L3 : Integrating cells into tissues and organs

Question 1

What holds cells together?

Answer 1

• cell-cell adhesion molecules
• Extracellular matrix protein (fibres)
• Internal-external scaffolding
• Close proximity (pressure effect)

Question 2

What are the characteristics of connective tissue layer

Answer 2

• extracellular matrix is plentiful
• cells are sparsely distributed
• matrix rich in fibrous polymers

Question 3

What are the characteristics of epithelial tissue layer?

Answer 3

• Extracellular matrix is scant - only basal lamina
• cells are tightly bound together into sheets - epithelia

Question 4

What is the primary cell of connective tissue and what is its function?

Answer 4

• MSC
• differentiate into fibroblast - produce extracellular fibres

Question 5

State the 3 components of connective tissue

Answer 5

• cells
• fibres
• ground substance

Question 6

State the function of connective tissue

Answer 6

• Protect internal organs
• mechanical support
• transport of substance within body
• insulation

Question 7

Where is epithelial tissue found in the body?

Answer 7

• lining of all cavities
• free surfaces

Question 8

What are the types of cell adhrenece both basal and lateral surfaces?

Answer 8

Basal

• Integrins
• Hemi-desmosomes
• Focal adhesion
• proteoglycans
• cell adhesion molecules

Lateral

• Tight junction
• Adheren junction
• desmosome
• Gap junction
• cell adhesion molecules

Question 9

State the characteristics and functions of Tight junctions

Answer 9

Characteristics

• very top of cell nearest to apical surface in lateral border
• long cell to cell fusion point

Function

• Seals neighbouring cells together in epitheial sheet - prevent leakage of molecules between them

Question 10

State the characteristics and functions of adhesion junction

Answer 10

Charactersitics

• Almost alwyas 1/3rd distance from apical surface o
• Found in pairs
• formed from intracellular actin filaments
• linked to E-cadherin proteins
• found only in epithelial and endothelial cells

Function

• tissue stabilising factor
• cell to cell actin bundle joining

Question 11

State the characteristics and functions of desmosome

Answer 11

Charactersitics

• strongest cell to cell adhesion
• found 1/2 between top and bottom of cells
• Cytokeratin fibres intercellularly
• E-cadherins intracellularly
• found in cardiac muscle, GI mucosa
• only cell to cell adhesion found in skin cells

Function

• Provide mechanical strength
• prevent tissue destruction
• cell to cell intermediate filament joining

Question 12

State the characteristics and functions of gap junction

Answer 12

Characteristics

• close to base of epithelial cells
• distributed throughout cardiac and smooth muscle
• Made of cylinders of proteins(connexins) arranged in hexagonal pattern that open and close (ATP)

Function

• allows free movement of small molecules (cell to cell)

Question 13

What is the connexin switch that occurs in myometrium of pregnant uterus in preperation for birth?

Answer 13

45 to 34

Question 14

State the characteristics and functions of Hemi-desmosome

Answer 14

Characteristic

• Attach to layer of extracellular matrix
• Intergrins : Attach Intracellular intermediate filaments of cytokeratin to basal lamina

Function

• Anchor epithelial cells to basal lamina

Question 15

State the characteristics and functions of focal adhesion

Answer 15

Characteristic

• Uses intracellular actin filament
• binds to fibronectin instead of lamina
• when bound to fibronectin, conformational change results in binding to collagen fibres

Function

• anchors actin filaments in a cell to basal lamina*

Question 16

State the characteristics and functions of Integrins

Answer 16

Characteristics

• works as alpha-beta dimer
• weak binders of extracellular matrix
• Phosphorylation by focal adhesion kinase produces heterotetramer - stronger bond

Question 17

What ions are needed for adhesion properties to work?

Answer 17

Ca

Question 18

What is the definition of mucous membrane?

Answer 18

The combination of epithelium, basal lamina and lamina propia

Question 19

Give examples of where the mucous membrane is found

Answer 19

• GI tract
• Urinary tract
• Respiratory tract

Question 20

State the characteristics of mucosal membrane

Answer 20

• lines all moist hollow internal organs
• continuous with skin at body openings
• secrete mucus

Question 21

State the function of mucousal membrane

Answer 21

• prevent pathogens and dirt from entering body
• prevent body tissues from dehydrated
• lubricate surface

Question 22

State the layers of the GI tract

Answer 22

*From inwards to outwards

• Mucosa lining the lumen
• Muscularis mucosae
• submucosa - contains blood vessels
• muscularis externa
• serosa - secretes fluid to lubricate outer layer

Question 23

What is the function of mucosa on GI tract

Answer 23

• abosrb substances from lumen
• prevent entry of pathogens
• move contents and expel water

Question 24

State the function of key layers in GI tract

Answer 24

• Epithelial cells : microvilli - absorption of food
• Lamina propria : contains lymphatic tissue - expels pathogens
• Muscularis mucosae : folds mucosa - increase surface area
• Muscularis externa : Peristalsis

Question 25

State the f**unction** of urinary tract

Answer 25

* Absorption of nutrients in kidneys * Prevention of pathogen entry * remove waste prodcuts

Question 26

State the layers of the urinary tract

Answer 26

\*same as GI tract except x submucosa, x serosa

Question 27

What cells are in abundance in the adventitia layer of bladder and what is its function?

Answer 27

* Fat cells * shock absorber for expanding bladder

Question 28

State the function of epithelial cells in bladder

Answer 28

* **secretes mucus** : protects bladder from damage by acidic urine

Question 29

The respiratory tract is divided into 2 parts. What are they? \*state the start and end of each portions

Answer 29

* **Conducting portion :** nasal cavity - bronchioles * **Respiratory portion :** respiratory bronchioles - alveoli

Question 30

State the layers of trachea structure

Answer 30

* **Mucosa :** respiratory epithelium + lamina propria * **Submucosa :** collagen, elastin fibres, fibroblast * **Cartilage :** Perichondirum, chrondrogenic layer

Question 31

State the characteristics of secondary and tertiary bronchi

Answer 31

\* similar to trachea except.. * cartilage not present as full

Question 32

Describe the structural characteristics of alveolus

Answer 32

* **Capillaries :** lined with endothelial cells attached to a fused basal lamina * **Basal lamina** : folded - allow expansion of air sacs when air drawn in * **Junctions :** collagen - add rigidity to mucosa * **Elastin fibres :** provide elastic recoil - return sac to empty state

Question 33

When do cells coalesce?

Answer 33

During embryogenesis

Question 34

What is a mesenchymal stem cell?

Answer 34

* Stem cell of connective tissue. * Pluripotent. * Can convert into different cell types

Question 35

What is submucosa?

Answer 35

Connective tissue containing artery and vein

Question 36

What is muscularis externae?

Answer 36

Has muscle fibres going in 2 directions * inner circular muscle * outer longitudinal muscle

Question 37

What is the musculare mucosa?

Answer 37

* Thin layer * seperate mucuousal layer from submucosa

Question 38

Where is muscle present in urinary tract?

Answer 38

* Ureter * bladder

Question 39

Why is there thick layer of muscle in urinary tract?

Answer 39

Prevent bladder from bursting

Question 40

What is mucous made of?

Answer 40

Mucin, water, electrolytes, antiseptic enzymes, immunoglobulins

Question 41

What do secretions from epithelium and submucosal gland in trachea contain?

Answer 41

* mucins * water * lysozyme