Unformatted text preview: 2/5/19 EXAM 2: Units 3c, 4, 5, and possibly 5a The Integumentary System
Bio 201 Outline
• Serous membranes
• Components of the Integumentary System
• Functions of Integumentary System
• Anatomy of the Epidermis
Important Cell Types of Skin
Layers
Factors affecting skin color • Dermis
• Accessory Structures: Sensory Receptors, Nails, Hair, Glands
• Clinical Considerations: Cancer, Androgenic Alopecia, Burns Before we start: let’s get a few things straight
Cell or plasma membrane Epithelial membranes Micro Macro Connective tissue membranes Macro Synovial membrane
Meninges (not shown) Serous membrane
Mucous membrane
Cutaneous membrane Macro-level membranes are generally a combination of different cell types to protect, cover, lubricate, nourish, etc. 1 2/5/19 Integumentary System: parietal = surround body cavities (pleural, abdominal pelvic) Skin and body membranes visceral = surround internal organs Note: We will briefly
discuss mucous and
synovial membranes
when we cover the
digestive/respiratory
systems and joints 4 Serous membrane Membranes in ventral body cavity
Serous membrane (also called the serosa): Thin coverings over surfaces in ventral body cavity
Parietal serosa lines internal body cavity walls
Visceral serosa covers internal organs (viscera)
Double layers are separated by slit-like cavity filled with serous fluid
help to absorb shock; protective mechanism to keep organs in their space Fluid secreted by both layers of membrane
(Pathophysiology note: pericardial effusion) Outer balloon wall
(comparable to parietal serosa) Figure 1.10 Serous
membrane relationships Air (comparable to serous cavity)
Inner balloon wall
(comparable to visceral serosa)
A fist thrust into a flaccid balloon demonstrates
the relationship between the parietal and visceral
serous membrane layers.
Heart Parietal
pericardium
Pericardial
space with
serous fluid
Visceral
pericardium The serosae associated with the heart. 2 2/5/19 Terminology: Fascia
Fascia is a general word that generally describes a sheet or band of connective tissue that lies just beneath the skin.
It helps to attach the skin to underlying structures (often muscles). Fascial sheaths or coverings also help to separate individual muscles and organs from each other within the body
Classifications:
Superficial fascia – blends the dermis with other structures
Deep fascia – separates muscles
Visceral & parietal fascia / membranes (as discussed in previous slides) – supports, covers, and separate internal organs. Components of Integumentary System Note: Hypodermis - Not
technically considered part
of integumentary system,
but shares some functions
The hypodermis is adipose and areolar connective tissue 3 2/5/19 “flaking” cells are the stratum corneum Skin consists of two distinct regions: increase the surface contact b/w the structures and the sloughing of the dermis stratified squamous epithelium Epidermis (red): superficial region; epithelial tissue and is avascular
Dermis (blue): under epidermis; fibrous connective tissue, vascular
Hypodermis (superficial fascia): • Subcutaneous layer deep to skin; mostly adipose tissue and areolar connective tissue
• absorbs shock and insulates
• anchors skin to underlying structures: mostly muscles
10 Functions of Integumentary System
• Protection
Physical barrier
Immune function
UV damage •
•
•
•
• Body Temperature Regulation
Synthesis of Vitamin D
Excretion
Sensation
Immune function Skin function: Regulation of Body Temperature when you return to heat, you are somewhat dehydrated and need to consume more fluids Regulation of conductive/convective heat loss
1.
2. 1.
2. • Blood vessels to skin : constrict (if cold) or
dilate (if hot) to regulate blood flow to skin • Skin blood flow regulated primarily by neural
mechanisms internal increase in blood pressure, urge to pee in cold weather Regulation of evaporative heat loss
• Neural regulation of activity of sweat glands 4 2/5/19 Skin function: Vitamin D3 synthesis calcitriol: stimulate absorption of calcium and phosphate principle inorganic molecules for bone remodeling, bone resorption
1,25-dihydroxyvitamin D3
or
Vitamin D3 lack of Vitamin D could lead to softening of the bone leads to condition
called osteomalacia in children Rickets: weak
structurally abnormal
bone due to lack of
calcium and
phosphorus Epidermis: Outermost Layers of Skin
Stratified squamous epithelium
Epidermis ranges in thickness
- Thin skin à
0.10 - 0.15 mm
- Thick skin à
0.5 - 4.5 mm palms of your hand and soles of your feet: Thick skin has stratum lucidum everywhere else: Thin skin
(located where?)
