Anatomy and Physiology Test 1
Anatomy and Physiology Test 1 BIOL 2500
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This 23 page Class Notes was uploaded by Jayne Molchan on Wednesday September 21, 2016. The Class Notes belongs to BIOL 2500 at Auburn University taught by Dr. Zachary Farris in Fall 2016. Since its upload, it has received 18 views. For similar materials see Anatomy and Physiology 1 in Biology at Auburn University.
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Date Created: 09/21/16
Anatomy & Physiology Day 1 Intro Hippocrates 460-377 BC Greek Hippocratic Oath Anatomy- study of structure - Gross (macroscopic) Anatomy: study of large, visible structures - Microscopic Anatomy: study of cells Physiology- study of function Organ Systems Integumentary – skin Skeletal -bones Muscular Nervous Endocrine -hormones Cardiovascular-heart Lymphatic -immune system Digestive Respiratory Urinary Reproductive Major Functions 1. Body covering 2. Support and movement 3. Integration and coordination 4. Transportation 5. Absorption and secretion 6. Reproduction Requirements of organisms Water, food, oxygen, heat, and pressure Homeostatic Mechanisms Stimulus>Receptors>Control Center>Effectors>Response - Negative Feedback Stimulus>Response> Return to Normal - Positive Feedback Stimulus> Response> Stimulus> More Response Anatomical Terminology Supine- subject is laying on their back face upward Prone- subject is lying on their belly face downward Bilateral- two-sided Affecting both sides equally. Ipsilateral- Located on same side of body, right arm and right leg Contralateral- on opposite side, right arm and left leg. Thoracic & Abdominal Membranes Visceral Layer- covers an organ Parietal Layer- lines a cavity or body wall Vocab to Know Pleural- Lungs Pericardium- Heart *know the different regions of the abdomen Chapter 3- Cells Cell Theory: 1. Basic structural and functional unit of living organisms 2. Activity of an organism depends on both the individual and combined activities of the cells 3. Biochemical activities of cells are dictated by their shapes and forms 4. Cells can only arise from other cells Major Parts of a Composite Cell: Nucleus: brain of the cell Cytoplasm: holds in place organelles Plasma Membrane: selectively permeable membrane that encloses cells o Controls what goes in and goes out o Cholesterol stabilizes the membrane o Proteins: Receptors Pores, channels, carriers Enzymes CAMS Self-markers o Phospholipid bilayer: water-soluble “heads” form surfaces; water- insoluble “tails” form interior; permeable to lipid-soluble substances o Tight junctions, Desosomes, Gap Junction (details in Ch.4 notes) Movements into and out of cell: 1. Passive Processes: no cellular energy required Simple Diffusion- o Movement of substances from regions of high concentration to regions of lower concentration (high to low concentration) o Unassisted diffusion o O2, CO2, and lipid-soluble substances Facilitated Diffusion- o diffusion across a membrane with the help of a channel or carrier molecule o EX. crowded in one room and empty in another but there is a door in the way; door is like a protein o large molecules unable to pass through phospholipid bilayer (glucose & amino acids) o Transport through- protein carriers, water filled protein channels Osmosis- o Movement of water through a selectively permeable membrane from high to low concentration; no cellular energy requirement o Water moves toward higher concentration of solutes o Osmotic Pressure- ability of osmosis to generate enough pressure to move a certain volume of water; increases as the concentration of non-permeable solutes increases o Hypertonic- higher osmotic pressure; more solutes in water o Hypotonic- lower osmotic pressure; more solutes in cell o Isotonic- same osmotic pressure Filtration- o Bulk flow transport o Smaller molecules are forced through porous membrane o Hydrostatic pressure important in the body o Faster than diffusion/ osmosis 2. Active Transport: carrier molecules transport substances across a membrane from low to high concentration; carries sugars, amino acids, sodium ions, potassium ion, etc. Vesicular Transport- large substances transported in vesicles o Endosytosis: brings substances INTO the cell Phagocytosis: engulfing molecules/bacteria; cell- eating