Introduction to Human Anatomy & Physiology Chapter 1

Questions since the beginning of time  How does the body work?  Study of the human body, both alive and cadavers  How does one treat injuries and illnesses?  Doctrine of Humors, Doctrine of Signatures, Trial & Error  How will herbs and potions help?  Trial & Error

Definitions  Anatomy – the study of the structures of the human body  Physiology – the study of the functions of the human body

Levels of organization

 Atoms  Molecules  Macromolecules  Organelles  Cells  Tissues  Organs  Organ systems  Human body

Characteristics of life  Movement  Responsiveness  Growth  Reproduction  Respiration  Digestion  Absorption  Circulation  Assimilation  Excretion

Maintaining life

Requirements for maintaining life

 Water  Food  Oxygen  Heat  Pressure

Water  Most abundant chemical in body  Required for many metabolic processes to take place  Important regulator of body temperature

Food  Provides the body with its necessary chemicals  As an energy source  As the building blocks for new matter  As a regulator for vital chemical reactions

Oxygen  Releases energy from food substances which can then drive other metabolic processes

Heat  A form of energy that is a byproduct of metabolic reactions  Amount of heat determines the rate at which reactions occur  The more heat; the more rapidly chemical reactions take place

Pressure  An application of force to something  Atmospheric pressure  The force on the outside of the body due to the weight of air  Important in the process of breathing  Hydrostatic pressure  The force exert by a liquid (ex. Blood pressure)  Important in the process of pushing blood through blood vessels

Homeostasis Maintaining a stable internal environment

Homeostasis Our body only functions well when the concentrations of those requirements for maintaining life remain within certain narrow limits.

Homeostasis 1. Receptors – provides information about specific conditions in our internal environment 2. Set point – the particular value a necessary component of our body should be 3. Effectors – causes responses within the body that alter conditions in our internal environment

Homeostatic mechanisms (blood sugars)

Homeostatic mechanisms (body temperature)

Negative feedback  Once the values for the set point are brought back in line, the effectors are shut down  Seen in the previous two examples  Most common homeostatic mechanisms

Positive feedback  Once the values for the set point have been altered, the effectors continue working  Seen in the next two examples

Homeostatic mechanisms (Blood clotting)

Homeostatic mechanisms (Uterine contractions)

“ ” Biology is a multidisciplinary science. Campbell Biology, 9 th edition (page 30) Human anatomy and physiology is no different.