1. 21-Dec-15Introduction to Physiology1 Introduction To Physiology Dr. Robert Mbelwa 07158320050785675676drrobertmbelwa@gmail

2. Learning Objectives Define physiology and its various specialties Define physiology and its various specialties Identify the major levels of organization in organisms. Identify the major levels of organization in organisms. Identify the 11 organ systems of the body and their major components. Identify the 11 organ systems of the body and their major components. Explain the concept of homeostasis, including both positive and negative feedback. Explain the concept of homeostasis, including both positive and negative feedback.

3. 21-Dec-15Introduction to Physiology3 Physiology The term physiology is derived from the Greek word PHYSIOLOGICOS The term physiology is derived from the Greek word PHYSIOLOGICOS –PHYSIS – Nature; LOGOS – Study Inquiry to Nature Inquiry to Nature –Physiology is the study of normal function and phenomenon of living things

4. 21-Dec-15Introduction to Physiology4 Physiology Aims at Describing, Explaining and Understanding Aims at Describing, Explaining and Understanding –How living things work or function; –The intricate control system and regulatory mechanisms »How and why plants grow? »What makes bacteria divide »How do fish obtain and use oxygen »How is food digested »What makes the heart beat

5. 21-Dec-15Introduction to Physiology5 Interrelation With Other Specialties In order to discover how living things work In order to discover how living things work –We need to know the actual structure of the body »The bones, muscles and their attachments, nerves different organs and their location (ie. Gross anatomy) The physiologist can then explain, for example how a limb moves The physiologist can then explain, for example how a limb moves

6. 21-Dec-15Introduction to Physiology6 Interrelation With Other Specialties Limb moves because Limb moves because –Particular set of muscles contract But this is not the end of story But this is not the end of story –Further questions arise »Why? And how? Do the muscles contract To answer these questions, the physiologist must know To answer these questions, the physiologist must know –The structure of the muscle (Histology)

7. 21-Dec-15Introduction to Physiology7 Interrelation With Other Specialties –What is happening at the cellular level (ie Biochemistry) There is an inter-relationship between the biological sciences There is an inter-relationship between the biological sciences –In order to understand physiology one needs to have knowledge of a number of other biological sciences

8. 21-Dec-15Introduction to Physiology8 Branches of Physiology Several branches of physiology according to the different types of living things Several branches of physiology according to the different types of living things –Physiology of plants, birds, insects, fish, mammals ; of which human physiology is of special interest for Health Sciences Specialties

9. 21-Dec-15Introduction to Physiology9 Branches of Physiology Human physiology can be further subdivided Human physiology can be further subdivided – according to the different systems »circulation, respiration, muscles, digestion, reproduction, nervous system, endocrine system

10. 21-Dec-15Introduction to Physiology10 Comparative physiology Studied in a variety of species Studied in a variety of species –emphasis on how a particular organ or system function in different species –Most of the knowledge about human physiology originated from experimentation on different animals. –     

11. 21-Dec-15Introduction to Physiology11 For the purpose of your course You will be concerned with Human physiology You will be concerned with Human physiology –During the first & second semesters you will be taught Basic & an aspect of clinical Physiology The course will be offered in ten modules The course will be offered in ten modules

12. 21-Dec-15Introduction to Physiology12 Basic Physiology Semester 1 Semester 1 –Covers modules 1-7 –Fluid and circulation »The cell and its immediate internal environment, Body fluids, homeostasis »Blood »The excitable tissue »The cardiovascular system

13. 21-Dec-15Introduction to Physiology13 Basic Physiology –Metabolism and excretory systems »The Respiratory system »The renal system »The Digestive system Semester 2 Semester 2 –Modules covered 8-10 »Reproduction »Neuroendocrine system The Endocrine system The Endocrine system The nervous system The nervous system –Sensory, motor, autonomic and special senses

14. 21-Dec-15Introduction to Physiology14 Method of Teaching Mainly Lectures Mainly Lectures –Provide only the backbone information –They are intended to stimulate and guide the students into a more detailed private study on the topics covered Practical Practical –Actual practical or practical demonstration Others Others Seminars, tutorials, student’s presentations Seminars, tutorials, student’s presentations –Intended to help the individuals to » revise materials covered »Cover new avenues related to what has already been covered

15. 21-Dec-15Introduction to Physiology15 Recommended Textbooks Textbook of Medical Physiology, by Arthur C. Guyton, 10 th edition Textbook of Medical Physiology, by Arthur C. Guyton, 10 th edition Review of Medical Physiology, by William F. Ganong, 20 th edition Review of Medical Physiology, by William F. Ganong, 20 th edition Physiology, by Berne, Robert &Mathew Physiology, by Berne, Robert &Mathew

