Levels of organization:
Chemical level:
□ Simplest level (smallest components) includes atoms &
molecules
□ Building blocks of matter
Organelles:
□ Atoms & molecules assemble to form specialized
structures within the cell with a variety of shapes, sizes, &
functions
□ Includes: nucleus, mitochondria, ribosomes
Cellular level:
□ Composed of a variety of different organelles that
assemble together. Basic structural & functional unit of an
organism. Same common function, vary in size & shape,
each type having its own unique function.
□ Includes: muscle cells, nerve cells, blood cells
Tissue level:
□ Groups of similar cells that have a common function.
□ Includes: Epithelial tissue, Connective tissue, Muscle
tissue, Nervous tissue
Organ level:
□ Composed of two or more different types of tissues. They
perform specific functions and have defined shapes.
□ Includes: Stomach, brain, heart, lungs
Organ system level:
□ Made of two or more different but related organs that have
a common function
□ Includes: Digestive system, Cardiovascular system
Organism level:
□ The sum total of all structural levels working together.
Homeostasis
1) Definition:
Maintaining relatively constant internal conditions (dynamic balance
within narrow ranges) even though outside is in constant change
2) Why is it called a “feedback” system. In other words what is fed back?
The RESULT of a process to restore homeostasis is fed back as the
new STIMULUS(STRESS)
3) Read the example below (Osmoregulation). Select a part(phrase) from the example
that provides an example of each term that follows: Control Center, Variable
(Controlled Condition), Stimulus (Stress), Receptor (Monitor), Effector, Response,
Result, and Feedback.
Osmoregulation
Osmoregulation is the regulation of water concentrations in the bloodstream,
effectively controlling the amount of water available for cells to absorb.
Due to exercise excessive sweating causes a decrease in water concentration in the
body. Osmoreceptors that are capable of detecting water concentration are situated on the
hypothalamus in the brainstem. The hypothalamus sends chemical messages to the
pituitary gland (in the brain) next to it. The pituitary gland secretes anti-diuretic hormone
(ADH), which targets the kidney responsible for maintaining water levels. When the
hormone reaches its target tissue, it alters the tubules of the kidney to become more
permeable to water. If more water is required in the blood stream, high concentrations of
ADH make the tubules more permeable thus increasing the volume of water in the
bloodstream. The osmoreceptors in the hypothalamus reevaluate the new water
concentration and determine what the next step is.
Control Center: __________pituitary gland________
Variable (Controlled Condition): Osmoregulation = regulation of water concentrations
in the bloodstream
Stimulus (Stress): exercise causing a decrease in water concentration
Receptor (Monitor): Osmoreceptors in the hypothalamus
Effector: _______kidney___________
Response: tubules of the kidney to become more permeable to water.
Result: increasing the volume of water in the bloodstream.
Feedback: the result is fedback as the new stimulus (New water concentration is
reevaluated by the Osmoreceptors in the hypothalamus) and/or Negative Feedback
because the Result conteracts the Stimulus