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BIOD27H3 Study Guide - Abdominopelvic Cavity, Extracellular Fluid, Fluid Compartments

Biological Sciences
Course Code

of 41
Chapter 3 Notes
Biological compartments = varied
oSome come are completely enclosed structured
Ex. cells
oSome dont even have visible walls
Development of life:
oSimple cell w/ only ICF and membrane intracellular compartments
developed w/ their own membranes single-celled organisms
cooperated and specialized their functions thus giving rise to
multicellular organisms as multicellular organisms became more
complex and larger, many separate functional compartments formed
Pros and cons to compartmentation:
Biochemical processes that would conflict w/ e/o are separated
from e/o
Contents in one compartment can differ from contents in
another compartment, even for adjacent compartments
Barriers make it hard for needed materials of one compartment
to move to that compartment
Functional Compartments of the Body
Human body has 3 major body cavities:
1.Cranial cavity (skull) [cranium, skull)
Contains the brain, our PRIMARY control center
2.Thoracic cavity (thorax)
Bounded by the spine and ribs on top and sides, w/ the muscular
diaphragm forming the floor
Surrounds the heart and the lungs
Heart is enclosed in a membranous pericardial sac [peri-,
around + cardium, heart]; both lungs are enclosed in
separate pleural sacs
3.Abdominopelvic cavity
Abdomen and pelvis form one continuous cavity
The peritoneum, a tissue lining, lines the abdomen and
surrounds the organs within it (stomach, intestines, liver,
pancreas, gallbladder, and spleen)
The kidneys lie OUTSIDE the abdominal cavity, b/w the
peritoneum and the muscles and bones of the back, just above
the waist level
The pelvis contains reproductive organs, the urinary bladder,
and the end portion of the large intestine
o these cavities are separated by bones and tissues, and they’re lined
w/ tissue membranes
the lumens of some organs are outside the body
the heart, lungs, blood vessels, and intestines are all HOLLOW organs, thus
creating another set of compartments within the body
olumen: the interior of any HOLLOW organ [lumin, window]
a lumen may be completely or partially filled w/ air or fluid
ex. blood vessels are filled w/ blood, a fluid
for some organs, the lumen is pretty much an extension of the
external environment
ex. the digestive tracts not really inside our body; its
lumen is part of the body’s external environment
to understand this, just think of a hole through a bead;
the hole passes through the bead, but isnt actually inside
the bead
Functionally, the body has three fluid compartments
Most cells ARE NOT in direct contact w/ the outside world
oThey’re, instead, surrounded by ECF
We can think of the body as being composed of 2 units: the cells that compose
the body, and the fluid that surrounds them
oUsing this concept of the body, we can divide the body into TWO
The intracellular fluid (ICF) in the cells
The extracellular fluid (ECF) outside the cells
ECF can be further divided into compartments:
oplasma: fluid portion of the blood
lies within the circulatory sys
ointerstitial fluid [inter-, b/w + stare, to stand]: lies
b/w the circulatory sys and the cells
These two compartments are separated by the barrier of the
cell membrane
note that even though weve considered cells to be of a single fluid
compartment, they are highly variable in size, shape, and composition
Biological Membranes
membrane [membrana, a skin] has two meanings in biology:
a.(before invention of microscopes) a tissue that lines a cavity or
separates 2 compartments
i.ex. mucous membrane, peritoneal membrane, pleural membrane
ii.VISIBLE, thin, translucent layers of cells
b.(after invention of microscopes) once scientists recognized a barrier b/w
the intracellular fluid and external environment of cells, they had
concluded that the outer surface of cells (cell membrane) was a thin
layer of lipids that separated the internal aqueous fluids from the
external environment