Pinocytosis- engulfing water; cell-drinking o Exocytosis: removing substance from cell Primary Active Transport- involved ATP and transport proteins to move substances against the concentration gradient (low to high concentration) o EX. sodium ions/potassium ions, ATPase pump Secondary Active Transport- simultaneous movement of 2 substances through transport protein; 1 provides energy to move other o Not actively seeking movement o Sodium ion’s movement causes an alternate vacuum that moves other molecules o Co-Transport (symport): substances going in same direction o Counter Transport(antiport): substances going in opposite direction Membrane Potential: electrical charge on each cell across plasma membrane Resting Membrane Potential: inside cell is a strong negative charge relative to outside (~ -70 MV); created via diffusion of potassium ions (K+); membrane is more permeable to K+ than Na+; 3 Na+ flow out of cell membrane for every 2 K+ that flow in Establishing the Potential 1. K+ diffuse down their steep concentration gradient via leakage channels; loss of potassium ions(K+) result in negative charge on inner plasma membrane face. 2. K+ move into cell because attracted to negative charge inside cell 3. Negative membrane potential (-90mV) is established when the movement of K+ cells moving in and out of cell equals out. 4. Sodium ions (Na+) enters cell through leaky channels bringing resting membrane potential(RMP) to `-70 mV o Electrochemical Equilibrium: concentrations of Na+ and K+ are equal across the membrane; not beneficial; need voltage difference across the membrane b/c change in membrane potential causes muscles to contract and generates nerve impulses. Cytoplasmic Organelles Endoplasmic Reticulum o Transport system o Rough ER Studded with ribosomes Protein synthesis o Smooth ER Lipid synthesis: added to proteins arriving from rough ER break down of drugs Ribosomes o Free-floating or connected to ER o Provide structural support Golgi Apparatus o Stack of flattened, membranous sacs o Modifies, packages and delivers proteins Vesicles o Membranous sacs o Store substances Mitochondria o Membranous sacs with inner partitions o Generate energy Cilia o Short hair-like projections o Propel substances on cell surface Flagellum o Long tail-like projection o Provides motility to sperm Nucleus o Control center o Nuclear Envelope Porous double membrane Separates nucleoplasm from cytoplasm o Nucleolus Dense collection of RNA and proteins Site of ribosome production o Chromatin Fibers of DNA and proteins Stores information for synthesis Chapter 4- Tissues (Histology) Groups of cells that are similar in structure and perform a common or related function. Four types of Tissue: 1. Epithelial- covers; forms boundaries, lines body cavities, cells readily divide, tightly packed, protective barrier Epithelial Tissue: an epithelium; a sheet of cells that covers a body surface or lines a body cavity Special Characteristics of Epithelium: 1. Polarity o Apical Surface: upper free surface exposed to the body exterior or the cavity of an internal organ o Basal Surface: lower surface o Basal Lamina: non-cellular, adhesive sheet consists largely of glycoproteins secreted by the epithelial cells plus some collagen fibers; acts as selective filter that determines which molecules diffusing from the underlying connective tissue are allowed to enter the epithelium; acts as scaffolding. 2. Specialized Contacts o Tight Junctions: help keep proteins in the apical region of the plasma membrane from diffusing into the basal region; impermeable junction; among cells that form linings o Desmosomes: “binding bodies”, anchoring junctions; mechanical couplings scattered like rivets along the sides of adjacent cells to the prevent their separation; among outer skin cells o Gap Junctions: tubular channels between cells; located in cardiac muscle cells 3. Supported by Connective Tissue o Reticular Lamina: a layer of extracellular material containing a fine network of collagen protein fibers that belong to the underlying connective tissue. o Basement membrane: helps it resist stretching and tearing; defines the epithelial boundary 4. Avascular but innervated o Avascular: contains no blood vessels o Innervated: supplied by nerve fibers 5. Regeneration o High regenerative