BIO 271 Exam 4 Study
Guide
I. Skin Structure
Components of the Integumentary System: List the epidermis, dermis, and hypodermis
(subcutaneous layer).
Functions of the Integumentary System: Describe protection (physical barrier, UV radiation,
dehydration, infection), sensation (touch, pressure, temperature, pain), thermoregulation
(sweating, vasodilation/vasoconstriction), vitamin D synthesis, and excretion of small amounts of
wastes.
Skin and Body Temperature Regulation: Explain how vasodilation of dermal blood vessels
releases heat and vasoconstriction conserves heat. Describe the role of sweat glands in
evaporative cooling.
Epidermal Features and Cells:Keratin: A tough, fibrous protein that provides structural
strength and waterproofing to the skin. Found throughout the epidermis.
Dying Keratinocytes: Cells in the stratum granulosum and stratum corneum undergoing
apoptosis; they are filled with keratin and contribute to the epidermal water barrier and protection.
Live Keratinocytes: The majority of cells in the stratum spinosum and stratum basale, actively
producing keratin.
, Dendritic Cells (Langerhans cells): Immune cells located in the stratum spinosum that
phagocytize pathogens and alert the immune system.
Tactile Cells (Merkel cells): Sensory receptors located in the stratum basale that detect light
touch and pressure.
Melanocytes: Cells located in the stratum basale that produce melanin.
Epidermal Water Barrier: Formed by tight junctions between keratinocytes and the lipids
released from lamellar granules in the stratum granulosum, preventing water loss.
Function of Melanin: Describe how melanin pigment absorbs UV radiation, protecting DNA
from damage. Explain how the amount and type of melanin contribute to different skin colors.
Dermis and Hypodermis:Papillary Layer (Dermis): Superficial layer composed of areolar
connective tissue; provides nutrients to the epidermis and contains dermal papillae that interlock
with epidermal ridges.
Reticular Layer (Dermis): Deeper layer composed of dense irregular connective tissue; contains
collagen and elastic fibers for strength and elasticity, as well as blood vessels, nerves, hair
follicles, and glands.
Hypodermis (Subcutaneous Layer): Located below the dermis, composed primarily of adipose
tissue and some areolar connective tissue; stores fat for insulation and cushioning, and anchors
the skin to underlying structures.
Dermal Conditions and Skin Color:Cyanosis: Bluish discoloration of the skin due to a
deficiency of oxygen in the blood; visible in the dermis.
Erythema: Abnormal redness of the skin due to increased blood flow in the dermis, such as
during inflammation, exercise, or fever.
Pallor: Paleness of the skin due to reduced blood flow in the dermis, which can result from
shock, anemia, or stress.
Jaundice: Yellowish discoloration of the skin and sclera (whites of the eyes) due to the buildup
of bilirubin in the blood; affects the appearance of the dermis.
Guide
I. Skin Structure
Components of the Integumentary System: List the epidermis, dermis, and hypodermis
(subcutaneous layer).
Functions of the Integumentary System: Describe protection (physical barrier, UV radiation,
dehydration, infection), sensation (touch, pressure, temperature, pain), thermoregulation
(sweating, vasodilation/vasoconstriction), vitamin D synthesis, and excretion of small amounts of
wastes.
Skin and Body Temperature Regulation: Explain how vasodilation of dermal blood vessels
releases heat and vasoconstriction conserves heat. Describe the role of sweat glands in
evaporative cooling.
Epidermal Features and Cells:Keratin: A tough, fibrous protein that provides structural
strength and waterproofing to the skin. Found throughout the epidermis.
Dying Keratinocytes: Cells in the stratum granulosum and stratum corneum undergoing
apoptosis; they are filled with keratin and contribute to the epidermal water barrier and protection.
Live Keratinocytes: The majority of cells in the stratum spinosum and stratum basale, actively
producing keratin.
, Dendritic Cells (Langerhans cells): Immune cells located in the stratum spinosum that
phagocytize pathogens and alert the immune system.
Tactile Cells (Merkel cells): Sensory receptors located in the stratum basale that detect light
touch and pressure.
Melanocytes: Cells located in the stratum basale that produce melanin.
Epidermal Water Barrier: Formed by tight junctions between keratinocytes and the lipids
released from lamellar granules in the stratum granulosum, preventing water loss.
Function of Melanin: Describe how melanin pigment absorbs UV radiation, protecting DNA
from damage. Explain how the amount and type of melanin contribute to different skin colors.
Dermis and Hypodermis:Papillary Layer (Dermis): Superficial layer composed of areolar
connective tissue; provides nutrients to the epidermis and contains dermal papillae that interlock
with epidermal ridges.
Reticular Layer (Dermis): Deeper layer composed of dense irregular connective tissue; contains
collagen and elastic fibers for strength and elasticity, as well as blood vessels, nerves, hair
follicles, and glands.
Hypodermis (Subcutaneous Layer): Located below the dermis, composed primarily of adipose
tissue and some areolar connective tissue; stores fat for insulation and cushioning, and anchors
the skin to underlying structures.
Dermal Conditions and Skin Color:Cyanosis: Bluish discoloration of the skin due to a
deficiency of oxygen in the blood; visible in the dermis.
Erythema: Abnormal redness of the skin due to increased blood flow in the dermis, such as
during inflammation, exercise, or fever.
Pallor: Paleness of the skin due to reduced blood flow in the dermis, which can result from
shock, anemia, or stress.
Jaundice: Yellowish discoloration of the skin and sclera (whites of the eyes) due to the buildup
of bilirubin in the blood; affects the appearance of the dermis.