(located where?) stratum corneum — outermost dead layer of the skin does not have a
capillary network
related to it; decrease
the amount of
metabolic demand • Separated from underlying dermis by basement membrane
• Avascular: what does this mean in terms of metabolic demand?
• Epidermal ridges project into dermis (why?) establishing a great amount of surface contact Epidermis: Cell Types
• Keratinocytes:
skin cell
produce an intermediate
– most abundant cell type
filament called keratin
– synthesize and accumulate the protein, keratin (an intermediate filament)
– produce lamellar granules, or lipid secretions • Langerhans (dendritic) cells: in stratum spinosum layer
– immune cells (phagocytic) that respond against
microbes and cancers; also can ”call” other immune
cells to location • Merkel (tactile) cells: in stratum basale layer
cell; changes in movement, pressure,
– mechanoreceptor: make contact with sensory neurons
touch
to elicit sensation of light touch associated with desmosomes keeps skin oily and moist have the ability to call other cells (chemotaxis) based on mechanical movement of the • Merkel’s disc = Merkel cell + nerve ending
• (only sensory cell in epidermis) • Melanocytes: in stratum basale layer
– produce melanin (pigment) • Stem cells (basal cells): in stratum basale layer
– attaches to dermis
active in cell division
– give rise to keratinocytes metabolically active cells, get energy from diffusion 5 2/5/19 Epidermis of the skin: 4-5 layers called the stratum spinosum (prickle cells)
as the cells divide, the daughter cells get pushed up into the upper layer Cell renewal Stratum corneum: 15- 30 layers dead keratinocytes lacking nuclei; water resistant, protects deeper layers against environment 7d: basale to corneum; 14d at corneum Superficial Deep (Stratum lucidum): layer of densely packed dead keratinocytes present in thick skin) – this layer helps to reduce friction Stratum granulosum: 3-5 cell layers of keratinocytes transition between metabolically active cells and superficial dead keratinized cells; lamellar granules released here; disintegration of organelles here transitional layer produces a number of substances
helps in part to keep the skin lubricated, water-proof Stratum spinosum: 8-10 cell layers of keratinocytes. Keratinocytes here appear spikey (called prickle cells); cells contain web-like system of intermediate filaments attached to desmosomes to resist forces and pulling acting about the skin produce keratin in large amounts
melanocytes and langerhans cells also located here Stratum basale: single layer of cuboidal / columnar cells
source of cell renewal (stem cells)
location of melanocytes and Merkel cells 21 days for a cell to migrate from the stratum basale to the stratum corneum; stratum corneum = 14 days borders the dermal area
vasculature through diffusion provide nutrients Melanocytes
Located in stratum basale layer specialized cell Contain melanosomes (organelle)
• synthesis of the pigment
melanin from the amino acid
tyrosine
• vesicles which are released at
the surface of the melanocyte
Melanosomes delivered intact to
neighboring keratinocytes
• granules surround nucleus to
protect epidermal cell DNA from
damage by UV light
• eventually degraded by
lysosomes in the keratinocytes
increase of activity Exposure to UV light stimulates
production of melanin à tanning
helps to protect the keratinocytes from UV radiation Some Factors affecting skin color
Epidermal pigmentation
Melanin; yellow-brown, brown-black pigment
differing rates / amounts / type / distribution of melanin = differences in skin
color among individuals (Note: within an individual, areas that are more darkly
pigmented than others may be due to differing densities of melanocytes) Carotene- orange-yellow pigment to your skin accumulation in epidermal cells: effect in pathological conditions or with
overconsumption of carotene rich foods Blood Flow to the skin:
Pigment in bloodà Hemoglobin
Oxygenated = Bright red
Deoxygenated = Dark red/purple
Redness/Flushing : Increased blood flow to skin
Note: Erythema- localized area of redness, due to excess blood in dilated
vessels blushing