capacity Simple Squamous Epithelium o Single layer flattened cells with disc-shaped central nuclei and sparse cytoplasm o Function: Allows materials to pass by diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae. o Location: Kidney glomeruli; air sacs of lungs; lining of heart, blood vessels, and lymphatic vessels, lining of ventral body cavity Simple Cuboidal Epithelium o Single layer of cube-like cells with large, spherical central nuclei o Function: Secretion and absorption o Location: Kidney tubules, ducts and secretory portions od small glands, ovary surface Simple Columnar Epithelium o Single Layer of tall cells with round to oval nuclei o Function: Absorption; secretion of mucus, enzymes o Location: Digestive tract, gallbladder, excretory ducts of some glands Pseudostratified Columnar o Single layer of elongated cells differing heights o Nuclei at two or more levels o Secretes substances o Line respiratory passageways Stratified Squamous o Thick membrane; many cell layers o Top cells are flat;bottom cuboidal o Top w/ keratin and dead cells o Outer layer of skin o Protects underlying tissue o Epidermis(keratin); esophagus (non) Transitional o Resembles both stratified squamous and cuboidal o Stretches readily o Permits travel of urine o Ureters, bladder, uretha Glandular i. Endocrine- glands are ductless; secrete hormones ii. Exocrine- glands have ducts; secrete to skin or cavities 1. Unicellular- composed of one cell, goblet cell(mucous) 2. Multicellular- composed of many cells; sweat glands, salivary glands; simple and compound Tubular Secretory (trees in winter) Simple Tubular Simple Branched tubular Compound tubular Alveolar Secretory Simple Alveolar Simple Branched Alveolar Compound Alveolar Compound tubuloalveolar Merocrine Glands: Fluid product Salivary glands Pancreas Sweat glands Apocrine Glands: Cellular product Portions of cells Mammary glands Ceruminous glands Holocrine Glands: Secretory products Whole cells Sebaceous glands 2. Connective- supports; binds other tissues together; protection; insulation, transportation, stores energy Characteristics of Connective Tissue 1. Arise from mesenchyme 2. Cells widely scattered within extracellular matrix (except adipose) 3. Most Highly vascularized (except cartilage) Extracellular Matrix A. Ground Substance a. Tissue fluid, cell adhesion proteins, proteoglycans B. Fibers a. Collagen Fibers- made of collagen (a fibrous protein) b. Elastic Fibers-made of elastin (a rubber-like protein) c. Reticular Fibers- made of collagen Cell Types 1. Macrophages: eat foreign molecules 2. Fibroblast(forming): secrete fibers until they mature into fibroctyes 3. Lymphoctyes: immune response 4. Mast Cells: inflammatory response 5. Adipocyte: fat cell Four Classes of Connective Tissue: Connective Tissue Proper 1. Loose Connective Tissue: Areolar Tissue- wraps and cushions organs, inflammation, holds tissue fluid; packages organs, under epithelia body, surrounds capillaries Adipose Tissue- provides reserve food fuel, insulates against heat loss, protects and supports organs; under skin in subcutaneous tissue Reticular Connective Tissue- supports other cell types including white blood cells, mast cells, macrophages; lymphoid organs 2. Dense Connective Tissue: Dense Regular Tissue- attaches to muscles to bones or to muscles, attaches bones to bones o Ligaments- attach bone to bone o Tendons- attach muscle to bone o Aponeuroses- sheet-like, attach muscle to muscle or bone o Fascia- “plastic wrap” for muscle Dense Irregular Tissue- withstands tension; fibrous capsules of organs and of joints, dermis of the skin Elastic Tissue- allows tissue to recoil after stretching; walls of large arteries Cartilage Matrix- gel-like(80% water) Avascular o Nutrients from blood vessels in perichondrium Cells called chondroblasts mature into choncrocytes Can withstand tension and compression 1. Hyaline Cartilage- supports and reinforces; costal cartilages of the ribs,nose,trachea,larynx 2. Elastic Cartilage – maintains the shape of a flexible structure; supports the external ear 3. Fibrocartilage- tensile strength allows it to absorb shock; intervertebral discs,pubic symphysis, discs of knee Bone Matrix (calcium salts, collagen fibers) Vascularized Osteoblasts mature into osteocytes Types of Bone 1. Compact