Chapter 3
Organization of the
Body
Human Physiology
DOERFLER
Introduction
 Molecules are placed into levels of organization, or
hierarchies
 Series or ordered groupings within a system
• Each level relies on properties of the lower level
Hierarchy of Human Structure
 Cell – basic structural unit and functional unit of the
human body
 Simplest characteristic of all organisms
• Unicellular – body comprised of one cell
• One cell must carry out all life functions (constant communication with
environment)
• Multicellular – consisting of many cells
• Cells cooperate with each other to carry out jobs
• DIFFERENTIATION
• Process by which cells mature in order to carry out the cells needs
Levels of Organization
 Cell – from previous
 Tissue – organized group
of cells
 Organ – organized group
of tissues
 Organ system – organized
group of organs
 Organism – individual
biological unit capable of
reproduction
 Any living thing
Levels of Organization, cont.
 The organism is NOT the highest level of
organization
 Society – groups of organisms interacting
• Outcomes of human interactions affect homeostasis
 Envirome – highest level of organization
• All environmental factors that affect the survival of organisms
• Enviromics
• Study of the envirome
• Investigates the balance of the environmental conditions and processes
that affect an organisms adaptations for survival
The Human Physiological
Environment
 Physiological environment – internal conditions
that optimize individual cell function and body
organization
 Cells would not survive without a suitable environment
• Internal environment – condition inside the cell
• External environment – conditions outside the cell
Water
 No life possible without water
 Most abundant molecule in the body
 55-60%
 When water level falls below a certain level, the
body is dehydrated
 State in which tissues are deprived of water
• Occurs from inadequate water in take or excessive water loss
• Diarrhea, sweating, vomiting
• Indicators are – extreme thirst, nausea and exhaustion
 Overhydration – body contains too much water
 Termed water excess or water intoxication
• Harmful because it disrupts the physiological environment
Water, cont.
 Human environment is aqueous
 Pertaining to water
 Water is a polar molecule
 Polarity permits water to dissolve most of the biochemicals
needed for human survival.
 Water is universal solvent
 Solvent – substance that dissolves other chemicals
 Solute – substances that dissolves in a solvent
• When a solute dissolves in a solvent, it forms a solution
• Uniform mixture of two or more substances
 Water has high specific heat
 Energy required to raise the temperature of a substance
• Prevents the body from heating or cooling too quickly
Ions
 play roles to help maintain the physiological
environment
 Electrically charged particles
 Classification of ions
 Minerals – nutrients needed for the body
 Metals – several elements that conduct heat and electricity
 Cations – positively charged ions
 Anions – negatively charged ions
 All ions are water soluble
 Most are lost by kidneys are they produce urine
 2nd is sweating, then feces, and vomiting
Major Ions Related to Human
Health
 Bicarbonate – fluid buffer that makes acidic
conditions neutral to slightly basic
 Regulated by kidneys and lungs
 Calcium – two forms:
 Diffusable – found in salts in bone
 Nondiffusable – bound to blood and cell proteins
 Chloride – in association with potassium and
sodium
 Potassium chlorine (KCl) and sodium chloride (NaCl)
 Copper, Iodine, and Iron help carry out chemical
reactions in the cell
Major Ions Related to Human
Health, cont.
 Magnesium – carries out many jobs done by calcium
 Critical for energy production and proper nerve function
 Phosphate – body fluid buffer regulated by kidney
 80% is used in the body bonds with calcium for bone
hardening
 Potassium – most abundant element inside of cells
 Controls muscle and heart contractions
 Sodium – most common mineral found outside of the
cell
 Controls water retention
 Sulfate – found as an anion attached to other
moelcules
 Acidic, lower the pH of body fluids
 STOP!!!!!