BIOL251 Human Anatomy & Physiology I
w/Lab 2025 | Module 7 Exam Review
|70+ Questions and Answers
**1. What are the two principal layers of the skin?**
- **Answer:** The epidermis and the dermis.
- **Rationale:** The skin is composed of the superficial epidermis
(epithelial tissue) and the deeper dermis (connective tissue). The
hypodermis (subcutaneous layer) lies beneath but is technically not
part of the skin.
**2. Which specific layer of the epidermis is the site of active cell
division and contains melanocytes?**
- **Answer:** Stratum basale (also known as stratum germinativum).
- **Rationale:** The stratum basale is the deepest epidermal layer. It is
constantly dividing to produce new keratinocytes and contains
melanocytes that produce melanin.
**3. Name the tough, fibrous protein that gives the epidermis its
protective properties.**
- **Answer:** Keratin.
- **Rationale:** As keratinocytes mature and move toward the skin
surface, they fill with keratin, a waterproof protein that provides
structural strength and protection against abrasion and water loss.
,**4. Which layer of the skin contains blood vessels, nerves, and
glands?**
- **Answer:** Dermis.
- **Rationale:** The dermis is the vascularized, living layer of skin. It
contains the blood supply, sensory nerve endings, hair follicles, and
glands (sweat and sebaceous).
**5. What type of tissue primarily makes up the reticular layer of the
dermis?**
- **Answer:** Dense irregular connective tissue.
- **Rationale:** This layer contains densely packed collagen and elastin
fibers arranged in a mesh-like pattern, providing the skin with strength
and elasticity.
**6. Explain the function of the arrector pili muscle.**
- **Answer:** It is a smooth muscle that contracts to pull the hair
follicle upright, causing "goosebumps" (piloerection).
- **Rationale:** This involuntary contraction occurs in response to cold
or fear. In animals with thick fur, this traps air for insulation. In humans,
it is a vestigial reflex.
**7. Identify the two main types of sweat glands and describe their
primary functions.**
- **Answer:** Eccrine (merocrine) glands and apocrine glands.
, - **Rationale:** Eccrine glands are found all over the body and secrete
a watery sweat for thermoregulation. Apocrine glands are found in
axillary and genital areas and secrete a thicker, odorless fluid that
develops an odor when broken down by bacteria.
**8. Which gland secretes an oily substance called sebum, and what is
its purpose?**
- **Answer:** Sebaceous (oil) glands. Sebum lubricates and
waterproofs the skin and hair, and has antibacterial properties.
- **Rationale:** Sebum helps prevent the skin from becoming dry and
brittle and inhibits the growth of some bacteria.
**9. What are the three main pigments that contribute to skin color?**
- **Answer:** Melanin, carotene, and hemoglobin.
- **Rationale:** Melanin (brown/black/yellow) is produced by
melanocytes. Carotene (yellow-orange) is from diet. Hemoglobin
(red/pink) is the oxygen-carrying pigment in red blood cells visible in
fair skin.
**10. What is the function of melanin?**
- **Answer:** To absorb and scatter ultraviolet (UV) radiation,
protecting the DNA of skin cells from damage.
- **Rationale:** UV radiation can cause mutations leading to skin
cancer. Melanin acts as a natural sunscreen to mitigate this damage.
w/Lab 2025 | Module 7 Exam Review
|70+ Questions and Answers
**1. What are the two principal layers of the skin?**
- **Answer:** The epidermis and the dermis.
- **Rationale:** The skin is composed of the superficial epidermis
(epithelial tissue) and the deeper dermis (connective tissue). The
hypodermis (subcutaneous layer) lies beneath but is technically not
part of the skin.
**2. Which specific layer of the epidermis is the site of active cell
division and contains melanocytes?**
- **Answer:** Stratum basale (also known as stratum germinativum).
- **Rationale:** The stratum basale is the deepest epidermal layer. It is
constantly dividing to produce new keratinocytes and contains
melanocytes that produce melanin.
**3. Name the tough, fibrous protein that gives the epidermis its
protective properties.**
- **Answer:** Keratin.
- **Rationale:** As keratinocytes mature and move toward the skin
surface, they fill with keratin, a waterproof protein that provides
structural strength and protection against abrasion and water loss.
,**4. Which layer of the skin contains blood vessels, nerves, and
glands?**
- **Answer:** Dermis.
- **Rationale:** The dermis is the vascularized, living layer of skin. It
contains the blood supply, sensory nerve endings, hair follicles, and
glands (sweat and sebaceous).
**5. What type of tissue primarily makes up the reticular layer of the
dermis?**
- **Answer:** Dense irregular connective tissue.
- **Rationale:** This layer contains densely packed collagen and elastin
fibers arranged in a mesh-like pattern, providing the skin with strength
and elasticity.
**6. Explain the function of the arrector pili muscle.**
- **Answer:** It is a smooth muscle that contracts to pull the hair
follicle upright, causing "goosebumps" (piloerection).
- **Rationale:** This involuntary contraction occurs in response to cold
or fear. In animals with thick fur, this traps air for insulation. In humans,
it is a vestigial reflex.
**7. Identify the two main types of sweat glands and describe their
primary functions.**
- **Answer:** Eccrine (merocrine) glands and apocrine glands.
, - **Rationale:** Eccrine glands are found all over the body and secrete
a watery sweat for thermoregulation. Apocrine glands are found in
axillary and genital areas and secrete a thicker, odorless fluid that
develops an odor when broken down by bacteria.
**8. Which gland secretes an oily substance called sebum, and what is
its purpose?**
- **Answer:** Sebaceous (oil) glands. Sebum lubricates and
waterproofs the skin and hair, and has antibacterial properties.
- **Rationale:** Sebum helps prevent the skin from becoming dry and
brittle and inhibits the growth of some bacteria.
**9. What are the three main pigments that contribute to skin color?**
- **Answer:** Melanin, carotene, and hemoglobin.
- **Rationale:** Melanin (brown/black/yellow) is produced by
melanocytes. Carotene (yellow-orange) is from diet. Hemoglobin
(red/pink) is the oxygen-carrying pigment in red blood cells visible in
fair skin.
**10. What is the function of melanin?**
- **Answer:** To absorb and scatter ultraviolet (UV) radiation,
protecting the DNA of skin cells from damage.
- **Rationale:** UV radiation can cause mutations leading to skin
cancer. Melanin acts as a natural sunscreen to mitigate this damage.