Bone Osteon (Haversion System)- fundamental unit Lamella- bone matrix ring Lacuna- space containing the osteocyte Central canal- haversion canal Volkmann’s canal- transverse canals Canaliculi- microscopic canals between lacunae 2. Spongy Bone Trabeculae- thin plates Blood Matrix (90% water) Red blood cells- erythrocytes, no nucleus White blood cells- leukocytes, nucleated o Neutrophils, lymphocytes, monocytes, eosinophils, basophils Platelets- thrombocytes, blood clotting 3. Muscle- produces movement; contracts, attaches to bones, heart, walls of hollow organs Characteristics of Muscle Tissue- Muscle fibers Contractile Types- 1. Skeletal Muscle a. Attached to bones b. Striated c. Voluntary 2. Smooth Muscle a. Walls of organs b. Skin c. Walls of blood vessels d. Involuntary e. Not striated 3. Cardiac Muscle a. heart wall b. involuntary c. striated d. intercalated discs 4. Nervous- controls; internal communication Characteristics Brain, spinal cord, and peripheral nerves Basic cells neurons Support and bind nervous tissue components Sensory reception Conduction of nerve impulses Chapter 6 Bones and Skeletal Tissue Functions: Protects Supports Movement/locomotion Mineral Storage Produces blood cells Energy Storage Hormone Production Axial Skeleton: Head, neck, trunk Appendicular Skeleton: Upper/lower limbs Pectoral girdle Pelvic girdle Classification: Long Bones Short Bones Flat Bones Irregular Bones Sesamoid Bones Bone Structure: Bone tissue predominates, but nervous tissue, cartilage, fibrous connective tissue, muscle cells, and epithelial cells are in its blood vessels Three levels of structures o Gross o Microscopic o Chemical Gross Anatomy: Parts of Long Bone Epiphysis o Distal o Proximal Diaphysis o Middle region o Compact bone o Contains medullary cavity o Filled with bone marrow Compact Bone o Outer part of bone Spongy Bone o Inside of bone Articular cartilage o Exists were bones meet o Hyaline cartilage Periosteum o The outer lining of bone; thin membrane o Full of blood vessels that carry nutrients Pass though shaft to medullary cavity via nutrient foramina o Outer- fibrous layer o Inner- osteogenic layer Contains osteogenic cells that differentiate into bone cells o Provides attachment points for tendons and ligaments Endosteum o Membrane that covers inside cavity o Lines the medullary cavity Dense irregular connective tissue Osteogenic stem cells Medullary Cavity o Red and yellow bone marrow; blood vessels o Trabeculae Gross Anatomy: Flat Bone Spongy bones covered by compact bone Has periosteum and endosteum No diaphysis or epiphysis Diploe=spongy bone of flat bones Skulls, sternum,s capla, ribs Gross Anatomy: Short Bones Roughly cube shaped bone Spongy bone covered by compact Periosteum and Endosteum No diaphysis and epiphyses Sesamoid Bone Type of short bone that form in a tendom Gross Anatomy: Irregular Bones Spongy bone covered by compact bone Have periosteum and endosteum No disphysis or epiphyses Vertebrae, coxal Bone Marrow: Red Bone Marrow o Hematopoiesis- blood cell formation o In newborns: medullary cavity, all areas of spongy bone o In adults: epiphyses of humerus and femur, in diploe and some irregular bones Yellow Bone Marrow o Stores fat o In adults: found mainly in medullary cavity Microscopic Anatomy of Compact Bone: a. Osteon- fundamental unit b. Lamella-bone matrix ring; form osteon i. Collagen Fibers ii. Run opposite directions c. Lacuna- space containing the osteocyte d. Central Canal- for blood vessels. Lymph vessels, nerve cells e. Volkmann’s canal- transverse canals; run perpendicular to central canal f. Canaliculi- microscopic canals between lacunae, connect all osteocytes of an osteon together; improve communication Microscopic Anatomy of Bone: 1. Osteogenic cells a. Found in periosteum/endosteum b. Miotically active c. Differentiate into osteoblasts 2. Osteoblasts a. Immature cells; forming b. Mitotically active c. Secrete bone matrix and enzymes for mineralization 3. Osteocytes a. Mature cells b. Multi-nucleated cells c. Differentiates from hematopoietic stem cells d. Bone resorption-break down bone 4. Bone-lining cells 5. Osteoclasts Bone Composition 1. Organic components- 35% of bone tissue by mass a. Cells (osteogenic, osteoblasts, osteocytes, osteoclasts) b. Osteoid- largely consists of Ground