Puzzle Piece 3: Integumentary System

What are the two main layers of the integumentary system?

Cutaneous Layer (skin) and Subcutaneous Layer (beneath the skin).

What structures are included in the integumentary system?

Hair, nails, skin glands, and sensory receptors.

What are the two components of the cutaneous layer?

Epidermis and dermis.

What type of tissue makes up the epidermis?

Stratified squamous epithelium.

Does the epidermis contain blood vessels?

No, the epidermis is avascular.

What type of tissue is the dermis composed of?

Dense irregular connective tissue.

What does the subcutaneous layer consist of?

Adipose tissue and loose areolar connective tissue.

What is the primary function of the integumentary system?

Protection against the external environment.

Why is the skin considered the largest organ of the human body?

It is composed of two or more tissues organized in a specific way, including epithelial and vascularized connective tissue.

How does the skin prevent dehydration?

The epidermis contains a lipid 'cement' that glues cells together, preventing water loss.

What role does sweating play in temperature regulation?

Sweating cools the body in hot environments.

How does hair contribute to temperature regulation?

Hair stands up to trap heat in cold environments.

What substances are excreted through the skin?

Water, salt (sodium chloride ions), and other components.

What is an example of a substance that can be absorbed through the skin?

Drugs (e.g., nicotine patches) and skincare products.

What sensory information can the skin detect?

Temperature, touch, pressure, and pain.

What begins the synthesis of vitamin D?

Exposure to sunlight.

What is the role of keratin in the epidermis?

It provides resistance to friction and trauma.

What is a key characteristic of the epidermis regarding blood vessels?

It is avascular, meaning it lacks blood vessels.

What is the significance of the stratified nature of the epidermis?

It makes the epidermis resistant to abrasion.

What happens to nutrients and waste in the epidermis?

They are exchanged with the nearby connective tissue since the epidermis is avascular.

What is the function of sensory receptors in the skin?

To sense the external environment.

How does the skin aid in waste removal?

By excreting substances through sweat.

What is a witty tip related to the skin's role in temperature regulation during exercise?

Exercising generates heat, leading to sweating to maintain body temperature.

What would happen if the epidermis was a single layer of cells?

We would scratch ourselves superficially and bleed because we would reach the dermis.

What type of tissue makes up the dermis?

Dense irregular connective tissue.

Why is the dermis well-suited to resist tension in all directions?

The fibers in dense irregular connective tissue are irregularly arranged.

What is the vascular status of the dermis?

The dermis is vascularized, containing blood vessels that nourish the epidermis.

What is the hypodermis also known as?

Subcutaneous layer.

What types of tissues are found in the hypodermis?

Adipose tissue and loose areolar connective tissues.

What are the functions of adipose tissue?

Heat insulation, cushioning, and energy storage.

What is the relationship between the dermis and hypodermis?

The hypodermis is located below the dermis.

What are keratinocytes?

Epidermal cells that produce keratin.

What percentage of keratinocytes are stem cells?

Approximately 10%.

Where are keratinocyte stem cells located?

In the stratum basale, the deepest layer of the epidermis.

How many layers does the epidermis have in thick skin?

5 layers.

What are the layers of the epidermis in thin skin?

Stratum corneum, stratum granulosum, stratum spinosum, stratum basale.

What additional layer is present in thick skin?

Stratum lucidum.

What mnemonic helps remember the layers of the epidermis from top to bottom?

"Come Let's Get Sun Burned".

What is the process by which keratinocytes become keratinized?

As they move towards the surface, they undergo keratinization, becoming more keratinized and gradually dying.

What happens to keratinocytes as they move towards the surface of the skin?

They are pushed upwards, undergo keratinization, and are gradually deprived of nutrients.

What is the primary role of keratin in the skin?

To strengthen the skin and help it resist trauma and friction.

What distinguishes thick skin from thin skin?

Thick skin has 5 layers and lacks hair, while thin skin has 4 layers and usually has hair.

What are the four layers of thin skin?

Stratum corneum, stratum granulosum, stratum spinosum, stratum basale.

What are the five layers of thick skin?

Stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale.

What is the significance of the stratum lucidum?

It is present only in thick skin, such as palms and soles.

What is the main function of the dermis?

To provide structural support and nourishment to the epidermis.

What are the specific layers of the epidermis mentioned in the notes?

Stratum spinosum, stratum granulosum, and stratum corneum.

How often does the epidermis renew itself?

Every eight weeks.

What happens to keratinocytes as they move upwards in the epidermis?

They become harder (keratinized) like bricks in a wall.

What do desmosomes do in the epidermis?

They provide strength and flexibility by holding live keratinocytes together.

What binds dying cells together in the epidermis?

A lipid extracellular matrix that acts as a cement.

Where are melanocytes located?

In the stratum basale.

What is the function of melanocytes?

