Connective Tissue and Skin

Question 0

What two things is the extracellular matrix made up of?

Answer 0

Ground substance (hyaluronate proteoglycan aggregates)
Fibres (collagen, reticular, elastic)

Question 1

What are the two components of connective tissue?

Answer 1

Cells and extra cellular matrix

Question 2

Name the two types of embryonic connective tissue

Answer 2

Mesenchyme

Mucous connective tissue

Question 3

What is the amino acid sequence of collagen

Answer 3

Glycine-X-Y

Question 4

Give the structure of collagen

Answer 4

Three alpha helix chains wrapped around eachother

Question 5

What type of collagen is in found in hyaline and elastic cartilage?

Answer 5

Type II

Question 6

Which connective tissue does Marfan’s syndrome affect?

Answer 6

Elastic tissue

Question 7

What type of inheritance is Marfan’s?

Answer 7

Autosomal dominant

Question 8

What type of connective tissue is the dermis?

Answer 8

Dense irregular

Question 9

How does the arrangement of collagen make skin more resistant to tearing

Answer 9

Bundles of collagen are densely packed but irregularly arranged so that they are orientated in different directions

Question 10

How are tendons arranged?

Answer 10

Collagen bundles lie in a parallel, densely packed formation in a line. Rows of elongated fibroblasts lie between the bundles.

Question 11

What do fibroblasts do?

Answer 11

Synthesis and secrete ground substance and the fibres that lie within the ground substance.

Question 12

Give three fibres that make up connective tissue

Answer 12

Collagen, elastin, reticular

Question 13

Name the four layers of the epidermis

Answer 13

Stratum corneum, granular layer, prickle cell layer, basal layer

Question 14

In which layer of the epidermis does keratinocytes mitosis mostly occur?

Answer 14

Basal layer

Question 15

In which layer do the keratinocyte daughter cells lose their ability to divide?

Answer 15

Prickle cell layer

Question 16

What do keratinocytes synthesise?

Answer 16

Keratins

Question 17

What happens to keratinocytes in the granular layer of the epidermis?

Answer 17

Lose their plasma membrane

Differentiate into corneocytes, the main cells of the stratum corneum

Question 18

Which layer of the epidermis contains keratohyalin granules?

Answer 18

Granular layer

Question 19

What are keratohyalin granules made up of?

Answer 19

Aggregations of keratins, other fibrous proteins, enzymes which degrade the phospholipid bilayer and cross-link proteins including fillagrin and involucrin.

Question 20

What type of cells is the stratum corneum made up of?

Answer 20

Flattened corneocytes

Question 21

What is the transit time of a keratinocyte from the basal layer to the stratum corneum?

Answer 21

30-40 days

Question 22

In which layer of the epidermis are Langerhans cells found?

Answer 22

Prickle cell layer

Question 23

What do Langerhans cells in the epidermis do?

Answer 23

Present antigens to T lymphocytes

Mediate immune reactions

Question 24

What is psoriasis?

Answer 24

Abnormal epidermal growth and differentiation

Question 25

What is vitiligo?

Answer 25

Autoimmune destruction of melanocytes.

Question 26

Where are melanocytes found?

Answer 26

The basal layer of the epidermis

Question 27

What is connective tissue?

Answer 27

Cells, fibres and ground substance which has a number of functions including joining together other tissues, supporting the body and its structures, and providing protection for underlying organs.

Question 28

What is the structure of a proteoglycan monomer?

Answer 28

A core protein with about 100 glycosaminoglycan (GAG) units attached.

Question 29

What charge do GAGs have and what does this do?

Answer 29

Negative | Attract water to form a hydrated gel

Question 30

Where can type I collagen be found?

Answer 30

In the skin dermis, tendons and capsules of organs.

Question 31

What is reticulin?

Answer 31

Type III collagen

Question 32

Where is reticulin found?

Answer 32

Forms fibrils around nerve and muscle cells and within lymphatic tissues and organs.

Question 33

Where are elastic fibres found?

Answer 33

Artery walls and dermis

Question 34

What do macrophages do?

Answer 34

Phagocytic - can degrade foreign organisms and cell debris | Professional antigen presenting cells (present foreign material to T lymphocytes of the immune system)

Question 35

What do mast cells do?

Answer 35

Become coated with Immunoglobulin E. When IgE binds cross links with an allergen, contents of granules in the mast cells are released. Granules contain heparin, histamine, substances that attract eosinophils and neutrophils.

Question 36

Describe the process of keratinocyte differentiation

Answer 36

Keratinocyte mitosis occurs in the basal layer Daughter keratinocytes move up to form the prickle cell layer. Terminal differentiation begins and they lose their ability to divide Keratinocytes synthesis keratins, which contribute to the strength of the epidermis. In the granular layer, keratinocytes lose their plasma membrane and begin differentiating into corneocytes, the main cells of the stratum corneum.

Question 37

What does the granular layer contain? (Detail!)

Answer 37

Keratohyalin granules which are aggregations of - keratins - other fibrous proteins - enzymes which degrade the phospholipid bilayer and cross link proteins

Question 38

What is allergic contact dermatitis?

Answer 38

Mediated by Langerhans cells

Question 39

What is malignant melanoma?

Answer 39

Malignant growth of melanocytes

Question 40

Give the main components of the dermis

Answer 40

``` Extracellular matrix of collagen (mostly type 1) and elastin Blood vessels Lymphatic vessels Mast cells Nerves ```

Question 41

What do scars mainly comprise of?

Answer 41

Collagen

Question 42

What are the four main functions of the skin?

Answer 42

Barrier Sensation Thermoregulation Psychosexual communication

Question 43

What four things can a loss of barrier function lead to?

Answer 43

``` Loss of fluids Loss of protein Loss of other nutrients Loss of heat Excessive absorption of potentially harmful exogenous agents ```

Question 44

List some macroscopic variations in the skin

Answer 44

``` Hairiness Thickness Oiliness Laxity Colour ```