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Year 2 - Committy 1 - Biochemistry > 2- Biochemistry of Epithelial Tissue > Flashcards

2- Biochemistry of Epithelial Tissue Flashcards

1
Q

Where are simple squamous tissues found and what’s their function?

A

1-lines of blood vessels and air sacks of lungs
2-permits exchange of nutrients, wastes and gases

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2
Q

Where are the stratified squamous tissues found and what is their function?

A

1-outer layer of skin mouth vagina
2- protect against abrasion (wear down), drying out and infection

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3
Q

Where are the simple cuboidal tissue and what is its function?

A

1-lines, kidney tube and glands
2- it’s a secretes and absorbs water and small molecules

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4
Q

Where is the stratified cuboidal tissue and what is it is function?

A

1-it lines the ducts of sweat glands
2-it’s secrets water and ions

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5
Q

Where is the of the simple columnar Tissue and what is it is function?

A

1-it lines most of the digestive organs. 2-it absorbs nutrients and produces mucus.

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6
Q

Where is the stratified colonial tissues and what is it is function?

A

1- it lines the epididymus, mammary glands and the larynx

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7
Q

What is the cytoskeleton?

A

It is a network of filamentous proteins which dynamically organized the interior of the living cells

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8
Q

What is the 3 functions of the cytoskeleton?

A

1- maintain cell shape
2- anchor organelles
3- Enable cell movement

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9
Q

How dose the cytoskeleton look like under the light micrograph ?

A

The microtubles are green and the microfilaments are blue where the intermediate filaments from most of the rest of the network.

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10
Q

What are the three types of fibers of the cytoskeleton ?

A

1- microtubules ( an insoluble polymers of tubulin ). 2- microfilaments ( insoluble polymers of actin ). 3- intermediate filaments ( insoluble keratin )

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11
Q

What are microtubules ?

A

They are cylindrical tubes, 20-25 nm in diameter

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12
Q

What are microtubules made from ?

A

It is composed of subunits of the protein tubulin

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13
Q

What is the function of microtubules ?

A

They determine the cell shape and its involved in the transport of material within cells .

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14
Q

Where do microtubules come from ?

A

They come from spindle fibers for separating chromosomes during mitosis

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15
Q

What is microtubules used for ?

A

It is used for locomotion when arranged inside flagella and cilia

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16
Q

What are microfilaments ?

A

It is a fine, thread like protein fibers 3-6 nm in diameter .

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17
Q

What are microfilaments made from ?

A

They are composed of contractile protein ( actin ), the most abundant protein in a cell

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18
Q

What is the function of microfilaments ?

A

Microfilaments are responsible for muscle contraction in association with myosin

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19
Q

What dose microfilaments carry out ?

A

They carry out cellular movements including contraction and cytokinesis

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20
Q

What are intermediate filaments ?

A

They are about 10 nm diameter and provide tensile strength for the cell, they are the strongest filaments of the cytoskeleton

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21
Q

What dose the fibers in the intestinal epithelial cells do ?

A

1- microfilaments project into the villi, giving shape to the cell surface.
2- microtubules grow out of the centrosome to the cell periphery.
3- intermediate filaments connect adjacent cell through desmosomes.

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22
Q

What is keratin ?

A

It os an intermediate filament

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23
Q

Where is keratin synthesized ?

A

It is synthesized in keratinocytes .

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24
Q

What is the structure of keratin ?

A

It has a fibrous structure .

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25
Q

What are the characteristics of keratin ?

A

It is stable, mechanically durable and insoluble .

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26
Q

What dose keratin form ?

A

It forms hard and robust structures like scale, teeth and horns

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27
Q

What are the two types of keratin ?

A

Alpha ( a- ) and beta ( B- ) keratin

28
Q

Alpha keratin in mammals are the main components of what ?

A

Hair and wool

29
Q

What dose Alpha-keratin contain what dose it form ?

A

Alpha-keratins it contains a hydrophilic amino acid in large amounts, they form left-handed superhelix structures.

30
Q

What dose Beta-keratins do in birds and reptiles ?

A

It takes place in feather, skin, claw and beaks.

31
Q

What is the structure characteristics of keratin ?

A

Keratin has many repeated heptapeptide motifs in its primary structure, these motif has three hydrophobic amino acids.

32
Q

How many protein chains dose microfibril / intermediate filament ?

A

They contain 32 protein chains, each chain has is a dime.

33
Q

What is damage of a perm to keratin in the hair ?

A

The chemical procedures affect structure of keratin as a rearrangement of disulfide bonds may cause structural damage to keratin.

34
Q

What happens in the epidermolysis bullosa simplex (EBS) ?

A

The mutations in KRT5 or KR14 gene prevents the keratin proteins from assembling into strong networks causing cells in the epidermis to become fragile and easily damaged.

35
Q

How are epidermal cells are easily broken ?

