Ben Carter
A neuroscientist trying to figure out how the brain does it all. I use MRI and data science methods to study neurophysiology and structure. Currently leading a team of undergraduates in a novel study.
Lab 2
Agenda
- Turn in Lab 1 by the staplers on the North bench.
- Needs names and group number
- ~10 min.: Q&A on Lab 1 material
- 20 min.: Quiz 1
- ~2 hrs.: Lab 2: pH & Buffers
- ~30 min.: Next lab reminders/questions/review
Lab 1 Q&A
Quiz 1
pH & Buffers
Lab 2
Lab Purpose
To allow students to experiment with the carbon dioxide and bicarbonate buffer system that regulates body pH and observe how changes in pH affect enzymatic function.
Lab objectives
- Define what a buffer is and be able to explain how buffers large changes in pH when an acid or a base is added.
- Be able to manipulate the bicarbonate reaction and understand the terminology of alkalosis and acidosis.
- Use the pH meter to determine how the pH of a salt solution (strong acid) changes when it is titrated with a strong acid.
- Use the pH meter to determine how the pH of a solution containing a weak anion changes when it is titrated with a strong acid.
- Be able to use the Henderson-Hasselbach equation.
Lab Safety
- Goggles!
- Closed toed shoes
- Gloves
- Adequate coverage from neck to ankles
- Put your hair up!
- If you spill acid tell me so we can clean it up properly.
What are we doing?
- We're experimenting with the bicarbonate buffer system.
- Add differing amounts of acid to solutions that mimic this system.
- Graph pH to make titration curve.
- Two analytes: NaHCO3 and NaCl.
pH Meter Demo
Core Principles
What is pH?
Why is pH important?
CO_2+H_2O \rightleftharpoons H_2CO_3 \rightleftharpoons H^+ + HCO_3^-
Carbonic
anhydrase
What is the law of mass action?
Henderson-Hasselbach Equation
pH = 6.1 + log(\frac{[HCO_3^-]}{[H_2CO_3]})
pH = 6.1 + log(\frac{[HCO_3^-]}{0.03 \frac{mmol}{L\times mmHg} \times PaCO_2})
Alkalosis or Acidosis?
- Is the pH higher or lower than normal?
- Normal = 7.35-7.45
- If high then alkalosis
- If low then acidosis
- Metabolic or respiratory?
- Is the bicarbonate abnormal?
- Is the PaCO2 abnormal?
- Could the lungs be trying to compensate?
Lab 3: Enzymes
- Read:
- Stanfield pgs. 65-72
- Silverthorn 98-101
- Bring:
- Goggles
- Calculator
- Wear adequate clothing
Lab 2
By Ben Carter
Lab 2
pH & Buffers
