1 Anatomy & Physiology Anatomy – Physiology – “The complementarity of structure and function.”

2 Levels of Organization Subatomic Particles – electrons, protons, and neutrons Atom – Molecule – water molecule, glucose molecule, etc. Macromolecule – Organelle – mitochondrion, Golgi apparatus, nucleus, etc. Cell – Tissue – epithelia, connective, muscle and nerve Organ – Organ System – skeletal system, digestive system, etc. Organism – the human

Levels of Organization Subatomic particles Atom Molecule Macromolecule Organelle Cell Tissue Organ Organ system Organism Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

4 Characteristics of Life (10) Movement – change in position; motion Responsiveness – Growth – increase in body size; no change in shape Respiration – obtaining oxygen; removing carbon dioxide; releasing energy from foods Reproduction – Metabolism –

5 Characteristics of Life Continued Absorption – passage of substances through membranes and into body fluids Circulation – Assimilation – changing of absorbed substances into chemically different forms Excretion – Digestion –

6 Maintenance of Life Life depends on five (5) environmental factors: 3 Nutrients: Chemicals needed for normal cellular function. Water Food Oxygen 2 Non-nutrients Heat Pressure

7 Requirements of Organisms Water - most abundant substance in body - - required for transport of substances - Food - provides necessary nutrients - - supplies raw materials

8 Requirements of Organisms Oxygen (gas) - one-fifth of air - Heat - - partly controls rate of metabolic reactions Pressure - - atmospheric pressure – important for breathing - hydrostatic pressure – keeps blood flowing

9 Homeostasis* * Maintaining of a stable internal environment Homeostatic Control Mechanisms – monitors aspects of the internal environment and corrects as needed. Variations are within limits. There are three (3) parts: Receptor - Control Center - tells what a particular value should be (called the set point) Effector -

Homeostatic Control Mechanisms Stimulus (Change occurs in internal environment.) Response (Change is corrected.) Receptors Effectors (muscles or glands) Control center (set point) (Change is compared to the set point.) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10

11 Homeostatic Control Mechanisms Receptors Thermoreceptors send signals to the control center. too high too low Normal body temperature 37°C (98.6°F) Control center The hypothalamus detects the deviation from the set point and signals effector organs. Control center The hypothalamus detects the deviation from the set point and signals effector organs. If body temperature continues to drop, control center signals muscles to contract Involuntarily. Stimulus Body temperature rises above normal. Effectors Skin blood vessels dilate and sweat glands secrete. Response Body heat is lost to surroundings, temperature drops toward normal. Receptors Thermoreceptors send signals to the control center. Effectors Skin blood vessels constrict and sweat glands remain inactive. Stimulus Body temperature drops below normal. Effectors Muscle activity generates body heat. Response Body heat is conserved, temperature rises toward normal. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

12 There are two (2) types: Negative feedback mechanisms Positive feedback mechanisms Homeostatic Control Mechanisms

13 Negative feedback summary: Prevents sudden, severe changes in the body Causes opposite of bodily disruption to occur, i.e. the ‘negative’ Examples: body temperature, blood pressure & glucose regulation Homeostatic Control Mechanisms

14 Positive feedback summary: Increases (accelerates) the actions of the body do not require continuous adjustments Examples: Homeostatic Control Mechanisms