Introduction to the Human Body PDF

INTRODUCTION TO THE HUMAN BODY Human anatomy – scientific study of the body's structure Microscopic anatomy – observed with only a microscope Cytology – study of cells Histology – study of tissues Gross anatomy – larger structures can be readily seen, manipulated, measured, and...

INTRODUCTION TO THE HUMAN BODY Human anatomy – scientific study of the body's structure Microscopic anatomy – observed with only a microscope Cytology – study of cells Histology – study of tissues Gross anatomy – larger structures can be readily seen, manipulated, measured, and weighed Regional anatomy – study of interrelationships in a specific body region Systemic anatomy – study of structures that make up a body system "anatomy" is the where, "physiology" is the how Physiology – study of the chemistry and physics of the structures of the body Form is closely related to function Evolution – change in gene expression Homeostasis – state of dynamic stability of the body's internal conditions Setpoint – normal physiological value Negative feedback – reverses a deviation from the setpoint Positive feedback – intensifies a change in the body's physiological condition Levels of Organization All matter in the universe is composed of unique pure substances called elements Atoms – smallest unit of pure substances Molecules – two or more atoms, the chemical building blocks of all body structures Cell – smallest functioning unit of a living organism, basic unit of life Organelles – functions inside the cell encased by cell membrane Tissue – group of cells that work together to perform a specific function Organ – composed of two or more tissue types Organ system – group of organs that perform major functions Anatomical Terminology Anatomical position – standard position of the body Prone – a face-down orientation of the body Supine – a face-up orientation of the body Directional Terms Anterior – describes the front of the body Posterior – describes the back of the body Superior – describes a position above or higher of the body Inferior – describes a position below or lower of the body Lateral – describes a structure toward the side of the body Medial – describes a structure toward the middle of the body  Superficial – describes a position closer to the surface of the body Deep – describes a position farther from the surface of the body Proximal – describes a position on a limb that is nearer to the point of attachment Distal – describes a position in a limb that is farther from the point of attachment Regions of the Human Body Sections and Planes Section – a slice of three-dimensional structure Plane – an imaginary slice through the body used in imaging Sagittal plane – plane divided vertically into right and left sides Midsagittal or Median plane – Sagittal plane directly down the middle Parasagittal or longitudinal plane – Sagittal plane unequal on each side Frontal plane – divides the body into anterior and posterior planes Transverse plane – divides the body horizontally into upper and lower portions Organization and Compartmentalization Serous membrane (serosa) - thins membranes the line thoracic and abdominopelvic cavities Parietal layers – line the walls of the body cavity Visceral layers – covers the organs Between the parietal and visceral layers is a very thin, fluid-filled serous space. Pleura – serous membrane of pleural cavity Pericardium – serous membrane of pericardial cavity Peritoneum – serous membrane of abdominopelvic cavity THE CELLULAR LEVEL OF ORGANIZATION Theories of Origin of Life 1. Spontaneous Generation or Abiogenesis – life originated from non-living things 2. Biogenesis – reproduction of life comes from pre-existing life, affirms the genetic theory of the origin of life 3. Cosmozoic Theory – living forms came from interstellar space then to earth 4. Special Creation Theory – supernatural power 5. Naturalistic or Physico-Chemical Theory – evolution and aggregation Basic Characteristics of Living Organisms Organization Irritability or sensitivity Movement Growth Reproduction Metabolism ○ Anabolism – forms complex substances from simple ○ Catabolism – breaks down complex substances Adaptability The Protoplasm – living substance of the cell. Properties of The Protoplasm a. Physical properties Heterogenous Colloidal Translucent, colorless, slimy, and viscous fluid Brownian movement Tyndall effect b. Chemical properties 1. Composed of elements 2. May be organic or inorganic compounds c. Physiological properties 1. Dissolves 2. Moistens surface for gas diffusion 3. Regulates body temperature 4. Helps sense organs  5. Lubricant for moveable surfaces 6. Cushion for brain and spinal cord Lipids – fat soluble compounds (CHO) Classification of Lipids Steroids – solid alcohols Simple lipids – contain glycerol and fatty acids Complex lipids – simple lipids plus other substances Three Major Types of Lipids Triglycerides – fatty acids (3 hydrocarbon chains) Phospholipids – two fatty acids Steroid – four interlocking rings of carbon atoms Proteins – most abundant in the protoplasm (CHON) Types of Proteins Fibrous – parallel polypeptides Globular – polypeptides tightly folded into spheres Conjugated – Simple protein with other substances Structure and Composition of the Cell Membrane Cell membrane – elegantly flexible structure composed of single layer phospholipids Phospholipids – make up approx. 