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."
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
What is Biology? • bios = “life” • -ology = “study of” • 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?
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
What is Anatomy and Physiology? Like all biology, directly influenced by the fields of • General chemistry • General physics • Biochemistry • Other fields of biology
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
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
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
Figure 1.2 Levels of structural organization .
Figure 1.4a The body’s organ systems and their major functions.
Figure 1.4b The body’s organ systems and their major functions.
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
Figure 1.2 Examples of interrelationships among body organ systems. Digestive system Respiratory system Takes in oxygen and Takes in nutrients, breaks them down, and eliminates unabsorbed eliminates carbon dioxide matter (feces) 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 Heart Urinary system Nutrients Eliminates nitrogenous wastes and Interstitial fluid excess ions Nutrients and wastes pass between blood and cells via the interstitial fluid Integumentary system Protects the body as a whole from Feces Urine the external environment
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 • In the 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?
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 • What is the set point for variables to list here body temperature?
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. Input: Information 3 4 Output: Information sent Control sent along afferent along efferent pathway to Center pathway to control effector. center. Afferent Efferent pathway pathway Receptor Effector 2 Receptor 5 Response detects of effector change. feeds back to reduce the 1 Stimulus effect of produces stimulus and change in BALANCE returns variable. variable to homeostatic level.
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
Figure 1.5 Body temperature is regulated by a negative feedback mechanism. Control Center (thermoregulatory center in brain) Afferent Efferent pathway pathway Receptors Effectors Temperature-sensitive cells in skin and brain ) Sweet glands Sweat glands activated Response Evaporation of sweat Body temperature Body temperature falls; rises stimulus ends BALANCE Stimulus: Heat Stimulus: Cold Response Body temperature Body temperature rises ; falls stimulus ends Receptors Effectors Temperature-sensitive Skeletal muscles cells in skin and brain Afferent Efferent Shivering begins pathway pathway Control Center (thermoregulatory center in brain)
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
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
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 2 Released Platelets chemicals adhere to site and Positive attract more release chemicals. feedback platelets. loop Feedback cycle ends when plug is formed. 4 Platelet plug is fully formed.
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