- subcutaneous layer deep to skin (not technically part of skin)
- made up of mostly adipose tissue
what kind of tissue is in the skin
Keratinized stratified squamous epithelium
what types of cells are in the epidermis
- keratinocytes
- melanocytes
- epidermal dendritic (langerhans) cells
- tactile (merkell) cells
what are the layers of the epidermis in order from deep to superficial
- Stratum Basale (basal layer)
- stratum Spinosum (prickly layer)
- stratum Granulosum (granular layer)
- stratum corneum (horny layer)
what layer of the skin is only in thick skin
Stratum Lucidum
what is the stratum basale (basal layer)
- deepest epidermal layer firmly attached to the dermis
- has a single row of stem cells
what is the stratum spinosm (prickly layer)
- made up of cells that contain a weblike system of intermediate prekeratin filaments attached to desmosomes
- and abundant melanin granules and dendritic cells
what is the stratum granulosum (granule layer)
- thin; 3 to 5 cell layers in which the cells flatten
- where keratohyaline and lamellated granules accumulate
what is the stratum lucidum (clear layer)
- located only in thick skin
- thin transparent band superficial to the stratum granulosum
- has a few rows of flat, dead keratinocytes
what is the dermis made up of?
- strong, flexible connective tissue
what kind of cells are located in the dermis
- fibroblasts
- macrophages
- occasionally mast cells and white blood cells
the dermis is made up of what 2 layers
papillary
reticular
what is the papillary layer of the dermis made up of?
- areolar connective tissue with collagen and elastic fibers and blood vessels
- dermal papillae
what does dermal papillae contain
- capillary loops
- meissners corpuscles
- free nerve endings
what is the reticular layer of the dermis
- 80% of the thickness of dermis
- collagen fibers provide strength and resiliency
- elastic fibers provide stretch-recoil properties
what 3 pigments contribute to skin color
- melanin
- carotene
- hemoglobin
what is melanin?
yellow to reddish- brown to black, responsible for dark skin colors
what is carotene
yellow to orange, most obivious in the palms and soles
what is hemoglobin
responsible for the pinkish hue of skin
what are the derivatives of the epidermis
- sweat glands
- oil glands
- hair and hair follicles
- nails
wha are the two main types of sweat (sudoriferous) glands
- Eccrine
- apocrine
what are the functions of the skin
- protects from abrasion and penetration
- waterproof
- barrier against biological, chemical, and physical assaults
where are eccrine (merocrine) sweat glands found
palms, soles, and forehead
what is sweat made up of
99% water
NaCI
Vitamin C
Antibodies
Metabolic Wastes
where are apocrine sweat glands found
- confined to axillary and anogenital areas
what do apocrine glands release
sebum
what is sebum
sweat + fatty substances and proteins
what type of sweat gland is only functional after puberty
apocrine
what are some specialized apocrine glands
- ceruminous glands- in external ear canal
- mammary glands
what are sebaceous (oil) glands
- widely disribted
- most develop from hair follicles
- becomes active at puberty
- releases sebum
what is responsible for softening hair and skin
sebum
what are the functions of hair
-Alerting the body to the presence of insects on the skin
- guarding the scalp against physical trauma, heat loss, and sunlight
hair is located everywhere on the body EXCEPT
palms
lips
nipples
and portions of external genitalia
what does hair consist of?
- dead keratinized cells
- contains hard keratin
- hair pigments: melanins
what creates gray/white hair
decreased melanin production, increased air bubbles in shaft
Hair extends from the ________ surface into __________
Epidermal
dermis
hair has a two-layered wall what do they consist of
outer connective tissue root sheath
inner epithelial root sheath
what is the hair bulb
the expanded deep end of hair follicle
there are ________ _______ _________ around each hair bulb
sensory nerve endings
by bending a hair you stimulate the what?
sensory nerve endings
what is the arrector pili
smooth muscle attached to follicle
responsible for goose bumps
what are the 2 types of hair
vellus
terminal
what is vellus hair
type of hair
pale, fine body hair of children and adult females
what is terminal hair
coarse, long hair of eyebrows, scalp, axillary, and pubic regions (and face and neck of males)
what is alopecia
hair thinning in both sexes after 40
what is true baldness
-genetically determined and sex-influenced condition
-male pattern baldness is caused by follicular response to DHT
what are the functions of the integumentary system
- protection
- body temp regulation
- cutaneous sensations
- metabolic waste
what are 3 types of protective barriers of the integumentary system
chemical
physical/mechanical barriers
biological barriers
glands release sweat through what process
exocytosis
if a cell has the suffix "blast", that means...
the cell is constantly dividing
if a cell has the suffix "cyte", that means what?
