Structure And Function Of Normal Skin

Question 1

Describe the epidermis ( external skin surface) layer

Answer 1

5 layers:

• stratum corneum: superficial layer of dead skin cells, shed daily, outermost layer, outer covering of the skin..like the bark of a tree
• stratum lucidum: clear layer of cells, only present in thick skin
• stratum granulosum: granular layer, 1-5 cells thick, aids in keratin Formation
• stratum spinous: spiny layer, several layers thick, cells begin to produce keratin and begin to flatten
• stratum germinativum: granular layer cells undergo mitosis to form new cells, provides support and facilitation of fluid and cell exchange between skin layers
• thickness is 0.1cm
• avascular
• function is a barrier to substance, micro organisms, prevents water loss, repels water

Question 2

Cells of the epidermis

Answer 2

Keratinocytes: manufacture keratin, which is a protein responsible for the toughness of the skin

Dermosomes: specialized structures which bind adjacent keratinocytes to one another

Melanocytes: produce and distribute melanin who’s purpose is to protect the body ny absorbing harmful UV Rays, it darkens when doing so producing pigmentation

Langerhans cells: active in the capture, first line of defense against environmental allergens

Basement membrane: where the dermis and epidermis meet, causes skin tears as we get older due to flattening out of this area.

Question 3

Describe the Dermis layer

Answer 3

• supports and nourishes the epidermis
• thick, dense, fibroelastic, connective tissue
• highly vascularized
• contains: nerves, sweat glands, sebaceous glands, hair follicles
• made up of gel like matrix, made up of sugars and proteins(collagen and elastin)
• function to provide a framework (scaffold) for cells, regulates cellular function, lubricates cells and provides a transport system for nutrients and waste products

Question 4

Cells of the Dermis

Answer 4

Macrophages: scavenger cells, eat dead tissue and cells, repair dead injured tissue, acts a defense mechanisms

Mast cells: contain heparin and histamine, provides defense mechanism such as clotting during injury

Fibroblast: cells fro which connective tissue is developed, produces collagen which is the protein that gives the skin tensile strength and elastin which is the protein that provides the skin with its elastic recoil

Nerves: convey I for,action about heat, cold, pain, touch, itch and pressure

Langerhans cells: first line of defense, found in the dermis and epidermis

Function: nourish the epidermis, protect against mechanical injury, protect against microorganism, senses the environment, thermoregulation

Question 5

What subcutaneous tissue?

Answer 5

Loose connective tissue lying under the dermis, bi dos the skin loosely to subjacent tissue, contains adipose tissue

Function: channels nutrients and oxygen to the dermis via capillaries that have branched out from arteries

Question 6

What is fascia?

Answer 6

White shirt sheath like covering for the muscles, nerves and. Look vessels, keeps the muscles tight so they can act as a single unit

Non viable fascia is grayish in color

Question 7

What are muscles?

Answer 7

Dull red in color, striated, contractile

Non viable muscle turns grey

Skeletal muscle type we can see and feel, attach to the skeleton

650 muscles

Question 8

What are bones?

Answer 8

206 bones
Support
Bone marrow, makes and stores blood cells
Periosteum, layer of dense connective tissue that surrounds most bones, turns brown if damaged

Question 9

What are ligaments?

Answer 9

Band or sheet of string fibrous connective tissue, connects 2 or more Bones or cartilage together

Facilitate motion, limit motion, add support

Question 10

What is cartilage

Answer 10

Thin layer of tough tissue, covers ends of bones where they meet at the joint , allowing bones to slide over one another, shock absorber

Very white, shiny, poor vascular flow

Question 11

What are tendons

Answer 11

Yellow or white attaches muscle to bone, strong fibrous tissue

Question 12

Arteries? Veins? RBC, WBC, PLATELETS.

Answer 12

Pg 11

Question 13

Describe functions of skin

Answer 13

• Protection from bacterial invasion against external elements like water, chemical, bacterial and viral, ultraviolet radiation
• prevents excessive loss of fluids & electrolytes, strive for homeostasis
• produces sebum, lipid rich oily substance secreted by sebaceous glands, keeps PH 4-5.5 slightly acidic inhibits growth of harmful bacteria and fungi, helps form the acid mantle which is a protective layer
• melanin, protects from UV Rays, su. Exposure increases melanin production to help,protect, levels of melanin depend on race and amount of sunlight exposure
• hold the body In Shape
• senses the environment such as: pain, touch, temperature, pressure
• retains water, tightly packed cells of the stratum corneum provide this protection
• immunologic response , WBC I the skin capture and destroy bacteria
• thermoregulation
• metabolism, when exposed to ultraviolet B rays cells in the epidermis convert cholesterol-related steroid to vitamin D known as cholecalciferol resulting in maintenance of calcium and phosphorus levels in the bone and blood.