


Study with the several resources on Docsity
Earn points by helping other students or get them with a premium plan
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Community
Ask the community for help and clear up your study doubts
Discover the best universities in your country according to Docsity users
Free resources
Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors
Background information on the role of the kidneys in maintaining homeostasis through excretion and the processes of filtration, reabsorption, and secretion in the nephron. It also explains how the kidneys produce different types of urine based on the body's needs and the role of the loop of henle and the collecting duct in urine production. The document concludes with an activity where students investigate the effects of drinking hypotonic, isotonic, and hypertonic solutions on urine specific gravity and volume.
Typology: Lab Reports
1 / 4
This page cannot be seen from the preview
Don't miss anything!
Human Physiology Lab – Zool 2200L Excretory Physiology
Name:____________________ Lab Section:_________________
Background: The kidneys play a role in maintaining homeostasis through excretion. The kidneys are the major route of excretion for wastes and toxins. The kidneys also play a major role in regulating the volume and composition of extracellular fluid by regulating the volume and composition of urine. The nephron is the functional unit of the kidney. The nephron has a vascular component and a tubular component. The processes of filtration, reabsorption and secretion occurring in the nephron determine the volume and composition of urine.
Define in terms of moving from vascular to tubular components in the nephron:
Filtration
Reabsorption
Secretion
The kidney can make hyperosmotic or hyposmotic urine depending on the body’s need. If the osmolarity of the extracellular fluid increases the kidneys will produce a low volume highly concentrated urine by reabsorbing most of the water filtered. If the osmolarity of the extracellular fluid instead decreases the kidneys will produce a large volume dilute urine by not reabsorbing most of the filtered water. The kidneys can make hyperosmotic urine because of a vertical osmotic gradient that develops in the renal medulla due to the action of the juxtamedullary nephrons.
The loop of Henle in the juxtamedullary nephrons extends deep into the renal medulla. The descending limb of the loop of Henle is permeable to water while the ascending limb is not. The ascending limb of the loop of Henle actively reabsorbs sodium, potassium and chloride while the descending limb does not. The flow through the descending limb runs countercurrent to the ascending limb. The active reabsorption of sodium, potassium and chloride in the ascending limb makes the extracellular fluid hypertonic which draws water out of the descending limb which concentrates the fluid in the loop of Henle. This then increases the amount of sodium, potassium and chloride reabsorbed from the ascending loop which in turns further concentrates the extracellular fluid drawing yet
more water out of the descending limb. This counter current multiplication is what sets up the vertical osmotic gradient in the medulla of the kidney with isosmotic conditions at the cortex medulla interface (300mOsm) to hypertonic conditions at the interior of the medulla (1400mOsm).
Label the following on the juxtamedulary nephron shown below: -Bowman’s capsule -descending limb of the loop of Henle -proximal tubule -ascending limb of the loop of Henle -distal tubule -collecting duct -where filtration, reabsorption and secretion occur
Notice that the collecting duct runs through the vertical osmotic gradient in the medulla. If the collecting duct is permeable to water, water gets reabsorbed and a small amount of hypertonic urine is produced. If the collecting duct is not permeable to water, water does not get reabsorbed and a large amount of hypotonic urine is produced. Antidiuretic hormone (ADH) controls the permeability of the collecting duct to water. When ADH is
Retain a sample of the urine to measure the specific gravity using the refractometer. Your TA will show you how to use the refractometer. You can also use one of the urinalysis sticks on your first urine sample as well as your last urine sample.
Ingest you treatment and record the time. Try to drink the treatment solution as quickly as possible.
Every 20 minutes for 80 minutes collect your urine and measure volume and specific gravity and record your data in the table.
Treatment: Time (min) Specific gravity Urine volume (ml) 0 20 40 60 80 100
How much urine did you produce from 20 – 100 minutes? Record your answer below as well as on the board.
What was the average specific gravity of your urine samples from 20-100 minutes? Record your answer below as well as on the board.
What was the average urine production and specific gravity for each treatment group?
Hypotonic:
Isotonic:
Hypertonic:
Are the results inline with your original hypotheses? Why or why not?