Substance and Collagen fibers c. Give bones flexibility and tensile strength 2. Inorganic Compounds- 65% of bone tissue by mass a. Hydroxyapatite= calcium phosphate salt is principal bone salt i. Found in and around collagen fibers in matrix ii. Gives bone its hardness and bone’s ability to resist compression Bone Development 1. Ossification (osteogenesis) is the process of bone tissue formation a. Formation of bony skeleton begins in month 2 of development b. Bone remodeling and repair are lifelong i. Endochondral: bone forms by replacing hyaline cartilage; forms most bones below cranial; begins at primary ossification center 1. Osteoblast secrete osteoid around diaphysis of hyaline cartilage=bone collar 2. Primary ossification Center: chondrocytes signal surrounding cartilage to calcify. Chrondrocytes die then cartilage matrix deteriorates forming cavities 3. Periosteal Bud: blood vessels, nerves, red marrow and bone cells invade the cavity and forms spongy bone 4. Osteoclasts in center break down nerly formed spongy bone creating medullary cavity. Cartilage along shaft calcifies, erodes and replaced with osteoid & hydroxyapatite. 5. Secondary ossification center: form epiphyses, cartilage calcifies, matrix deteriorates forming cavities, periosteal bud invades and forms spongy bone 6. Only hyaline cartilage remaining is articular cartilage and at epiphyseal plates ii. Intramembranous: bone develops from fibrous membrane; membrane bones; cranial bones of skull; mainly forms flat bones; starting material: mesenchyme 1. Mesenchymal cells differentiate into osteogenic (stem) cells and cluster in center of tissue. Then differentiate into osteoblasts 2. Osteoblasts secrete osteoid, which become calcified. Osteoblasts that get trapped in matric mature into osteocytes. 3. Osteoid is laid down between blood vessels forming trabeculae=woven bone. Periosteum forms on outside of woven bone from mesenchyme. 4. Just deep periosteum, trabeculae thicken. iii. Control of Remodeling: Remodeling occurs continuously but is regulated by genetic factors and two control groups o Hormonal Controls: Calcium functions in many processes such as nerve transmission, muscle contraction, blood clots Parathyroid Hormone(PTH): produced by parathyroid glands in response to low blood calcium levels; stimulates osteoclasts to resorb bone; calcium is released into blood, raising levels; PTH secretion stops with homeostatic calcium levels are reached Calcitonin: produced by parafollicular cells of thyroid gland in response to high levels of blood calcium levels; effects are negligible, but at high doses it can lower blood calcium levels temporarily o Response to mechanical Stress Bone Pathologies 1. Osteomalacia: in adults; deficiency of vitamin D or Ca resulting in bone demineralization a. Bones soften and weaken 2. Rickets: in children; deficiency of vitamin D or Ca a. Bones remain soft b. Bowed legs c. Deformities of pelvis, skull, rib cage 3. Osteoporosis: more bone resorption than formation a. Results in reduced bone mass b. bones weaken c. older age Chapter 7: Axial-Appendicular Skeleton Axial Skeleton: middle of body; 80 bones 1. Skull 2. Ear Ossicles 3. Hyoid Bone 4. Thoracic Cage 5. Vertebrae Functions: 1. Forms the longitudinal axis of the body 2. Supports the head, neck, and trunk 3. Protects the brain, spinal cord and organs of thoracic cavity Skull: Cranial and Facial Bones Skull consists of 22 bones; 8 cranial bones; 14 facial bones Sutures: interlocking joints; flat bones joined together o Frontal Bone o Parietal Bones: joined by sagittal suture o Occipital bone Foramen Magnum: hole where brain meets spinal cord Occipital Condyles: articulate with first cervical vertebra o Temporal Bone o Schenoid bone Keystone of cranium Sella Turcica: where pituitary gland sits o Ethmoid Bone Cribriform: form roof of nasal cavity Crista Galli: site of attachment for dura mater Perpendicular plate: forms superior portion of nasal septum Superior and middle nasal conchae: form part of lateral walls of nasal cavity Facial Bones Functions: Framework of face Cavities for special sense organs of sight, hearing, taste and smell Openings for air and passage of food Secure the teeth Anchor for facial muscles of expression 1. Mandible- anchors lower teeth 2. Vomer- forms part of