A Journey Through Medical School

Some pre-matriculation shopping is in order.

Thu, 10 May 2012 21:41:38 -0400

Some pre-matriculation shopping is in order.

In the meantime...

Sun, 06 May 2012 22:48:46 -0400

I’ll start posting on August 10th, the day of my white-coat ceremony. In the meantime, I’ll enjoy the summer with my wonderful girlfriend. See you soon.

Richard Young has a tumblr: John Mayer Autographed Photo Giveaway!

Sun, 06 May 2012 22:30:32 -0400

Richard Young has a tumblr: John Mayer Autographed Photo Giveaway!:

iamrichardyoung:

Hey all, I wanted to let you know that I’m giving away this autographed John Mayer photo! It’s from the Heavier Things era and I think by all accounts is pretty rare. If more of these exist, good luck finding one! It’s 100% authentic. I would prefer it go to someone who doesn’t have an…

iamrichardyoung: Since it is Friday and because I’m admittedly...

Fri, 16 Mar 2012 20:04:23 -0400

iamrichardyoung:

Since it is Friday and because I’m admittedly curious about tumblr reach, I am giving away a signed copy of John Mayer’s “Inside Want Out” to one lucky person who reblogs this post. You must reblog this post by Sunday, 3/18 at 11:59 PM EST to be eligible. I will literally pick someone at random and will contact you afterwards for your details.

Please note, this is a signed copy of the re-release of Inside Wants Out distributed by Columbia Records.

Good luck and spread the word!!

-RY

PS, international people outside of the US will be eligible!

First ‘Heartless’ Man: You don't really need a Heart, or a Pulse

Mon, 13 Feb 2012 23:33:27 -0500

First ‘Heartless’ Man: You don't really need a Heart, or a Pulse:

ziyadmd:

Two doctors Billy Cohn and Bud Frazier from the Texas Heart Institute successfully replaced a dying man’s heart with a device — proving that it is possible for your body to be kept alive without a heart, or a pulse.

In the short film ‘Heart Stop Beating’ by Jeremiah Zagar of Focus…

NSAIDS

Mon, 13 Feb 2012 23:16:55 -0500

First post in while is coming tomorrow. Topic: Non-steroidal anti-inflammatory drugs (NSAIDS)

MCAT

Sun, 26 Jun 2011 10:47:13 -0400

I got a 31R on my MCAT!!! Looks like creating this tumblr and re-writing my notes from scratch was a smart idea! Wahoo.

Photo

Wed, 25 May 2011 23:20:19 -0400

jhnmyr: Aaron Sterling’s Amazing Live Delay Drumming

Fri, 20 May 2011 12:53:01 -0400

jhnmyr:

Aaron Sterling’s Amazing Live Delay Drumming

Done With The MCAT

Thu, 12 May 2011 11:47:32 -0400

I finished the MCAT! I totally (think I) did great but I have to wait a month. I’m not really sure what else to use tumblr for now.

Ideal and Real Gases

Sun, 01 May 2011 22:42:49 -0400

I’ve been so busy with studying that I forgot how valuable typing up confusing things can be.

Ideal Gases: By using ideal gases, we are able to study the effects of temperature, pressure, volume, and mol amount of gas. By the simple equation PV=nRT, all variable relationships can be seen. Ideal gases are best used at high temperature and low pressures to decrease any chance of intermolecular attraction

Avagadro’s Law: V1/n1 = V2/n2. Simply put, as the amount of gas increases in an expandable container, the volume will increase. An example would be blowing up a balloon.

Charles Law: V1/T1 = V2/T2. As the temperature of a gas increases, so does the volume.

Boyle’s Law: P1*V1 = P2*V2. Pressure and volume are inversely related (in a non-linear way. As one increases, the other decreases.

Real Gases: Here comes the semi-confusing part. At low temperatures and high pressures, the size of the gas molecules becomes noticeable. The real volume will always be higher. Videal = [Vreal - (nb)] where b is a constant that is always positive. If you solve for Vreal, you can see that Videal + nb is a larger number than the ideal volume. Pressure is slightly (but not by much) more complicated. When the molecules are attracted to each other through forces like dipole-dipole interactions, hydrogen bonding, or ionic attractions, the pressure will decrease. This means that Preal<Pideal. When they repel, there will be a great pressure against the walls of the container Preal>Pideal. This part of the equation is Pobs = Preal + (n^2/V^2)(a). Solving for Preal, well see that it is equal to Preal = Pideal - (n^2/V^2)(a). If the molecules are attracted to each other, “a” is a positive number and Preal is less than Pideal. If the molecules are repelled by one another, “a” is a negative number, and Pdeal will be added to the (a) value creating a higher Preal.

It’s much more simple to remember that when molecules are attracted, they come together and there will be less pressure. (a = +) When they repel, there is a large pressure against the walls of the container (b = - ). For volume, the real volume is always greater than the ideal volume.

Combining the equations, we get [Preal + (a)(n^2/V^2)][Videal - nb] = nRT

Male and Female Anatomy

Wed, 06 Apr 2011 13:46:03 -0400

Males: The gonads in males are the testes. Inside the testes, sperm is made in the seminiferous tubules. These convoluted tubules are associated with two really important types of cells - Leydig and Sertoli cells. Leydig cells are stimulated by leutinizing hormone (LH) and convert cholesterol into testosterone. Testosterone is required for male secondary sex characteristics like pubic hair, lowered voice, growth of the larynx, and fusion of the epiphyseal plate (growth plate). Testosterone also acts on adjacent cells called Sertoli cells. Testosterone acts to encourage sperm production. In the Sertoli cells, testosterone is converted to dihydrotestosterone. Secondly, Sertoli cells are induced by Follicle Stimulating Hormone (FSH) which is required for sperm production. Negative feedback is used by both Leydig cells and Sertoli cells. If too much testosterone is produced, it can act to inhibit GnRH production by the hypothalamus as well as LH production in the anterior pituitary. Similarly, Sertoli cells can inhibit FSH production of the Anterior Pituitary by releasing a peptide hormone called “Inhibin.”