doesnt divide
what is blood resevoir
up to 5% of bodys blood volume
what is excretion
nitrogenous wastes and salt in sweat
what are risk factors to skin cancer
- overexposure to UV radiation
- frequent irritation of the skin
what are 3 major types of skin cancer
- basal cell carcinoma
- squamous cell carcinoma
- melonoma
what is basal cell carcinoma
- stratum basale cells proliferate and slowly invade dermis and hypodermis
- cured by surgical excision in 99% of cases
what is squamous cell carcinoma
- involves keratinocytes of stratum spinosum
- most common on scalp, ears, lower lip, and hands
- good prognosis if treated by radiation therapy or removed surgically
what is melanoma
- highly metastatic and resistant to chemotherapy
- treated by wide surgical excision accompanied by immunotherapy
what are some characteristics of melanoma
A- Asymmetry; the two sides of the pigmented area do not match
B- Boder exhibits indentations
C- color is black, brown, tan and sometimes red or blue
D- diameter is larger than 6 mm (size of a pencil eraser)
what are the types of burns
Heat
electrical
radiation
chemical
what do burns cause
tissue damage
denatured protein
cell death
what is the immediate threat of burns
dehydration and electrolyte imbalance, leading to renal shutdown and circulatory shock
what is the rule of nines
used to estimate the volume of fluid loss from burns
what is a first degree burn
epidermal damage only
- localized redness, edema, and pain
what is a second degree burn
epidermal and upper dermal damage
- blisters appear
what is a third degree burn
entire thickness of skin is damaged
- gray/white, cherry red, or black
- no initial edema or pain (nerve endings destroyed)
- skin grafting usually necessary
burns are considered critical when?
25% of the body has second-degree burns
10% of the body has third-degree burns
face, hands or feet bear third-degree burns
what is the lanugo coat
the covering of delicate hairs in fetal developement
the ectoderm gives rise to the...
epidermis
the mesoderm gives rise to the....
dermis and hypodermis
what is the vernix caseosa
sebaceous gland secretion; protects skin of fetus
what are the transitions of skin from adolescent to adult hood
- sebaceous gland activiy increases
- effects of cumulative environmental assaults show after age 30
- scaling and dermatitis become more common
what are the transitions of skin from adult to old age
- epidermal replacement slows, skin becomes thin, dry and itchy
- subcutaneous fat and elasticity decrease, leading to cold intolerance and wrinkles
- increased risk of cancer
what are tissues
groups of cells similar in structure and function
what are the types of tissues
Epithelial tissue
connective tissue
muscle tissue
nerve tissue
nervous tissue is responsible for what and located where
internal communication
brain, spinal cord, and nerves
muscle tissue does what and is located where
Contracts to cause movement
attached to bones, heart, walls of hollow organs; skeletal, cardiac, smooth
what does epithelial tissue do and where is it found
forms boundaries between different environments, protects, secretes, absorbs filters
skin surface
lining of GI tract organs
other hollow organs
what does connective tissue do and where is it found
supports, protects, binds other tissues together
bones
tendons
fat and other soft padding tissue
what are the 2 types of epithelial tissue
covering and lining epithelia
glandular epithelia
cells have two types of surfaces
apical
basal
apical surface
- upper free
- may bear microvilli or cilia
basal surface
noncellular basal lamina of glycoprotein and collagen lies adjacent to basal surface
characteristics of epithelial tissue are
- composed of closely packed cells
- supported by a connective tissue reticular lamina
- avascular but innervated
- high rate of regeneration
when classifying epithelia ask what 2 questions
1. how many layers?
1= simple
>1= stratified
2. what type of cell?
