Science Wor-Wic Community College Salisbury, MD

RENAL STRUCTURE & FUNCTION ACTIVITY Terry Thompson Department of Math/Science Wor-Wic Community College Salisbury, MD This activity includes three seq...
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RENAL STRUCTURE & FUNCTION ACTIVITY Terry Thompson Department of Math/Science Wor-Wic Community College Salisbury, MD This activity includes three sequential classroom activities with pairs of students using worksheets. This was created as part of a HAPS-Institute course and the original intention was to use this activity in class, following lecture on kidney structure & function, allowing students to immediately apply their new knowledge (lecture notes) in another format (worksheet) interactively way with a partner. This would be non-graded reinforcement, allowing instructor to identify and further discuss areas of confusion and/or misinformation and provide another study tool for students to take home. By allowing students to use only their and their partner’s notes (not textbook) to complete the activity, this can also facilitate a self-check for the completeness of student notes after the lecture. However, this activity could easily be divided into separate sections, using only part of the activity, such as sequencing or nephron image alone. The table worksheet could also be used as a graded homework assignment or as an assessment/quiz in a later class, after students have had time to study their notes on renal structure & function. Activity 1: Renal Sequencing This kinesthetic activity involves students placing renal blood & filtrate flow segments into the correct sequence. The worksheet is designed to be printed or copied directly on labels (Avery#6460 – 1 X 2⅝” removable labels) available in office supply stores. This allows student pairs to stick and re-stick the labels into two sequential flow charts: one for blood flow and one for filtrate flow. This should be completed without using textbook figures showing these structures, so students are encouraged to visualize and discuss the process themselves. You need one set of stickers per 2 students. The team will have to decide how to share the final product if supplies are limited; or give a new unsorted one to each pair to take home. The PDF version reformats the page, so it will NOT match the label layout when printed. To get a copy of the MS Word document formatted specifically for printing onto the AVERY stickers, contact Ms. Terry Thompson at ([email protected]). You could also have students cut the paper version printed from the PDF document and move those around instead of stickers. Activity 2: Renal Nephron Overview This worksheet has a drawing of the nephron & associated blood vessels. This is designed so that students will color the different parts of the “equations” at the top and color the corresponding part of nephron or 3 arrows (for Fick principle). The lettered parts and numbered major functions on this drawing will then be matched to the Table worksheet in Activity 3. Activity 3: Renal Microanatomy Structure & Function This Table-format worksheet provides a chance for students to fully appreciate the differences in cell-level structure throughout the nephron and correlate this anatomical ultrastructure to the different physiological processes involved in renal function.

©2007 Terry Thompson

References: Costanzo, L. S. (1998). Physiology Text & Review. Phila. PA.:W.B. Saunders/Elsevere Science. Eaton, D. C. & Pooler, J. P. (2004). Vander’s Renal Physiology 6th edition. N.Y.: Lange Medical Books/McGraw-Hill. Hansen, J. T., Koeppen, B. M. & Netter, F. H. (2002). Netter’s Atlas of Human Physiology. Teterboro, N.J.: Icon Learning Systems. Young, B. & Heath, J. W. (2000). Wheater’s Functional Histology: A text and colour atlas. Edinboro: Churchill Livingstone/Harcourt.

©2007 Terry Thompson

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Filtration

Reabsorption

Solute in Renal artery (Fick Principle)

A

B

C

D

=

+

Secretion

Solute in Urine

E

F

G

+

=

Excretion

Solute in Renal vein

H I J

Major Functions: 1. autoregulation of filtration (GFR) 2. efficient plasma filtration without RBC & large plasma proteins 3. efficient iso-osomotic solute & water reabsorption 4. countercurrent multiplier to create medullary interstitial osmotic gradient 5. countercurrent exchange to preserve medullary interstitial osmotic gradient 6. dilution of tubular fluid 7. variable water reabsorption 8. selective excretion of excess ions/waste 9. gas exchange

K L M N O

RENAL STRUCTURE/FUNCTION WORKSHEET DIRECTIONS: Match each cell type in table to lettered location on nephron drawing & numbered major renal function. A cell type may use more than one letter/number REMINDER: At the cell/tissue level, epithelial tissue has free surface & basement membrane. Renal free surface will be either inside blood vessel or nephron space. Renal basement membrane will be either shared with another epithelial layer or toward an interstitial connective tissue.

