ADH Podcast

Link to the Podcast: Click Here

Transcript:

Antidiuretic hormone, also known commonly as arginine vasopressin, is a nine amino acid peptide produced in a part of the brain called the hypothalamus. Within hypothalamic neurons, the hormone is packaged in secretory vesicles with a carrier protein called neurophysin, and both are released upon hormone secretion.

The hormone is released from the pituitary gland, a small gland at the base of the brain.  Therefore, ADH follows the simple neuroendocrine pathway, in which the stimulus attaches to sensory neuron in hypothalamus and a hormone is secreted.

·      Solubility

ADH is soluble in water because it contains a hydroxyl group at the end of the peptide chain. Since hydroxyl group makes the molecule polar, it can dissolve in polar solvent such as water.

·      Function

The single most important effect of antidiuretic hormone is to conserve body water by reducing the loss of water in urine. A diuretic is an agent that increases the rate of urine formation. Injection of small amounts of antidiuretic hormone into a person or animal results in antidiuresis or decreased formation of urine, and the hormone was named for this effect.

Antidiuretic hormone is a peptide hormone that increases water permeability of the kidney's collecting duct and distal convoluted tubule by inducing translocation of aquaporin-CD water channels in the kidney nephron collecting duct plasma membrane.

·      Receptor

Antidiuretic hormone binds to receptors on cell’s surface in the collecting ducts of the kidney and promotes reabsorption of water back into the circulation. In the absence of antidiuretic hormone, the collecting ducts are virtually impermeable to water, and it flows out as urine.

·      Regulation

The production of ADH is a negative feedback system. The most important variable regulating antidiuretic hormone secretion is plasma osmolarity, or the concentration of solutes in blood. Osmolarity is sensed in the hypothalamus by neurons known as an osmoreceptors, and those neurons, in turn, stimulate secretion from the neurons that produce antidiuretic hormone. When osmolarity is high in the blood, the pituitary gland releases less ADH. Then, kidneys remove water from blood so more water is lost in urine, which lowers the osmolarity.

On the other hand, the hypothalamus releases more ADH when the water level in blood is low. Then, kidneys remove less water from the blood so less water is lost in urine.

Reference:

http://arbl.cvmbs.colostate.edu/hbooks/pathphys/endocrine/hypopit/adh.html

http://www.nlm.nih.gov/medlineplus/ency/article/003702.htm

http://www.abpischools.org.uk/page/modules/homeostasis_kidneys/kidneys6.cfm?coSiteNavigation_allTopic=1

Cell Respiration Lab

Yeast Cell Respiration Lab

Introduction: Cell respiration is a process in which the organisms transform glucose and oxygen into carbon dioxide, water, and ATPs. ATPs give energy to the cells to function. Yeasts are a type of fungi. They can respire only in certain environments. With the presence of oxygen and glucose, yeasts can undergo the process of cell respiration.

Equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

Objective:  In order to see the effects of temperature on the rate of cell respiration, we can collect the amount of gas produced by yeasts in different temperatures, given the same amount of time.

Hypothesis: Cell respiration operates faster at a higher temperature due to the intensive movement of particles at a higher temperature.

Materials

1.     Water

2.     Sugar

3.     Yeast

4.     Salt

5.     3 Thermometers

6.     Graduated Cylinders

7.     Scale

8.     Weighing paper

9.     3 Syringes

       3 Test Tubes

       Heating Block

       Ice Box

Procedure:

1.     Measure 3 sets of following materials: 35 mL of water, 1g of sugar, 1g of yeast, and 0.2g of salt

2.     Dump all materials except yeast into each test tube

3.     Dump yeast into each test tube and start the timer

4.     Shake test tubes well

5.     Connect the syringes to the stoppers. Start the syringes at 1mL.

6.     Collect data every 5 minutes

Safety:

1.     Be careful of the fermentation of the yeast. Wash your hands after touching the solution.

2.     Do not put your hands into the heating block

3.     Do not put your hands too long in the ice box

Results:

Time (minutes)	Volume at 5 degrees celcius (mL)	Volume at 18.6 degrees celcius  (mL)	Hot temp 49 degrees celcius  (mL)
0	1	1	1
5	1	1.1	2.6
10	1.1	1.1	4.5
15	1.1	1.2	6.3

Cell Respiration Rates at Different Temperatures

Horizontal Axis: Time (Minutes)

Vertical Axis: Volume (mL)

Conclusion:

According to the graph, the volumes of gas produced in 5 degrees and 18.6 degrees merely changed in the 15 minutes interval. However, the volume of gas produced in 49 degrees raised significantly, almost 6 times larger than the other two. As a result, we have evidence to confirm our hypothesis that cell respiration of yeast runs faster at a higher temperature. One of the main reasons for the pace of cell respiration is the increased motion of particles at a higher temperature.

Standards: SP1/1, SP4/1, SP6/1

I am able to ask questions, post hypothesis, collect and analyze data, and apply scientific principles and evidence to explain phenomena.