10:19:2021 lecture chapter 6 Integumentary system PDF

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Comprehensive lecture notes from Anne Dower's lecture. Good luck...

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Lecture 10/19/2021 Tuesday, October 19, 2021

7:50 AM

Integumentary System:

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• Skin • Hair • Nails • Sweat glands • Sebaceous (oil) glands Functions of Integumentary System: • Protection ○ Protect the deeper underlying structures ○ Ex. Mechanical abrasions § UV exposure from the sun • Immunity ○ Creates a barrier from foreign objects from getting inside the body ○ Immune cells are found within the skin • Sensation ○ Detect heat, pain, different types of sensations • Thermoregulation ○ The skin can preserve our temperature ○ Release heat ○ Conserve heat § Blood can carry heat. When blood vessels dilate, it means they get bigger □ More blood is coming when the blood dilates making more heat □ (not going to be on the exam about blood vessels dilate) • Waterproofing ○ Keratin is found on the skin and waterproofs our skin ○ Preserves homeostasis, makes sure our cell isn't going to shrivel up or taking in t • Secretion and Absorption: ○ Secretion from our glands ○ Can absorb products § Sunlight

o much water

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§ Drugs Vitamin D synthesis: ○ Convert sunlight into vitamin D ○ (need to know just this for now, gets more into it in the skeletal system) Communication: ○ Key to achieving homeostasis ○ Nerves can send signals to the brain

Skin: • Epidermis: ○ Superficial region that we have ○ Epithelial tissue § What type of ET? Keratinized squamous ○ Avascular • Dermis: ○ Underlies epidermis ○ Papillary layer § Areolar connective tissue ○ Reticular layer § Dense irregular connective tissue • Hypodermis: (Not part of the skin) ○ Subcutaneous layer ○ What type of CT? § Adipose § Areolar Cells of the Epidermis: (KNOW WHERE THEY ARE, LOCATION, WHERE THEY ARE IN THE EPID • Keratinocytes: ○ Major cell of epidermis ○ Produce Keratin • Melanocytes: (don’t need to know the shape) ○ Spider-shaped cell ○ Produce melanin § Pigment ○ Located in deep epidermis • Dendritic (Langerhans) Cells ○ Star-shaped macrophage ○ Patrol the deep epidermis ○ Activate immune system • Tactile (Merkel) Cells:

RMIS)

Oval cells Located in deep epidermis Sensory receptors § Touch Layers of the Epidermis: • Thick skin: Superficial ○ Stratum corneum ○ Stratum lucidum ○ Stratum Granulosum ○ Stratum spinosum ○ Stratum Basale deep § Layer that is next to the dermis ○ (found in hands and feet) • Thin Skin: ○ Stratum Corneum ○ Stratum granulosum ○ Stratum spinosum ○ Stratum Basale ○ (Found in almost all of your body) • PNEUMONIC: ○ Come, Lets Get Sun Burn! Stratum Basale: (makes cells, new cells get pushed up superficially) • Deepest epidermal layer • Attached to the dermis • Very thin, about 1 layer in here • Stem cell ○ Cell division occurs here ○ New cells get pushed up and the old cells get sloughed off from the skin • Consists of: ○ Keratinocyte stem cells ○ Melanocytes § They make pigment, melanin ○ Tactile (Merkel Cells) § Helps with touch reception Stratum Spinosum: • 8-12 layers • Daughter cells from stratum Basale • Consists of: ○ ○ ○

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Need to know the layers of the epidermis, order from superficial to deep and vice versa

EED TO KNOW: 1. Where the location 2. How many layers are in there 3. What type of cells are in there

