Human Physiology: Integumentary System

Which cell type produces melanin?

• Keratinocyte

• Carotene

• Melanocyte

• Langerhans

Answer explanation

Melanocytes are the specialized cells responsible for producing melanin, the pigment that gives color to skin, hair, and eyes. Keratinocytes are involved in skin structure, while Langerhans cells are part of the immune system.

Which factor determines the amount of melanin activity in an area?

• The length of melanocyte tentacles and the number of keratinocytes

• The number of melanocytes

• Hemoglobin levels

• The length of melanocyte tentacles only

Answer explanation

The amount of melanin activity is influenced by both the length of melanocyte tentacles, which help transfer melanin, and the number of keratinocytes, which receive the melanin. Thus, the correct choice is the length of melanocyte tentacles and the number of keratinocytes.

An individual has a lighter skin tone, while another individual has a darker skin tone. Which statement below best describes the reason?

• The darker skin tone has more melanocytes

• The lighter skin tone has fewer keratinocytes

• The darker skin tone has more active melanocytes

• The lighter skin tone has more hemoglobin

Answer explanation

The darker skin tone is primarily due to more active melanocytes, which produce more melanin, leading to increased pigmentation. This is why individuals with darker skin have a richer color compared to those with lighter skin.

Wound repair can be compared to repairing a home. Which phase of the healing process is similar to containing a burst pipe?

• Proliferative

• Remodeling

• Hemostasis

• Inflammation

Answer explanation

Hemostasis is the phase where the body stops bleeding, similar to containing a burst pipe to prevent further damage. This initial response is crucial before the healing process can continue.

What is the primary purpose of a fibrin clot?

• To reduce the appearance of a scar over time

• To phagocytize bacteria

• To call other cells to the wound site

• To seal broken capillaries and prevent infection

Answer explanation

The primary purpose of a fibrin clot is to seal broken capillaries and prevent infection. It forms a barrier that protects the wound site, allowing healing to occur while minimizing the risk of pathogens entering the body.

Growth factors are responsible for calling additional cells to a wound. Which types of cells might respond to the growth factors?

• Fibroblasts and melanocytes

• Connective tissue cells

• Epithelial and muscle cells

• Neutrophils and macrophages

Answer explanation

Neutrophils and macrophages are key responders to growth factors during wound healing, as they play crucial roles in inflammation and tissue repair by clearing debris and fighting infection.

How long does the inflammatory phase last?

• One to four days after the injury

• Two to three weeks after the injury

• A month after the injury

• Years after the injury

Answer explanation

The inflammatory phase typically lasts from one to four days after an injury, during which the body initiates healing processes and responds to tissue damage.

Which option below mainly contributes to scar formation?

• Excess collagen and buildup

• Poor diet and exercise

• Excess melanocyte activity

• Redness from inflammation

Answer explanation

Excess collagen and buildup primarily contribute to scar formation as the body produces more collagen during the healing process, leading to thickened and raised scars. Other options do not directly cause scar tissue.

What produces a yellow/orange hue in the skin?

• Low hemoglobin

• High melanin

• High carotene

• Low melanin

Answer explanation

High carotene levels in the skin can lead to a yellow/orange hue, as carotene is a pigment found in many fruits and vegetables. This is distinct from melanin, which affects skin color differently.

What produces a pale grey/blue hue in the skin?

• High carotene

• Low hemoglobin

• High melanin

• Low melanin

Answer explanation

A pale grey/blue hue in the skin is typically caused by low hemoglobin levels, which reduce the blood's red color, leading to a bluish appearance. High carotene and melanin levels do not produce this effect.