nasal septum 3. Maxilla 4. Palatine Bones 5. Zygomatic Bones- cheek bones 6. Lacrimal Bones- form part of medial wall of orbits 7. Nasal Bones- forms bridge of nose 8. Inferior nasal conchae- form part of lateral walls of nasal cavity Hyoid Bone Attachment for tongues Ear Bones Functions: transmit and amplify soundwaves Malleus (hammer) Incus (anvil) Stapes (stirrup) Without these bones we would not hear. Vertebrae Cervical Vertebrae (C1-C7) Thoracic Vertebrae (T1-T12) Lumbar Vertebrae (L1-L5) Sacral Vertebrae (5 fused vertebrae) Coccyx (4 fused vertebrae) Intervertebral disc (collagen fibers) Anatomy Irregular bone Centrum=body, weight bearing region Spinous process (points posteriorly) Transverse Process (lateral projections) Vertebral Foramen- for spinal cord Superior and inferior articular processes Cervical Vertebrae Smallest and lightest vertebrae Transverse foramina= holes Atlas= C1 o No body, no spinous process, superior articular facets-articulate with occipital condyles Axis=C2 o Odontoid process- superior projection; allows head to pivot o No transverse foramina Thoracic Vertebrae Spinous process long, angled inferiorly Body is heart shaped Lumbar Vertebrae Larger, bulkier Spinous process short, hatchet shaped Sacrum 5 fused vertebrae Sacral Foramina- holes for passage of blood vessels and nerves Coccyx Tailbone 4 fused vertebrae Give some support for pelvic organs Attachment for muscles and tendons Thoracic Cage Protects organs of thoracic cavity Support shoulder girdles and upper limbs Attachment for muscles of neck, back, chest Sternum Fusion of three bones o Manubrium- articulate with clavicle and ribs 1-2 o Body- articulates with ribs 2-7 o Xiphoid Process- attachment point for some abdominal muscles Ribs 12 pairs 1-7= True Ribs o Directly attached to sternum by individual costal cartilages 8-12= False Ribs o first 3 pairs attach to sternum indirectly by shared costal cartilages 11-12= floating rib; no attachments Appendicular Skeleton Function: carry out movements Pectoral Girdle shoulder girdle attaches L and R arms to axial skeleton consists or scapula and clavicle = pectoral girdle where the clavicle and scapula meet is called the Acromioclavicular joint Humerus Brachial Region Trochlea- forms elbow joint Radius lateral forearm bone head slightly larger Ulna medial forearm bone trochlear notch Wrist and Hand Bones Carpals Metacarpals Phalanges Pelvic Girdle 2 Coxae = bilaterally symmetrical, fuse to sacrum supports trunk of body, protects viscera, acetabulum o Ilium- iliac crest, ilias spines, greater sciatic notch o Ischium- ischial spines, lesser sciatic notch o Pubis- obturator foramen, symphysis pubis, pubic arch Male: long and narrow, pubic arch <80 degrees, obturator foramen round in shape Female: short and wide, pubic arch 80-90 degrees, obturator foramen oval in shape Lower Limb Femur o Largest bone in body Patella Tibia o Medial, second largest bone in body, shin bone Fibula o smaller than tibia, lateral to tibia, does not support body weight Tarsals o ankle bones Metatarsals o first bones within the foot region Phalanges o toes Chapter 6-7 Skin largest organ in body 16% of body weight skin and accessory structures are the largest organ system skin is made up of multiple layers of cells and tissues o Epidermis Avascular Keratinized (keeps it water proof), stratified squamous Thickest on palms and soles Melanocytes provide melanin Rests on basement membrane Cell Types Keratinocytes o Produce keratin=protein, hardness, water- resist. o Produced at the basal layer of skin and migrates upward o Dead at surface o Millions slough off everyday Melanocytes o Secrete melanin- deep in epidermis o Dark colored cells o Melanosomes-intercellular vesicles; produce melanin o Shade the keratinocyte nucleus- UV protections, production is stimulated by UV. Merkel Cells o Found in epidermal/dermal junction o Associated with nerve endings, remember epithelial tisure does not have nerves o Merkel cell + nerve=touch receptor Langerhans’ Cells o Arise from bone marrow and migrate into epidermis o Function as macrophages engulfing bacteria, foreign particles and damaged cells o Macrophages that activate immune system o form a network layendin the epidermis- an immune barrier. 