Body BugsBody Bugs
NOVA | Bugs That Live on You
Follicular Mites – found in all hair follicles
Dust Mites – found on your body, your bed, any fluffy surface that you spend time with
Skin colorSkin color
Normal Skin Color DeterminantsNormal Skin Color Determinants
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Determined by a combo of: Types of pigments present Blood circulation Stratum corneum thickness
Normal Skin Color DeterminantsNormal Skin Color Determinants
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Melanin Yellow, brown or black pigments
produced in melanocytes found in stratum basale – transferred to keratinocytes
Local accumulations form freckles & pigmented moles
Amount of melanin produced depends upon genetic and exposure to sunlight
Solar elastosis – clumping of elastin fibers = leathery looking skin
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Carotene Orange-yellow
pigment from some vegetables
Vitamin A precurser – vitamin A forms retinal which is needed for sight
Accumulates in adipose and stratum corneum cells
Normal Skin Color Determinants
Normal Skin Color DeterminantsNormal Skin Color Determinants
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Hemoglobin & blood circulation Red coloring from oxygenated blood cells in dermis capillaries
Oxygen content determines the extent of red coloring
More obvious in fair skinned individuals
Blood flowBlood flow
Vasodilation causes increase in Vasodilation causes increase in flowflow
Vasoconstriction causes Vasoconstriction causes decrease in flowdecrease in flow
Skin as a DiagnosticSkin as a Diagnostic
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Skin color is influenced by emotional & disease states: You should know the states that cause these. Cyanosis – bluish color - lack of oxygen Erythema – redness – heat, inflammation,
fever Add this -Pallor – paleness – lack of
blood flow Jaundice – yellowish color – liver damage Bronzing – bronze (tan) – Addison’s
disease Hematomas – black & blue – blood under
skin
Skin DerivativesSkin Derivatives
Hair AnatomyHair Anatomy
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Central medulla
Cortex surrounds medulla
Cuticle on outside of cortex
Single layer of overlapping cells
Split ends – cuticle flakes off – fibers in cortex fray out
Figure 4.7b
Hair anatomyHair anatomy
Hair shaft Hair shaft – – above skinabove skin
Hair root Hair root – – below skinbelow skin
Appendages of the SkinAppendages of the Skin
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Hair
Shaft – projects from skin
Add in margins: Shape determines hair curliness
Flat = curly
Oval = wavy
Round = straightFigure 4.7c
Hair FollicleHair Follicle
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Hair - Extends into dermis & hypodermis
Produced by hair bulb- expanded end
Papilla contains capillaries in bulb for hair nourishment (fix in notes!)
Matrix = growth zone – directly surrounds papilla
Figure 4.7c
Associated Hair StructuresAssociated Hair Structures
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Arrector pilli Smooth muscle regulated
by emotions
Contraction pulls hair upright - Normally at angle
Figure 4.7a
Arrector Pili MuscleArrector Pili Muscle
Hair ColorHair Color
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Caused by proportions of 3 types of melanin
Determined by genetics
Melanin is replaced by air bubbles in gray/white hair – causes different texture
Figure 4.7b
Hair TypesHair Types
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Vellus hair – softer body hair
Terminal hair – coarser hair found in axillary & anogenital regions & other body regions
Lanugo – newborn baby fuzz
Figure 4.7a
Hair GrowthHair Growth
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Influenced by (in order):
Nutrition: main influence
hormones
Blood flow
Figure 4.7a
CyclesCycles
Thought Question: know the Thought Question: know the answers to these questions!!answers to these questions!!
Why is the hair on your head longer than the Why is the hair on your head longer than the hair in your eyebrows?hair in your eyebrows?
Why does some hair fall out every day?Why does some hair fall out every day?
Approx 100 hairs per day are lost from your Approx 100 hairs per day are lost from your head! That is why your sink is stopped up!head! That is why your sink is stopped up!
Androgenetic Alopecia Androgenetic Alopecia
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Male pattern baldness Sex linked,
recessive trait Punnett Square!
Figure 4.7a
Causes thinning hair in women
Androgenetic AlopeciaAndrogenetic Alopecia
Increased activity in androgen receptors causes hair loss & increases other health risks such as coronary heart disease and prostate cancer in men and polycystic ovary syndrome in women
Terminal hair replaced by vellus hair -progresses posteriorly
Treatment: drugs that inhibit testosterone Treatment: drugs that inhibit testosterone production (Rogaine, Propecia)production (Rogaine, Propecia)
FYI: Polycystic Ovarian SyndromeFYI: Polycystic Ovarian Syndrome
More on these topics when we study the Endocrine System
Imbalance: FYIImbalance: FYI
Thinning hair can be caused by an abundance Thinning hair can be caused by an abundance of factors.of factors. Heterozygous traitsHeterozygous traits NutritionNutrition MedicationsMedications Stress (affects nutrition & hormones)Stress (affects nutrition & hormones) HormonesHormones Physical factorsPhysical factors
Appendages of the SkinAppendages of the Skin
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Nails: Just know diagram & these imp. facts – add to diagram: Scale-like modifications of the epidermis
Heavily keratinized Stratum basale extends beneath the nail
bed to form nail matrix Which is responsible for growth
Lack of pigment makes them colorless
Nail StructureNail Structure
Nail StructureNail Structure
Know all parts labeled on diagramKnow all parts labeled on diagram
Why is lunula white?Why is lunula white?
