Epithelia And Connective Tissue

Question 1

Characteristic features of epithelium

Answer 1

Forms dense cellular sheets (cells attached to each other via desmosomes, adherents junctions)

Has no blood vessels (relies on diffusion from blood)

Sits on basal lamina complex (separates epithelium from underlying connective tissue to provide support and attachment between them)

Question 2

Classification of an epithelium

Answer 2

Cell shape (squamous, cuboidal, columnar)

Cell arrangement (stratified, simple, pseudostratified)

Cell specialisations (cilia, microvilli, keratinisation)

Specialised cells present (goblet cells)

Question 3

Locations of simple squamous

Answer 3

Lines surfaces involved in passive transport of gases (lungs), fluids (endothelium of capillaries)

Question 4

Locations of simple cuboidal

Answer 4

Lines small ducts and tubules, collecting tubules of the kidneys, small excretory ducts of salivary glands and pancreas

Question 5

Location of simple columnar

Answer 5

Often absorptive surfaces (small intestines), secretory surfaces (stomach)

Question 6

Microvilli
Function
Size
Structure

Answer 6

Increase SA for absorption

0.5-1um long

Shape maintained by actin anchored to cell membrane
Base of actin filaments form part of terminal web, linked to intermediate filaments

Question 7

Describe goblet cells

Answer 7

Modified columnar epithelial cells that synthesise and secrete mucus (glycoproteins stored as granules)
Found in many epithelial linings in the respiratory and GI tract
Stains poorly with H and E

Question 8

Location of pseudostratified columnar epithelium

Answer 8

Lines upper respiratory tract (trachea, bronchi, bronchioles)

Question 9

Cilia
Function
Size
Structure

Answer 9

Motile structures for moving fluids and particles along epithelial surface

7-10um

At the top of the cilia, central MT pair surrounded by 9 pairs of MT

At the basal body of the cilia, 9 MT triplets surround central core

Question 10

Purpose of stratified epithelium

Answer 10

Physical protection in oral cavity, pharynx, oesophagi, anal canal, uterine cervix
Sites subject to mechanical abrasion, kept moist by glandular secretions
Nucleated cells

Question 11

Location of keratinizaed stratified squamous

Answer 11

Physical protection, prevent desiccation

Top layer composed of dead enuculeated cells

Question 12

Keratinisation

Function

Answer 12

Protection from UV, thermal, chemical, mechanical sources

Prevention of desiccation

• cells become squamous
• keratinisation cross linked by S-S bridges
• cells die, lose nuclei and other organelles, become dehydrated, packing keratin filaments together

Question 13

Structure of skin in layers

Function of each layer

Answer 13

Stratum corneum (only keratin found here)
Stratum granuloum (many keratinohyalin granules containing keratin found here)
Stratum spinosum (many desmosomes here to prevent tearing)
Stratum basale (mitosis and renewal of keratinocytes)

Question 14

What cells are found in the transitional epithelium

Function of cells here

Answer 14

Stratified epithelium, only in urinary tract

• Distention, accommodate large degrees of stretch
• Protection, from toxic content
• Waterproof, prevent water leaking into conc urine

Nucleated cells, more rounded than surface stratified epithelium

Question 15

Functions of connective tissue

Answer 15

Forms architectural support framework of body, preserve body form

• Filler for space between other tissue types
• Structural support
• Attachment
• Physical protection
• Defence via immune cells
• Condiut for blood vessels and nerves
• Lipid store
• Wound healing

Question 16

Soft connective tissue properties

Answer 16

Organ capsule
Tendons and ligaments
Areolar, adipose tissue

Phagocytise, immunocompetent cells

Physical barrier preventing transport of microorganisms that pass through epithelial
Nutrient role

Question 17

Examples of hard connective tissue

Answer 17

Bone

Cartilage

Question 18

Composition of soft connective tissue

Answer 18

Major constituent = ECM (GAGs, protein fibres, scattered cells, tissue fluid)
Consistency depends on properties of components, can vary

Question 19

Cell of the connective tissue

Answer 19

Permanent cells (fibroblasts, adipocytes)

Transient cells (mast, plasma, leukocytes, lymphocytes)

Question 20

Function of fibroblasts

Answer 20

Synthesise collagen and ground substance
When mature, nuclei condense, elongate with sparse cytoplasm
Active fibroblasts have more cytoplasm w RER and Golgi

Question 21

Function of adipocytes

Answer 21

May be isolated/small groups within connective tissue
Largest energy store in body
In continuous turnover and sensitive to hormonal, nervous stimuli
Deposits in form of pads (shock absorber)
Fill spaces between tissues, help keel tissues in place

Question 22

Structure of proteolysis S

Answer 22

Have a protein core (core protein), GAG side chains

Question 23

Properties of collagen

Answer 23

Inelastic tensile strength (flexible and strong)

In parallel arrays forming bundles

Question 24

Properties of elastic fibres

Answer 24

Stretchable, resilient fibres and sheets
Hydrophobic, assembles by cross linking
Made from tropoelastin which polymerises in ECT
Microfibrils of structural glycoproteins fibrillation incorporate in elastin => form fibres

Question 25

Types of soft connective tissue

Answer 25

Basal lamina
Loose
Dense

Question 26

Structure and location of loose connective tissue

Answer 26

Abundant elastic fibres and collagen bundles embedded in ground substance
Component of lamina proprietary of GI and resp tract and hypodermics

Question 27

Classification of dense connective tissue

Answer 27

Subclassified according to orientation of collagen fibres as irregular and regular

Question 28

Location of irregular dense connective tissue

Answer 28

Dermis of skin, irregular arrangement of collagen fibre bundles
Consists of papillary and reticular layers

Question 29

Function of the papillary layer of the dermis

Answer 29

Very folded to strengthen the connection between the epidermis and dermis
Abundance of capillary loops, nerve fibres, Meissner’s corpuscles (light touch)

Question 30

Function of the reticular layer of the dermis

Answer 30

Densely packed with collagen, elastic and reticular fibres

Give the dermis strength, elasticity and extensibility

Question 31

Location of regular dense connective tissue

Answer 31

Tendons, ligaments, regular parallel bundles of collagen fibres separating linear rows of fibrocytes
Large amount of colllagen for tensile strength, stop overstretching