To produce melanin, the pigment that gives skin its color.

How is melanin delivered to keratinocytes?

Melanin is delivered to keratinocytes in the stratum spinosum to protect the skin from UV damage.

What determines the amount and type of melanin produced?

Genetics.

What condition is characterized by the absence of melanin production despite the presence of melanocytes?

Albinism.

What is vitiligo?

An autoimmune disease where the immune system destroys melanocytes, resulting in white patches on the skin.

What is melanoma?

The most aggressive type of skin cancer that occurs when melanocytes divide uncontrollably.

What are Merkel cells and where are they found?

Merkel cells are found in the stratum basale and serve as touch receptors.

What do Langerhans cells do?

They protect the skin from pathogens and act as intra-epidermal macrophages.

Where are Langerhans cells located?

In the stratum spinosum.

What is the stratum basale also referred to as?

The germinative layer of the epidermis.

Why is the stratum basale called the germinative layer?

Because it is where cells are dividing and generating new cells throughout life.

What is the location of the stratum basale in relation to the dermis?

It is the deepest epidermal layer, closest to the blood vessels of the dermis.

What type of cell junction is used to hold cells together in the stratum basale?

Desmosomes.

What is the role of Merkel disks?

They are associated with Merkel cells and transmit sensory information to the central nervous system.

What happens to keratinocytes as they shed from the top layer?

They become free in the environment, forming whitish dust.

What is the relationship between melanocytes and skin color?

The difference in skin color is due to the quantity and type of melanin produced, not the number of melanocytes.

What is the significance of eumelanin?

Higher concentrations of eumelanin result in darker skin color.

What type of cell junction holds cells together in the epidermis?

Desmosomes, which use keratin.

What is the primary cell type found in the stratum basale?

Keratinocytes.

What role do melanocytes play in the skin?

They produce melanin, which gives skin its color and protects against UV rays.

What are the two types of stem cells found in the stratum basale?

Melanocyte stem cells and keratinocyte stem cells.

How do keratinocyte stem cells function throughout a person's life?

They are capable of dividing throughout life to generate new skin cells.

What happens to older keratinocytes as they move upwards in the epidermis?

They move away from the dermis' nutrients, eventually die, and become more distant from the source of oxygen.

What is the location of the stratum spinosum?

It is located above the stratum basale.

What types of cells are found in the stratum spinosum?

Numerous keratinocytes, Langerhans cells, and dendritic extensions of melanocytes.

Why are Langerhans cells located in the stratum spinosum?

They need to be close to the dermis for nutrients and oxygen to survive.

What characterizes the stratum granulosum?

Cells undergoing apoptosis and containing granules involved in keratinization and lipid secretion.

What is the significance of the lipid extracellular matrix in the upper layers of the epidermis?

It acts as a waterproof layer and cements dead cells together.

What happens to cells in the stratum granulosum as they are too far from the dermis?

They undergo apoptosis due to lack of nutrients.

What is the function of the lipid cement in the stratum granulosum?

It cements the cells together and prevents water loss.

What is the role of the lipid layer in the skin?

It makes the skin waterproof and prevents the passage of water in and out of the body.

What happens to 7-dehydrocholesterol when exposed to UV rays?

It is converted into a vitamin D precursor.

Where is the active form of vitamin D (calcitriol) primarily converted in the body?

In the kidneys, and to a lesser extent in the liver.

What is the relationship between the dermis and the epidermis?

The dermis supplies nutrients to the epidermis, which lacks blood vessels.

What is the consequence of older keratinocytes being pushed upwards?

They become more distant from nutrients and oxygen, leading to a higher prevalence of dead cells.

Why do cells in the stratum granulosum contain granules?

The granules are involved in keratinization and lipid secretion.

How does the structure of the stratum spinosum appear under a microscope?

It appears spiny due to the projections holding the cells together.

What is the protective function of melanocytes in the epidermis?

They store melanin in dendritic extensions to shield cells from UV rays.

What is the significance of the keratinocytes pushing older cells upwards?

It facilitates the renewal of the skin layer and the eventual shedding of dead cells.

What type of tissue is the epidermis classified as?

Epithelial tissue.

What lipid in the epidermis is converted into a vitamin D precursor when exposed to UV rays?

7-dehydrocholesterol.

What is the active form of vitamin D that is produced from its precursor?

Calcitriol.

What role does calcitriol play in the body?

It regulates calcium and phosphate metabolism and promotes their absorption from the intestines.

What condition may develop in children who lack vitamin D?

Rickets, leading to abnormal bone formation.

Where is the stratum lucidum located?

Above the stratum granulosum and only present in thick skin.

What is the composition of the stratum lucidum?

Clear, flat, dead keratinocytes.

What is the top layer of the epidermis called?

Stratum corneum.

What is the primary composition of the stratum corneum?

Flat, dead keratinocytes with lots of keratin.