Human Anatomy Lab 2 or the skin and bones lab

1. Human Anatomy Lab 2 (or the skin and bones lab) The Integumentary System and Intro to the Skeletal System

2. The Integumentary System Epidermis and Dermis Hypodermis Integumentary glands (sweat, oil, etc.) Hair and Nails

3. Skin Facts Largest organ of the body (15% of body weight) and most vulnerable to disease Fastest to regenerate Covers 1.5 – 2 square meters Most skin is 1 – 2 mm thick but can range from .5 – 6 mm The skin functions to: regulate body temp protect underlying tissue excrete H20 and salt receives stimuli for touch, pain, temp change, etc.

4. Overview of the Skin Epidermis stratified squamous epithelium (keratinized) contains 5 layers no blood vessels or sensory receptors Dermis connective tissue layer forms structural framework contains blood vessels and receptors for touch, pain, etc. Skin rests on subcutaneous layer or hypodermis not a layer of the integument, but anchors the integument to underlying tissue abundant adipose tissue

5. Functions of the Skin Barrier = tough, dry, acid mantle, water barrier, UV barrier Vitamin D synthesis begins in epidermal keratinocytes under influence of UV light helps maintain health of skeleton Sensory functions receptors for heat, cold, touch, pressure, vibration & pain Thermoregulation = thermoreceptors and sweat glands hypothalamus constricts or dilates cutaneous arteries and sweat glands to retain or dissipate heat Psychological and social functions appearance & social acceptance facial expression and nonverbal communication

6. Cell Types & Layers of the Epidermis

7. 5 Layers of the Epidermis

8. Stratum Basale Single layer of cuboidal or low columnar cells sitting on basement membrane Cell types in this layer keratinocytes undergo mitosis to replace epidermis most of cells of epidermis melanocytes synthesize melanin distribute melanin from cell processes melanin picked up by keratinocytes &used to shade their nuclei from UVradiation

9. Stratum Spinosum Several layers of keratinocytesthick Contains dendritic (Langerhans)cells macrophages from bone marrowthat migrate to the epidermis 800 cells/millimeter2 help protect body against pathogens by “presenting” them to the immune system

10. Stratum Granulosum 3 to 5 layers of flat keratinocytes Produces lipid-filled vesicles thatrelease a glycolipid by exocytosisto waterproof the skin forms a barrier between surface cellsand deeper layers of the epidermis cuts off surface strata from nutrient supply

11. Stratum Lucidum Thin translucent zone seen onlyin thick skin Keratinocytes are packed witheleidin, a precursor to keratin does not stain well Cells have no nucleus ororganelles

12. Stratum Corneum Up to 30 layers of dead, scaly,keratinized cells surface cells flake off (exfoliate)

13. The Dermis Thickness = 0.6mm to 3mm Composition Dense Irregular Connective Tissue Dermal papillae are upward extensions of the dermis into the epidermis forming the ridges of the fingerprints Layers papillary layer is areolar tissue & dermal papillae of upper 1/5 of the dermis reticular layer is deeper part of dermis

14. Layers of the Dermis Papillary layer Reticular layer

15. Dermis Responsible for the structural integrity of the integumentary system Composed primarily of closely bundled fibers (mostly collagen) along with blood vessels, nerves, sensory receptors, hair follicles, and glands

16. Sensory Receptors in the Dermis Sensory information in the dermis is received by several structures: Light touch corpuscles – allow for the perception of very light touch stimuli Meissner’s corpuscles (upper dermis) Merkel discs (upper dermis, lower epidermis) Deep touch (pressure) receptors Pacinian

17. Other Sensory Receptors in the Dermis Warm and Cool receptors both are firing when we are at a comfortable temperature Pain receptors naked nerve endings in the dermis that respond to numerous environmental stimuli

18. The Hypodermis Known as subcutaneous tissue or superficial fascia Has more adipose than dermis Functions energy reservoir thermal insulation Hypodermic injections into subcutaneous tissue since highly vascular

19. Cutaneous Glands Sudoriferous (sweat) glands merocrine apocrine Sebaceous (oil) glands Ceruminous (earwax) glands Mammary glands

