1 Review What is cellular specialization
Explain How do cellular junctions and receptors
help an organism maintain homeostasis
2 Description Use an area in your life- school sports,
etc…, to construct an analogy that explains why
specialization and communication are necessary
for you to function well.
CH 7 CELL STRUCTURE AND FUNCTION
7.4 Homeostasis and Cells
Homeostasis


Relatively constant internal physical and chemical
conditions
To keep constant unicellular organisms grow,
respond to the environment, transform energy,
and reproduce.


Unicellular organisms are most numerous
Eukaryotes may also be unicellular.
Multicellular Organisms



Cells are independent but work together
Cells specialize
Cells communicate.
Levels of Organization

Tissue
 Group
of similar cells that performs a particular
function.
Levels of Organization

Organ
 Groups
of tissues that work together.
Levels of Organization

Organ system
 Group
of organs that work together to perform a
specific function.
Cellular Communication


Use chemical signals between cells
Cells can form cellular junctions
 For

holding cells together or to allow messages to pass
Receptor
 Receives
the chemical message.
Mitochondria Distribution



Scientists studied several organs in the mouse to
see how many mitochondria were found in each.
They described the amount of mitochondria as a
percentage of total cell volume (the greater the
volume=the greater number of mitochondria)
The graph is on the next slide.
Interpret Graphs
What approximate
percentage of cell
volume is
composed of
mitochondria?
Calculate Approximately how much more cellular volume
is composed of mitochondria in the left ventricle
than in the pituitary gland?
Infer There are four chambers in the mouse heart, the
tight and left ventricle, and the left and right atria.
Based on the data given, which chamber- the left or
right ventricle, do you think pumps blood from the
heart to the rest of the body- Explain?