University:
Kentucky State University
Course:
BIO 301 | Human Anatomy
Academic year:

2019
Views:

363

Pages:

32
Author:

Madelyn Bradshaw

Ski n o Skin covers the outer surface of the .body and is the largest organ o Skin and its accessory structures hair, sweat glands, sebaceous( glands, and nails) make up .the integumentary system o Its primary functions are to protect the body from the environment and .prevent water loss Layers of skin o :Skin consists of two layers .1 Epidermis: outer layer of stratified .squamous keratinized epithelium .2 ,Dermis: underlying layer of dense irregular CT that contains other structures .)such as hair follicles and sweat glands( o Dermal papillae: At the irregular junction between the dermis and epidermis, these projections interdigitate with invaginating epidermal ridges to strengthen adhesion of .the two layers Hypodermi s o Deep to the dermis the hypodermis/subcutaneous is a layer of varying thickness of,layer loose and adipose CT .tissue o The hypodermis/subcutaneous binds the skin loosely to layer underlying tissues andthe corresponds the superficial fascia of to anatomy gross . Sheet note #1 • Skin is the largest organ in our body. • Another function of skin is to regulate body temperature. • The junction between the Epidermis layer and the dermis layer is like the junction between the cardiac muscles. • Hypodermis/ subcutaneous layer is not considered part of skin it’s under the skin . • ( hypo,sub means :under). • Hypodermis a layer of loose CT and adipose tissue( white fat). Epidermi s The epidermis consists mainly • a stratified squamous keratinized of • epithelium composed of cells • .keratinocytes called • There are also three much less epidermal cell abundant • :types pigment producing Melanocytes: in stratum( cells • Langerhans .)basale cells: identical tissue macrophages to (in )spinosum stratum • Merkel .cells: tactile epithelial cells stratum (in .)basale Sheet note #2 • Most of the cells in the Epidermis are keratinocytes because they produce keratin protein. • Keratinocytes are the most abundant epidermal cells. • Markel cells are considered mechanoreceptors ( a receptor responsible for sensation of gentle touch). • Langerhans cells are also found as resident fixed cells in connective tissue. epidermis Melanocytes between basal keratinocytes dermis Basal cells Melanocytes This slide is very important Epidermi L sayers of keratinocytes Sheet note #4 >> Keratinocytes is named with this name because it synthesize keratin , it is synthesized in a particular process Gradually until the cells in apical layer become fully differentiation ( for keratin ) . >> the number of layers of epidermis differ according to type of skin. >> stratum : it means layer‫طبقة‬ Stratum basale : Blue coloured cells : merkel cells brouwn coloured cells : melanocyte cells Stratum spinosum : there are extensions between cells (like spines) , this is why it named with this name. Stratum granulosum : Kerato-hyaline granules = dark basophilic granules. Stratum lucidum : Not found in all types of skin , only found in thick skin. Stratum corneum : Fixed layer in all layers of epidermis , in the previous lectures we used to call it “keratin layer” . Anucleate = dead cells. Types of ski n o Skin is classified into two types (epidermis forms the major distinction between thick & thin :)skin skin 5>( .1 :Thick (hairless) mm) covers the palms of the hands and the soles of .the feet .2 Thin (hairy) skin: (1-4mm) covers the rest of the body . Sheet note #5 >> Skin is classified into thick & thin skin according to two criterea : 1- thickness of epidermis (number of its layers). 2- presence of hair. Two places in our bodies are hairless : - palms of the hand & soles of the feet … and are considered thick skin because thy are hairless & thickness of epidermis is more than 5 mm . Sebaceous gland & arrector pilli muscle are NOT present in thick hairless skin . Sweat gland is present in the two types of skin  Please check the picture in the previous slide carefully. Layers of epidermi s Epidermis: stratified squamous keratinized epithelium divided into five strata (or :)layers .1 .2 .3 .4 .5 Stratum Corneum Stratum Lucidum: highly refractive zone only seen in thick Stratum Granulosum .)skin Stratum Spinosum Stratum Basale 4 layers of epidermis 5 layers of epidermis Stratum Spinosum Dermis Dermis is connective tissue that supports the :epidermis. It consists of two layers .1 Papillary layer: more superficial layer of dermis; composed of areolar CT; forms dermal papillae; contains subpapillary .vascular plexus .2 ;Reticular layer: deeper layer of dermis composed of dense irregular CT surrounding hair follicles, sebaceous