Steven and Brenda had eagerly anticipated the birth of their first child, a boy named
Garth. The first year was joyous and Garth grew normally with no apparent problems
other than some trauma induced blistering of the skin.
By Garth's third birthday, Brenda noticed that his nails showed some deformities. She
mentioned this to his pediatrician during his annual physical but since there were no
other problems, the physician decided to just watch the condition and to keep a record
of what Garth was doing.
At four, Garth exhibited thickening of the palms and soles of the feet and gradual loss of
the eyebrow hair. His lovely thick eyelashes were also becoming sparse. By age five,
hyperhidrosis over the nose and cheeks were observed.
Garth was referred to a dermatologist for follow up where he was determined to have a
genetic mutation in the plakophilin gene resulting in a condition known as epidermolysis
bullosa a form of ectodermal dysplasia.
- Describe the five different layers of the skin.
- Describe the four different cell junctions.
- What is the purpose of the plakophilin gene?
- How would mutations in the plakophilin gene disrupt cell to cell interactions?
- How would mutation in the plakophilin gene lead to hyperhidrosis
Full Answer Section
The epidermis is further divided into five sublayers:
- Stratum corneum: The stratum corneum is the outermost layer of the epidermis and is made up of dead keratinized cells. These cells are constantly being shed and replaced.
- Stratum lucidum: The stratum lucidum is a clear layer of cells that is found only in thick skin, such as the palms of the hands and the soles of the feet.
- Stratum granulosum: The stratum granulosum is made up of cells that contain keratohyalin granules. Keratohyalin granules are responsible for producing keratin, the protein that gives the skin its strength and structure.
- Stratum spinosum: The stratum spinosum is made up of cells that have a spiny appearance. These cells are connected to each other by desmosomes, which are cell junctions that provide strength and adhesion.
- Stratum basale: The stratum basale is the deepest layer of the epidermis and is made up of columnar cells. These cells are responsible for dividing and producing new skin cells.
Dermis
The dermis is the middle layer of the skin and is made up of connective tissue. The dermis contains blood vessels, lymph vessels, nerves, and hair follicles. The dermis is responsible for providing support and structure for the skin, as well as for regulating blood flow and temperature.
Subcutaneous tissue
The subcutaneous tissue is the deepest layer of the skin and is made up of loose connective tissue. The subcutaneous tissue contains fat cells, which provide insulation and cushioning for the body.
The four different cell junctions
Cell junctions are specialized structures that connect cells together. There are four main types of cell junctions:
- Tight junctions: Tight junctions form a watertight seal between cells. This prevents water and other molecules from leaking between cells. Tight junctions are found in the epidermis and other tissues where it is important to prevent leakage, such as the intestines and the kidneys.
- Adhering junctions: Adhering junctions provide strong mechanical attachments between cells. This helps to keep tissues together and to resist mechanical stress. Adhering junctions are found in the epidermis, dermis, and other tissues where it is important to maintain tissue integrity.
- Gap junctions: Gap junctions allow molecules to pass between cells. This allows cells to communicate with each other and to coordinate their activities. Gap junctions are found in all tissues of the body.
- Desmosomes: Desmosomes are specialized cell junctions that provide strong mechanical attachments between cells. Desmosomes are found in the epidermis, dermis, and other tissues where it is important to resist mechanical stress.
The purpose of the plakophilin gene
The plakophilin gene encodes a protein called plakophilin. Plakophilin is a component of desmosomes. Desmosomes are cell junctions that provide strong mechanical attachments between cells.
Mutations in the plakophilin gene can lead to a variety of skin disorders, including epidermolysis bullosa (EB). EB is a group of genetic disorders that cause the skin to be fragile and blister easily.
In the case of Garth, his mutation in the plakophilin gene is causing his skin to be fragile and blister easily. This is because the desmosomes in his skin are not functioning properly.
Conclusion
The skin is a complex organ that is made up of multiple layers and cell types. The plakophilin gene is important for the formation and function of desmosomes, which are cell junctions that provide strong mechanical attachments between cells. Mutations in the plakophilin gene can lead to a variety of skin disorders, including epidermolysis bullosa.
Sample Answer
The five different layers of the skin
The skin is the largest organ in the body and is made up of three main layers: the epidermis, dermis, and subcutaneous tissue.
Epidermis
The epidermis is the outermost layer of the skin and is made up of stratified squamous epithelium. This means that the epidermis is made up of many layers of flattened cells. The epidermis is responsible for protecting the body from the environment and for preventing water loss.