Anatomy LE 1: Connective TIssue and the Skin and its Appendages

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Questions and Answers

What is the primary function of plasma cells?

Forming connective tissue proper

Producing antibodies against antigens (correct)

Producing granules displaying metachromasia

Participating in diapedesis

What is the histologic appearance of plasma cells?

Large, ovoid cells with basophilic cytoplasm (correct)

Small, spherical cells with a large nucleus

Multinucleated cells with acidophilic cytoplasm

Fibroblast-like cells with pale cytoplasm

What is diapedesis?

The process of immune cells entering connective tissue (correct)

The process of immune cells leaving connective tissue

The process of immune cells differentiating into plasma cells

The process of immune cells undergoing apoptosis

What is the main function of myofibroblasts in wound healing?

Enhancing contractile function for wound closure Signup and view all the answers

What is the function of leukocytes?

To defend against antigens or antibodies Signup and view all the answers

What is the main function of macrophages in tissue repair?

Uptake or phagocytosis of cellular debris for presentation to immune cells Signup and view all the answers

Where are plasma cells mostly seen?

In lymphoid tissues and the lamina propria of the GI tract Signup and view all the answers

What is the characteristic arrangement of chromatin granules in plasma cells?

Alternating dark and light granules in a 'spokes of wheel' or 'clock face' appearance Signup and view all the answers

What is the histologic appearance of an active macrophage?

Eccentrically located, irregular surface Signup and view all the answers

What happens to leukocytes during inflammation?

They migrate between endothelial cells of venules to enter connective tissue Signup and view all the answers

What is the function of reticulin fibers in the liver?

Supporting hepatocytes and sinusoids Signup and view all the answers

What is the characteristic appearance of macrophage cytoplasm under light microscopy?

Foamy Signup and view all the answers

What is the lifespan of leukocytes?

Hours to days Signup and view all the answers

What is the main difference between a fibrocyte and a macrophage?

Shape: fibrocyte is spindle-shaped, macrophage is irregular Signup and view all the answers

What is the function of growth factors secreted by macrophages?

Activation of immune cells Signup and view all the answers

What is the role of myofibroblasts in tissue repair?

Enhancing contractile function for wound closure Signup and view all the answers

What is the result of excessive rubbing on the skin?

Protective thickening and hardening of outer cornified epidermal layers Signup and view all the answers

What is the main function of the stratum spinosum?

To actively synthesize keratins Signup and view all the answers

What is the characteristic of the cells in the stratum germinativum?

Central nuclei with prominent nucleoli Signup and view all the answers

What is the function of tonofibrils?

To hold cell layers together Signup and view all the answers

What happens to the cells in the stratum spinosum during fixation?

They shrink and develop intracellular spaces Signup and view all the answers

What is the difference between thick and thin skin?

Thick skin has more tonofibrils and desmosomes Signup and view all the answers

What is the result of friction blisters?

Lymph-filled spaces between epidermis and dermis of thin skin Signup and view all the answers

What is the characteristic of the stratum spinosum in thick skin?

Thicker with more tonofibrils and desmosomes Signup and view all the answers

What type of muscle is attached to the hair follicle just below the sebaceous gland?

Smooth muscle Signup and view all the answers

What is the main function of the arrector pili muscle?

To pull the hair shaft to a more erect position Signup and view all the answers

What is the structure at the base of the hair follicle?

Hair bulb Signup and view all the answers

What is the function of the dermal papilla in hair growth?

To provide nutrition to the root sheath Signup and view all the answers

What is the longest phase of hair growth?

Anagen Signup and view all the answers

Which of the following skin regions does not have hair?

Skin of the palms Signup and view all the answers

What is the process by which hair acquires melanin pigments?

Melanin accumulation Signup and view all the answers

What is the origin of skin appendages?

Ectodermal Signup and view all the answers

What is the primary characteristic of cutis laxa?

Reduced skin elasticity Signup and view all the answers

What is the term for the condition characterized by skin depigmentation?

Vitiligo Signup and view all the answers

What is the appearance of the skin in cutis laxa?

Loose and inelastic Signup and view all the answers

What is the cause of skin depigmentation in vitiligo?

Absence of melanocytes Signup and view all the answers

What is the characteristic histologic appearance of vitiligo?

