorption

• Filtration

• Secretion

Epithelium Characteristics

• Cells fit closely together

• Always has 1 free surface

• Lower surface is bound by a basement membrane (non-living)

• Avascular – no blood supply

�Diffusion

• Regenerate easily if well nourished

Classification of Epithelium• Based on # of layers & shape

• # of cell layers

• Simple – 1 layer

• Stratified – more than 1 layer

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Classification of Epithelium• Shape of cells

• Squamous – flattened

• Cuboidal – cube shaped

• Columnar – tall, slender cells

Simple Epithelium• Simple squamous

• Single layer of flat cells

• Nucleus usually oblong

• Site of diffusion & filtration

• Usually forms membranes

• Lines body cavities -lungs & capillaries

Simple Epithelium

• Simple cuboidal

• Single layer of cube cells

• Spherical nucleus

• Common in glands & ducts

• Forms walls of kidney ureters

• Covers ovaries

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Simple Epithelium• Simple columnar

• Single layer of tall cells

• Nucleus near basement membrane

• Sometimes ciliated (uterine tube)

• Lines digestive tract

• Often includes goblet cells, which produce mucus

Simple Epithelium• Pseudostratified

• Single layer, but some cells are shorter than others

• Looks like a double cell layer with nucleus is various layers

• Sometimes ciliated, (respiratory tract)

• May function in absorption or secretion

Stratified Epithelium• Stratified squamous

• Cells at the free edge are flattened; basement cuboidal or columnar

• Protective covering where friction is common

• Locations

• Skin

• Mouth

• Esophagus

• Accumulates as keratin

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Stratified Epithelium

• Stratified cuboidal - 2 layers of cuboidal cells that forms a lumen

• Sweat, salivary & mammary glands

• Stratified columnar - surface cells are columnar, cells underneath vary in size & shape

• Line vas deferens, male urethra, & part of pharynx

Stratified Epithelium

• Transitional epithelium

• Stratified; begins as cuboidal and flatens as cells fill

• Shape of cells depends upon the amount of stretching

• Lines Bladder & Uterus

Glandular Epithelium

• Cells that secretes a particular product

• 2 major gland types

• Endocrine gland

• Ductless

• Secrete into blood or a tissue

• EX. hormones

• Exocrine gland

• Empty through ducts to the outside surface

• Ex. sweat & oil glands

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Exocrine glandular secretions• Classified by the way they secrete products

� Merocrine – release fluids by exocytosis; EX. Saliva, sweat, pancreatic glands

� Apocrine – secrete small portions of cell bodies EX. Mammary & cerumin

� Holocrine – release entire cells EX. sebaceous

Goblet Cells

• Cells present in epithelial tissues that

secrete mucus

Epithelial Tissue Summary

• Table 5.5 page 161

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Connective Tissue• The most abundant & widely distributed

tissues

• Functions

• Binds tissues together

• Supports the body

• Provides protection

• Stores fat

• Produces blood

• Repairs tissues

Connective Tissue Characteristics

• More loosely arranged than epithelial

• Vary in blood supply

• Some well vascularized & others are avascular

• Extracellular matrix between cells

• Non-living material that surrounds living cells; contains proteins & chemicals necessary for life

Connective Tissue Cell Types• Fixed cells – reside in tissue a long time

– Fibroblast

• Most common

• Star shaped cells that produce protein fibers *next slide

– Mast cells

• Large cells near blood vessels

• Releases heparin – prevents blood clotting

• Releases histamines – promotes allergies, hay fever & inflammation

– Macrophages

• Phagocytosis – WBC’s that clean up foreign materials & debris

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Connective Tissue Fibers• Fibroblast – fixed cells that secrete

protein fibers

• 3 types

• Collagen fibers – thick strands with some flexibility; bind structures together Dense connective tissuesEX. Ligaments & tendons

• Elastic fibers – weaker than collagen but more flexible; easily stretched & return to original shapeEx. vocal cords, aorta, blood vessels

• Reticular fibers – thin, delicate branching fibers EX. Spleen, lymph nodes

Connective Tissue Categories

• Loose connective tissues

• Areolar

• Adipose

• Reticular

• Dense connective tissues

• Dense regular

• Dense irregular

• Elastic

• Specialized

• Cartilage

• Bone

• Blood

• Areolar connective tissue

• Most widely distributed connective tissue

• Soft, pliable tissue that cushions organs & binds them to skin

• Has fibroblast, elastic and collagen fibers

Types of Connective Tissue

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Connective Tissue Types

• Adipose tissue (fat)

