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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

Slide Slide 4.144.14

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Determined by a combo of: Types of pigments present Blood circulation Stratum corneum thickness




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

14Slide 4.14


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




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



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



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



Hair

Shaft – projects from skin

Add in margins: Shape determines hair curliness

Flat = curly

Oval = wavy

Round = straightFigure 4.7c

Hair FollicleHair Follicle


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



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



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



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



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



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




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



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




• 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




Ceruminous glands

Modified apocrine gland Found in outer 1/3 of ear canal Produce ear wax to trap “invaders”




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!

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