BI222 Lecture 12ii Worksheet: How do animals accomplish exchange and bulk flow?
Topic 12, part ii – Osmoregulation & Excretion
Name:_______________________________ Student ID:___________________________
Name:_______________________________ Student ID:___________________________
Name:_______________________________ Student ID:___________________________
Name:_______________________________ Student ID:___________________________
QUESTION 1.
1a. Label the 10 anatomical structures in the mammalian excretory system below:
Kidney
Urethra
Bladder
Nephron
Ureter
Renal vein
blue
renalvein
red
renalartery
Renal pelvis
Renal artery
Renal medulla
Renal cortex
kidney
renal medulla
bladder
Urethra
Ureter
renal cortex
renal pelvis
nephron
1b. Place
stars
next to the 5 structures that are exclusively carrying fluid that is considered to
be a part of the “outside” environment.
QUESTION 2. Contrast the wastes leaving the mammalian excretory system vs. the wastes leaving the
mammalian digestive system. How are these processes for waste removal different?
BI222 Lecture 12ii Worksheet: How do animals accomplish exchange and bulk flow?
Topic 12, part ii – Osmoregulation & Excretion
QUESTION 3.
Organize the three forms of nitrogenous waste (ammonia, urea, uric acid) from most to least toxic.
uric acidleast toxic
ammonia most toxic
urea
QUESTION 4.
In the mammalian kidney, glomerular capillaries are not permeable to blood cells or large solutes.
However, H2O and small solutes (e.g., urea) can freely pass from glomerular capillaries into the
Bowman’s capsule through tiny pores that act like a filtration membrane.
Conceptual Model
Blood:
• Blood&cells
• Large&solutes&(e.g.,
proteins)
• H2O
• Small&solutes&(e.g.,&
urea,&salts,&glucose)
Blood
Initial'filtrate:
• H2O
• Small)solutes)(e.g.,)
urea,)salts,)glucose)
Initial Filtrate
4a. Circle the 3 elements that freely pass from glomerular capillaries into the Bowman’s capsule
during the “filtration” step that forms the initial filtrate:
water / cells / urea / proteins / glucose
4b. Thus, the concentration of urea in the initial filtrate is
as compared to the concentration of urea in blood plasma .
4c. As the filtrate moves along the nephron, up to 99% of
higher / about the same / lower
H2O / urea is reabsorbed.
4d. Such processing of the initial filtrate yields a hyperosmotic / isoosmotic / hypoosmotic final
waste product with respect to blood plasma.
4e. The volume of this final waste product is much higher / similar to / lower
volume of the initial filtrate.
than the
4f. Hormones (e.g., antidiuretic hormone: ADH) control permeability of the nephron to water and
can make a more dilute or concentrated final waste product based on need. Thus, the kidney is a
powerful osmoregulatory / excretory organ that can maintain appropriate osmolarity of
internal fluids (e.g., during variable access to drinking water).
4g. While controlling water balance, the mammalian nephron
also removes the nitrogenous waste product called:
urea
Thus, the kidney also plays a critical role in the process of
osmoregulation / excretion.