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Integumentary System Overview and Functions
Sep 6, 2024
BSC 2085: Anatomy and Physiology 1
Lecture on the Integumentary System
Introduction
Instructor
: Professor Mariah Evans
Focus
: Skin and bones for the next exam.
Overview of the Integumentary System
Includes skin, hair, and nails.
Involves sweat glands and sebaceous glands.
Structure of Skin
Two Main Regions
:
Epidermis
: Superficial layer.
Dermis
: Underlying layer.
Hypodermis
: Beneath the skin, not a true skin layer but shares components.
Layers of the Epidermis
Thick Skin
: 5 layers.
Thin Skin
: 4 layers.
Layers (from deep to superficial)
:
Stratum Basale
: Actively mitotic, basal layer.
Stratum Spinosum
: Prickly layer with spiny keratinocytes.
Stratum Granulosum
: Granular layer with keratohyalin granules.
Stratum Lucidum
: Clear layer, only in thick skin.
Stratum Corneum
: Horny layer, 20-30 layers of dead cells.
Cells in the Epidermis
Keratinocytes
: Contain keratin.
Melanocytes
: Produce melanin for skin color.
Dendritic (Langerhans) Cells
: Immune function, phagocytize invaders.
Tactile (Merkel) Cells
: Sensory receptors for touch.
Dermis
Layers
:
Papillary Layer
: Areolar connective tissue, tactile corpuscles.
Reticular Layer
: Dense irregular connective tissue, collagen fibers.
Contains blood vessels and nerve fibers.
Skin Color
Melanin
: Pigment protein for skin, eye, and hair color.
Carotene
: Yellow-to-orange pigment.
Hemoglobin
: Pinkish hue in fair-skinned individuals.
Sun Exposure and Skin Damage
UV damages DNA, can lead to cancer.
Destroys folic acid, necessary for DNA synthesis.
Photosensitivity from drugs (antibiotics, antihistamines).
Abnormal Skin Colors
Cyanosis
: Blue skin, lack of oxygen.
Erythema
: Redness from various causes.
Pallor
: Pale skin, can indicate anemia or fear.
Jaundice
: Yellow skin, often due to liver issues.
Bronzing
: Indicative of steroid hormone imbalance.
Bruises
: Blood clots under the skin.
Hair
Functions: Sensory, protection, heat retention.
Structure: Keratinized, color from melanin.
Hair growth cycles and thinning with age.
Alopecia
: Hair loss.
Hirsutism
: Excessive hair growth.
Nails
Made of hard keratin.
Fingernails have free edges without nerve endings.
Glands
Sweat Glands
: Eccrine (most numerous), Apocrine (axillary/anogenital).
Sebaceous (Oil) Glands
: Secrete sebum, lubricate skin and hair, can lead to acne.
Functions of Skin
Protection
: Physical, chemical, and biological barriers.
Body Temperature Regulation
: Sweating and blood flow.
Cutaneous Sensations
: Sensory receptors for touch.
Metabolic Functions
: Vitamin D synthesis.
Blood Reservoir
: Holds 5% of blood volume.
Excretion
: Nitrogenous wastes through sweat.
Skin Cancer and Burns
Types of Skin Cancer
: Basal cell carcinoma, squamous cell carcinoma, malignant melanoma (most deadly).
Burns
:
First Degree
: Epidermal damage.
Second Degree
: Affects dermis, blistering.
Third Degree
: Full thickness, requires grafting.
Conclusion
Review of integumentary system structures and functions.
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