Summary Biology 173 Exam 2 Study Guide

Exam 2 Study Guide 1


Exam 2 Study Guide: Chapters 5-8, Lecture Guide Pages 85-164
Anatomy and Physiology 1
Dr. Surmacz
Date of Exam: October 23, 2017

Chapter 5: The Integumentary System
 2 Major Parts
o The skin (cutaneous membrane)
o Accessory structures
 Hair, glands, nails, etc.
 The Skin
o 2 Distinct Layers
 Epidermis
 Upper; thinner
 Dermis
 Deep; thicker
 Hypodermis
 AKA subcutaneous layer
OR superficial fascia
 Not skin
 Made of adipose and
areolar tissue
 Anchors skin to
underlying organs
 The Epidermis
o Stratified squamous epithelium
o Made up of cells called keratinocytes that make keratin
o Thick vs. Thin
 Thick
 .5 mm thick
 5 layers
 Found on palms and soles
 Thin
 .08 mm thick
 4 layers
 Found everywhere else
o Stratum Corneum
 15-30 rows of dead flat cells that are interlocked by
desmosomes
 Keratinized or cornification occurs
 Water resistant, not waterproof
o Stratum Lucidum
 Found in thick skin only
 Clear, glassy layer
 Flat, densely packed keratinocytes filled with keratin
o Stratum Granulosum
 Cells start to die and dehydrate
 Darkly stained layer containing 3-5 rows of keratinocytes
that have stopped dividing, cells grow thicker and flatter

, Exam 2 Study Guide 2


 Synthesis begins of KERATOHYALIN and KERATIN, the
waterproofing proteins
o Stratum Spinosum
 8-10 rows of spiny shaped keratinocytes held together by
desmosomes
 Langerhans (dendritic) cells: immune function, defend
against bacteria
 Stimulate against microorganisms that manage to
penetrate the superficial layers of the epidermis and
superficial skin cancers
 Look like miniature pincushions
 Contains cells that are involved in the immune response
o Stratum Germinativum or Basale
 Single layer of stem cells capable of cell division
 Attached to the
basement membrane (BM)
that separates
epidermis from dermis
 Forms epidermal ridges
that extend into
dermis
 Interlocks with the
dermis
 Forms epidermal ridges
that are adjacent to
dermal projections
called dermal papillae
 Has Merkel cells scattered among the basale cells
 Contains melanocytes that produce melanin
o Takes about 7-10 days to go from stratum basale to corneum
o Takes a couple weeks for corneum cells to jump off
o Roles of the Epidermal Growth Factor (EGF)
 Promoting the divisions of basal cells in the stratum
basale and stratum spinosum
 Accelerating the production of keratin in differentiating
keratinocytes
 Stimulating epidermal development and epidermal repair
after injury
 Stimulating secretory product synthesis and secretion by
epithelial glands
o EGF can be used in tissue culture to stimulate the growth and
division of epidermal cells
 The Dermis
o Made of connective tissue
o Contains networks of blood vessels, lymphatic vessels, and nerve
fibers
o Dermatitis is an inflammation of the skin that primarily involves
the papillary layer
o Papillary Layer

, Exam 2 Study Guide 3


 Top, thinner
 Composed of areolar connective tissue
 Contains capillaries and sensory nerves
 Contains fingerlike projections called papillae
 Gives ridge like pattern to skin; fingerprints
o Reticular Layer
 Composed of dense irregular connective tissue (collagen and
elastic fibers)
 Contains sensory receptors (touch, temperature, pressure,
vibration, pain) and nerves
 Contains blood vessels
 Contains nerves
 Contains hair follicles and glands
 Fiber bundles responsible for lines of cleavage
o Collagen fibers are very strong and resist stretching, but they
are easily bent or twisted
o Elastic fibers permit stretching and then recoil to their
original length
 When elastic fibers are overstretched, stretch marks result
o Bundles of fibers can be known as tension lines
 Hypodermis
o The boundary between the hypodermis and the dermis is generally
indistinct because of the connective tissue fibers
o Very elastic
o Primarily adipose tissue, 80% of body fat
o Blood reservoir
 Why doctors use hypodermic needles to inject drugs
 Skin Color
o Due to interaction between: pigments in the epidermis and blood
flow in the dermis
o Melanin
 2 kinds
 Eumelanin
o Brown-black color
 Pheomelanin
o Red-yellow color
 The more melanocytes present, the darker the skin color
 Is used for UV protection from the sun
o Carotene
 Orange-yellow pigment that normally accumulates in
epidermal cells
 An overabundance of carotene can give someone’s skin an
orange color
o Cyanosis
 When the skin takes on a bluish color
o Disease-related changes in skin color
 Jaundice
 The liver is unable to excrete bile, so a yellowish
pigment accumulates in body fluids