Spikey-looking keratinocytes § No keratinocytes in here though § Melanocytes § Dendritic cells Stratum Granulosum: • 4-6 layers of thin keratinocytes • Keratinization begins ○ Keratinocytes fill with keratin ○ Nucleus and organelles disintegrate ○ Beginning to die, grey transition zone § Could be some dead cells, could be some alive cells Stratum Lucidum: • Only in thick skin • Thin, translucent band of keratinocytes ○ 2-3 rows ○ Flat § No nuclei, no organelle because they are dead ○ Dead § They are dead because as you get my superficial, you are moving away fro § The dermis is the blood supply § If there are no blood or nutrients being supplied to the cell, they will end u ○ Filled with protein, eleidin § NOT filled with keratin, the step before § Gives the cell a white, translucent look. Stratum Corneum: • Most superficial layer • 20-30 rows of keratinized cells ○ Anucleated ○ Dead • Sloughed off • Calluses • Provide majority of skin functions Review Questions: One day as you were walking out of the ocean, you stepped on a spiky sea urchin. Sta where the spike penetrated the foot, what is the order of epidermal layers the spike p 1. Stratum lucidum 2. Stratum basale 3. Stratum granulosum ○

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the dermis dying

ting from the point netrates through ?

4. 5. A. B. C. D.

Stratum corneum Stratum spinosum 1,2,3,4,5 4,1,3,5,2 4,3,5,2 2,5,3,1,4 If the spiky sea urchin damaged dead keratinocytes, what epidermal layer(s) is(are) b 1. Stratum Corneum 2. Stratum lucidum If the spiky sea urchin damaged melanocytes, what epidermal layer(s) is(are) being p 3. Spinosum 1. Basale

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Dermis: • Two layers ○ Papillary ○ Reticular • Cells/contents: ○ Fibroblasts ○ WBC's § Macrophages § Mast cells ○ Nerves ○ Blood vessels ○ Hair follicles ○ Sebaceous glands ○ Sweat glands

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Dermis Papillary Layer: • Superficial layer: ○ Areolar connective tissue • Fingerlike projections into epidermis ○ Dermal papillae: § Blood vessels § Nerves • Friction ridges ○ Only in thick skin ○ Dermal and epidermal folds and valleys

ng penetrated?

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Contain sweat pores § Fingerprint Dermis: Reticular Layer • Composes~ 80% of dermis • Dense Irregular connective tissue ○ Irregularly arranged collagen bundles ○ Few elastic fibers Tension/Collagen Lines and Striae: • They make specific patterns on the body • Gaps between collagen fibers • Affect healing rates and formation of scars ○ Want to go parallel with the tension lines ○ If you go perpendicular, it damages collagen fibers and forms scars • Striae: stretch marks Hypodermis: • Subcutaneous layer • NOT PART OF THE SKIN • Function: ○ Anchors skin to deeper structures • Composed of: ○ Areolar CT ○ Adipose Tissue • Abundant blood supply Skin Pigmentation: • Melanin ○ Mostly determines skin color § Not about how many melanocytes, but how rather how much melanin do t produce ○ Protects keratinocyte DNA § UV exposure § Don’t want mutations to occur □ Sets us up for the formation of cancer ○ Variations of pigmentation: § Freckle □ Melanin accumulation in one spot § Mole/Nevus □ Raised feeling, because it is an overgrowth of melanocytes in the are § Albinism ○

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ese melanocytes

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□ More at risk for mutating the DNA as well ○ Carotene: § Yellow-orange □ Get it from eating foods like carrots ® If you eat too many carrots, you can turn orange LOL □ Turns Carotene into vitamin A for eyes and other functions ○ Hemoglobin: § Pinkish-red § Found in red blood cells § More present in people who have fair skin Accessory Structures of the Integument: Hair, Nails, And Glands • Hair: ○ Dead keratinized cells ○ Located everywhere on the body except § Palms § Soles § lips § Lips external genitalia ○ Functions: § Protection □ Ex. Eyelashes, stops things from getting into our eyes § Facial expression □ If you furrow your brows, you can tell their angry etc. § Heat retention □ Not as good in humans but hair conserves heat § Sensory reception □ Hair acts as nerve receptors, pain, sensation § Visual identification □ Describe someone with their hair • Hair Structure: ○ Regions: § Shaft: □ Extends from the scalp □ Keratinization is complete § Root: □ From bulb to surface □ Keratinization is complete Surrounded by hair follicle § Bulb: S lli tb

