A contact lens is a lens placed on the cornea of the eye.
Importance of buffers in contact lens products:
Buffers: They aim to keep the pH of the solutions at values between 6.6 and 7.8 in order to maintain the lens parameters and the effectiveness of the solutions. They are made by the combination of an acid and its sodium salt (phosphate and acetate for example). Borate and citrate buffers are used.
Importance of isotonicity in contact lens products:
The solution composed by isotonic saline solution.
Isotonia is expressed by osmolarity or cryoscopic lowering
- 0.236 to 0.446 mOsmoles / l (increases during the day)
- If the osmolarity of the mixture is different from that of the tears, it causes discomfort and irritation
• Increased tear secretion
• Increase the blink frequency
- If hypotonia, entry of water to the epithelial cells, if hypertonia: inverse
- Osmolarity restored 1 or 2 minutes after instillation
Answer:
The right answers are mentioned in the picture.
A base pair (bp) is the pairing of two nucleobases located on two complementary strands of DNA or RNA. This pairing is carried out by hydrogen bridges. There are four types of nucleic bases: A-T-C-G, these letters Adenine, Thymine, Cytosine, and Guanine. A with T and C with G.
It is also necessary to take into account the antiparallel character of the DNA strands. If a strand is in the 5 '3' direction, its complete strand is in the 3 '5' direction.
Explanation:
An action potential involves potassium ions moving <u>outside </u>the cell and sodium ions moving <u>inside </u>the cell.
<h3>how does it action potential work?</h3>
Neurons have a negative concentration gradient most of the time, meaning there are more positively charged ions outside than inside the cell. This regular state of a negative concentration gradient is called resting membrane potential. During the resting membrane potential there are:
- more sodium ions
outside than inside the neuron
- more potassium ions
inside than outside the neuron
The concentration of ions isn’t static though! Ions are flowing in and out of the neuron constantly as the ions try to equalize their concentrations. The cell however maintains a fairly consistent negative concentration gradient (between -40 to -90 millivolts). How?
- The neuron cell membrane is super permeable to potassium ions, and so lots of potassium leaks out of the neuron through potassium leakage channels (holes in the cell wall).
- The neuron cell membrane is partially permeable to sodium ions, so sodium atoms slowly leak into the neuron through sodium leakage channels.
- The cell wants to maintain a negative resting membrane potential, so it has a pump that pumps potassium back into the cell and pumps sodium out of the cell at the same time.
Learn more about action potential
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The practice of caloric restriction involves consuming a balanced diet but restricting your caloric intake by approximately 25% below the level of energy consumed in a freely chosen diet.
Answer:
B. The hamstrings must relax.
Explanation:
When the quadriceps contact, the hamstrings must relax at the same time.
