Histology of Integumentary System Flashcards

Comprehensive practice questions covering the histology of the integumentary system, including skin layers, appendages, cell types, glands, hair growth cycles, and clinical applications like cancer and burns.

What are the components of the integumentary system?

The skin (cutaneous membrane) and its appendages, including sweat glands, sebaceous glands, ceruminous glands, tarsal (Moll’s) glands, hair, and nails.

What is the largest single organ of the body, and what percentage of total body weight does it account for?

The skin is the largest organ, accounting for $15-20\%$ of total body weight.

What are the three main layers of the skin structure?

The epidermis, the dermis, and the subcutaneous tissue (hypodermis).

What term refers to the study of the ridge patterns formed by the interdigitation of dermal papillae and epidermal ridges?

Dermatoglyphics

What is the layer of loose connective tissue beneath the dermis that may contain pads of adipocytes?

The subcutaneous tissue or hypodermis, also known as the Panniculus adiposus.

What type of epithelium makes up the epidermis?

Stratified squamous keratinized epithelium composed of cells called keratinocytes.

Name the three less abundant epidermal cell types besides keratinocytes.

Melanocytes, Langerhans cells, and Merkel cells (tactile epithelial cells).

What is the typical thickness range of the epidermal layer in thick skin versus thin skin?

Thick skin varies from $400$ to $1400\,\mu m$, while thin skin varies from $75$ to $150\,\mu m$.

Where is thick skin located on the human body?

On the palms of the hands and the soles of the feet.

Which epidermal layer is characterized by intense mitotic activity and renewal every $15-30$ days?

Stratum basale

What structures help bind cells of the stratum basale to the basal lamina?

Hemidesmosomes

Why is the stratum spinosum also known as the 'prickly layer'?

In tissue sections, the cells shrink and pull back, making their exposed desmosomes resemble spikes or spines.

What type of granules fill the cytoplasm of cells in the stratum granulosum?

Keratohyalin granules

Which epidermal layer consists of translucent, extremely flattened eosinophilic cells and is more apparent in thick skin?

Stratum lucidum

What are the flattened, non-nucleated keratinized cells of the stratum corneum called?

Squames or horny, cornified cells.

What brownish-black pigment is produced by specialized cells in the basal layer and hair follicles?

Eumelanin

From which embryonic derivative are melanocytes originated?

Neural crest

What is the medical condition caused by a hereditary inability of melanocytes to synthesize melanin due to a lack of tyrosinase activity?

Albinism

What skin disorder is characterized by the degeneration and disappearance of entire melanocytes, resulting in patchy pigment loss?

Vitiligo

What is the primary function of Langerhans cells in the epidermis?

They are bone marrow-derived cells that bind, process, and present antigens to T lymphocytes.

Where are Merkel's cells located, and what is their suspected function?

They are present in the thick skin of palms and soles and may serve as sensory mechanoreceptors.

What are the two distinct layers of the dermis?

The papillary layer and the reticular layer.

What type of connective tissue identifies the papillary layer of the dermis?

Loose connective tissue

Which layer of the dermis is thicker and composed of irregular dense connective tissue, mainly Type I collagen?

The reticular layer

What is the principal glycosaminoglycan found in the dermis?

Dermatan sulfate

Do the effector nerves of the skin provide parasympathetic or sympathetic innervation?

Sympathetic innervation only (postganglionic fibers of the paravertebral chain).

What are the two arterial plexuses located in the skin?

The subpapillary plexus (between papillary and reticular layers) and the plexus located between the dermis and hypodermis.

Name three examples of capsulated sensory receptors in the skin.

Pacinian corpuscles, Ruffini ending, and Meissener's corpuscles.

What areas of the body are completely hairless?

Palms, soles, lips, glans penis, clitoris, and labia minora.

What is the terminal dilatation of the hair follicle called?

Hair bulb

What are the three stages of the hair growth cycle?

Anagen (growing), Catagen (intermediate), and Telogen (rest).

What is the typical duration of the anagen stage for scalp hair follicles?

$3$ to $5$ years

Which hair structure is responsible for pulling hair shafts to an erect position (goose bumps)?

Arrector pili muscle

What is the thickened basement membrane that separates the hair follicle from the dermis?

Glassy membrane

The nail plate arises from which structure?

The nail matrix

What is the technical name for the cuticle of the nail?

Eponychium

Where is the hyponychium located in relation to the nail?

It is the epidermal fold at the distal end of the nail plate where the nail becomes free of the nail bed.

Where are sebaceous glands NOT found?

In the glabrous skin of the palms and soles.

What is the oily substance produced by sebaceous glands?

Sebum

What are the two types of sweat glands in the skin?

Eccrine sweat glands and apocrine sweat glands.

Which type of sweat gland is the most effective means of temperature regulation in humans?

Eccrine sweat glands

Where are apocrine sweat glands largely confined to in the body?

The skin of the axillary and perineal regions.

Although called 'apocrine', what is the actual mode of secretion for these glands?

Merocrine secretion (exocytosis of apical secretory granules).

What are the three types of skin cancer?

Basal cell carcinoma, Squamous cell carcinoma, and Malignant melanoma.

Which skin cancer is the most common and least vicious?

Basal cell carcinoma

What criteria are used in the 'ABCD' rule for detecting Malignant melanoma?

Asymmetry, Border irregularity, Color (multiple), and Diameter ($>6\,mm$).

Which degree of burn involves damage to only the epidermis, causing redness and pain?

First-degree burn

What distinguishes a second-degree burn from a first-degree burn?

Damage to the epidermis and upper regions of the dermis, resulting in the appearance of blisters.

Why is there no initial pain in a third-degree burn?

The nerve endings in the skin are destroyed.

According to the 'Rule of 9’s', what percentage of second-degree burns would classify a burn as critical?

$$25\%$$