Y khoa, y dược - Chapter 1: The human body: an orientation

The Human Body: An Orientation: Part AChapter 1 Overview of Anatomy and PhysiologyAnatomy: The study of structure of the bodySubdivisions:Gross or macroscopic (e.g., regional, surface, and systemic anatomy)Microscopic (e.g., cytology and histology)Developmental (e.g., embryology)Overview of Anatomy and PhysiologyEssential tools for the study of anatomy:Anatomical terminologyObservationPalpation Auscultation Overview of Anatomy and PhysiologyPhysiology: The study of function of the body at many levelsSubdivisions are based on organ systems (e.g., renal, digestive, cardiovascular physiology)Overview of Anatomy and PhysiologyEssential tools for the study of physiology:Ability to focus at many levels (from systemic to cellular and molecular)Basic physical principles (e.g., electrical currents, pressure, and movement) Basic chemical principlesPrinciple of ComplementarityAnatomy and physiology are inseparable.Function always reflects structureWhat a structure can do depends on its specific formLevels of Structural OrganizationChemical: atoms and molecules (Chapter 2)Cellular: cells and their organelles (Chapter 3)Tissue: groups of similar cells (Chapter 4)Organ: contains two or more types of tissuesOrgan system: organs that work closely togetherOrganismal: all organ systemsCardiovascularsystemOrganelleMoleculeAtoms Chemical levelAtoms combine to form molecules. Cellular levelCells are made up ofmolecules. Tissue levelTissues consist of similartypes of cells. Organ levelOrgans are made up of different typesof tissues. Organ system levelOrgan systems consist of differentorgans that work together closely. Organismal levelThe human organism is made upof many organ systems.Smooth muscle cellSmooth muscle tissueConnective tissueBlood vessel (organ)HeartBloodvesselsEpithelialtissueSmooth muscle tissue123456Figure 1.1, step 6Overview of Organ Systems Major organs and functions of the 11 organ systems Digestive systemNervous systemRespiratory systemCardiovascular systemLymphatic systemUrinary system Organ SystemsMuscular systemSkeletal systemIntegumentary systemEndocrine systemReproductive systemOrgan Systems InterrelationshipsAll cells depend on organ systems to meet their survival needs Organ systems work cooperatively to perform necessary life functionsNecessary Life Functions Boundary: Maintaining boundaries between internal and external environmentsPlasma membranes SkinMovement: (contractility)Of body parts (skeletal muscle)Of substances (cardiac and smooth muscle)Necessary Life FunctionsResponsiveness: The ability to sense and respond to stimuliWithdrawal reflex Control of breathing rateDigestion:Breakdown of ingested foodstuffsAbsorption of simple molecules into bloodNecessary Life FunctionsMetabolism: All chemical reactions that occur in body cellsCatabolism and anabolismExcretion: The removal of wastes from metabolism and digestion Urea, carbon dioxide, fecesNecessary Life FunctionsReproduction: Cellular division for growth or repairProduction of offspringGrowth: Increase in size of a body part or of organismSurvival NeedsNutrients:Chemicals for energy and cell building Carbohydrates, fats, proteins, minerals, vitaminsOxygen:Essential for energy release (ATP production)Survival NeedsWater:Most abundant chemical in the bodySite of chemical reactions Body temperature:Affects rate of chemical reactions Atmospheric pressure:For adequate breathing and gas exchange in the lungsHomeostasisIt is the maintenance of a relatively stable internal environment despite continuous changes both inside and outA dynamic state of equilibriumHomeostatic Control MechanismsInvolve continuous monitoring and regulation of many factors (variables)Nervous and endocrine systems accomplish the communication via nerve impulses and hormonesComponents of a Control MechanismReceptor (sensor)Monitors the environmentResponds to stimuli (changes in controlled variables)Control centerDetermines the set point at which the variable is maintainedReceives input from receptor Determines appropriate responseComponents of a Control MechanismEffectorReceives output from control centerProvides the means to respond Response acts to reduce or enhance the stimulus (feedback) Stimulusproduceschange invariable. Receptordetectschange. Input: Informationsent along afferentpathway to controlcenter. Output:Information sent alongefferent pathway toeffector. Responseof effectorfeeds backto reducethe effect ofstimulusand returnsvariable tohomeostaticlevel. ReceptorEffectorControlCenterBALANCEAfferentpathwayEfferentpathwayIMBALANCEIMBALANCE12345Figure 1.4, step 5Negative FeedbackThe response reduces or shuts off the original stimulusExamples:Regulation of body temperature (a nervous mechanism)Regulation of blood volume by ADH (an endocrine mechanism)Figure 1.5Sweat glands activatedShiveringbeginsStimulusBody temperaturerisesBALANCEInformation sentalong the afferentpathway to controlcenterInformation sentalong the afferentpathway to controlcenterAfferentpathwayAfferentpathwayEfferentpathwayEfferentpathwayInformation sentalong the efferentpathway toeffectorsInformation sentalong the efferentpathway to effectorsStimulusBody temperature fallsReceptorsTemperature-sensitivecells in skin and brainReceptorsTemperature-sensitivecells in skin and brainEffectorsSweat glandsEffectorsSkeletal musclesControl Center(thermoregulatorycenter in brain)Control Center(thermoregulatorycenter in brain)ResponseEvaporation of sweatBody temperature falls;stimulus endsResponseBody temperature rises;stimulus endsNegative Feedback: Regulation of Blood Volume by ADHReceptors sense decreased blood volumeControl center in hypothalamus stimulates pituitary gland to release antidiuretic hormone (ADH)ADH causes the kidneys (effectors) to return more water to the bloodPositive FeedbackThe response enhances or exaggerates the original stimulusEnhancement of labor contractions by oxytocin (Chapter 28)Platelet plug formation and blood clottingFeedback cycle endswhen plug is formed.Positive feedbackcycle is initiated.Positivefeedbackloop Break or tearoccurs in bloodvessel wall. Plateletsadhere to siteand releasechemicals. Releasedchemicalsattract moreplatelets. Platelet plugforms.1234Figure 1.6, step 4Homeostatic Imbalance Disturbance of homeostasis Increases risk of disease Contributes to changes associated with aging May allow destructive positive feedback mechanisms to take over (e.g., heart failure)