Bio 103 Human Anatomy Integumentary System Notes
Bio 103 Human Anatomy Integumentary System Notes Biology 103
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This 7 page Class Notes was uploaded by Erika Chalker on Wednesday February 17, 2016. The Class Notes belongs to Biology 103 at California State University Chico taught by Gary Arnet in Fall 2016. Since its upload, it has received 37 views. For similar materials see Principles of Human Anatomy in Biology at California State University Chico.
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Date Created: 02/17/16
The Integumentary System Largest organ in the body Accessory organs are hair, nails, cutaneous glands (sweat/oil glands) Cutaneous Membrane is made up of the epidermis and dermis Subcutaneous tissue is made up of the hypodermis, deep fascia, and skeletal muscle Functions of the skin o Resistance to trauma and infection o Keratin makes up the protein o Many desmosomes o Bacteria cannot penetrate it o Retains water and is a barrier to water o First step of Vitamin D synthesis o Nerve endings make it the most sensitive organ in the body o Vasodilation= Blood vessel expansion o Vasoconstriction= Blood vessel constriction Skin is classified as thick or thin based on the thickness of the epidermis Epidermis Made up of keratinized stratified squamous epithelium Is avascular because nutrients are received from the dermis 5 layers of the epidermis: 1.Stratum Basale o Adult stem cells o One layer of low columnar to cuboidal shaped cells o Produce the basal lamina (basement membrane) 2.Stratum Spinousum o Has keratinocytes (cuboid to squamous shaped) o Synthesize keratin, which causes cells to flatten o Layer named for the spiny looking desmosomes o Usually the thickest layer of the epidermis o Keratinocytes migrate to the surface in 30-40 days 3.Stratum Granulosum o 3-5 layers of cells that have dark staining granules (can be seen under the microscope) o Where apoptosis (cell death) occurs 4.Stratum Lucidum o Translucent zone seen only in thick skin o Cells don’t have any organelles and cannot stain well 5.Stratum Corneleum o 30 layers of dead cells (no organelles) that are filled with keratin o Resistent to abrasion, penetration, and water loss Exfoliation= When cells come off the surface 2 Other cells of the Epidermis o Melanocytes= Found in the stratum basale. They produce melanin, which can be a brown or black pigment. There are the same amount of melanocytes in all people. o Merkel (tactile) Cells= Sensory receptors o Dendritic (Langerhans) Cells= Are macrophage cells that carry foreign materials to the lymph nodes in the immune system o Melanin shields DNA from UV radiation damage. However, in lighter skinned people, lysosomes digest melanin. Tanning blocks lysosome production, causing a mutation in DNA and causes cells to keep producing melanin nonstop, creating skin cancer. Dermis Mainly composed of collagen Has a large blood supply Contains= Cutaneous glands, hair follicles, and pilierector muscles. 3 layers in the Dermis: 1.Papillary (nipple shaped) o Superficial, is the top 20% of the dermis o Loose areolar connective tissue o Rich in blood vessels o Dermal Papillae= Resists slippage of the epidermis and has a vascular supply and nerves closer to the surface o Epidermal Ridge= Sweat glands that project downward 2.Reticular Layer o Deeper, 80% of dermis 3 o Thick bundles of collagen o Is made up of dense irregular connective tissue o Striae (stretch marks)= Stretching of the collagen o Langer Lines= Tension lines that keeps the skin under constant tension 3.Hypodermis o Not a true layer of the skin o Located below the dermis o Contains loose areolar and connective tissue o Supports and binds the dermis to the deep fascia and stores adipose tissue Skin Color 2 types of melanin 1. Eumelanin= Brownish black 2. Pheomelanin= Reddish yellow Hemoglobin= Red pigment of the blood Carotene= Yellow orange, concentrates in the stratum corneleum Diagnostic skin colors: o Cyanosis= Blueness of the skin from a lack of oxygen o Erythema= Redness of the skin from increased blood flow o Pallor= Pale skin from reduced blood flow o Albinism= White color from a genetic lack of melanin. Often have blue eyes o Jaundice= Yellow color from liver problems o Hematoma= A bruise 4 Hair A filament of keratinized cells that grows from a hair follicle (tube) Grows everywhere except lips, nipples, parts of genitals, and palms/soles Functions of the hair: o Scalp= Retains heat and blocks the sun o Torso= Is sensory, too little hair for heat retention o Auxillary/Pubic= Scent glands that advertise sexual maturity o Vibrissae (guard hairs)= Found in the nose, ears, and eyelashes. They protect orifices (openings) o Eyebrows= Facial expressions and sun protection 3 types of hair 1.Lanugo= Fine and downy unpigmented hair of the fetus 2.Vellus= Fine and unpigmented. 2/3 of it are on women, while 1/10 are on men. Kids have all of it. 3.Terminal= Course and pigmental, mostly found on ment 3 zones of hair 1.Bulb= Swelling at the base where the hair originates. The dermal papillae provide nutrition and the hair matrix is the hair’s growth center 5 2.Root= Remainder of the hair within the follicle. It is made up of dead tissue 3.Shaft= Portion above the skin surface 3 layers of hair 1.Medulla= Internal layer 2.Cortex= Bulk of hair made up of melanocytes 3.Cuticle= Outer layer, overlapping scaly cells Pilierector Muscle= Small muscles that cause the hair to stick up Sweat Glands 1.Merocrine= Most numerous glands o Produces perspiration to cool down the body o Mainly made up of water, 90% to be exact o Secretes to the surface of the skin in the sweat pores o Abundant on the palms, soles, and forehead o Simple tubular gland= Tube that is coiled up o Myoepithelial cells= Contractile cells that squeeze the fluid out 2.Apocrine Gland o Found in the groin, anal region, areola, axilla, and beard of males o Sweat is thicker because of more fatty acids o Is odorless o Doesn’t develop until puberty o Associated with sex pheromones o Bromhidrosis= Disagreeable body odor 3.Sebaceous Glands o Associated with hair o Produces an oily secretion called sebum 6 o Usually opens into the hair follicle and is found everywhere except thick skin o Keeps skin and hair from becoming brittle o Is a source of acne 4.Ceruminous Glands o Found in the auditory canal o Cerumen= Earwax, a combination of sebum and dead epidermal cells o Keeps the eardrum pliable, has a waterproof canal, kills bacteria, and coats guard hairs Skin Cancer Induced by UV rays Most commonly found in the elderly and fair skinned people 3 types of skin cancer 1.Basal Cell Carcinoma o Most common form of skin cancer o Least dangerous of them, it hardly metastasizes o Arises in the stratum basale and invades the dermis 2.Squamous Cell Carcinoma o Arises from keratinocytes of the stratum spinousum o Can metastasize to the lymph nodes o Can be lethal 3.Malignant Melanoma o Arises from melanocytes o Metastasizes quickly o Is often fatal if not treated quickly 7
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