glands and sweat glands, nerves, and deep plexus of blood vessels extending .into subcutaneous layer Sheet note #7 .Dermis consist of superficial layer and deep layer ● Superficial is papillary , and it loose Connective tissue and we call it papillary ● .dermis Most of the dermis layer is dense irregular Connective tissue with a little bit of loose ● .CT in papillary dermis The section(Dermis) in picture is thin skin because doesn’t have sebaceous glands ● .and hair follicles .Epidermis thin skin because no stratum lucidum ● Sebaceous gland, sweat glands, and hair follicles Sheet note #8 .hair follicles related with sebaceous glands ● .the white color is fat tissue ● .the section is thin skin ● Sebaceous glands, sweat glands, arrector pili muscle, and hair follicles Sheet note #9 .the section is thin skin because it contains hair follicles ● Skin is classified into thick & thin according to number of layers • Body Membrane s • Body membranes •Thin sheets of tissue that cover the body, line .a cavity or cover a part of the body (organs) •:Two main categories of body membranes are .1 Epithelial membranes .2 .Connective tissue membranes Sheet note #10 Epithelial Membranes •Consist of epithelial tissue and the underlying connective tissue. The main types :of epithelial membranes are Mucous .1 lineMembranes the body cavities that open to the outside. Epithelial cells form a barrier to microbes and tight • between the cells prevent simple diffusion of most substances. Mucous is secreted from underlying glands to junctions surface moist. These membranes also called mucosae (epithelial tissue + lamina propria). Lining keep respiratory, and reproductive ,digestive .tracts Serous .2 Membranes Consist of 2 layers ( every single layer consists of epithelial tissue + loose CT): 1) parietal layer lines body • that do not open directly to the outside, 2) visceral layer which covers the organs located in thosecavities Between the 2 layers there is a thin layer of serous fluid that is secreted by mesothelial cells. Serous fluid .cavities the membrane and reduces friction and abrasion when organs move against each other or the cavity lubricates Examples: pleura, peritoneum and .wall .pericardium Cutaneous membrane .3 • (skin)and consist of epidermis and cover body surface dermis Sheet note #11 Mucous membrane Line open body cavities. Open to the outside of the body, ex: Respiratory tract, digestive tract, urinary/ reproductive tract, ear/eyes. don't forget that each of the membranes consist of epithelial tissue and underlying connective tissue . Mucous, produced by glands called goblet cells, covers the membrane. A serous membrane is an epithelial membrane that lines the closed cavities of the body, that is, those cavities that do not open to the outside. Sheet note #12 Serous membranes Sheet note #13 this picture represented a respiratory tract why? because we have the goblet cells and pseudostratified columnar ciliated epithelium Connective Tissue Membranes • contain only connective tissue. Synovial membranes and meninges belong to this .category Synovial Membranes line the cavities of the freely movable joints such as the shoulder, elbow, and knee. Like • membranes, they line cavities that do not open to the outside. Unlike serous membranes, serousthey do have a layer of epithelium. The superficial regions are usually well vascularized. Synovial not secrete synovial fluid into the joint cavity, and this reducing friction on all internal surfaces, and membranes nutrients and oxygen to the articular supplies .cartilage Meninges The connective tissue covering on the brain and spinal cord, are called meninges. They provide • for these vital protection .structures Sheet note #14 membrane Synovial line the capsule that surround and movable joint. >> synovial membrane which is connective tissue and line The Joint cavity and line the inner capsule which is consist of collagen type 1 ,so have the white color. >> the synovial fluid a nutrient nutrition the hyaline cartilage. >> Well vascularized which means I have a lot of blood vessels. >> any close cavity line by the serous membrane or synovial membrane but the synovial membrane being around the movable joint. examples which cavity surrounded by synovial membrane ? a. Ankle joint b. Epidedeims c. Esophagus d. trachea. Ans : ankle joint Synovial membrane Meninge s Sheet note #15 Meninges refer to the membranous coverings of the brain and spinal cord. There are three layers of meninges, known as the dura mater, arachnoid mater and pia mater. These coverings have two major functions: Provide a supportive framework for the cerebral.

Histology of Skin

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