BCMB 230 1st Edition Lecture 1 Outline of Last Lecture I None Outline of Current Lecture I The Basics II Homeostasis III Feedback Systems IV Components of Homeostatic Control Systems V Processes Related to Homeostasis Current Lecture I The Basics Physiology the study of how the body works functions and processes often paired with Anatomy which is the study of structure Physiology includes the study of individual molecules molecular level looking at protein shape how it works what it influences and how changing the shape works the study of complex processes that depend on the integrated functions of many organs in the body ex heart kidneys and several glands all work together to cause the excretion of more sodium ions in the urine when a person has eaten salty food How the body is organized cells simplest structural units built by molecules into which a complex multi cellular organism can be divided and still retain the functions characteristic of life Four major categories of Types of Function that cells can perform are specialized for muscle cells neurons epithelial cells connective tissue tissues formed by differentiated cells with similar properties Four general types of tissues muscle tissue nervous tissue epithelial tissue connective tissue These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute the term tissue is also used to denote the general cellular fabric of any organ or structure ex kidney tissue tissues can also build a functional unit functional unit when organs are organized into small similar subunits that perform the function of the organ ex functional unit of the kidney is the nephron total production of urine by the kidneys is the sum of the amounts produced by the 2 million or so individual nephrons organ one type of tissue combines with other types of tissues organ systems when organs work together to perform an overall function then there are multi organ processes that lead to a total organism II Homeostasis Internal environment of the body refers to the fluids that surround cells and exist in blood Homeostasis relatively stable condition of internal environment that results from regulatory system actions characteristics of homeostatic control systems the activities of the cells tissues and organs must be regulated and integrated with each other so that any change in the extracellular fluid initiates a reaction to correct the change not always the same there are variations depending on the variable III Feedback Systems Mechanisms to promote idea of homeostasis cellular processes are related by feedback Negative feedback characteristic of control systems in which system s response opposes the original change in the system have physiological process enzyme sequence end product acts to reduce activity of earlier step end product inhibition controls production of active product acts to provide us with relatively stable state if you have too much of something stop making it providing for homeostasis body maintains steady internal environment plays a vital part in the checks and balances on most physiological variables Examples Figure 1 4 hypothetical example of negative feedback blood pressure temperature plasma blood pH very acidic Positive Feedback characteristic of control systems in which an initial disturbance sets off train of events that increase the disturbance even further process produces something goes back to accelerate process which leads to an explosive system creates more of active product counter to the principle of homeostasis because it has no obvious means of stopping much less common in nature than negative feedback Examples ex Blood clotting produce protein to prevent blood loss also helps keep homeostasis ex Contractions during labor stimulates another contraction builds until delivery Feed Forward aspect of some control systems that allows system to anticipate changes in a regulated variable improves the speed of the body s homeostatic responses and reduces the amount of deviation from the set point maintain homeostasis by minimizing changes to the body Examples moving from a warm area to a colder one salivating when smelling good food IV Components of Homeostatic Control Systems Set Point operating point steady state value maintained by homeostatic control system doesn t have to be exact gives predicted value ex If temperature not where expected then something is wrong fever infection how close around set point depends on what you are measuring Reflex a specific involuntary unpremeditated unlearned built in response to a particular stimulus check Figure 1 5 predictable response to a stimulus receptor detects environmental change and translates stimulus to something body recognizes integrating center integrator brain region that compares the actual value of a variable ex body temperature to a set point afferent pathway to carry to component that transmits information from receptor to integrating center effector cell or cell collection whose change in activity constitutes the response in a control system efferent pathway to carry away from component that transmits information from integrating center to effector negative feedback will influence a stimulus ex nervous system Hormone type of chemical messenger secreted into the blood by cells of the endocrine system Local homeostatic responses response acting in immediate vicinity of a stimulus without nerves or hormones and having net effect of counteracting stimulus Three types of reflex endocrine reflex nervous reflex or neuroendocrine reflex Extrinsic outside of system Intrinsic inside of system Ex Control of stomach nervous system hormones extrinsic local chemical messengers intrinsic Nerves and hormones extrinsic endocrine Local intrinsic paracrine effect on next door neighbor autocrine cell releases chemical messenger acts on itself Paracrine substances agents chemical messengers involved in local communication between cells generally inactivated rapidly by locally existing enzymes so that they do not enter the bloodstream in large quantities Autocrine substances agents when a chemical messenger is secreted by a cell into the extracellular fluid and then acts upon the very cell that secreted it V Processes Related to Homeostasis Adaption change in gene frequency over generations biological characteristic that favors survival in a particular environment Accommodation change in physiological