2 line of defense Major Layers in Epidermis o Stratum Corneum Cells completely dead Avascularized Outermost layer Replaced every four weeks o Stratum Lucidum Layers od dead cells; palms, feet Keratinized Avascularized o Stratum granulosum Alive with granules ( vesicles) Lamellar granules Keratin granules Lipid layer (extra protection), combined with keratin for water-proof layer o Stratum Spinosum Thick layer, largest layer (5-7 layers) Langerhans’ cells Immunity o Stratum Basale Deepest, most active layer Active mitosis, melanocytes Push new layer up o Dermis Core, innermost layer Contains dermal papillae Irregular dense connective tissue Hair follicles, blood vessels, nerve cells, muscle cells, glands Two layers: Papillary Layer o Just below stratum basal of epidermis o Areolar connective tissue with collagen and elastic fibers o Very vascularized o Capillary loops Reticular Layer o 80 % of dermis o collagen fibers o dense irregular connective tissue with large bundles of collagen and elastin o Subcutaneous (hypodermis) layer Lose connective tissue Adipose tissue Major blood vessels Anchors skin to underlying bone, muscle o Pigmentation 3 pigments: melatonin, Carotene, Hemoglobin Melanin Made of tyrosine (AA) Range in color Same number of melanocytes in all humans Freckles are local accumulations of melanosomes Light stimulates melanocytes to make melanin- tan o Accessory Structure of Skin Hair, nails and glands Sweat glands- Sudoriferous-Two main types Eccrine- sweat glands Apocrine- pinching Holocrine- whole cells Widespread in skin Orginated in deeper dermis or hypodermis Ceruminous glands-ear wax Modified apocrine glands found in the lining of ear Secrete a sticky bitter substance called cerumen Insect deterrent, block foreign objects from entering ear Mammary Glands Specialized sweat gland (modified apocrine gland)that secrete milk Sebaceous Glands Present everywhere Secrete sebum Made of oily lipid and cell fragments, oily holocrine secretion Softens and lubricates hair and skin Hair Heavily keratinized skin cells Originate from dermis Dead Sensory, heat loss, cushion, sunblock, filtration Anagen- growing phase Catagen- regressive phase Hair Follicles Pushed up by epidermal cells Tube-like depression Extends into dermis Hair root Hair shaft Hair papilla- rapid cell growth Dead epidermal cells Melantin – melanocytes-melanosomes produce melanin; color of shin Arrecter pili muscle-smooth muscle; causes hair to stand straight Nails Protective covering Keratinized Nail plate Nail bed Lunula Ability to grasp things Eponychium- cuticle Hyponychium-area under free edge Skin protects in 3 ways 1. Physical Barrier a. Limits entry of foreign materials b. Waterproof c. Hair-insulation 2. Biological Barriers a. Activates immune system b. Vermal macrophages c. DNA absorbs UV radiation 3. Chemical Barrier a. Skin secretions-acidic to slow bacterial growth b. Protected peoptides, melanin Body Temperature Regulation Increase in temperature stimulates sweat glands to begin secretory activity Evaporation of sweat pulls heat away from the body and cools us Cold weather blood vessels constrict so wardm blod bypasses the skin, allowing the skin temp to drop and conserve heat in the body core- cold hands Sensation Cutaneous receptors Epidermis- touch receptors; Meissner’s corpuscles Dermis- touch receptors, merkel cells Pain receptors- nociceptors Temperature receptors- thermoreceptors Pressure receptors Hair follicle receptors-hair movement Metabolism When skin is exposed to sunlight, cholesterol In the blood is converted to vit. D precursor Transported to the liver and the kidneys to be metabolized into vitamin d Vit d aids in Ca absorption in the small intestine Skin cells produce some important proteins Blood Reservior Holds 5% of blood volume, when organs need more blood Excretion Limited amounts of nitrogenous waste via sweat glands Disorders of skin Skin cancer o Basal Cell Carcinoma o Squamous Cell Carcinoma o Melanoma Cancer of the melanocytes and most dangerous Highly metastatic and resistant to chemotherapy Originate form preexisting moles that get larger Healing of Burns First Degree burn- superficial partial-thickness Second degree burn- deep partial-thickness Third Degree burn- full-thickness; autograft, homograft, various skin substitutes
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