What is Anatomy? What is Physiology?

Human Anatomy

• Egypt: 1600 BCE

• Greece: Hippocrates, Aristotle (4th century BCE)

• Galen (2nd century) was chief physician to the gladiators in AD 158 but mainly studied animal anatomy; his was THE authority for all medical writers and physicians for the next 1300 years

Cadaver dissection15th century painting

Leonardo da Vinci1452 - 1519

1510

Andreas Vesalius’s De Humani Corporis Fabrica

1543

Introduction

• Anatomy = study of structure

• Physiology = study of function

• how do the parts work?

• what do the parts do?

• what controls them?

Levels of Structure thatYou Will Learn

Homeostasis and Feedback

Homeostasis • Homeostasis refers to the

dynamic constancy of the internal environment.

• What happens if there is no homeostasis?

• How is homeostasis controlled?

What is the internal

environment?

Feedback• Feedback is a process in which the effect

or output of an action is ‘returned’ (fed-back) to modify the next action (what happens affects what happens next)

• Feedback is essential in the management of all regulatory mechanisms

• Examples?

Components of a Feedback Loop

1. Sensors (receptors) monitor the variable

2. Integrators compare the sensor information to the setpoint

3. Effectors cause an change (effect) on the variable

Negative Feedback• Negative feedback is

stabilizing; as a variable deviates from a setpoint, negative feedback ‘pushes’ it back towards the setpoint

• "The more product or result you have...

In physiological systems, is the setpoint fixed?

Hmmmm…..

Another Example of Negative Feedback

Positive Feedback• Destabilizes the system

• why would you want that?

• "The more you have...

• So what stops them?

Positive Feedback Loops

What are other examples of variables in the body controlled by positive feedback loops?