- squamous
- cuboidal
- columnar
Simple squamous Epithelium:
describe:
single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm; the simplest of the epithelia
Simple squamous Epithelium:
Function:
Allows passage of materials by diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae
Simple squamous Epithelium:
Location:
Kidney glomeruli;
air sacs of lungs;
linings of heart,
blood vessels,
and lymphatic vessels;
lining of ventral body cavity
Simple Cuboidal Epithelium:
Description:
Single layer of cubelike cells with large, spherical central nuclei
Simple Cuboidal Epithelium:
function:
secretion and absorption
Simple Cuboidal Epithelium:
Location:
kidney tubules; ducts and secretary portions of small glands; ovary surface
Simple Columnar Epithelium:
Description
single layer of tall cells with round to oval nuclei; some cells bear cilia; layer may contain muscus-secreting unicellular glands
Simple columnar Epithelium:
Function:
Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliary action
Simple columnar Epithelium:
Location:
Nonciliated type lines
most of the digestive tract (stomach to anal canal)
gallbladder
and excretory ducts of some glands ciliated variety lines small bronchi uterine tubes
and some regions of the uterus
Pseudostratified columnar Epithelium:
Description:
single layer of cells of differing heights, some not reaching the free surface; nuclei seen at different levels; may contain mucus-secreting cells and bear cilia
Pseudostratified columnar Epithelium:
Function:
Secretion, particularly of mucus; propulsion of mucus by ciliary action
Pseudostratified columnar Epithelium:
Location:
Nonciliated type in males sperm-carrying ducts and ducts of large glands; ciliated variety lines the trachea, most of the upper respiratory tract
Stratified Squamous Epithelium:
Description
thick membrane composed of several cell layers; basal cells are cuboidal or columnar and metabolically active; surface cells are flattened (squamous); in the keratinized type, the surface cells are full of keratin and dead; basal cells are active in mitosis and produce the cells of the more superficial layers
Stratified Squamous Epithelium:
Function:
Protects underlying tissues in areas subjected to abrasion
Stratified Squamous Epithelium:
Location:
nonkeratinized type forms the moist linings of the esophagus,
mouth,
and vagina;
keratinized variety forms the epidermis of the skin,
a dry membrane
Transitional Epithelium
Description:
resembles both stratified squamous and stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cells dome shaped or squamouslike, depending on degree of organ stretch
Transitional Epithelium:
Function:
stretches readily and permits distension of urinary organ by contained urine
Transitional Epithelium:
Location:
Lines the ureters, urinary bladder, and part of the urethra
what is a Glandular epithelia
a gland that is one or more cells that makes and secretes an aqueous fluid
glandular epithelia is flassified by
- site of product release- endocrine or exocrine
- relative number of cells forming the gland- unicellular or multicellular
endocrine glands are..
- ductless glands
- secrete hormones that travel through lymph or blood to target organs
exocrine glands are...
- more numerous than endocrine glands
- secrete products into ducts
- secretions released onto body surfaces(skin) or into body cavities
- examples include mucous, sweat, oil and salivary glands
the only important exocrine gland is the...
goblet cell
multicellular exocrine glands are composed of what?
- duct
- secretory unit
multicellular exocrine glands are classified according to:
- duct type (simple or compound)
- structure of their secretory units (tubular, alveolar, or tubuloalveolar)
what are the modes of secretion
merocrine
holocrine
what is the merocrine mode of secretion
gland examples
- products are secreted by exocytosis
- pancreas, sweat and salivary glands
what is the holocrine mode of secretion
ex. sebaceous glands
products are secreted by rupture of gland cells
what is the most abundant and widely distributed tissue type
connective tissue
what are the four classes connective tissue
Connective tissue proper
cartilage
bone
bone tissue
blood
what are the major functions of connective tissue
- binding and support
- protection
- insulation
- transportation (blood)
what are the characteristics of connective tissue i.e. what do they have?
- mesenchyme as their common tissue of origin
- varying degrees of vascularity
- cells seperated by nonliving extracellular matix
what are the structural elements of connective tissue
- ground substance
- three types of fibers
- cells
in connective tisue, what does the ground substance do and what is it made up of?
- a medium in which solutes diffuse between blood capillaries and cells
- made up of 3 components:
1. interstitial fluid
2. adhesion proteins
3. proteoglycans
what are proteoglycans
a protein core + large polysaccharides that trap water of the ground substance
what are the 3 types of fibers in connective tissue
- collagen
- elastic
- reticular
what is collagen fiber
- (white fibers)
- strongest and most abundant type
- provides high tensile strength
what is elastic fiber
networks of long, thin, elastin fibers that allow for stretch
what is reticular fibers
short, fine, highly branched collagenous fibers
what kind of cells are found in connective tissue proper?
fibroblasts
what kind of cells are found in cartilage
chondroblasts
chondrocytes
what kind of cells are found in bone
osteoblasts
osteocytes
what kind of cells are found in bone marrow
hematopoietic stem cells
what are the 2 types of connective tissue
loose connective
dense connective
what type of cells uncontrollably divide in melanoma
melanocytes
what are the 3 types of cartilage
hyaline
elastic
fibrocartilage
what are the types of epithelial membranes
cutaneous membranes
mucous membranes
serous membranes
what are the steps in tissue repair
1. inflammation
2.organization and restored blood supply
3. regeneration and fibrosis
what are the primary germ layers of skin
ectoderm
mesoderm
endoderm
what tissues come from the ectoderm germ layer
nerve tissue
what tissues come from the mesoderm germ layer
muscle and connective tissue
what germ layer does the epithelial tissues arise from
all three germ layers
in "RULE OF NINES" what is the percentage of fluid loss on the anterior and posterior head and neck?
9%
in "RULE OF NINES" what is the percentage of fluid loss on the anterior and posterior upper limbs 18%
in "RULE OF NINES" what is the percentage of blood loss on the anterior and posterior trunk
36%
in "RULE OF NINES" what is the percentage of fluid loss on the perineum area
1%
in "RULE OF NINES" what is the percentage of fluid loss on anterior and posterior lower limbs
36%
what are the subclasses of bone tissue
compact bone
spongy bone
what are the classes of loos connective tissue
areolar
adipose
reticular
what are the classes for dense connective tissue
regular
irregular
elastic
what is chromatin?
threadlike strands of DNA
30% histone
60% proteins
10% RNA
-arranged in fundemental units called nucleosomes
-condense into barlike bodies called chromosomes when the cell starts to divide
what is the cell cycle?