50% of the cell membrane by weight "Head" - negatively charged, polar and hydrophilic "Two Fatty Acid Tails" - uncharged, nonpolar and hydrophobic Therefore, phospholipids are amphipathic Human tissues are aqueous environments Intracellular fluid (ICF) - fluid interior of the cell Extracellular fluid (ECF) - fluid environment outside of the cell membrane Interstitial fluid (IF) - ECF not contained within blood vessels; plasma is ECF within blood vessels Membrane Proteins Transmembrane protein – is a protein that spans the membrane from its intracellular to its extracellular side Channel proteins – allows select materials to pass into or out of the cell Receptors – selectively bind a specific molecule outside the cell and translate the binding into a chemical reaction inside the cell Ligand – the specific molecule that binds to and engages the receptor Glycoprotein – a protein with carbohydrate molecules attached  Many are form a coat called glycocalyx Peripheral Proteins – can be anchored to interior and exterior but do not the span the membrane Transport Across the Cell Membrane The membrane is often referred to as selectively permeable Concentration gradient – difference in concentration of a substance Passive transport – movement along the concentration gradient and does not consume ATP (downhill movement) Diffusion - term for the movement of molecules Facilitated diffusion – diffusion of molecules down their concentration gradient Osmosis – diffusion of water through a semipermeable membrane Isosmotic – two solutions that have the same concentration of solutes Tonicity – describes the osmolarity of the ECF and ICF Isotonic – the concentration of water molecules is the same outside and inside the cell (remains the same) Hypertonic – more solute, water moves out of the cell Hypotonic – less solute, water moves into the cell Active transport – against the concentration gradient and uses energy from ATP (uphill movement) Primary Active Transport – directly uses ATP Sodium-Potassium pump – transports sodium out while moving potassium into the cell Secondary active transport – uses concentration gradient of a molecule for a second molecule Symporters – moves two substances in the same direction Antiporters – moves two substances in opposite directions Endocytosis – taking a material in by enveloping it in a portion of its cell membrane (vesicle = a sac inside the cell) Phagocytosis – endocytosis of large particles Pinocytosis - "cell drinking" Receptor-mediated endocytosis – when membrane-bound receptors bind their ligand Exocytosis – exporting material by wrapping the material in a vesicle, and then fusing the vesicle with the plasma (ECF) The Cytoplasm and Cellular Organelles Cytoplasm – watery inside of the cell with all its compartments and organelles Cytosol – jellylike substance within the cell that is necessary for biochemical reactions and functions of the cell  Organelles – functioning units found within the cell or cytosol Nucleus – largest organelle and contains DNA Endoplasmic Reticulum (ER) - system of channels that is continuous with the membrane of the nucleus Rough ER – has ribosomes attached (deals with proteins) Smooth ER – absence of ribosomes (lipid synthesis, detoxification, and storage) Golgi apparatus – sorting, modifying, and shipping off the products from the Rough ER Lysosomes – digests unneeded cellular components, such as a damaged organelle Autolysis "self-destruct" and Apoptosis "purposeful death" Peroxisomes – similar to Smooth ER, performing lipid metabolism and chemical detoxification Mitochondrion – "energy transformer" of the cell Inner membrane (with folds called cristae) - metabolic processes Outer membrane – protection, structure, etc. The Cytoskeleton – made up of fibrous proteins Microtubules – thickest tubulin protein, maintains cell shape and structure Microfilaments – thinner actin protein, move the whole cell Intermediate filaments – intermediate in thickness, maintains cell shape structure Centrioles – cellular origination point for microtubules Cell Surface Specializations Microvilli – expands the surface area of a cell Cilia – move waste materials Flagellum – appendage larger than a cilium, for cell locomotor The Nucleus and DNA Genome – Full set of genetic instructions of an organism Nuclear membrane – consists of two adjacent lipid bilayers with thin fluid space between (in contrast to