Biology 2331 Anatomy and Physiology I "If you want something you've never had, then you've got to do something you've never done." 1 Learn and Understand A new language At this stage, science drives the discipline Human A&P is focused but draws upon knowledge of other disciplines Structural and functional hierarchy the whole is the sum of its parts Systems of the organism attempt to maintain internal conditions that sustain life while allowing for temporary deviations 2 bios = life -ology = study of What is Biology? Greek and Latin important languages in biology and science in general Etymology Pronunciation key in glossary (G-1) Roots, suffixes and prefixes on last pages of book How is science different from other disciplines? 3 1
What is Anatomy and Physiology? A subset of the larger field of biology Anatomy: scientific discipline that investigates the body s structure and relationships between its parts Readily observable Physiology: scientific investigation of the processes or functions of living things At times, not easily observed based on tested hypotheses which are subject to change when new information comes to light Anatomy and physiology are inseparable Function always reflects structure What a structure can do depends on its specific form 4 What is Anatomy and Physiology? Like all biology, directly influenced by the fields of General chemistry General physics Biochemistry Other fields of biology 5 Topics of Anatomy Gross or macroscopic: structures examined without a microscope Regional: studied area by area Systemic: studied system by system Surface: external form and relation to deeper structures Microscopic: structures seen with the microscope Examples: Cytology: cells Histology: tissues 6 2
Topics of Physiology Reveals dynamic nature of living things Often focuses on cellular and molecular processes. Examples: Cell physiology: examines processes in cells Neurophysiology: examines nervous tissue biochemistry and physics Cardiovascular physiology: heart and blood vessel tissue biochemistry and physics 7 Subjects That Encompass Both Anatomy and Physiology Pathology: structural and functional changes caused by disease Exercise Physiology: changes in structure and function caused by exercise Example: bone density and training 8 Figure 1.2 Levels of structural organization. 9 3
Figure 1.4a The body s organ systems and their major functions. 10 Figure 1.4b The body s organ systems and their major functions. 11 Interdependence of Body Cells Humans are multicellular To function, must keep individual cells alive Most cells depend on organ systems to meet their survival needs All body functions spread among different organ systems Organ systems cooperate to maintain life Some redundancy will be observed Note also, symbiosis with microbes 12 4
Figure 1.2 Examples of interrelationships among body organ systems. Digestive system Takes in nutrients, breaks them down, and eliminates unabsorbed matter (feces) Respiratory system Takes in oxygen and eliminates carbon dioxide Food O 2 CO 2 Cardiovascular system Via the blood, distributes oxygen and nutrients to all body cells and delivers wastes and carbon dioxide to disposal organs Blood CO 2 O 2 Nutrients Heart Interstitial fluid Urinary system Eliminates nitrogenous wastes and excess ions Nutrients and wastes pass between blood and cells via the interstitial fluid Feces Integumentary system Protects the body as a whole from Urine the external environment 13 Why Do Human Bodies Work the Way They Do? Humans, like all living things on this planet: Are subject to universal laws of chemistry and physics Have evolved complex cellular chemistry in order to thrive within an environment to function best within a complex environment maximizing survivability and reproduction optimized for a particular environment Have catalogued their complexities as traits present in the genetic material inherited from parents Inthe natural world, both evolution and environmental change occur very slowly over tens of thousands of years What are the characteristics of the environment humans are adapted to? 14 Homeostasis Values of variables fluctuate around the set point - establish a normal range Set point: the ideal normal value of a variable essentially an average But changeable for temporary circumstances There are too many body variables to list here What is the set point for body temperature? 15 5
16 Controlling Body Parameters: Feedback Systems Components Receptor: monitors the value of some variable; responds to change Control center: establishes the set point; evaluates change; coordinates appropriate response Effector: can change the value of the variable; changes feedback on the stimulus Stimulus: deviation from the set point; detected by the receptor Response: produced by the effector Two examples: negative and positive Figure 1.4 Interactions among the elements of a homeostatic control system maintain stable internal conditions. 2 Receptor detects change. 1 Stimulus produces change in variable. 3 Input: Information sent along afferent to control center. Receptor Afferent Control Center BALANCE Efferent 4 Output: Information sent along efferent to effector. Effector 5 Response of effector feeds back to reduce the effect of stimulus and returns variable to homeostatic level. 17 18 Negative Feedback Any deviation from the set point is made smaller (resisted) Response reduces or shuts off original stimulus Variable changes in opposite direction of initial change Most feedback mechanisms in body are NF Examples Regulation of body temperature Regulation of blood glucose by insulin Regulation of blood pressure 6
Figure 1.5 Body temperature is regulated by a negative feedback mechanism. Control Center (thermoregulatory center in brain) Afferent Efferent Receptors Temperature-sensitive cells in skin and brain) Effectors Sweet glands Body temperature rises Stimulus: Heat BALANCE Sweat glands activated Response Evaporation of sweat Body temperature falls; stimulus ends Response Body temperature rises; stimulus ends Stimulus: Cold Body temperature falls Effectors Skeletal muscles Receptors Temperature-sensitive cells in skin and brain Shivering begins Efferent Afferent Control Center (thermoregulatory center in brain) 19 Positive Feedback When a deviation occurs, the response is to make the deviation greater - response enhances or exaggerates original stimulus Not as common as negative feedback, purposefully leads away from homeostasis Usually controls infrequent events that do not require continuous adjustment 20 21 Positive Feedback Examples of positive feedback: Labor and delivery cervical pressure, oxytocin, and uterine contraction Blood pressure changes during hemorrhage Peripheral blood pressure drops are not resisted in order to maintain core blood pressure and heart-lung-brain connection If blood loss continues - heart s ability to pump blood decreases Heart and brain starved, death Platelet plug formation the response to platelet adhesion is more platelet adhesion obviously must be carefully controlled 7
Figure 1.6 A positive feedback mechanism regulates formation of a platelet plug. 1 Break or tear occurs in blood vessel wall. Positive feedback cycle is initiated. 3 Released chemicals attract more platelets. Positive feedback loop 2 Platelets adhere to site and release chemicals. Feedback cycle ends when plug is formed. 4 Platelet plug is fully formed. 22 8