lack of oxygen Bluish Coloration (Cyanosis): Decreased oxygen content of blood
Pale: Decreased blood flow to skin, decreased amount of hemoglobin in blood 6 2/5/19 Dermis
Location of
• blood vessels
• lymph vessels
• nerves / sensory receptors
• hair follicles
• oil & sweat glands
Papillary layer (layer of nutrient delivery)
• presence of dermal papillae
• vascular areolar CT
Reticular layer
deeper layer of connective
tissue with abundant collagen
and elastin fibers
ground substance
80% thickness of dermis Papillary layer: superficial layer of areolar connective tissue consisting of loose, interlacing collagen and elastic fibers and blood vessels
Dermal papillae: fingerlike projections up into epidermis containing capillary loops, free nerve endings, and Meissner’s corpuscles)
In thick skin, dermal papillae lie on top of dermal ridges, which give rise to epidermal ridges
Collectively ridges are called friction ridges, which enhance gripping ability, contribute to sense of touch Epidermis Papillary
layer Reticular
layer
Dermis Reticular Layer
Makes up ~80% of dermal thickness difference between papillary layer and reticular layer areolar connective tissue Consists of coarse, dense fibrous connective tissue
Elastic fibers provide stretch-recoil properties
Collagen fibers provide strength and resiliency
bind water, keeping skin hydrated
Cutaneous plexus: network of blood vessels between reticular layer and hypodermis 7 2/5/19 Accessory structures: Sensory receptors in the skin
Mechanoreceptors: physically disrupted
Merkel’s discs (stratum basale): touch and pressure on especially on glabrous skin
Meissner’s corpuscle (dermal papillae): sensitive to fine touch and pressure
Ruffini corpuscle (deep dermis): sensitive to skin distortion and pressure
Pacinian corpuscle (deep dermis/hypodermis): sensitive to deep pressure and
vibration;
Nerve endings surrounding hair root, sensitive to hair movement glabrous skin: skin that has no hair (i.e, nipples, palms, soles of feet, lips) neuron wrapped around every hair shaft Nociceptors: sensitive
to painful stimuli, free nerve
endings pain receptors prostiglandins Thermoreceptors: sensitive to temperature, free
nerve endings bag of cells surrounding a neuron What’s a corpuscle? becomes flat on top so it’s not constantly stimulating the neuron Accessory structures: Nails vaginations: folding of the deeper layers Nails are dense layers of dead,
heavily keratinized, keratinocytes
Function: protection, limit
distortion, tools Nail root: deep epithelial /
epidermal fold (purple); contains a
stratum basale that gives rise to
the nail
Nail body: visible portion of the
nail
Nail bed: the epidermal layer
just below the nail body
Lunula: base of nail where blood
vessels are not visible
Cuticle (eponychium): extension
of stratum corneum from the root
over base of nail 8 2/5/19 Accessory Structures: Hair • Consists of dead keratinized cells
• Functions: – Warning system: example: bug on skin
– Protect from heat loss
– Protect from physical trauma (hair on head)
– Protect from sunlight
Glabrous skin: contain no hair (palms, soles, lips, nipples, and portions of external genitalia) Accessory Structures: Hair deeper layer: hair root, hair shaft: what you can see Hair: dead, keratinized cells, which
project above surface of skin
Keratin: a fibrous protein
(intermediate filament) that
protects epithelial cells in the
skin. Keratinized tissue is
extremely tough (similar to chitin
in an insect’s shell) smooth muscle grouping of cells controlled by
autonomic nervous system Produced in organs within the
dermis called hair follicles
Types of hair:
Vellus hair: small, short, and
delicate peach fuzz
Terminal hair: large, course,
and usually pigmented (note:
distribution of melanin into hair
as it is produced)
hair, arms, external genitalia Accessory Structures: Hair stem cells located in hair matrix Follicle: Specialized
invagination of epidermis
within surrounding
connective tissue sheath
Base of follicle:
• Hair papilla: indentation
in connective tissue
(blood vessels)
• Hair bulb: surrounds
papilla and is site of
production Smooth
muscle Sensory
nerve