20. Sweat Glands Filtrate of plasma containing some waste products 500 ml of insensibleperspiration/day sweating with visible wetnessis diaphoresis Merocrine glands is simpletubular gland millions of them (size of kidney) cool the body Apocrine glands produce sweat containing fatty acids found only near hair follicles & respond to stress bromhidrosis is body odor produced by bacterial action on fatty acids

21. Sebaceous Glands Oily secretion called sebum that contains broken-down cells lanolin in skin creams is sheep sebum Flask-shaped gland with duct that opens into hair follicle

22. Ceruminous Glands Found only in external ear canal Their secretion combines with sebum to produce earwax waterproof keeps eardrum flexible bitterness repel mites & other pests

23. Mammary (lactiferous) Glands Breasts of both sexes rarely contain glands secondary sexual characteristic of females mammary glandular tissue found only during lactation and pregnancy modified apocrine sweat gland thicker secretion released by ducts open on the nipple

24. Structure of Hair Follicle Epithelial root sheath is an extension of the epidermis (lies next to hair root) Connective tissue root sheath is derived from the dermis (surrounds it) Hair receptors entwine each follicle Arrector pili muscle goose bumps

25. Functions of Hair Body hair too thin to provide warmth alert us to parasites crawling on skin Scalp hair provides heat retention & sunburn cover sex and individual recognition Beard, pubic & axillary hair indicate sexual maturity & help distribute sexual scents Guard hairs & eyelashes prevent foreign objects from getting into nostrils, ear canals or eyes Expression of emotions with eyebrows

27. Axial and Appendicular Skeleton

28. Bone as a Tissue Dynamic tissue that continually remodels itself Bones and bone tissue bone or osseous tissue is a connective tissue with a matrix hardened by minerals (calcium phosphate) Bones make up the skeletal system individual bones are made up of bonetissue, marrow, cartilage & periosteum

29. Composition of Osseous Tissue Dry weight is 30% organic & 70% inorganic matter Organic matter collagen, glycosaminoglycans, proteoglycans & glycoproteins Inorganic matter 85% hydroxyapatite (crystallized calcium phosphate salt) 10% calcium carbonate other minerals (fluoride, sulfate, potassium, magnesium) Combination provides for strength & resilience minerals resist compression; collagen resists tension bone adapts to tension and compression by varying proportions of minerals and collagen fibers

30. General Features of Bones Shaft (diaphysis) A cylinder of compact bone containing marrow cavity (medullary cavity) & lined with endosteum Enlarged ends (epiphyses) are spongy bone covered with a layer of compact bone enlarged to strengthen joint & provide for attachment of tendons and ligaments Joint surface covered with articular cartilage (reduces friction) Remainder of bone covered with periosteum outer fibrous layer of collagen fibers continuous with tendons or perforating (Sharpey’s) fibers that penetrate into bone matrix inner osteogenic layer important for growth & healing Epiphyseal plate or line depends on age

31. Structure of a Long Bone

32. Epiphyseal Plates

35. Periosteum Dense connective tissue sheath covering the outer surface of bone house osteoblasts which function to produce more bone mass site where nerves and blood vessels occur on outer surface of bone anchoring point for tendons and ligaments

36. Bone Classification Bones come in many different shapes, sizes, etc. Based on shape, bones can be classified into four different categories Long Bones Short Bones Flat Bones Irregular Bones

37. Shapes of Bones

38. Microscopic Structure of Bone The modular unit of bone is called an osteon Each osteon has a hole in the middle called the central (haversian) canal serves to house blood vessels and nerves Around the central canal are rings called lamellae layers of dense mineral salts Between these rings are open areas called lacunae house osteocytes connected by thin tubes called canaliculi Canaliculi connect to the central canal

39. Microscopic Structure of Bone

40. Fig. 7.4c

41. Bone Cell types Osteoblasts active bone forming cells Osteocytes most common cell type strain sensors that tell osteoblasts to deposit more bone Osteoclasts break down bone

42. Next Week Quiz #2 Lab #9: Appendicular Skeleton Excercises Lab 7: 1-6, 12-17, 19, 21 Lab 8: 1-10, 12-15