Inside and Outside the Body
Model 1
Critical Thinking Questions:
1. Label the organ systems represented in the drawing (there are six of them).
skin/integumentary, circulatory, respiratory, digestive, urinary, reproductive
2. On the two lines, label “Inside” and “Outside”.
3. What organ system creates the fundamental barrier between the inside and the
outside of the human body?
skin/integumentary
4. Using your pencil, track the pathway that a molecule of undigested food (waste)
would follow. See figure above Does this molecule ever enter the body? YES NO
Students may answer this either YES or NO depending on their level of understanding
of the model – I would accept either answer at this point, but in a follow-up
assessment question, the only correct answer would be NO.
5. Use the above model and the first answer provided in the table below to determine
if the listed item is inside or outside the body. (Complete the table by putting an “X”
in the correct column).
Inside the body
Outside the body
Air in lungs
X
Food in digestive tract
X
Urine in bladder
X
Blood in circulatory system
X
A fetus developing in
uterus
X
6. Examine the model and circle the small arrows. See figure above Complete the table
below identifying what body systems the arrows “bridge” and predict the
physiological activity represented by the arrows.
Body System 1
Specific Organ
Body System 2
Respiratory
Lungs
Circulatory
Digestive
Small Intestine
Circulatory
Urinary/Renal
Kidney
Circulatory
Reproductive
Uterus/placenta
Circulatory
Predicted Function
Oxygen and CO2 exchange
Absorption of nutrients
Removal of wastes and
reabsorption of nutrients
Nutrient and waste exchange
7. Oxygen is essential for life; it is found both on the inside and the outside of the body.
7a) List three anatomical structures
7b) List three structures (or organs)
where oxygen is outside the body
where oxygen is inside the body
1. ____nose/mouth______________
1. _____(many answers possible)___
2. ____pharynx__________________
2. ____________________________
3. ____trachea (also larynx)_______
3. ____________________________
8. Blood is inside the body, but it sometimes comes out. What must happen for blood
to move from the inside to the outside of the body?
There must be a break in the barrier that separates the inside from the outside of the
body. Examples include a break in the skin or damage to the lining of the digestive
system, the latter of which could result in vomitting blood or having bloody stool.
9. Patients with third degree burns (the most serious) are highly susceptible to
infection. Using your understanding of inside and outside the body, explain why this
is and predict what precautions a hospital might take to prevent infections in burn
patients.
The burn has damaged the barrier between the inside and outside of the body. The
inside of the body is now exposed to bacteria, fungi, fluid loss, etc. The hospital
should cover burns with artificial skin or barriers such as sterile bandages. Sterile
techniques must be used in the facility. No plant life will be allowed.
10. As a group, write one grammatically correct explanation as to how to determine if
an item is inside or outside the body. (Hint: examine the model)
Answers will vary. An example might be, “A molecule is determined either inside or
outside based on its position relative to the skin and the membrane of any of the
organ systems shown in the figure above.”
11. A biology student decides that he loves mitochondria so much that he gets a tattoo
to represent this passion. Is the tattoo inside or outside the student’s body? Explain
your reasoning.
Since the tattoo is located “on the line”, i.e. within the barrier of the skin, some
groups might argue that it is inside and some might argue that it is
outside. New tattoos are often the site of infection and frequently
result in bacteria entering the body. It is also possible that some of the
tattoo ink will seep into the lymphatic system.
12. Shade everything outside the body in blue. Shade everything inside the body in red.