intro-notes - BIOL 326 - General Physiology Introductory...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
BIOL 326 - General Physiology Introductory Lecture Notes : Physiologic principles, Homeostasis . January 6- 8 , 2010 Dr M. Sweeney-Nixon th Objectives 1: At the end of this section, you will be able to 1. Define homeostasis. 2. List the components of biological control systems. 3. Identify 6 physiologic variables and their set points in humans. Physiology refers to the function : the science of how living organisms and their parts (including chemical and physical processes) function to sustain the organism’s life by working together to maintain homeostasis. Thus, homeostasis is the goal of physiologic processes: Homeostasis is the maintaining of a relatively stable internal conditions . The internal environment of our bodies and all living creatures must have certain conditions within tolerable limits to continue healthy functioning. The ability to maintain homeostasis has obvious survival advantage since the organism has control over its survival i.e. it can adapt internally to ever-changing environmental conditions (i.e. external) that are outside of its control. Each different ‘internal condition’ is called a physiologic variable , and it is at homeostasis when its value is at its own set point . Examples of physiological variables in humans set point (usually a range) in humans heart rate 70 (60-90) beats per min blood pressure 120/80 mmHg concentration of glucose in blood (plasma) 100 (70-120) mg/dl (3-6mM) osmolarity (amount of total dissolved substances) 300 (270-320) mOsm cellular pH (acidity or concentration of H ions) + 7.4 (7.35-7.45) body temperature 36.5 - 37.5 C o Physiologic variables are maintained at set point by physiologic processes which regulate the internal environment to maintain homeostasis: Regulation refers to the ability to change (increase or decrease) the speed or intensity of a biological process to meet changing demands on an organism, conserve resources, avoid waste, and to be efficient . This is energetically costly and requires orderly information. It is as important to turn on a process as it is to turn it off , again to conserve this energy and resources, and to keep changes small and manageable (i.e. operate as efficiently as possible). [Note that some variables are not regulated in some organisms e.g. fish do not regulate body
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 7

intro-notes - BIOL 326 - General Physiology Introductory...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online