chapter 6: integumentary system
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Transcript of chapter 6: integumentary system
Chapter 6
Integumentary System
OrganAn organ consists of two or more types of tissues grouped together that perform a specialized task.
Integumentary System Includes the skin plus accessory structuresSkin is the largest organ in our body
Functions of skin include1. Forms protective coating
2. Retards water loss
3. Vitamin D synthesis
4. Temperature control
5. Houses sensory receptors
The skin is composed of 2 layers 1. Epidermis
2. Dermis
The subcutaneous layer (hypodermis) lies beneath the skin, but is not considered part of the skin.
EpidermisOutermost layer of skin
Stratified squamous epithelium
Outermost layers are keratinized
No direct blood supply – Receives nutrients by diffusion
There are five (5) layers of the epidermis: Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale
Stratum corneumIs the outermost layer of epidermisComposed of tightly packed dead cellsCells are keratinized
Keratin = water insoluble protein
Stratum basaleDeepest layer of epidermisCells are nourished by dermal blood vesselsSite of cell growth and divisionStratum Basal contains Melanocytes
Layers of the epidermis
MelanocytesSecrete melanin – pigment
Number of melanocytes is similar in all people
Darker skin from darker and larger melanin granules
Albinism – mutation resulting in no melanin production
Figure 6.4a A melanocyte with melanin granules
Figure 6.5 The red eyes and pale skin reflect the lack of melanin in albinism.
DermisDeeper layer of skinComposed of dense irregular connective tissueContains dermal papillaeBlood vessels and nervesHair folliclesSweat glands and Sebaceous glands
Figure 6.2 Section of skin
Sweat Glands - secrete sweat onto surface of the skinEccrine glands – respond to elevated temperaturesApocrine glands - anxiety, sexual arousal, and pain
Sebacous glandsAssociated with hair folliclesSecretes Sebum – oilKeeps hair and skin soft and waterproof
Subcutaneous layer (often called hypodermis)Subcutaneous layer – not part of skin
Comoposed of adipose tissue, areolar tissue, and blood vessels
The subcutaneous layer binds skin to underlying organs
Adipose insulates the body
End of Chapter 6