Week 4 - Tissues of the body

Question 1

What makes up the cell cytoskeleton?

Answer 1

• Actin microfilaments
• Microtubules
• Intermmediate filaments

Question 2

What are actin microfilaments?

Answer 2

Polar, double stranded helical array of G actin (7nm diameter)

Question 3

What are microtubules in cell cytoskeleton?

Answer 3

Dimers of alpha and beta tubulin arraged as hollow cylinders (25nm diameter)

Require MTOC for assembly

Question 4

What are intermmediate filaments?

Answer 4

Rope-like twisted fibres of various proteins (10nm diameter)

Question 5

What are all of these parts?

Answer 5

Question 6

What are centrioles?

Answer 6

Groupings of microtubules arranged in 9 + 0 pattern

Organise assembly of microtubules which help movement of chromosomes during cell division

Question 7

What are the properties of tight junctions (zona occludens)?

Answer 7

• Pentalaminar (5 layered)
• Continuous line of intramembranous particles (occludins, claudins, junctional adhesion molecule (JAM)
• Prevent movement of membrane from apical surface to lateral cell surface
• Limit movement of water and molecules through intercellular space

Question 8

What are the properties of adherent junctions (zona adherens)?

Answer 8

• 20nm gap
• Cell adhesion molecules (cadherins, integrins, selectins, immunoglobulin superfamily)
• Provide mechanical stability by linking cytoskeleton of adjacent cells

Question 9

What are the properties of desmosomes (macula adherens)?

Answer 9

• 20nm gap
• Discoid
• Desmocollin and desmoglein between cells
• Intracellular attachment plaques
• Link to intermediate filaments in cytoplasm
• Perpendicular to basement membrane

Question 10

What are the properties of hemidesmosomes?

Answer 10

Face basement membrane

Question 11

What are the properties of gap junctions (communicating junction)?

Answer 11

• Allow direct communication between adjacent cells
• Allow passage of ions, AA’s, sugars, secon messengers and metabolites
• Permits coordinated cell activity
• Made of pretieins (connexions) which assemble into channels (connexons)

Question 12

What are the properties of ground substance?

Answer 12

• Occupies large volume for small mass
• Hydrophilic
• GAGs (glycosaminoglycans)
  
  • Acidic
  • Negatively charged hydroxyl, carboxyl and sulphydryl groups

Question 13

What are the 3 types of fibrous molecules and their properties?

Answer 13

Collagen

• Tensile strength
• Secreted as tropocollagen and extracellularly polymerised to form collagen

Reticulin

• Type 3 collagen - branched

Elastin

• Stretch and elastic recoil
• Tropoelastin polymerises to elastin
• Requires fibrillin for assembly

Question 14

What are the 2 different types of structural glycoproteins and their properties?

Answer 14

Filamentous

• Fibrillin (microfibrils 8-12nm) - links to elastin
• Fibronectin - deposition and orientation of collagen and its links to cells via integrin

Non-filamentous (links cells and ECM)

• Laminin - major basement membrane component
• Entactin - binds laminin to type 4 collagen
• Tenascin - binds to integrins

Question 15

What separates epithelia from underlying ECM?

Answer 15

Basement membranes

Question 16

What are the 3 surface specialisations of epithelia?

Answer 16

• Ciliated
• Microvilli
• Keratinised

Question 17

What are the 4 different shapes of epithelial cells?

Answer 17

• Squamous
• Cuboidal
• Columnar
• Transitional

Question 18

What are the 3 different layer types of epithelia?

Answer 18

• Simple
• Stratified
• Pseudostratified

Question 19

Where are simple squamous epithelial cells found?

Answer 19

Terminal air sacs and part of kidney tubules

Question 20

Where are simple squamous mesothelial cells found?

Answer 20

Linings of body cavities and covering organs within

Question 21

Where are simple squamous endothelial cells found?

Answer 21

Lining of blood vessels and lymphatics

Question 22

What are the properties of stratified squamous cells?

Answer 22

May be keratinised or non-keratinised

Question 23

Where are stratified cuboidal cells found?

Answer 23

Some dubts of sweat glands

Question 24

Where are stratified columnar cells found?

Answer 24

Ducts of mammary glands and larger ducts of salivary glands

Question 25

Where are simple cuboidal cells found?

Answer 25

Many glands and portions of their ducts

Question 26

Where are simple columnar cells found?

Answer 26

Gall bladder, surface of stomach, uterus and oviduct

Question 27

Where is transitional eputhelium found?

