Hello! I am third year student at the University of Cambridge studying Neurobiology.
Biology, Chemistry and Maths all make up my degree. I also studied these at IB Higher Level so I would love to share my passion for science with students! I will make sure tutorials are engaging, enjoyable and well-explained.
I studied at Sevenoaks School for 5 years on a double academic scholarship, graduating with 43 points at IB and 10 A*s at (I)GCSE. I am, of course, very well-versed with the unique aspects of the IB such as science coursework, exam practice and the Extended Essay (EE). In my EE in Chemistry I achieved 35 out of 36 marks.
I know this summer is a critical time for university admissions and interview preparation! As such, I can give students in-depth mentoring on personal statements, admissions advice and Oxbridge interview preparation. It is really useful to get this done before the start of the academic year so you're as prepared as possible.
In my free time I enjoy catching up with science news and learning to fly.
I'm a friendly and organised person, so I look forward to hearing from you though a free Meet The Tutor session!
|Biology||A Level||£22 /hr|
|Extended Project Qualification||A Level||£22 /hr|
|Maths||13 Plus||£20 /hr|
|-Personal Statements-||Mentoring||£22 /hr|
|Extended Essay in Chemistry||Baccalaureate||A|
|Theory of Knowledge||Baccalaureate||A|
Felicia (Parent) November 27 2016
Elena (Student) August 11 2016
Elena (Student) August 24 2016
Elena (Student) August 23 2016
Electical impulses usually arrive at the dendrites of a neuron. These then pass through the cell body and a propagated down the longest part of the neuron, the axon.
This is the potential difference across the membrane of the axon when there is no action potnential being carried. It is established by sodium-potassium pumps and membrane channels. The pumps pump out sodium from the cell and pump potassium into it. This, in iteslef, does not change membrane potential as an equal number of ions are pumped in an out, and sodium and potassium ions have equal yet oppostie charges. However, there are also membrane channels which allow sodium or potassium to move passively across the membrane. At resting potential, these are usually closed but the potassium channel is slightly leaky. This means that some of the potassium ions inside the cell are able to move down the concentration gradient to outside the cell. This establishes a negative charge inside the cell, of about -70mV. This is the resting potential.
The sodium and potassium channels in the membrane are voltage-gated. Therefore, when an action potential arrives from further up the axon, it stimulates the sodium channels, which open. This allows the sodium ions to move from outside to inside the cell. This causes a relatively higher charge inside the cell compared to outside, and thus an action potential of around +30mV. The cell is now depolarised.
The potassium pumps are slightly slower to respond, but are eventually activated by this voltage. They open, allowing potassium ions to flow out of the cell. This causes the membrane potential to fall to just below the original resting potential, as the potassium ions flow down the concentration gradient outside the cell. This is known as hyperpolarisation.
The resting potential is eventually re-established by the sodium-potassium pumps.
This sequence is repeated by adjacent channels further down the axon and in this way the action potnential is propagated.see more