BLY 207 Chapter Notes - Chapter 4: Neoplasm, Mnemonic, Merocrine

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Published on 2 Mar 2017
School
USA
Department
Biology
Course
BLY 207
Professor
CHAPTER 4: INTEGUMENTARY SYSTEM
The integumentary system consists of the integument (skin) and its accessory structures
GENERAL FUNCTION OF THE SKIN
Protection the skin forms a barrier between the inside and outside of the body
Excretion the cells of our body need water to maintain their shape, size, and metabolic
activities
Maintenance of normal body temperature by means of dilation of blood vessels to
release heat and by constricting to conserve heat
Synthesis site of synthesis of the steroid vitamin D
Sensory input the skin is endowed with several sensory receptors for touch, pain,
pressure, and temperature
Immune response substances produced in keratinocytes of the epidermis help regulate
inflammation and immune responses
The skin is composed of the epidermis, dermis, hypodermis, and several accessory structures.
EPIDERMIS
The outer layer is called the epidermis and is often incorrectly referred to as dead skin
From the inside out, the layers of the epidermis are:
1. Stratum germinativum (basale) this is the basal (basement) layer
contains melanocytes, which are responsible to a large degree for the color
of a person’s skin
2. Stratum spinosum some of the cells in this layer continue to divide as they are
pushed towards the surface
3. Stratum granulosum the cells in this layer produce granules of a chemical that will
be converted into keratin, which is a waterproofing material for the skin.
4. Stratum lucidum this is a thin layer of dying cells found only in thick skin.
5. Stratum corneum this is the exterior layer and is about 25-30 cell rows thick
Langerhans cells are dendritic cells that initiate an immune response if a microorganism or
other foreign material invades the epidermis, and work to remove the material via
phagocytosis as well as present it on the cell surface
The epidermis is the sight of vitamin D production; ultraviolet radiation from the sunlight
converts a cholesterol-related steroid into vitamin D3 (cholecalciferol) The liver converts
vitamin D3 into the hormone calcitriol.
o Calcitriol is essential for normal calcium and phosphorus adsorption by the small
intestines
DERMIS
The dermis is composed of two layers:
o Papillary layer this is the superficial layer that contains capillaries that nourish the
epidermis
o Reticular layer this is the deep layer
Contains Fibroblasts which secrete collagen and elastic fibers
o Collagen fibers are strong and resistant to stretching
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