Introduction to Physiology

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Overview

When I lectured in the classroom, I always had notes with me, and so I have re-worked my notes for you and they are on this page.  (If they look like someone's notes, they are!). These notes do NOT substitute for the reading.

Chapter 1 of our textbook, which you are reading this week, focuses on giving students an overview of the history of physiology, homeostasis, the scientific method, physiology journals, and reminding students of some basic things they learned in Anatomy (a pre-requisite for this course).  Please make sure you read Chapter 1 of your textbook in detail.  

How to study

If a student is not doing well in Physiology, most of the time it is because their study skills need improvement.  I can't guarantee that you'll learn to study through taking my course, but here are a few tips:

  • Look at the title of a chapter. 

    That seems obvious, doesn't it?  But usually we're so eager to get the job done, we don't look at the little things that make us think.  Titles and subheadings too are really important.  They tell you what you're supposed to get out of it.

  • Look at the "Learning Outcomes" at the beginning of each section. 

    Then when you're done reading the section, did you learn them?  If not, sorry, but you're like most of us.  We don't always get it first time around

  • Turn every page of the chapter, leaf through it
    Look at the pictures

  • Read the summary 

    (one section at a time) at the end of the chapter, which covers the main points.  But, after reading each section of the summary, go back and read that section of the textbook.  Go back and forth.  The summary tells you what the main information is going to be.

  • Checkpoints
    Test yourself with the checkpoints before you go on to the next section.  I sometimes use these as essay questions on quizzes and tests.

  • Bold words
    If you don't know them, write them down.  Use index cards to learn them, or Quizlet.

Introduction to Physiology

Physiology is the study of the function of the human body.

  • Physis = Greek word for “nature”; logos means to study

Comparative Physiology – the physiology invertebrates and different vertebrates

  • Humans are mammals
  • Much of what is known was learned through studies of other mammals.
  • Our DNA is only 1% different from chimps.

Pathophysiology is the study of how physiological processes are altered by disease.

Scientific Method


There are different ways to learn about physiology:

Discovery: make observations and acquire information and draw conclusions.  e.g. the human genome sequencing
            A technique was carried out and the information was obtained.

Hypothesis-based science, the Scientific Method, when you test questions in an unbiased method and ask whether the results can be reproduced.

1) Observation – you see something that interests you

2) You gather data

3) You analyze the data

4) You come to a conclusion about how something works, which is really a hypothesis, or an educated guess based on the data you gathered

5) You test the hypothesis.  A hypothesis is something that can be tested

6) You set up a series of experiments: If I do X than Y should happen

7) You gather data

8) You analyze the data

9) Conclusion: did the results support or refute the hypothesis

10) Keep repeating this until you come up with a hypothesis that explains the phenomoneon. 

11) Publish the data in a peer reviewed journal

Theory

Do not get confused with the common use of this term, which is flat-out wrong in the science community. 

  • What is a theory?  A scientifically proven fact, supported by a huge amount of evidence, which has wide-reaching significance, such as EVOLUTION (all life comes from pre-existing life) or the CELL THEORY (1) all life is made up of cells; all cells come from pre-existing cells; the cell is the fundamental unit of structure and function of living things).
  • What is not a theory?  A spur of the moment idea that someone has to explain something.  This is the type of theory that is the common use of this term used in "everyday" talk.

A Brief History of Physiology

  1. Aristotle – Greece (384-322 BC) – speculated about body function  (thinkers, not doers)
  2. William Harvey – England (1578-1657) – demonstrated that the heart pumps through a closed system of vessels
  3. Claude Bernard – France (1813-1878) – observed that the internal environment (milieu interieur) stays relatively constant although changes are occurring
  4. Walter Cannon – US (1932) – coined the term, homeostasis, to describe the internal consistency of the body

Homeostasis – a maintenance of steady state

Homeostasis refers to the body's ability to maintain a steady state.  To achieve homeostasis, the body carries out biochemical processes, which are negative feedback processes.  There is a negative feedback process to maintain thousands of intricate aspects of the body within their "normal" range or at a specific value called a set point.

  • How does the body do this?  By negative feedback loops.
    See figure 1.1 in Text
    Pathway
    1. Sensors in the body to detect change and send information to the:
    2. Integrating center, which assesses change around a set point.  The integrating center then sends instructions to an:
    3. Effector, which can make the appropriate adjustments to counter the change from the set-point

  • SET POINT – a normal range for a condition of the body (see Table 1.2).  The body keeps within its set points by antagonistic mechanisms.  Shivering and sweating are the body’s way of maintaining its set point of body temperature around 98.6 or 37 degrees Celsius.
  • Positive Feedback Mechanisms do occur in the body, but they are not the means for homeostasis.
    • EXAMPLES
      • Blood clotting – activation of one clotting factor activates another clotting factor
      • Contraction of the uterus during childbirth- stimulated by oxytocin; more contractions stimulate the secretion of greater oxytocin.
  • Here is a video I made for you on homeostasis:

Body Organization

  • Students need to have remembered this from anatomy.
  • Need to know things like these from anatomy:  Keratin protein is part of which cell?  Keratinocyte (squamous cell)  tissue?  Epithelial; organ = skin, organ system = integumentary,

Perkins' Introduction to Physiology Lecture-Video

Please make sure you understand all of the concepts in the video I made.  I have it in mind to shorten this video, chunk it into segments, but as I have not yet done that, please pause this video and go back to it as needed.

 

 

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