16. 21-Dec-15Introduction to Physiology16 Recommended Textbooks Others Others –Human Physiology, the Mechanisms of body Function; by Vander, Sherman,& Luciano. 6 th edition –Essentials of Medical Physiology, by Johnson, Leonard R. 2 nd edition –Physiology, NMS, by Bullock, Boyles, Wang. 3 rd edition Others Sources Others Sources –There are several books on systemic physiology »Respiratory physiology »Cardiovascular physiology, etc –From the Internet

17. 21-Dec-15Introduction to Physiology17 Assessment Continuous assessment tests Continuous assessment tests –Mainly at the end of module –End of Semester university examination Mode of examination Mode of examination –Mixture of multiple choices Questions, matching items & short answers, essays

18. Organization of the human body 21-Dec-15Introduction to Physiology18

19. Levels of structural organization The human body exhibits 6 levels of structural complexity : The human body exhibits 6 levels of structural complexity : 1.Chemical 2.Cellular 3.Tissue 4.Organs 5.System Level 6.Organismic Level

20. Levels of Structural Organization cont’d 1- Chemical level the simplest level of structural ladder the simplest level of structural ladder At this level atoms combine to form molecules such as water, sugar, & proteins At this level atoms combine to form molecules such as water, sugar, & proteins 21-Dec-15Introduction to Physiology20

21. Levels of Structural Organization cont’d 2- Cellular level the smallest functional/livin g units of living things. the smallest functional/livin g units of living things. 21-Dec-15Introduction to Physiology21

22. Levels of Structural Organization cont’d 3- Tissue level groups of similar cells that have a common function (4 basic types) groups of similar cells that have a common function (4 basic types) a.Epithelium b.Muscle c.Connective tissue d.nerve 21-Dec-15Introduction to Physiology22

23. Levels of Structural Organization cont’d 4- Organ level, an organ is a structure composed of 2 or more tissue types that performs a specific function. 4- Organ level, an organ is a structure composed of 2 or more tissue types that performs a specific function. 21-Dec-15Introduction to Physiology23

24. Organ level - consists of two or more types of primary tissues that function together to perform a particular function or functions Organ level - consists of two or more types of primary tissues that function together to perform a particular function or functions 21-Dec-15Introduction to Physiology24

25. –Example: Stomach »Inside of stomach lined with epithelial tissue »Wall of stomach contains smooth muscle »Nervous tissue in stomach controls muscle contraction and gland secretion »Connective tissue binds all the above tissues together 21-Dec-15Introduction to Physiology25

26. Levels of Structural Organization cont’d 5- Organ System is a group of organs that work together to accomplish a common purpose 5- Organ System is a group of organs that work together to accomplish a common purpose –each organ has its own job to do sometimes an organ is part of more than one system sometimes an organ is part of more than one system 21-Dec-15Introduction to Physiology26

27. Levels of Structural Organization cont’d 6- organismic level 6- organismic level Comprises of one living individual Comprises of one living individual represents the highest level of structural organization represents the highest level of structural organization consists of Groups of organs that perform related functions and interact to accomplish a common activity essential to survival of the whole body consists of Groups of organs that perform related functions and interact to accomplish a common activity essential to survival of the whole body Do not act in isolation from one another Do not act in isolation from one another –Human body has 11 systems 21-Dec-15Introduction to Physiology27

28. summary

29. 1. Integumentary system 2. Nervous system 3. Skeletal system 4. Endocrine system 5. Muscular system 6. Cardiovascular system 7. Lymphatic system 8. Urinary system 9. Respiratory system 10. Digestive system 11. Reproductive system Body systems:The human body has 11 systems

42. Homeostasis & Feedback systems for controlling body functions 21-Dec-15Introduction to Physiology42

43. Homeostasis Describes the body’s ability to maintain relatively stable internal conditions even though the outside world is continuously changing Describes the body’s ability to maintain relatively stable internal conditions even though the outside world is continuously changing The literal translation of homeostasis is “unchanging,”( homeo= the same, stasis = standing still which is not true). The literal translation of homeostasis is “unchanging,”( homeo= the same, stasis = standing still which is not true).