A

To form separated layers due to a defective keratin filaments as a result the skin is less resistant to friction and minor trauma and blisters easily.

36
Q

What type of allele is EBS and how many people dose it effect ?

A

It is an autosomal dominant allele and it affects 1 in every 30,000 to 50,000.

37
Q

What is the epidermal permeable barrier ?

A

It is a multilayered epithelium that protects the organism from the environment.

38
Q

What is the function of the epidermal permeability barrier ?

A

The barriers function in human epidermis depends on the transglutaminase-mediated cross-linking of structural proteins and lipids .

39
Q

What are Transglutaminases (TGases) ?

A

It is a protein cross-linking (a post-translational modification) enzymes, its a Ca++ dependent.

40
Q

What dose the TGases do ?

A

Its from an interprotein cross-links that hold proteins together and play a key role in the formation of cross-linked cornfield envelopes during keratinocyte terminal differentiation ( formation of corneocytes ).

41
Q

What dose TGases catalyze ?

A

It catalyze the formation of the isopeptide bond between the carboxamido group of protein-bound glutamine in one protein and lysine residue of other protein. The reaction product is a stable and insoluble macromolecule .

42
Q

What is the mutation of keratinocyte transglutaminase 1 (TGM1) ?

A

The TGM1 cause lamellar ichthyosis, its a severe congenital skin disorder characterized by generalized large scale and variable redness.

43
Q

What is the TGM1 is involved in ?

A

The TGM1 is involved in the formation of the cornfield cell envelope.

44
Q

What dose the mutation in the TGM1 cause ?

A

It causes defects in the intercellular lipid layers in the stratum corneum leading to defective barrier function of the stratum corneum and to the ichthyotic phentotype.

45
Q

What is the lamellar ichthyosis ?

A

It is a rare autosomal recessive disorder where a baby born covered with a transparent membrane (sheds within 1-14 days) revealing generalized scaling with redness of the skin.

46
Q

What is melanin ?

A

It is a 5,6-dihydroxyindole polymer its synthesized from tyrosine, its insoluble in large molecule, its synthesized in specified organelles (melanosomes) of melanocyte ( skin and hair follicles ).

47
Q

What is the amount of melanin synthesized in melanosomes correlate to ?

A

The skin and hair color

48
Q

What is the function of the dendrites of melanocytes ?

A

They are placed among the keratinocytes like an octopus and transfer the melanosome content to keratinocytes .

49
Q

What are the two types of melanins ?

A

1- Eumelanin
2- Pheomelanin

50
Q

What is Eumelanin ?

A

It is the most common form of the biological melanin, a brown-black polymer of dihydroxyindole carboxylic acids and their reduced forms .

51
Q

What is the pheomelanin ?

A

Its the other form of melanin is where a cysteine-containing red - brown polymer of the benzothiazine units largely responsible for red hair and freckles.

52
Q

What happens when the melanosomes are transferred to keratinocytes ?

A

They from perinuclear protective cap over the nucleus, this cap helps protect the nuclear DNA from damaging effects of UV radiation .

53
Q

What happens when the melanosomes are transferred to keratinocytes ?

A

They from perinuclear protective cap over the nucleus, this cap helps protect the nuclear DNA from damaging effects of UV radiation

54
Q

What is albinism ?

A

Albinism is an autosomal recessive genetic disorder characterized by the complete or partial absence of melanin in the skin, hair and eyes due to absence or defect of tyrosinase.

55
Q

What is the name of patients with complete absence of pigment ?

A

Albino

56
Q

What is oculocutaneous albinism ?

A

Its the common form of albinism which involves both eyes and skin.

57
Q

What is a gland ?

A

A gland is an organ is an animal body that synthesizes a substance for release of substances

58
Q

What dose the mammalian stomach secrete ?

A

Its a highly acidic gastric juice ( 0.1M HCL)

59
Q

What secrets hydrophobic acid ?

A

They are secreted by partial cells located by parietal cells located in gastric mucosa.

60
Q

How many alveoli dose lungs have ?

A

2-3 million alveoli

61
Q

What are the two types of epithelial cells that the alveolar wall consist of ?

A

1- Type I : alveolar cells are thin and flat, they are responsible for gas transport.
2- Type II : alveolar cells that are round and secret surfactant .

62
Q

What is the composition of surfactant ?

A

90% lipids and 5-10% surfactant-specific proteins

63
Q

What are surfactant ?

A

It is a surface-active agent.

64
Q

What is the function of surfactant ?

A

It increases pulmonary compliance where the lung ability to stretch and expand

65
Q

What is the role of surfactant during inspiration ?

A

When the alveoli expand the surfactant molecules move apart .

66
Q

What is the role of surfactant during expiration ?

A

When the lungs molecules move together and become concentrated the surface tension is reduced.

Year 2 - Committy 1 - Biochemistry (4 decks)

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