Match

Cell Microanatomy

Structural Details & Implications for Function:

Special epithelial cells with channels for sodium & potassium (selective transcellular transport) driven by sodium/potassium “pump” toward interstitium; receptor for ADH stimulates/adds more aquaporins & receptor for aldosterone stimulates sodium/potassium channels (hormone regulation) Epithelial cells with tight junctions & many microvilli forming brush border toward lumen (increased surface area) with many aquaporins & many different cotransporters & countertransporters for glucose, amino acids & ions (selective transcellular transport) driven by sodium/potassium “pump” toward interstitium Specialized epithelial cells with interlaced finger-like pedicel extensions & thin filaments over intercellular filtration slits (selective pore size); endocytotic vesicles (phagocytosis); contactile microfilaments (change surface area); share basement membrane with underlying embraced endothelial cells (large protein molecule barrier) Network (increased surface area) of endothelial cells with intercellular fenestra larger than typical capillary slit pores but smaller than formed elements in blood (selective pore size); hemodynamics create relatively higher pressure than typical capillaries (increased hydrostatic pressure)

RENAL STRUCTURE/FUNCTION WORKSHEET CONTINUED 2 Match

Cell Microanatomy

Structural Details & Implications for Function: Epithelial cells with 2-ion cotransporters for sodium & chloride but no aquaporins (selective transcellular transport) driven by sodium/potassium “pump” toward interstitium; receptor for parathyroid hormone stimulates calcium channels (hormone regulation) Network (increased surface area) of endothelial cells with intercellular fenestra (selective pore size); hemodynamics create relatively lower pressure & higher colloidal osmolarity than typical capillaries (decreased hydrostatic & increased osmostic pressure) Thin epithelial cells with a few passive channels for sodium, chloride & urea (selective transcellular transport); many aquaporins (osmosis); opposite & parallel limbs (counter-current) Thick epithelial cells with load-dependent 3-ion cotransporters for sodium, potassium & chloride but no aquaporins (selective transcellular transport) driven by sodium/potassium “pump” toward interstitium; receptor for ADH stimulates sodium, potassium, chloride channels (hormone regulation) Specialized epithelial cells with hydrogen ion “pump” and hydrogen ion/potassium “pump” (selective transcellular active transport)

Specialized smooth muscle cells associated with baroreceptors (autoregulation); contractile microfilaments (change surface area); vesicles secrete renin (hormone-like regulation)

RENAL STRUCTURE/FUNCTION WORKSHEET CONTINUED 3 Match

Cell Microanatomy

Structural Details & Implications for Function: Specialized mesenchyme cells with endocytotic vesicles (phagocytosis); contractile microfilaments (change surface area); vesicles secrete chemicals for local vasoconstriction (autoregulation) Specialized tall, thighly packed epithelial cells (increased surface area) with sodium chloride sensors and vesicles to release chemicals for local vasoconstriction & inhibition of renin release (autoregulation) Opposite & paralell limbs (counter-current) of endothelial cells with intercellular fenestra (selective pore size); hemodynamics create relatively lower pressure than typical capillaries (decreased hydrostatic pressure) Epithelial cells with hydrogen ion “pump” and hydrogen ion/potassium “pump” (selective transcellular active transport); channels for sodium & urea (selective transcellular transport); receptor for ADH stimulates sodium & urea channels and receptors for ANP inhibit sodium channels (hormone regulation) Epithelial cells with tight junctions & a few microvilli toward lumen (increased surface area) with aquaporins & countertransporters for chloride, sodium, phosphate, hydrogen & bicarbonate (selective transcellular transport) driven by sodium/potassium “pump” toward interstitium; receptor for parathyroid hormone inhibits phosphate cotransport and receptor for aniotensin stimulates sodium countertransporter (hormone regulation) facilitated by carbonic anhydrase & ammonium Thin epithelial cells with many passive channels for sodium, chloride & urea (selective transcellular transport); opposite & parallel limbs (counter-current)