cell membrane with one bilayer of phospholipid) Nuclear pore – tiny passageway for proteins, RNA, and solutes between the nucleus and cytoplasm Nucleolus – region responsible for manufacturing the RNA Histone – stored DNA Nucleosome – DNA-histone complex Chromatin – loosely organized DNA Chromosomes – condensed form of chromatin Proteome – full complement of proteins Gene – a segment of DNA that provides genetic information to build a single protein IMPORTANT NOTE: DNA strands are antiparallel. Therefore if one strand is 5' to 3', then the complementary strand would be 3' to 5' DNA to RNA: Transcription mRNA "messenger" – a single stranded nucleic acid that carries a copy of the genetic code for a single gene out of the nucleus and into the cytoplasm 1. Initiation – DNA strands are separated by RNA polymerase and begins to synthesize a complementary RNA molecule 2. Elongation – RNA polymerase adds new nucleotides 3. Termination – RNA polymerase reaches the end of the gene and mRNA transcript are released from the DNA strand Splicing removes noncoding regions RNA to Protein: Translation rRNA "ribosomal" - what makes up ribosomes, the site of protein synthesis tRNA "transfer" - carries amino acids to the ribosome 1. Initiation – assembly of ribosome subunits around and mRNA transcript 2. Elongation – with various enzymes and energy, the tRNA adds amino acids to the matching anticodon of the growing polypeptide strand 3. Termination – after reaching the final codon, the "stop" message signals termination and a newly synthesized protein is complete Somatic cells – general term for body cells except the cells that produce sperm and eggs Germ cells – cells that produce sperm and egg cells Most human somatic cells contain 23 homologous pairs of chromosomes (haploid number), subsequently with 46 sister chromatids The Cell Cycle Mitosis – division of genetic material, into two identical cells with the same DNA of the parent Meiosis – germ cells produce egg and sperm cells with half of the original DNA of the parent Interphase – when the cell is not replicating where most of cellular life is spent, grows and carries out functions of the cell G1 phase – cells are growing, making proteins, and carrying out functions Synthesis – cell replicates DNA G2 phase – continues to grow and prepares for mitosis Note that there are several checkpoints during interphase, faulty will give the cell time to repair but it may self-destruct if beyond repair DNA Replication i. Initiation – two complementary DNA strands are separated by DNA helicase and other enzymes ii. Elongation – DNA polymerase, assisted by primase, synthesizes the complementary strand of DNA  iii. Termination – once the two strands are bound to each of their new complementary strands, DNA replication is sealed by ligase and hence a product of two identical DNA molecules Prophase – DNA condenses into chromosomes, the spindle begins to form, and nuclear membrane begins to disintegrate Metaphase – chromosomes line at the center (Metaphase plate) and moved by the microtubule spindles Anaphase – chromatids are pulled away from each other by the spindle to opposite poles of the cell Telophase – DNA begins to revert to chromatin, nuclear membrane begins to form, spindle begins to disintegrate, and the presence of a cleavage furrow–microfilaments (actin) Cytokinesis – splits into two new cells (daughter cells) Stem cells – unspecialized cells that can differentiate into specialized cells THE TISSUE LEVEL OF ORGANIZATION Tissue – group of cells functioning together Histology – microscopic study of tissue Cellular Connections 1. Tight junctions – fuses cells tightly, blocks the movement of substances 2. Anchoring junctions – stabilize cell structurally and provide strong and flexible connections a. Desmosomes – unite two cells b. Hemidesmosomes – links cell to ECM 3. Gap junctions – passageway between membranes Extracellular matrix (ECM) - network of substances that surround and support the cells in a tissue Collagen – most abundant, leather–tough and protective, but flexible and allowing movement Proteoglycan – carbohydrate and protein, keeping cells hydrated, and trap and store nutrients and growth factors Four Types of Tissues 1. Epithelial – covers exterior surfaces of the body, lines cavities, and forms glands Endothelium – lining for structures inside the body Epithelium – lining for structures exposed to the outside Apical side – exposed to the external environment Basal surface – side of the tissue facing the ECM Basement membrane – ECM that supports and anchors the basal epithelium  Lamina lucida – glycoproteins and collagen that attach the epithelium Lamina densa – tough collagen fibers that connects the epithelium to the underlying connective tissue Epithelial tissues are nearly completely avascular Epithelial cells are polarized Classification of Epithelial Tissues 1. Simple Epithelium – single layer a. Simple cuboidal – boxlike cells found in places of transport b. Simple columnar – tall column-like cells for absorption and secretion of molecules c. Pseudostratified columnar epithelium – single layer of irregularly-shaped cells Goblet cells – mucus secreting cells of simple and pseudostratified columnar 2. Stratified Epithelium – multiple apical layers, frequently shed due to friction a. Stratified squamous epithelium – most common and found in places that are dry b. Stratified cuboidal and columnar epithelium – uncommon only in a few larger glands and ducts c. Transitional epithelium – found in the urinary bladder Glands of Epithelia Glands – synthesize and secrete chemicals Endocrine – secretions are hormones and ductless Exocrine – release through a duct to the epithelial surface Methods and Types of Secretion 1. Merocrine – most common and accomplished through exocytosis 2. Holocrine – rupture an entire gland cell Serous gland – watery secretions from blood plasma Mucous gland – watery viscous glycoprotein mucin 2. Connective – most diverse and binds cells an organs together Ground substance – fluid material between the cells and protein fibers Connective tissues function for protection, transport, and stores energy via adipose cells Classification of Connective Tissues 1. Connective tissue proper – semisolid and flexible 2. Supportive connective tissue – structural-bone and cartilage 3. Fluid connective tissue – liquid-blood and lymph Three Main Types of Fibers 1. Collagen – flexible but have great tensile strength, resist stretching, and give ligaments and tendons resilience and strength 2. Elastic – contain elastin protein and lesser amounts of other proteins glycoproteins 3. Reticular – same protein as collagen fibers; however, remain narrow and branching network Loose Connective Tissue – absorb shock and bind tissues together Areolar tissue – collagen fibers with smaller amount of elastin fibers Adipose tissue – packed cells with few fibers, for fat storage Dense Connective Tissue – far more collagen fibers Supportive Connective Tissues Cartilage – semisolid offers structure and protection while maintaining flexibility Chondrocytes – generate chondroitin Lacunae – small spaces in cartilage matrix Perichondrium – encapsulates and supports the cartilage Types of Cartilage Hyaline – most common, short and dispersed collagen fibers and large amounts of proteoglycans, both strong and flexible Fibrocartilage – thick bundles of collagen fibers, toughness and durability, found in places of intense weight-bearing Elastic – more elastic fibers Bone – the hardest connective tissue due to calcium and phosphorus content Fluid Connective Tissue – cells circulate in a liquid ECM called plasma Hematopoietic stem – located in the bone marrow where elements that circulate in blood are derived from Erythrocytes (red blood cells) - transport oxygen and other gasses 3. Muscle – contractile and provides movement Skeletal muscle – attached to bones and make body movements and posture possible Striation – consistent arrangement of contractile proteins, actin, and myosin Cardiac muscle – contractile walls of the heart, cardiomyocytes are the cells that also appear striated Smooth muscle – involuntary movement of internal organs 4. Nervous – short and long-distance communication throughout the body, making up the brain, spinal cord, and peripheral nerves Neurons – respond to stimuli and send signals to achieve communication called action potentials  Glial cells – support more functional neurons Three Main Parts of a Neuron Cell body – includes the cytoplasm, the organelles, and the nucleus Dendrites – shorter branches that receive signals Axon – longer and send signals to other cells Myelin – wrap axon in insulation, made up of glial cells Synapse – gap between neuron and its target Tissues Membranes – thin sheet that covers the outside of the body Mucous membranes – composites of connective and epithelial tissues, line the body cavities and passageways that open up to the external environment Serous membranes – epithelial membranes that line cavities that do not open to the external environment Synovial membranes – line the cavity of a freely moveable joint, lubricated by synovial fluid Tissue Injury and Repair Inflammation – standard and initial response of the body to injury Acute – short-term Chronic – too long Vasodilation – widening of blood vessels, increased blood flow allows more leukocytes (white blood cells) Histamine – makes blood vessel "leaky" to move white blood cells into interstitial spaces Edena – excess liquid in tissue Angiogenesis – growth of new blood vessels Cancer – cells escape regulatory signals Uncontrolled growth, invasion into adjacent tissues, and colonization of other organs Malignant – group of cells that break off from a tumor Benign – Tumors that neither metastasize nor cause disease