- defines changes from formation of the cell until it reproduces
includes
interphase
mitosis
what is interphase
Resting period for cells
- period from cell formation to cell division
what are the 4 subphases of interphase
G1 (gap 1)
G0 (gap)
S(synthetic)
G2 (gap 2)
what is G1
a subphase of interphase
metabolically active
grows vigerously
the centrioles begin replicating
what is G0-
subphase of interphase
gap phase in cells that permanently cease dividing
what is S phase
subphase of interphase
DNA is replicating
makes sure that the future cells are identically copied
what is G2
subphase of interphase
final preparations for mitosis are completed and centrioles finish replicating
what is DNA Replication?
-DNA helices begin unwinding from the nucleosomes
-helicase untwists the double helix and exposes complementary chains
-the y-shaped site of replication is the replication fork
-each nucleotide strand serves as a template for building a new complementary strand
what happens during DNA Polymerase
- continuous leading strand is synthesized
- discontinuous lagging strand is synthesized in segments
- DNA ligase splices together short segments of discontinuous strand
what is the end result of DNA polymerase
two DNA molecules formed from the original
this process is called semiconservative replication
what is mitosis essential for?
body growth and tissue repair
mitosis does not occur in...
mature cells of nervous tissue
skeletal muscle
cardiac muscle
what 2 major events occur in cell division?
Mitosis
Cytokinesis
what are the stages of mitosis
prophase
metaphase
anaphase
telophase
what is mitosis
nuclear division of cells
what is cytokinesis
division of cytoplasm by cleavage furrow
what happens during prophase
- chromosomes become visible, each with two chromatids joined at a centromere
- centrosomes separate and migrate toward opposite poles
- mitotic spindles and asters form
what happens during metaphase
-centromeres of chromosomes are aligned at the equator
- this plane midway between the poles is called the metaphse plate
what happens during anaphase
- shortest phase
- centromeres of chromosomes split simultaneously
- chromosomes (v shaped) are pulled toward poles by motor proteins of kinetochores
- polar microtubules continue forcing the poles apart
what is telophase
- begins when chromosome movement stops
- the two sets of chromosomes uncoil to form chromatin
- new nuclear membrane forms around each chromatin mass
- Nucleoli reappear
- spindle disappears
what happens during cytokinesis
- begins during late anaphase
- ring of actin microfilaments contracts to form a cleavage furrow
- two daughter cells are pinched aprart, each containing a nucleus identical to the original
what are "go signals"
gives the cells signals to start the division process when area of membrane is inadequate for exchange
what are "stop signals"
tells the cell when to stop dividing
what is protein synthesis
what is the role of mRNA
carries instructions for building a polypeptide, from gene in DNA to ribosomes in cytoplasm
what is the role of rRNA
a structural component of ribosomes that, along with tRNA, helps translate messages from mRNA
what is the role of tRNA
bind to amino acids and pair with bases of codons of mRNA at ribosome to begin process of protein synthesis
what is protein synthesis
- DNA is the master blueprint
- deals with the coding of an amino acid
what is a gene
segment of DNA with blueprint for one polypeptide
what is a triplet
specifies a particular amino acid
what is transcription
transfers DNA gene base sequence to a complementary base sequence of an mRNA
transcription factors
- loosens histones from DNA in area to be transcribed
- binds to promotor, a DNA sequence specifying start site of gene to be transcribed
- mediates the binding of RNA polymerase to promotor
what is RNA polymerses role in transcription
- enzyme that oversees synthesis of mRNA
- unwinds DNA template
- adds complementary RNA nucleotides on DNA template and joins them together
- stops when it reaches termination signal
- mRNA pulls off the DNA template, is further processed by enzymes, and enters cytosol
what is translation
- converts base sequence of nucleic acids into the amino acid sequence of proteins
involves all 3 types of RNA
what is the genetic code
each three-base sequence on DNa is represented by a codon
codon
complementary three-base sequence on mRNA
t or f
anticodon of a tRNA binds to its complementary codon and adds its amino acid to the forming protein chain
true
what is the role of rough ER
ribosome complex is directed to rough ER by a signal-recognition particle (SRP)
- forming protein enters the ER
- sugar groups may be added to the protein, and its shape may be altered
- protein is enclosed in a vesicle for transport to golgi apparatus
what is the wear and tear theory
- little chemical insults and free radicals have cumulative effects
immune system disorders
autoimmune responses and progressive weakening of the immune response
genetic theory
cessation of mitosis and cell aging are programmed into genes