Bio 348 Human Anatomy Physiology Janice Lapsansky BI

Bio 348 Human Anatomy & Physiology Janice Lapsansky BI 305 Email: janice. lapsansky@wwu. edu Phone: x 7337

Levels of Organization • • • Chemical Cellular Tissue Organs Organ System Organism

Overarching Themes (How do we know something is alive? ) Living things are … • composed of a single cell or a group of cells • AT LEAST physical and chemical machines • respond to short term changes in their environment • grow and reproduce • adapt to long term changes in their environment through natural selection For a review of the chemistry of life, and cell structure and function, study the slide sets posted on the course web page.

The Boundary Organ Concept

Homeostasis of Body Fluids • Separation of fluid compartments – intracellular fluid (ICF) = within cells – extracellular fluid (ECF) = outside cells • intercellular fluid = tissue fluid = interstitial fluid • plasma = fluid portion of blood, part of ECF Practice these terms! Always confusing! • Composition of fluids change as substances move between compartments – nutrients, oxygen, ions and wastes move in both directions across capillary walls

Differential Distribution of Solutes in the ICF and ECF An estimated ___ % of cytoplasmic ATP is used to run the Na-K pump in most human cells.

How is this (homeostasis) controlled?

Components of Feedback Loop • Receptor – monitors a controlled condition • Control center – determines next action • Effector – receives directions from the control center – produces a response that changes the controlled condition

Eg. Homeostasis of Blood Pressure • Pressure receptors in walls of certain arteries detect an increase in BP – Blood Pressure = hydrostatic pressure; the force of blood on walls of vessels • Brain receives input and signals heart and blood vessels • Heart rate slows and arterioles dilate (increase in diameter) • BP returns to normal

Eg. Positive Feedback during Childbirth • Stretch receptors in walls of uterus send signals to the brain • Brain releases hormone (oxytocin) into bloodstream • Uterine smooth muscle contracts more forcefully • More stretch, more hormone, more contraction etc. • Cycle ends with birth of the baby & decrease in stretch