• Nucleus pushed to side

• Functions

• Insulates the body

• Protects, cushions organs

• Reserve fuel storage

Connective Tissue Types

• Reticular connective tissue

• Delicate network of reticular fibers

• Forms lymphoid organs

• Lymph nodes

• Spleen

• Bone marrow

• Dense Regular Connective tissue

• Mostly collagen fibers

• Fibroblast cells

• Tightly packed waves

• Poor blood supply

• Ex.

• Tendon –

• Ligaments –

Types of Connective Tissue

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• Elastic Connective

• Many elastic fibers

• Some collagen &

fibroblast

• Locations: attachment

between vertebrae , wall of large arteries, airways

Types of Connective Tissue

Elastic fibers

Collagenous

fibers

Cartilage

• Cartilage – rigid connective tissues

• Poor blood supply

• Chondrocytes –

• 3 types of cartilage

� Hyaline cartilage

� Elastic cartilage

� Fibrocartilage

Types of Connective Tissue• Hyaline cartilage

• Most common cartilage

• Composed of:

• Chondrocytes – lie in lacunae (cavity)

• Fine collagen fibers

• Rubbery matrix

• End of long bones, fetal skeleton, nose, trachea, ribs

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• Elastic cartilage

• Chondrocytes lie in lacunae

• More elastic fibers present; more flexible

• Provides elasticity

• EX. External ear

Types of Connective Tissue

Chondrocyte

Elastic fibers

Nucleus

Extracellular

matrix

(b)

Lacuna

• Fibrocartilage

• Highly compressible; shock absorber

• Thick collagen fibers

• Ex: discs between vertebrae, meniscus of knee

Types of Connective Tissue

Chondrocyte

Collagenousfiber

(b)

Types of Connective Tissue

• Bone (Osseous)

• Protect & support the body

• Hematopoiesis –

• Composed of:

• Bone cells (osteocytes) in lacunae

• Hard matrix of Ca salts

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Bone Cell Structures

• Osteon – bone unit

• Lamella –

• Central canal – nerve and blood flow in

center of osteon

• Osteocyte –

• Canaliculi – connects cells to each other

• See Fig. 5.26 page 170

Canaliculi

Osteocytein lacuna

Centralcanal

Lamella

Nucleus

Osteocyte

Canaliculus

(c)

Osteon

Connective Tissue Types• Blood – RBC & WBC

• Blood cells surrounded by fluid matrix (plasma)

• Fibers visible during clotting (platelets)

• Functions

• Transport materials

• Fights infections

• Clotting

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Connective Tissue Summary

• Table 5.7 page 171

Types of Membranes

1. Serous Membranes• Line body cavities that

do not open to the

outside

• Reduce friction

• Inner lining of thorax

and abdomen

• Cover organs of thorax

and abdomen

• Secrete serous fluid –

lubricates

2. Mucous Membranes• Line tubes and organs

that open to outside world

• Lining of mouth, nose,

throat, etc.

• Secrete mucus

3. Cutaneous Membranes• Covers body

• Skin

4. Synovial Membranes• Composed entirely of

connective tissue

• Lines joints

• There are 4 types of epithelial membranes:

Muscle Tissue

• Function in movement

• Contractile tissues

• 3 types

• Skeletal muscle

• Cardiac muscle

• Smooth muscle

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Muscle Tissue Types• Skeletal muscle

• Voluntarily controlled

• Cells usually attached to bone

• Striations

• Multinucleated

• Long, cylindrical

• Stimulated by nerve cells

Muscle Tissue Types• Cardiac muscle

• Only in the heart

• Involuntary

• Cells attached to other cardiac muscle cells at intercalated disks

• Striated cells

• 1 nucleus/cell

• Branches

Muscle Tissue Types

• Smooth muscle

• Involuntary

• Surrounds hollow organs

• No striations

• 1 nucleus per cell

• Spindle shape

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Nervous Tissue• Neurons - nerve

cells

• Sends impulses to all areas of the body

•Axon -

•Dendrite –

•Neuroglia –support neurons