Answer 27

Urinary tract, pelvis of kidney, ureter, bladder and part of urethra

Question 28

Where are pseudostratified ciliated columnar epithelial cells found?

Answer 28

Respiratory passages to bronchioles, male reproductive tract from efferent ducts to vas deferens

Question 29

What is the funciton of simple epithelia?

Answer 29

Absorption

Question 30

What is the function of stratified epithelium?

Answer 30

Protective

Question 31

What are other functions of epithelium?

Answer 31

* Secretion * Sensory perception * Movement of materials * Wound repair

Question 32

What are the properties of microvilli?

Answer 32

* Apical plasma membrane * Increase surface area * Core of microfilaments * Anchored in terminal web

Question 33

What are the properties of cilia?

Answer 33

* Apical surface * Very numerous * Transport material across surface * Microtubules

Question 34

What are the properties of stereocilia?

Answer 34

* Non-motile * Microfilament core - modified microvilli

Question 35

What is the function of basal infoldings?

Answer 35

Increase surface area

Question 36

What are exocrine glands?

Answer 36

Secrete out of body via ducts

Question 37

What are endocrine glands?

Answer 37

Do not have ducts but secrete directly into the body, into blood capillaries

Question 38

How can exocrine glands be classified?

Answer 38

* Tubular * Acinar * Tubulo-acinar * Simple * Compound

Question 39

What are the different types of secretions from serous, mucous and mixed glands?

Answer 39

Serous = watery fluid Mucous = more viscous containing mucin Mixed = micture of serous and mucous fluids

Question 40

What are eccrine glands?

Answer 40

Glandular cells aren't injured upon secretion

Question 41

How do apocrine glands work?

Answer 41

* Secretion gathers at outer apical end of secretory cell * Is pinched off with a portion of the cellcytoplasm * Most of cell is unaffected * Cycle repeats after refractory period

Question 42

How do holocrine glands work?

Answer 42

* Accumulation of secretion within cell cytoplasm * Cells die * Dead cells dischargedwith secretion contained in them

Question 43

How do endocrine cells store their products?

Answer 43

* Intracellular storage * In form of intracytoplasmic storage granules * Secreted directly into blood capillaries * Extracellular storage * Within an intercellular follicle surrounded by secretory cells * Secretes into follicle * Re-uptake into cytoplasm * Secretion into capillaries in contact with basal ends of secretory cells

Question 44

What is the function of the basement membrane?

Answer 44

* Controls spread of disease and infection * Boundary between epithelia (basal lamina), muscle and nerve (external lamina) and connective (support) tissue * Condensed layer of ECM * Impenetrable barrier but permits flwo of nutrients and metabolites (molecular sieve) * Constituents = heparan sulphate, type 4 collagen, fibronectin, laminin, enactin

Question 45

What are the characteristic of connective tissue?

Answer 45

* Cells often separated by ECM * Contains blood vessels and nerves * Cells may communicate * Cells often have slow turnover * Cells interact with ECm (adhesion molecules)

Question 46

What is the most important cell in connective tissue?

Answer 46

Fibroblasts

Question 47

What cells are derived from mesenchyme?

Answer 47

* Fibroblasts (responsible from synthesis and maintenance of ECM) * Adipocytes * Defence cells

Question 48

How do you classify connective tissue?

Answer 48

* Mesenchyme (embryonic) * Loose areolar * Dense (mechanical support) --\> iregular or regular * Reticular * Adipose

Question 49

What are connective tissue diseases example?

Answer 49

* Elhers-Danlos syndrome * Marfans syndrome * Scurvy * Homocystinuria * Mucopolysaccharidoses * Fibroma

Question 50

What are the components of cartilage?

Answer 50

* Ground substance * Fibres * Type 2 collagen - hyaline cartilage * Type 2 + 1 collagen - fibrocartilage * Type 2 + elastic - elastic cartilage * Chondroblasts (secrete matrix) * Chondrocytes (maintain matrix)

Question 51

How is cartilaged maintained and grown?

Answer 51

* Matrix permeable to water * Delivers oxygen and nutrients * Waste products removed * Mainly non-vascular * Relies on diffusion * Grows by intersaitital and appositional growth

Question 52

What are the 3 types of cartilage and their properties?

Answer 52

* Hyaline * Articular surfaces, tracheal rings etc. * Fibrocartilage * Intervertebral discs, pubic symphysis * Elastic cartilage * External ear, auditory canal, epiglottis etc.