SI2101 Introductory Physiology Lecture Notes PDF

Introductory Physiology SI2101 Dr. Nicole Burns Lecture 1: Introduction & Homeostasis [email protected] Physiology Physiology is the study of processes and functions in living organisms. Ranges from the functions of individual molecules and cells to the interaction of ou...

Introductory Physiology SI2101 Dr. Nicole Burns Lecture 1: Introduction & Homeostasis [email protected] Physiology Physiology is the study of processes and functions in living organisms. Ranges from the functions of individual molecules and cells to the interaction of our bodies with the external world. An important part of physiology is understanding how different cell populations that make up tissues are controlled, how they interact, and how they adapt to changing conditions. University ofGalway.ie Concepts presented in this course: Homeostasis Body compartments and water distribution Electrolyte balance and osmolarity Blood constituents and their functions Basic principles of immunology Basic principles of the nervous system Basic structure and function of skeletal and smooth muscle. Basic structure and function of the endocrine system University ofGalway.ie This module: SI2101 10 ECTs 12 weeks duration 3 lectures per week 4 review lectures (tutorials) 7 lab practicals, beginning in week 3 Allocation of day University ofGalway.ie University ofGalway.ie Staff for this Module (SI2101) Dr Nicole Burns (Module coordinator & Lecturer) [email protected] Dr. Louise Horrigan (Lecturer) [email protected] Dr. Brendan Higgins (Lecturer & Year Head) [email protected] Dr. Leo Quinlan (Lecturer) [email protected] Dr. Brian McDonagh (Lecturer) [email protected] University ofGalway.ie  Lectures…. Lectures notes will be posted prior to lectures Students should engage in some background reading on topics Come prepared… Canvas University ofGalway.ie Recommended textbook Vander’s Human Physiology: The Mechanisms of Body Function. 16e By: Widmaier EP, Raff H and Strang KT Publisher: McGraw Hill Edition: 16th edition (International Student Edition- 2023) Online: Vander’s Human Physiology: The Mechanisms of Body Function. 16e By: Widmaier EP, Raff H and Strang KT Publisher: McGraw Hill Alternative textbooks https://openstax.org/de tails/books/anatomy- and-physiology Free online textbook Assessment Approach 2 Continuous Assessment Quizzes = 20% Multiple choice quizzes (MCQ) Lab reports (x6) = 20% Completed during the lab practical classes End of Semester Exam (Christmas)= 60% MCQ & Short-answer questions (Cumulative) University ofGalway.ie Attendance, and who to contact and when? Attendance at lectures and labs is required If it is necessary to be absent: For 1 or 2 lectures on a once-off No need to notify For more than 1 week of lectures Contact Physiology administrator ([email protected]) with a sick cert, cc’ module coordinator ([email protected]) For 1 lab class Contact Physiology administrator ([email protected]) with a sick cert/notice of intervarsity competition/documentation of bereavement For more complex issues affecting attendance or for ongoing absence/illness Contact module coordinator ([email protected] ) University ofGalway.ie Attendance, and who to contact and when? If you have a LENS report That information is supposed to be shared with the module coordinator via disability services, but coming up to first MCQ maybe double check we know For issues or questions related to lectures or lecture material Contact the relevant lecturer who is giving those lectures If you have an issue that relates to all of your physiology modules for the year Contact the Year Head ([email protected] ). It may also be appropriate to cc’ the module coordinators also University ofGalway.ie Questions? Photo by Green Chameleon on Unsplash Let’s get started!!!! Today’s Learning Outcomes: Understand the concept of homeostasis Know the background to the development of the concept Understand that conditions can change within a normal range Know what is meant by a feedback system and its components Differentiate between a positive and a negative feedback response Understand how normal body temperature is maintained University ofGalway.ie The Basis of Physiological Regulation: We are constantly subjected to all kinds of disturbances, yet we keep going for a lifetime. It is clear that conditions and processes in the body must be closely controlled and regulated, i.e., kept within appropriate values or set points. Departures from appropriate values may result in dysfunction, disease, or death.  