1. Considers the operation of specific organ systems
Physiology
Considers the operation of specific organ systems
Renal – kidney function
Neurophysiology – workings of the nervous system
Cardiovascular – operation of the heart and blood vessels
Focuses on the functions of the body, often at the cellular or molecular level

2. Physiology
Understanding physiology also requires a knowledge of physics, which explains electrical currents, blood pressure, and the way muscle uses bone for movement

3. Principle of Complementarity
Function always reflects structure
What a structure can do depends on its specific form

4. Levels of Structural Organization
Chemical – atoms combined to form molecules
Cellular – cells are made of molecules
Tissue – consists of similar types of cells
Organ – made up of different types of tissues
Organ system – consists of different organs that work closely together
Organismal – made up of the organ systems

5. Levels of Structural Organization
Smooth muscle cell
Molecules
Cellular level Cells are made up of molecules 2
Atoms 1
Chemical level Atoms combine to form molecules
Smooth muscle tissue
Heart 3
Tissue level Tissues consist of similar types of cells
Cardiovascular system
Blood vessels
Epithelial tissue
Smooth muscle tissue
Blood vessel (organ) 6
Organismal level The human organism is made up of many organ systems
Connective tissue 4
Organ level Organs are made up of different types of tissues 5
Organ system level Organ systems consist of different organs that work together closely
Figure 1.1

6. HOME0/STATIS => SAME STAY => SAME STATE
DEFINED AS “DYNAMIC CONSTANCY OF THE INTERNAL ENVIRONMENT”
Claude Bernard — “mileu interieur” = internal environment remains fairly constant with changing external or internal conditions
1893 — experiment with dogs
Question: How is food broken down to supply energy?
It was thought that food (sugar) was completely used up in the body for energy

7. Sacrificed both – found both had sugar in blood
DEFINED AS “DYNAMIC CONSTANCY OF THE INTERNAL ENVIRONMENT”
Claude Bernard — “mileu interieur” = internal environment remains fairly constant with changing external or internal conditions
EXPERIMENT:
Sugar-fed dog
Meat-fed dog
Sacrificed both – found both had sugar in blood
Bernard later went on through series of experiments to show that sugar was stored in the liver in the form of glycogen
Glucose (in the blood) actually INHIBITS glycogen breakdown
Led to the concept of feedback
From Walter cannon described and coined the term (term) homeostasis

8. Logic:
1) All organisms (living systems) are open systems
2) Open systems are subject to disturbances
3) Disturbances are kept within narrow limits
4) By automatic adjustments (feedback)
5) System is NOT in equilibrium
6) But steady state
Organisms are open systems, which are kept in a steady state (homeostasis) by feedback mechanisms
What is a feedback mechanism?
Process or event that causes another event which has an effect on the initial or subsequent event
Simplest: A —— B —— A
Common: A —— B —— C —— A
Two types: positive or negative

9. Chemical, thermal, and neural factors interact to maintain homeostasis
Homeostasis is the ability to maintain a relatively stable internal environment in an ever-changing outside world
The internal environment of the body is in a dynamic state of equilibrium
Chemical, thermal, and neural factors interact to maintain homeostasis

10. Homeostatic Control Mechanisms
The variable produces a change in the body
The three interdependent components of control mechanisms are:
Receptor – monitors the environments and responds to changes (stimuli)
Control center – determines the set point at which the variable is maintained
Effector – provides the means to respond to the stimulus

11. Homeostatic Control Mechanisms3
Input: Information sent along afferent pathway to
Control center 4
Output: Information sent along efferent pathway to
Effector
Receptor (sensor) 2
Change detected by receptor 5
Response of effector feeds back to influence magnitude of stimulus and returns variable to homeostasis
Stimulus: Produces change in variable 1
Imbalance
Variable (in homeostasis)
Imbalance
Figure 1.4

12. Negative Feedback
In negative feedback systems, the output shuts off the original stimulus

13. Negative Feedback Figure 1.5 Signal wire turns heater on
heater off
Response;
temperature
rises
drops
Stimulus:
rising room
dropping room
Balance
Effector
(heater)
Set
point
Control center
(thermostat)
Heater
off
Receptor-sensor
(thermometer in
Thermostat) on
Imbalance

14. Negative Feedback (Regulation of blood glucose levels)

15. Example: Regulation of blood clotting
Positive Feedback
In positive feedback systems, the output enhances or exaggerates the original stimulus
Example: Regulation of blood clotting
Figure 1.6

16. Homeostatic Imbalance
Disturbance of homeostasis or the body’s normal equilibrium
Overwhelming of negative feedback mechanisms allowing destructive positive feedback mechanisms to take over

17. Organ Systems Interrelationships
Nutrients and oxygen are distributed by the blood
Metabolic wastes are eliminated by the urinary and respiratory systems
Figure 1.2

18. Necessary Life Functions I
Maintaining boundaries – the internal environment remains distinct from the external
Cellular level – accomplished by plasma membranes
Organismal level – accomplished by the skin
Movement – locomotion, propulsion (peristalsis), and contractility
Responsiveness – ability to sense changes in the environment and respond to them
Digestion – breakdown of ingested foodstuffs

19. Necessary Life Functions II
Metabolism – all the chemical reactions that occur in the body
Excretion – removal of wastes from the body
Reproduction – cellular and organismal levels
Cellular – an original cell divides and produces two identical daughter cells
Organismal – sperm and egg unite to make a whole new person
Growth – increase in size of a body part or of the organism

20. Nutrients – chemical substances used for energy and cell building
Survival Needs
Nutrients – chemical substances used for energy and cell building
Oxygen – needed for metabolic reactions
Water – provides the necessary environment for chemical reactions
Maintaining normal body temperature – necessary for chemical reactions to occur at life-sustaining rates
Atmospheric pressure – required for proper breathing and gas exchange in the lungs