- Slides: 42
Unit 3 PPT part 2 Skin color
Normal Skin Color Determinants · Determined by a combo of: · Types of pigments present · Blood circulation · Stratum corneum thickness Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 4. 14
Normal Skin Color Determinants · 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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 4. 14
Slide 4. 14 Normal Skin Color Determinants · 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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 4. 14
Blood flow · · · Vasodilation causes increase in flow – to release heat Vasoconstriction causes decrease in flow - to direct heat inward VERY important in body temperature homeostasis!!
Skin 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 · Pallor – paleness – lack of blood flow · Jaundice – yellowish color – liver damage · Hematomas – black & blue – blood under skin Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 4. 14
End of Worksheet #1 Material Remember to study pages 5 -7 of notes along with page 1
Hair 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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 4. 7 b Slide 4. 19
Hair anatomy n n Hair shaft – above skin Hair root – below skin
Appendages of the Skin · Hair · Shaft – projects from skin · Add in margins: Shape determines hair curliness · Flat = curly · Oval = wavy · Round = straight Slide 4. 18
Hair Follicle · Hair - Extends into dermis & hypodermis · Produced by hair bulb- expanded end · Papilla contains capillaries in bulb for hair nourishment · Matrix = growth zone actively mitotic– directly surrounds papilla Slide 4. 18
Associated Hair Structures · Arrector pilli · Smooth muscle regulated by SNS · Contraction pulls hair upright - Normally at angle Figure 4. 7 a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 4. 20
Arrector Pili Muscle
Hair 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. 7 b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 4. 19
Hair Types · Vellus hair – softer body hair · Terminal hair – coarser hair found in axillary & anogenital regions & other body regions · Lanugo – newborn baby fuzz Figure 4. 7 a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 4. 20
Hair Growth · Influenced by (in order): · Nutrition: main influence · hormones · Blood circulation Figure 4. 7 a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 4. 20
Discuss Growth Cycles
Thought Question: know the answers to these questions!! n n n Why is the hair on your head longer than the hair in your eyebrows? Why does some hair fall out every day? Approx 100 hairs per day are lost from your head! That is why your sink is stopped up!
Appendages of the Skin · Nails: 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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 4. 21
Nail Structure · Know all parts labeled on diagram · Why is lunula white? · What happens if matrix is damaged?
Sweat Glands · Sudoriferous (sweat) glands · Three types · Eccrine (merocrine) 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 p. H · Function: thermoregulation Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 4. 16
Sweat Glands • 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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 4. 17
Sweat Glands Ceruminous glands · Modified apocrine gland · Found in outer 1/3 of ear canal · Produce ear wax to trap “invaders” Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 4. 17
Appendages of the Skin · Sebaceous (holocrine) 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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 4. 15
Imbalances n n n Upper right hand box in notes; Acne – active infection of sebaceous glands Whitehead - Sebaceous gland duct blocked by sebum Blackhead – sebum oxidizes, dries, and darkens Seborrhea – “cradle cap” – Over activity of sebaceous glands in infants
Protection - biological n Biological protection – cells – macrophages & Langerhan’s cells engulf invaders.
Protection - mechanical n Mechanical – physical protection n Continuity – skin is made impermeable through the tight junctions & desmosomes Keratin – physically blocks the passage of water and water soluble substances FYI: Molecules that can pass through your skin: n Lipid soluble – O 2, CO 2, ADEK, steroids, nicotine, & other transdermal medications n Oleoresins – poison ivy & poison oak, etc – you have less than 10 min to wash it off!
Protection - Chemical n n Skin secretions: tears, sweat, oil lower p. H and contain lysozyme (chemical that lyses cells) Melanin – pigment shield against UV radiation
Excretion n n Limited amounts of nitrogen containing wastes (most is excreted in urine unless you have a kidney disorder in which case urea will be excreted in small amounts through skin) Sodium chloride through sweat Water through sweat Heat through sweat
Homeostasis of Body Temperature n n Heat production – chief determinant is muscle activity Heat loss/gain n n 80% of heat transfer is through the skin – the rest is through the mucosa (dogs are opposite!) Regulated by adjusting blood flow to skin through vasoconstriction & vasodilation since heat is carried primarily in the water content of the blood (reminder: on page 1 of notes)
Understand what is happening in these diagrams!! Might want to sketch it out for later study!
Vitamin D Production n Vitamin D is important in the uptake of Calcium from the food you eat. n n n Ca has to be absorbed from your stomach into the blood to go anywhere Cholesterol molecules when exposed to UV light become a Vitamin D precurser Precurser becomes active in the liver & kidneys
Sensation – skin receptors Don’t need to memorize n
End of Quiz Material Now Study!