Absence of melanocytes at the basal cell layer Signup and view all the answers

What is the term for the degradation of elastin fibers?

Elastolysis Signup and view all the answers

What is the characteristic appearance of individuals with cutis laxa?

Aged appearance Signup and view all the answers

What is the name of the condition characterized by loose inelastic hanging folds of skin?

Cutis laxa Signup and view all the answers

What is the underlying cause of cutis laxa?

Abnormal elastin metabolism Signup and view all the answers

What is the typical appearance of the skin in vitiligo?

Depigmented patches Signup and view all the answers

Study Notes

Connective Tissue Proper

Myofibroblasts are a type of fibroblast involved in wound healing with well-developed contractile function, enriched with actin.

Macrophages

Main function: uptake or phagocytosis of cellular debris for presentation to immune cells
Turnover of protein fibers and removal of apoptotic cells, tissue debris, or other materials abundant at sites of inflammation
Secrete growth factors for tissue repair and lymphocyte activation via antigens
Histologic appearance: active macrophage has an irregular surface, eccentrically located, oval or kidney-shaped nucleus, deeply stained, and surrounded by lysosomal granules in the cytoplasm, which appears foamy under light microscopy.

Mast Cells

Types of connective tissue proper
Histologic appearance: spindle-shaped
Display metachromasia when stained with toluidine blue

Plasma Cells

Antibody-producing cells that arise from lymphocytes
Migrate back to lymphoid organs after performing immune activity in the connective tissue
Mostly seen in lymphoid tissues and the lamina propria of the gastrointestinal (GI) tract
Histologic appearance: large, ovoid cells with basophilic cytoplasm and a spherical, eccentrically located nucleus containing alternating dark heterochromatin granules and light euchromatin granules arranged in a “spokes of wheel” or “clock face” appearance.

Leukocytes

White Blood Cells (WBCs) include: Neutrophils, Eosinophils, Basophils, Monocytes, and Lymphocytes
Migrate between the endothelial cells of venules to enter connective tissue via diapedesis
First line of defense against antigens or antibodies that have invaded the CT
Short-lived (hours-days), must be replaced continually via apoptosis.

Skin Appendages

Hair follicles, sweat and sebaceous glands, arrector pili muscles
Derived from the epidermis
During development, grow into and reside within the dermis surrounded by connective tissue
Embryonic origin: Ectodermal

Hair Pilosebaceous Unit

Consists of: hair follicle, sebaceous gland, arrector pili muscle
Arrector pili muscle contracts, causing hair strands to become erect (goosebumps) to trap warm air next to the skin.

Hair Bulb

Found at the base of the hair follicle
Also known as the “terminal dilation of the growing hair follicle”
Composed of keratinocytes similar to the spinous and basal layer
Divide rapidly and undergo keratinization, melanin accumulation, and terminal differentiation.

Hair Growth Process

Keratinization
Melanin accumulation
Terminal differentiation
Phases: anagen (long period of mitotic activity and growth), catagen (brief period of arrested growth and regression of hair bulb), and telogen (final long period of inactivity where hair may shed).

Thin Skin

Found in most areas of the body
Histologic appearance: stratum spinosum (spinous layer) with cytoplasm consisting of packed keratin filaments.

Friction Blisters

Lymph-filled spaces between epidermis and dermis of thick skin due to excessive rubbing
Can lead to protective thickening and hardening of outer cornified epidermal layers, forming corns and calluses.

Stratum Spinosum (Spinous Layer)

Thickest layer
Main function: actively synthesizing keratins (above basal layer)
Cells in this layer have cytoplasmic projections called tonofibrils, which terminate at desmosomes and function to hold cell layers together.

Cutis Laxa (Elastolysis)

Abnormal elastin metabolism leading to reduced skin elasticity
Degenerative, rare, inherited or acquired CT disorder
Characterized by loose, inelastic hanging folds of skin around the face and neck, giving a "bloodhound appearance".

Vitiligo

Skin depigmentation due to loss or decreased activity of melanocytes or absence of melanocytes in the epidermis
Discolored/depigmented patches in different areas of the body, hair, and mucous membranes
Histologic appearance: lacks melanocytes at the basal cell layer.

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