Claude Bernard (1813-1878) Noted that various physiological parameters remain stable despite changes in environmental conditions le milieu intérieur Blood sugar levels Photo by Julia Zyablova on Unsplash  “stability of the internal environment is the primary condition for a free and independent existence” A Stable Departures from optimal conditions may result in dysfunction, disease, or death internal Regulation (Homeostatic) Environment: Adjustments are made to maintain this stable Claude internal environment A good example is the ability of warm-blooded Bernard animals to live in different climates. Over a wide range of external temperatures, core temperature in mammals is maintained constant by both physiological and behavioural mechanisms.  Walter B. Cannon (1871-1945) identified the body's capacity for self-regulation Homeostasis: Homeo = sameness; stasis = standing still The maintenance of a relative stable internal environment The body’s ability to maintain homeostasis is essential for survival Homeostasis Body cells require an environment which provides Desired temperature Adequate nutrients: glucose and other metabolites Oxygen and carbon dioxide concentrations Relatively stable blood pressure (osmotic pressure) Concentrations of hydrogen, sodium, potassium, calcium, and magnesium ions  Dynamic equilibrium – maintaining limits Maintaining homeostasis = maintenance of variables in a steady state This steady state involves fluctuations around a set point Conditions stabilised above and below set point Dynamic equilibrium University ofGalway.ie  Figure 1.4 Changes in Blood Glucose Concentration During a Typical 24-Hour Period Blood glucose levels increase after eating, and then levels return to their set point via homeostasis. This is an example of dynamic constancy. Levels change over short periods of time, but remain relatively constant over long periods of time. © McGraw Hill, LLC 21 How does the body maintain homeostasis? Homeostatic Control Mechanisms: Compensating methods by which cells, tissues and organs are regulated and integrated Feedback systems When a change is detected, the body activates mechanisms to return conditions to normal University ofGalway.ie Feedback systems Require 3 components 1. Receptor - to detect the change 2. Control centre - to process the information and coordinate a response 3. Effector - to produce a response Homeostasis is regulated by the nervous system and the endocrine system, acting together or independently University ofGalway.ie  Homeostatic regulation ▪ Feedback systems ▪ Negative feedback systems ▪ Reverses a change in a controlled condition ▪ e.g. regulation of blood pressure, core temperature, blood glucose ▪ Very common mechanism ▪Positive feedback systems ▪ Reinforces a change in a controlled condition ▪ e.g. childbirth, blood clotting Copyright © 2017 John Wiley & Sons, Inc. All rights reserved. ▪ Less common  Negative feedback loop Thermoregulation: Core body temperature ▪Controlled variable: core body temperature ▪ Set point 36-38oC ▪Receptor: Thermoreceptors: skin & hypothalamis ▪Control centre: Hypothalamus ▪Effectors: ▪ When body temp rises above 37oC ▪ Sweat glands ▪ Skin blood vessels – dilate (flushed appearance) ▪ When body temp falls below 37oC ▪ Skin blood vessels- constrict (pale appearance) ▪ Piloerector muscles (piloerection – goosebumps) ▪ Skeletal muscles (shivering – increased heat production)  Positive feedback loop Childbirth ▪Uterine contractions cause stretching of cervix ▪Stretch receptors in the cervix send nerve impulses to the brain ▪Oxytocin is released into the blood ▪Uterine contractions enhanced, stretching cervix further RESERVED. COPYRIGHT © 2017 JOHN WILEY & SONS, INC. ALL RIGHTS ▪More oxytocin is released ▪Cycle continues until stretching of cervix stops- birth of baby  Aging and Homeostasis Aging is a normal process, characterized by a decline in the body’s ability to restore homeostasis. CAN YOU THINK OF AN EXAMPLE WHERE PEOPLE DISRUPT THE BODY’S HOMEOSTASIS AND PUT THEMSELVES AT RISK FOR DISEASE? When homeostasis is disrupted, it may result in disease, disorder, or even death. Summary: The functions of the human body are dynamic, and continually adjust to maintain homeostasis Maintenance of homeostasis involves a: (1) receptor, (2) control centre and (3) effector Feedback mechanisms allow regulation of function Positive feedback leads to perpetuation of a change eg. childbirth Negative feedback leads to a reversal of the change eg. body temperature regulation University ofGalway.ie