Skin structure and function 3

Question 1

What is the dermo-epidermal junction ?

Answer 1

Interface between epidermis and dermis

Question 2

What is the function of the dermo-epidermal junction?

Answer 2

•Key role in epithelial–mesenchymal interactions:

• –Support, anchorage, adhesion, growth and differentiation of basal cells
• –Semi-permeable membrane acting as barrier and filter

Note mesenchymal = Mesenchymal cells are able to develop into the tissues of the lymphatic and circulatory systems, as well as connective tissues throughout the body, such as bone and cartilage.

Question 3

Appreciate the structure of the dermo-epidermal junction as shown in the pic

Answer 3

• Basal cells
• Lamina lucida
• Lamina densa
• Sub-lamina densa zone

Think Big Ladies Dont Sprint

Question 4

What condition is shown here ? (describe the condition briefly)

Answer 4

Bullous phemphigoid:

Bullous pemphigoid is an acute or chronic autoimmune skin disease, involving the formation of blisters, more appropriately known as bullae, at the space between the skin layers epidermis and dermis. It is classified as a type II hypersensitivity reaction, with the formation of anti-hemidesmosome antibodies.

Question 5

If bullous phemphigoid is suspected what is done to confirm the diagnosis ?

Answer 5

A skin biopsy is taken to confirm it, immunofluroescence may be used to show up the antibodies, and a blood sample may be taken and checked for the presence of pemphigoid antibodies.

Question 6

Name and briefly describe the condition shown here ?

Answer 6

Epidermolysis bullosa - Epidermolysis bullosa (EB) is a group of inherited connective tissue diseases that cause blisters in the skin and mucosal membranes, with an incidence of 20 per million newborns in the United States. It is a result of a defect in anchoring between the epidermis and dermis, resulting in friction and skin fragility.

Question 7

What is the dermis made up of ?

Answer 7

It is made up of:

• Ground substance - The ‘ground substance’ of extracellular matrix is an amorphous gelatinous material. It is transparent, colourless, and fills the spaces between fibres and cells. It actually consists of large molecules called glycosoaminoglycans (GAGs) which link together to form even larger molecules called proteoglycans.
• Cells - mainly fibroblasts, macrophages, mast cells, lymphocytes and Langerhans cells
• Muscles, blood vessels, lymphatics, nerves

Question 8

The person on the left is actually the older of the two, why might the person on the right appear older ?

Answer 8

Photoaging - Photoaging is premature aging of the skin caused by repeated exposure to ultraviolet radiation (UV) primarily from the sun, but also from artificial UV sources.

Question 9

Describe the flow of blood in skin

Answer 9

Arteriole ====> precapillary sphincters =====> arterial =====> venous capillaries ====> post-capillary venules =====> collecting venules

Question 10

What is shown here and briefly describe what it is

Answer 10

Angioma - A tumor (abnormal growth), such as a hemangioma or lymphangioma, that mainly consists of blood vessels or lymphatic vessels.

Question 11

Describe the lymphatic vessels in the skin

Answer 11

Subepidermal meshed networks.

Smaller non-contractile vessels ====> larger contractile lymphatic trunks

Question 12

What do lymphatic vessels do and what are there important immune functions ?

Answer 12

• Continual drainage of plasma proteins, extravasated cells and excess interstitial fluid
• Important immune functions:
• • immune surveillance by circulating lymphocytes and Langerhans cells
• • channelling of micro-organisms / toxins

Question 13

Name and briefly describe the condition shown here ?

Answer 13

Chronic lymphoedema:

Lymphedema is a condition of localized fluid retention and tissue swelling caused by a compromised lymphatic system

Question 14

What are the specialised somatic sensory receptors found in the skin ?

Answer 14

Pacinian corpuscles and Meissners corpuscles and free nerve endings

Question 15

What do Pacinian corpuscle receptors sense in the skin ?

Answer 15

Pressure

Question 16

What do Meissners corpuscles sense in the skin ?

Answer 16

Vibrations

Question 17

What are the areas that somatic sensory innervation is arranged into called ?

Answer 17

Arranged into dermoatomes

Question 18

Describe the innervation of the skin

Answer 18

The entire surface of your skin receives its nerve supply from the central nervous system (CNS) and the autonomic nervous system (ANS).

Your central nervous system receives sensory information about touch, pressure, temperature and pain from areas of your skin. (these areas = dermatomes).

Receptors in different areas of your skin send nerve impulses or messages via spinal nerves to the spinal cord. This information is then transmitted up the sensory or ascending spinal tracts in your spinal cord to the brain.

The autonomic nervous system controls the blood vessels, sweat glands and oil (sebaceous) glands in your skin.

Question 19

What does the autonomic nerve supply control in the skin ?

Answer 19

Blood vessels, nerves and glands

Question 20

What is shown here ?

Answer 20

Pacinian corpuscles

Question 21

Name and briefly describe the condition shown ?

Answer 21

Neurofibromatosis:

• Neurofibromatosis is the general name for a number of genetic conditions that cause tumours to grow along your nerves.
• Tumours are swellings formed by a growth of cells. In neurofibromatosis, the tumours are usually non-cancerous (benign).

Question 22

What are the 3 main different skin glands in the skin ?

Answer 22

• Sebaceous
• Apocrine
• Eccrine

Question 23

Label the skin glands as indicated by the arrows

Answer 23

Question 24

How do sebaceous glands secrete and what do they secrete ?

Answer 24

• Holocrine secretion into pilary canal
• Secrete sebum - which is a oily, waxy substance made up of squalene, wax esters, TG (triglycerides) and FFA (free fatty acids)

Note - Holocrine secretions are produced in the cytoplasm of the cell and released by the rupture of the plasma membrane.

Also these glands are inactive pre-puberty and are the biggest on the chest and face

Question 25

What is the function of sebaceous glands ?

Answer 25

* Control moisture loss * Protection from fungal infection

Question 26

Name and briefly describe the condition shown

Answer 26

Acne - a skin condition characterized by red pimples on the skin, especially on the face, due to inflamed or infected sebaceous glands and prevalent chiefly among adolescents.

Question 27

What hormone are apocrine glands dependant on and what is this glands function ?

Answer 27

* Dependant on androgen * Produce oily fluid ====\> odour after bacterial decompostion (involved in scent)

Question 28

Where are eccrine glands located and what stimulates there function ?

Answer 28

* Located on the whole skin surface - particularly palms, soles and axillae * Sympathetic cholinergic nerve supply – mental, thermal and gustatory (relating to or associated with eating or the sense of taste) stimulation

Question 29

What is the function of eccrine sweat glands ?

Answer 29

* Cooling by evaporation * Moisten palms / soles to aid grip * Ultrafiltration - can be \> 10L per day, NaCl + HCO3 reabsorbed

Question 30

What type of sweat glands are shown in the pics ?

Answer 30

Sebaceous sweat glands

Question 31

What type of sweat glands is shown in the pic

Answer 31

Apocrine sweat glands

Question 32

What type of sweat glands is shown in the pic ?

Answer 32

Eccrine sweat glands