Bio 348 Human Anatomy & Bio 348 Human Anatomy & PhysiologyPhysiology

Janice LapsanskyBI 305

Email: janice.lapsansky@wwu.edu Phone: x7337

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

• Composition of fluids change as substances move between compartments– nutrients, oxygen, ions and wastes move in both

directions across capillary walls

Practice these terms! Always confusing!

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