Physiology Week 1 Notes: Jan 6-Jan 9
Physiology Week 1 Notes: Jan 6-Jan 9 BIOL 3160
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This 3 page Class Notes was uploaded by MBattito on Sunday January 10, 2016. The Class Notes belongs to BIOL 3160 at Clemson University taught by Dr. Tamara McNutt-Scott in Fall 2015. Since its upload, it has received 83 views. For similar materials see Human Physiology in Biological Sciences at Clemson University.
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Date Created: 01/10/16
Week 1 Notes: 1/6-‐1/8 Chapter 1: The Study of Body Function Physiology: • Fundamentally represents the study of how living organisms work o Molecules à cells à tissue à organ à organ system o How organisms accomplish tasks essential for life • Function and integration o Body parts work together at various levels of organization and whole organism o No “part” works in isolation • Mechanisms and their effects o Sequence of events à parts of larger stories • Misconception: all is known History of Physiology: • Aristotle: o Speculated on function of human body o Good health associated with balance of humours § Humours: black bile, yellow bile, phlegm and blood • Erasistratus: “father of physiology” o Applied physical laws to study of human body o Studied cardiovascular and nervous systems o Performed dissections on live humans à noted increase in heart rate • William Harvey: o First to study biology quantitatively o One of the first to be able to accurately describe the parts of the body and systematic circulationà identified parts and their functions • Claude Bernard: “father of modern physiology” o Observed the milieu interieur o Found that animals possess control systems that could adjust to external and internal stimuli o Internal environment remains remarkably constant despite constantly changing external environment Father of American Physiology: Robley Dunglison • In the early 19 century in the US physiology was treated as an aspect of theory and practice of physics • 1824: Thomas Jefferson and the board members of the University of Virginia added Dunglison to the first faculty of the U of VA • Dunglison: o English physician o Professor of Anatomy, Physiology, Surgery, Materia Medica, Pharmacy and History of Medicine o Teaching was an explanation of “successive theories” o Published several books and articles § Human Physiology (1832) à landmark text Homeostasis and Feedback Control: • Homeostasis: maintenance of a relatively stable internal environment o Basically represented by the state of equilibrium of the body’s internal environment by dynamic processes of feedback and regulation o Reason for regulatory mechanisms o Is not an easy accomplishment § Every organ system is involved with the maintenance and necessitates integrated function o Major foundation for medical diagnostic procedures • Walter Cannon: coined the term homeostasis in his book, The Wisdom of the Body • How is the maintenance of homeostasis accomplished? Feedback mechanisms Feedback Mechanism: maintain homeostasis • Set point: normal range of measurements and values o Variable: factor or event being regulated • Control systems that promote homeostasis are characterized by 3 interdependent components: o Receptor: serve as sensors to determine what is out of balance § Uses afferent pathways (sensory pathways toward central nervous system) o Control/integrating center: uses efferent pathways (motor pathways away from central nervous system) o Effector: bring balance back • Why is it referred to as a “loop”? o “Loop” emphasizes feedback mechanism is a continuous cycle to maintain homeostasis • Is our internal environment absolutely constant? Are we always in a state of balance? o Our internal environment is not absolutely constant. We maintain a dynamic balance or consistency; that is overall our body is constant within a range but is not absolutely constant. Conditions stabilize around a set point; they must be in the range so physiological processes can run efficiently. Negative Feedback Mechanism: reverse direction control mechanism • Most common homeostatic control mechanism • Works because output of system causes a decrease or shuts off the original stimulus o Continuous, ongoing processes • All negative feedback mechanisms have the same goal: preventing sudden, severe changes in the body • Antagonistic effects: effectors have antagonistic actions, allowing for finer degree of control • Integration center does not always have to be in the central nervous system Positive Feedback mechanism: same direction control system • Enhance or exaggerate the response over the original stimulus, thus the output is increased • Usually control episodic or infrequent events that do not require continuous adjustments o Ex: blood clotting, breast feeding, parturition (child birth) • Limited occurrence because it proceeds with very little control Homeostatic imbalance: • Places an individual at higher risk of disease • Typically a result of certain pathological conditions and aging Homeostatic Regulation: • Regulatory mechanisms for homeostasis o Intrinsic: within organ o Extrinsic: “outside” organ § Nervous system: impacts homeostasis via nerves § Endocrine system: impacts homeostasis via hormones • Advantages: self regulatory and self initiated • Disadvantages: automatic response sometimes does not help
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