What happens if matrix is damaged?What happens if matrix is damaged?
Sweat GlandsSweat Glands
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Sudoriferous (sweat) glands Three types
Eccrine glands
Widely distributed in skin: abundant on palms, soles, forehead
Open via duct to pore on skin surface
Sweat composition: mostly water with a slightly acidic 4-6 pH
Function: thermoregulation
Sweat GlandsSweat Glands
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• Apocrine glands (also sudoriferous)
Ducts empty into hair follicles Found mainly in anogenital & axillary region Begin to function at puberty due to
hormones Organic contents: Fatty acids and proteins
– can have a yellowish color that stains clothes
Odor is from associated bacteria
Sweat GlandsSweat Glands
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Ceruminous glands
Modified apocrine gland Found in outer 1/3 of ear canal Produce ear wax to trap “invaders”
Appendages of the SkinAppendages of the Skin
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Sebaceous glands (all over except palms and soles of feet)
Produce oil for waterproofing
Lubricant for skin & kills bacteria
Most with ducts that empty into hair follicles
Glands are activated at puberty: stimulated by hormones
ImbalancesImbalances
Upper right hand box in notes;Upper right hand box in notes; AcneAcne – active infection of sebaceous glands – active infection of sebaceous glands WhiteheadWhitehead - Sebaceous gland duct blocked - Sebaceous gland duct blocked
by sebumby sebum BlackheadBlackhead – sebum oxidizes, dries, and – sebum oxidizes, dries, and
darkensdarkens SeborrheaSeborrhea – “cradle cap” – Over activity of – “cradle cap” – Over activity of
sebaceous glands in infantssebaceous glands in infants
Integumentary FunctionsIntegumentary Functions
Protection - biologicalProtection - biological
Biological – cells – macrophages & Biological – cells – macrophages & Langerhan’s cells engulf invaders.Langerhan’s cells engulf invaders.
Protection - mechanicalProtection - mechanical
Mechanical – physicalMechanical – physical Continuity – skin is made impermeable through Continuity – skin is made impermeable through
the tight junctions & desmosomesthe tight junctions & desmosomes Keratin – physically blocks the passage of water Keratin – physically blocks the passage of water
and water soluble substancesand water soluble substances FYI: Molecules that can pass through your skin:FYI: Molecules that can pass through your skin:
Lipid soluble – O2, CO2, ADEK, steroids, Lipid soluble – O2, CO2, ADEK, steroids, nicotine, & other transdermal medicationsnicotine, & other transdermal medications
Oleoresins – poison ivy & poison oak, etc – you Oleoresins – poison ivy & poison oak, etc – you have less than 10 min to wash it off!have less than 10 min to wash it off!
Protection - ChemicalProtection - Chemical
Chemical Chemical Skin secretions: tears, sweat, oil lower pH and Skin secretions: tears, sweat, oil lower pH and
contain lysozyme (chemical that lyses cells)contain lysozyme (chemical that lyses cells) Melanin – pigment shield against UV radiationMelanin – pigment shield against UV radiation
ExcretionExcretion
Limited amounts of Limited amounts of nitrogennitrogen containing containing wastes (most is excreted in urine unless you wastes (most is excreted in urine unless you have a kidney disorder in which case urea will have a kidney disorder in which case urea will be excreted in small amounts through skin)be excreted in small amounts through skin)
Sodium chloride through sweatSodium chloride through sweat Water through sweatWater through sweat Heat through sweatHeat through sweat
Homeostasis of Body TemperatureHomeostasis of Body Temperature
Heat production – chief determinant is muscle Heat production – chief determinant is muscle activityactivity
Heat loss/gainHeat loss/gain 80% of heat transfer is through the skin – the rest 80% of heat transfer is through the skin – the rest
is through the mucosa (dogs are opposite!)is through the mucosa (dogs are opposite!) Regulated by vasoconstriction & vasodilation Regulated by vasoconstriction & vasodilation
since heat is carried primarily in the water content since heat is carried primarily in the water content of the blood (reminder: on page 1 of notes)of the blood (reminder: on page 1 of notes)
Understand what is happening in these diagrams!!
Vitamin D ProductionVitamin D Production Vitamin D is important in Vitamin D is important in
the uptake of Calcium the uptake of Calcium from the food you eat.from the food you eat. Ca has to be absorbed from Ca has to be absorbed from
your stomach into the blood your stomach into the blood to go anywhereto go anywhere
Cholesterol molecules when Cholesterol molecules when exposed to UV light become exposed to UV light become a Vitamin D precursera Vitamin D precurser
Precurser becomes active in Precurser becomes active in the liver & kidneysthe liver & kidneys
Sensation – skin receptorsSensation – skin receptorsDon’t need to memorizeDon’t need to memorize
Free nerve ending = pain Free nerve ending = pain Meissner’s corpuscles = discriminating touch, Meissner’s corpuscles = discriminating touch,
light pressure (think fly on your arm)light pressure (think fly on your arm) Krause’s – coldKrause’s – cold Ruffini’s – heatRuffini’s – heat Merkel Disc – Medium pressureMerkel Disc – Medium pressure Pacinian corpuscle – Deep pressurePacinian corpuscle – Deep pressure
See diagram in notesSee diagram in notes
End of Quiz 2 MaterialEnd of Quiz 2 MaterialNow Study!Now Study!