LESSON 5: INTEGUMENTARY SYSTEM LBBBIO7
FIRST TRIMESTER | 2025-2026
Skin composition
SYNCHRONOUS MEETING NOTES
Integumentary System
Essential Terms
● Hypodermis
○ Not considered part of the skin.
○ Serves as an anchorage.
○ Made of loose connective tissue (areolar +
adipose).
●
● Integument involves all of the skin and accessory
structures: hair, nails, muscles, and nerves.
● Skin is also called the cutaneous membrane.
● The subcutaneous membrane (hypodermis) is under the
skin.
○ Contains fats and muscles.
Introduction
● Dermis divided into 2 regions:
○ Papillary region (in contact with the stratum
basale/stratum germinativum).
■ Contains Meissner’s corpuscles (touch
receptors with afferent nerve endings).
○ Reticular region (major part of the dermis).
■ Contains reticular fibers, hair follicles,
sweat glands, sebaceous glands, and
arrector pili muscles.
● Skin is the largest organ of the body. ■ Hair follicle extends into the
● Regulates temperature through sweat glands. epidermis.
● Provides waterproofing via keratin released by ■ Hair shaft projects outward.
keratinocytes. ■ Sweat glands:
● Supplies sensory information through nerve endings ● Eccrine: more abundant.
found in the papillary layer of the dermis. ● Apocrine: less abundant,
● Excretes wastes through sweat glands, though minimally more oily.
(most liquid waste comes from kidneys). ■ Sebaceous glands connect to hair
● Produces vitamin D through UV activation of precursors follicles, releasing sebum to coat hair.
found near melanocytes. ■ Arrector pili muscles erect the hair
● UV protection depends on melanin pigment. shaft in fear/distress, causing
goosebumps.
LBBBIO7: Histology Laboratory LESSON 5 1
FIRST TRIMESTER | 2025-2026
Skin composition
SYNCHRONOUS MEETING NOTES
Integumentary System
Essential Terms
● Hypodermis
○ Not considered part of the skin.
○ Serves as an anchorage.
○ Made of loose connective tissue (areolar +
adipose).
●
● Integument involves all of the skin and accessory
structures: hair, nails, muscles, and nerves.
● Skin is also called the cutaneous membrane.
● The subcutaneous membrane (hypodermis) is under the
skin.
○ Contains fats and muscles.
Introduction
● Dermis divided into 2 regions:
○ Papillary region (in contact with the stratum
basale/stratum germinativum).
■ Contains Meissner’s corpuscles (touch
receptors with afferent nerve endings).
○ Reticular region (major part of the dermis).
■ Contains reticular fibers, hair follicles,
sweat glands, sebaceous glands, and
arrector pili muscles.
● Skin is the largest organ of the body. ■ Hair follicle extends into the
● Regulates temperature through sweat glands. epidermis.
● Provides waterproofing via keratin released by ■ Hair shaft projects outward.
keratinocytes. ■ Sweat glands:
● Supplies sensory information through nerve endings ● Eccrine: more abundant.
found in the papillary layer of the dermis. ● Apocrine: less abundant,
● Excretes wastes through sweat glands, though minimally more oily.
(most liquid waste comes from kidneys). ■ Sebaceous glands connect to hair
● Produces vitamin D through UV activation of precursors follicles, releasing sebum to coat hair.
found near melanocytes. ■ Arrector pili muscles erect the hair
● UV protection depends on melanin pigment. shaft in fear/distress, causing
goosebumps.
LBBBIO7: Histology Laboratory LESSON 5 1