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Swelling at base Deep in dermis Keratinization is occurring

Goosebumps: ○ Connected to each of our hair follicles is the arrector pili muscle relaxed § Not standing straight up, like a 45 degree angle relaxed § Contracts due to stress, fear, temperature □ Causes the hair to stand straight up, looks like a pimple ® Called GOOSEBUMPPPPP Internal Hair Structure: ○ Cuticle: § Single layer of keratinocytes § Contains hard keratin □ Keratinocytes are filled up with hard keratin ® Different from the keratin on our skin, soft keratin □ More for mechanical protection for the deeper layers ○ Cortex: § Multiple layers of keratinocytes § Contains hard keratin ○ Medulla: § Only found in thick hair § Central core of keratinocytes § Contains soft keratin § Doesn’t really need protection cause it's the deepest layer in there Hair Growth: ○ Similar to how skin cells move up and die ○ The deepest layer is the Hair Matrix (like the stratum Basale): § Where you have the stem cells and where cell division is occurring § When the cell divides, the daughter cells get pushed up towards the super § As long as it keeps dividing, our hair will keep growing and break through t ○ Hair Papilla (blood vessels and nerves): § Dermal tissue § Contain capillaries § Sensory receptors § Provide nutrients and blood supply □ The further you get away from this, the hair is going to die Hair Growth contiued: ○ Stages: § Growth:

ial layer e surface

Growth: □ Cells divide and push cells further from blood supply □ 1-1.5 cm/month □ Duration varies § Resting: □ Mitosis in matrix ends ® Mitosis is complete, cell division stops, no hair growth occurs h □ Hair is pushed towards surface ® The hair falls out or pushed out by a new cycle of hair growth ® Not every part of our hair is part of the same cycle § Hirsutism: □ Hairiness increases □ Happens in people that are female □ Hair growth grows hair where men typically have hairs growing like t § Spot Baldness: □ Circular bald patches □ Hair loss in a circular pattern § Diffuse Hair Loss □ From scalp ® Excessive hair loss □ Usually hormonal related, see this more in women ® Due to nutrition deficiency or iron deficiency § Pattern Baldness: □ Crown region of scalp ® Back of the hair is bald and moves forehead □ Genetic and hormonal factors Hair Pigment and Texture: § Pigment: □ Melanin: ® Increase or decreased production ® Different types § Texture: □ Lanugo ® Thin, nonpigmented hair ◊ Covers all of your body and hair falls out ® 3rd trimester (during development) □ Vellus ® Pale, fine hair ◊ Unpigmented §

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◊ Unpigmented ® Primarily upper and lower limbs ® Once you reach puberty it changes Terminal: ® Coarse, thick, pigmented hair ® Found on ◊ Scalp, eyebrows, axillary and pubic regions ® More terminal hair on men than women

Nails: ○ Composed of stratified squamous epithelium § Filled with keratin ○ Functions: § Protective cover § Tool Nail Structure: (KNOW THESE TERMS AND CAN YOU IDENTIFY THEM ON AN IMAGE) ○ Nail plate § Most visible structure § Divided into 2 parts □ Nail body and nail root ○ Free edge § Extending from the distal end from the nail body § No tissue, no nail bed underneath it § This is what we cut ○ Nail body § Superficial to tissue underneath § Nail body covers nail bed § Made up for keratinized squamous epithelium ○ Nail root § Cant really see it because it is deep to our skin ○ Nail bed § Nail body covers nail bed ○ Nail matrix § Actively dividing cells just like the hair matrix § Where the growth is going to occur in the matrix ○ Lunula § Proximal to the free edge, moon looking thing at your nails § More keratin is found in the area ○ Nail folds ○ Eponychium (cuticle)

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§ Skin proximal region around the nail Hyponychium § Division of where the free edge meets the nail bed § Where dirt and debris get caught into it Lateral and medial folds: § Just skin...