44. Homeostasis cont’d The term does not really mean a static, or unchanging, state. The term does not really mean a static, or unchanging, state. Rather, it indicates a dynamic state of equilibrium, or a balance, in which internal conditions vary, but always within relatively narrow limits. Rather, it indicates a dynamic state of equilibrium, or a balance, in which internal conditions vary, but always within relatively narrow limits. In general, the body is in homeostasis when its needs are adequately met and it is functioning smoothly. In general, the body is in homeostasis when its needs are adequately met and it is functioning smoothly. Homeostasis is essential for survival and function of all cells Homeostasis is essential for survival and function of all cells If homeostasis is not maintained, death may result If homeostasis is not maintained, death may result

45. Control of Homeostasis

46. Autoregulation or intrinsic regulation – results when cell, organ or system adjusts its activity automatically. Autoregulation or intrinsic regulation – results when cell, organ or system adjusts its activity automatically. Extrinsic regulation - results from activity of nervous system or endocrine system Extrinsic regulation - results from activity of nervous system or endocrine system Homeostasis cont’d Two general points within homeostasisTwo general points within homeostasis

47. Homeostatic Control Mechanisms Communication within the body is essential for homeostasis. Communication within the body is essential for homeostasis. Communication is accomplished chiefly by the nervous and endocrine systems Communication is accomplished chiefly by the nervous and endocrine systems which use neural electrical impulses or blood borne hormones, respectively, as information carriers. which use neural electrical impulses or blood borne hormones, respectively, as information carriers. Regardless of the factor being regulated(the variable)all homeostatic control mechanisms have at least three interdependent components. Regardless of the factor being regulated(the variable)all homeostatic control mechanisms have at least three interdependent components. 21-Dec-15Introduction to Physiology47

48. Homeostatic Control Mechanisms  The first component, the receptor, is some type of sensor that monitors the environment and responds to changes, called stimuli, by sending information (input) to  the second component, the control center. Input flows from the receptor to the control center along the so-called afferent pathway. The control center, analyzes the input it receives and then determines the appropriate response or course of action. 21-Dec-15Introduction to Physiology48

49. Homeostatic Control Mechanisms The third component, the effector, provides the means of response (output) to the stimulus. Information flows from the control center to the effector along the efferent pathway. The third component, the effector, provides the means of response (output) to the stimulus. Information flows from the control center to the effector along the efferent pathway. The results of the response then feed back to influence the stimulus, either depressing it (negative feedback) so that the whole control mechanism is shut off or enhancing it (positive feedback) so that the reaction continues at an even faster rate. The results of the response then feed back to influence the stimulus, either depressing it (negative feedback) so that the whole control mechanism is shut off or enhancing it (positive feedback) so that the reaction continues at an even faster rate. 21-Dec-15Introduction to Physiology49

50. Components of homeostatic control mechanismsComponents of homeostatic control mechanisms

51. Homeostatic control mechanisms are TWO: Homeostatic control mechanisms are TWO: –Negative feedback mechanisms – the net effect of the response to the stimulus is the shut off of the original stimulus or to reduce its intensity I,e the original stimulus is reversed »E.g. – body temp, blood chemical levels –Positive feedback mechanisms – tend to increase the original disturbance (stimulus) and push the variable farther from its original value i.e original stimulus is intensified »E.g. – ovulation, blood clotting, birth

52. Negative Feedback Mechanisms Most homeostatic control mechanisms are negative feedback mechanisms. In these systems, the output shuts off the original stimulus or reduces its intensity. These mechanisms cause the variable to change in a direction opposite to that of the initial change, returning it to its “ideal” value; thus the name “negative” feedback mechanisms Most homeostatic control mechanisms are negative feedback mechanisms. In these systems, the output shuts off the original stimulus or reduces its intensity. These mechanisms cause the variable to change in a direction opposite to that of the initial change, returning it to its “ideal” value; thus the name “negative” feedback mechanisms 21-Dec-15Introduction to Physiology52

53. Negative Feedback Loop 21-Dec-15Introduction to Physiology53

54. Negative Feedback Loop

55. A good example of a non- biological negative feedback system is a home heating system connected to a temperature-sensing thermostat. is a home heating system connected to a temperature-sensing thermostat. If the thermostat is set at 20°C (68°F), the heating system (effector) is triggered ON when the house temperature drops below that setting. If the thermostat is set at 20°C (68°F), the heating system (effector) is triggered ON when the house temperature drops below that setting. As the furnace produces heat and warms the air, the temperature rises, and when it reaches 20°C or slightly higher, the thermostat triggers the furnace OFF. As the furnace produces heat and warms the air, the temperature rises, and when it reaches 20°C or slightly higher, the thermostat triggers the furnace OFF. 21-Dec-15Introduction to Physiology55