endings Hair root: anchors hair,
extends from base to
halfway to skin surface
Hair shaft: extends from
halfway point to surface 9 2/5/19 Hair Growth
Hair grows continually ~
0.33 mm/day (scalp) eumelanin: true melanin pheomelanin: combination that gives hair its different color has 3 life cycles Hair matrix: most highly active region
within the hair bulb
site of epidermal stem cells
(divide, pushed up, keratinized) Medulla, cortex, and cuticle
inner to outer layers = less to more
keratin Keratinization complete at
border of root and shaft Androgenic Alopecia largely influenced by hormones due to higher levels of testosterone Hormonal influence of hair growth on
a genetically prone scalp (age also a
factor)
Males: “male patterned” baldness Hair loss from top of head first, and may
then be followed by loss at sides Female hair loss in a different pattern:
more diffuse over the top of scalp
and rarely leads to total baldness
not as common 5a reductase Testosterone Dihydrotestosterone
(DHT) DHT shortens the growth phase. In
early stages hair still present but
smaller. Over time hair disappears Finasteride (i.e., Propecia): Pharmacological treatment for male patterned baldness
- 5a reductase inhibitor
Minoxidil (i.e., Rogaine): over the counter pharmacological treatment for androgenic
alopecia
- vasodilator 10 2/5/19 Accessory structures: Modes of Glandular Secretion salivary glands,
sweat glands losing part of the cells
mammary glands skin child ingests cellular matter bursting/destroying of the cell Accessory structures: Glands
Sebaceous (oil) glands / Sebaceous follicles: • Widely distributed, except for thick
skin of palms and soles
• Most develop from hair follicles and
secrete into hair follicles
• Holocrine secretion called sebum:
complex mixture of lipids
water, lipids • Function: waterproofing layer,
moisturizing, antimicrobial action Holocrine: secretions produced in cytoplasm and released by rupture of pl.
mem. (destroying cell) Accessory structures: Glands
Sweat (sudoriferous) glands
not associated w/ a hair follicle
1. Eccrine sweat gland
• 99% water, salts, vitamin C,
antibodies, dermcidin (microbekilling peptide), metabolic wastes
• regulated by nervous system
• thermoregulation and excretion
• NOT connected to a hair follicle
• merocrine secretion 2. Apocrine sweat gland: • associated with a hair follicle • found in the axillary (armpits) and anogenital areas • release glandualar contents by merocrine function NOT apocrine
• associated with scent merocrine secretion 11 2/5/19 Dermal
connective
tissue
Sebaceous
gland duct Sweat
pore Sebaceous
gland
Hair in
hair follicle Eccrine
gland Secretory cells
Photomicrograph of a
sectioned sebaceous
gland Accessory structures: Glands Ceruminous glands (“cera” is root for wax); ear canals Secretions from these glands combine with sebum to form a wax-like, thick substance Mammary glands For milk production / secretion (Reproductive system) Skin cancers
• Non-melanoma
– Basal cell carcinoma: most common type of skin cancer ( ~75% of all skin
cancers), but least lethal (rarely metastasizes) stratum basale layer that becomes carcinogenic – Squamous cell carcinoma: second most common type of skin cancer, more
aggressive than basal cell carcinoma.
• keratinocytes Melanoma
– Malignant MELANOMA: cancerous melanocytes, most aggressive form of skin
cancer 25% of those infected are malignant(?) A: assymetry B: border C: color D: diameter Nonuniform
appearance Irregular outline Mixture of colors Larger growths
>5 mm diameter
~ pencil eraser E: evolving
Watch for changes
In Rules ABC&D Early detection of melanoma: ABCDEs 12 2/5/19 Burns
Classified based on the depth of the burn 37 Skin graft 2nd Degree 4th Degree Rule of Nines 38 Totals
4 1 ⁄2 % How much surface area has been burned on a person’s body? Must be able to calculate Anterior and posterior
head and neck, 9%
Anterior and posterior
upper limbs, 18% How much surface area (skin) was burned over the body? 4 1 ⁄2 %
4 1 ⁄2 %
Anterior
trunk, 18% 9% 9% Anterior and posterior
trunk, 36% Perineum, 1% Anterior and posterior
lower limbs, 36%
100% 13 ...
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