56. Example continued This process results in a cycling of “furnace-ON” and “furnace-OFF” so that the temperature in the house stays very near the desired temperature of 20°C. Your body “thermostat,” located in a part of your brain called the hypothalamus, operates in a similar fashion. This process results in a cycling of “furnace-ON” and “furnace-OFF” so that the temperature in the house stays very near the desired temperature of 20°C. Your body “thermostat,” located in a part of your brain called the hypothalamus, operates in a similar fashion. 21-Dec-15Introduction to Physiology56

57. Negative Feedback: The Control of Body Temperature

58. Homeostasis of Blood Pressure Baroreceptors in walls of blood vessels detect an increase in BP Baroreceptors in walls of blood vessels detect an increase in BP Brain receives input and signals blood vessels and heart Brain receives input and signals blood vessels and heart Blood vessels dilate, HR decreases Blood vessels dilate, HR decreases BP decreases BP decreases

59. Some of the variables that need to be regulated by negativeback mechanisms include Some of the variables that need to be regulated by negativeback mechanisms include –Body temperature,blood volume, heart rate,blood pressure,the rate and depth of breathing, and blood levels of oxygen, carbon dioxide, minerals..etc 21-Dec-15Introduction to Physiology59

60. Positive Feedback Mechanisms In positive feedback mechanisms, the result or response enhances the original stimulus so that the activity (output) is accelerated. This feedback mechanism is “positive” because the change that occurs proceeds in the same direction as the initial disturbance, causing the variable to deviate further and further from its original value or range. In positive feedback mechanisms, the result or response enhances the original stimulus so that the activity (output) is accelerated. This feedback mechanism is “positive” because the change that occurs proceeds in the same direction as the initial disturbance, causing the variable to deviate further and further from its original value or range. 21-Dec-15Introduction to Physiology60

61. Positive feedback cont’d In contrast to negative feedback controls, which maintain many physiological functions or keep blood chemicals within narrow ranges In contrast to negative feedback controls, which maintain many physiological functions or keep blood chemicals within narrow ranges  positive feedback mechanisms usually control infrequent events that do not require continuous adjustments However, TWO familiar examples of their use as homeostatic mechanisms are the enhancement of labor contractions during birth and blood clotting. However, TWO familiar examples of their use as homeostatic mechanisms are the enhancement of labor contractions during birth and blood clotting. 21-Dec-15Introduction to Physiology61

62. Positive Feedback: Blood Clotting In positive feedback an initial stimulus produces a response that enhances the change in the original condition. For instance:In positive feedback an initial stimulus produces a response that enhances the change in the original condition. For instance: Damage to blood vessel wall will cause release of chemicals. Damage to blood vessel wall will cause release of chemicals. Chemicals will trigger blood clottingChemicals will trigger blood clotting Clotting process increases release of chemicalsClotting process increases release of chemicals More chemicals means accelerated clottingMore chemicals means accelerated clotting Accelerated clotting means more chemicalsAccelerated clotting means more chemicals

63. Positive Feedback during Childbirth Stretch receptors in walls of uterus send signals to the brain Stretch receptors in walls of uterus send signals to the brain Brain induces release of hormone (oxytocin) into bloodstream Brain induces release of hormone (oxytocin) into bloodstream Uterine smooth muscle contracts more forcefully Uterine smooth muscle contracts more forcefully More stretch, more hormone, more contraction etc. More stretch, more hormone, more contraction etc. Cycle ends with birth of the baby & decrease in stretch Cycle ends with birth of the baby & decrease in stretch

64. Homeostatic Imbalance Homeostasis is so important that most disease can be regarded as a result of its disturbance, a condition called homeostatic imbalance. Homeostasis is so important that most disease can be regarded as a result of its disturbance, a condition called homeostatic imbalance. As we age, our body’s control systems become less efficient, and our internal environment becomes less and less stable. These events increase our risk for illness and produce the changes we associate with aging As we age, our body’s control systems become less efficient, and our internal environment becomes less and less stable. These events increase our risk for illness and produce the changes we associate with aging Examples of homeostatic imbalance are provided throughout this course to enhance understanding of normal physiological mechanisms. Examples of homeostatic imbalance are provided throughout this course to enhance understanding of normal physiological mechanisms. 21-Dec-15Introduction to Physiology64

65. Final word Hard work is the only cure for hard life Hard work is the only cure for hard life I wish you all the best in your academic pursuit I wish you all the best in your academic pursuit You will all make it You will all make it 21-Dec-15Introduction to Physiology65