Females: The gonads in females are the ovaries. By birth, all of the ova that a female will produce are made. During puberty, these ova will be released into the fallopian tubes (ovaducts) and try to get fertilized. In order for all this to happen, lets back up a little. A primary oocyte is surrounded by granulosa cells which together are called a primary follicle. Thecal cells now surround this primary follicle and create what is called a secondary follicle. Theca and granulosa cells are similar to Leydig and Sertoli cells in men. Theca cells are stimulated by LH and make testosterone from cholesterol. The testosterone is then converted to estrodiol (a form of estrogen) in Granulosa cells. Similar to Sertoli cells, Granulosa cells are stimulated by FSH which help mature primary oocytes.

The female menstrual cycle can be broken down into an average of 28 days. During the first 14 days, the primary oocyte has matured to a secondary oocyte. On the 14th day, there is a surge of estrogen which causes a subsequent surge of LH. This LH surge (known as the luteal surge) causes the secondary follicle to burst, releasing the secondary oocyte into the ovaduct.The left over follicle is now called the Corpus Luteum and begins to secrete both estrogen and progesterone. In combination, these two steroid hormones inhibit LH secretion from the anterior pituitary. This allows for the endometrium to grow and thicken. This occurs for 2 weeks after ovulation. If fertilization does not occur, the endometrium will be shed and the Corpus Luteum will degrade into the Corpus Albicans.

The period of 14 days up till ovulation is known as the Follicular Phase. The period from ovulation until degredation of the Corpus Luteum is known as the Luteal Phase. The shedding of the uterine lining is known as “flow.” Flow represents the last 5 days of the cycle and is observed by vaginal bleeding.

Photo

Thu, 24 Mar 2011 15:55:50 -0400

Acids and Bases

Thu, 24 Mar 2011 14:03:08 -0400

Time for some chemistry!

Acids and Bases can be classified by 3 different defintions

1. Arrhenius Acids and Bases: An Arrhenius acid in water will increase the [H+] concentration. An Arrhenius base will increase the hydroxide [OH-] concentration.

2. Bronsted/Lowry: An acid will donate a proton while a base will accept a proton.

3. Lewis Acids/Bases: A Lewis acid (electrophile) will accept an electron while a Lewis Base (neutrophile) will donate an electron. Usually, a Lewis acid has a positive charge or an empty orbial (such as BF3). Transition metals like Fe3+ are also Lewis acids because of their positive charge. Lewis bases want to become neutral so they have negative charges due to carrying extra electrons.

A compound can be classified as a strong acid or base if it dissociates 100% in water

Strong Acids: HNO3, HCl, HBr, HI, H2SO4, HCLO4, HCLO3

Strong Bases: LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, Ba(OH)2

Water is unique in that it is amphoteric. It can act as either an acid or a base

The strength of an acid or base is defined in 2 ways. Its pH/pOH, and its pKa/pKb.

pH = -log[H+], pOH = -log[OH-]. pH is on a scale from 0-14 with 0 being extremely acidic and 14 being extremely basic. Depending on the concenrations, numbers can be below 0 (negative) or above 14.

Pure H20 will ionize completely. H20 -> H+ + OH-

Writing out the Keq equation, Keq = Kw = [H+][OH-] = 10^-14, meaning H and OH have values of 10^-7. THIS IS ONLY VALID AT 25 degrees C. If the temperature is raised, there is a large amount of H+ and OH-. Looking at equilibrium stresses, a shift to the products side means that the reaction is endothermic.

For example, if the new Kw = 10^-12, H+ and OH- are equal to 10^-6 (which is a much higher concentration than 10^-7. The -log(10^-6) = pH = 6. The new neutral pH at that higher temperature is equal to 6.

geneticist: Sand dollar zygotes during the first mitosis. The...

Thu, 24 Mar 2011 13:43:44 -0400

geneticist:

Sand dollar zygotes during the first mitosis. The microtubules and chromosomes have been stained.

If I remember correctly, DAPI staining is used to visualize nucleic acid.

Photo

Thu, 24 Mar 2011 13:42:10 -0400

Photo

Wed, 16 Mar 2011 04:15:31 -0400

Waves

Tue, 15 Mar 2011 17:48:30 -0400

Waves are defined as a disturbance in a medium. They transfer both energy and momentum but do not transfer any of the medium.

1. Frequency (f): The amount of round trips that occur in 1 second. It is inversely proportional to period.

2. Period (T): How long it takes for 1 round trip to occur. It is inversely proportional to frequency.

3. Amplitude (A): The max displacement from equilibrium. This quantity does NOT depend on frequency, period, or velocity. Amplitude is determined by how much energy is put into the system!

As you can see in the transverse wave. The movement (propagation) of the wave is perpendicular to the oscillations. In longitudinal waves, the movement is parallel to the oscillations.

An extremely important and well recognized equation is (λ)(f) = v where λ is the wavelength, f is the frequency, and v is the velocity. Another important equation is v =sqr(tension/linear density). This equation shows that velocity is actually an intrinsic property that depends on the medium and NOT on the frequency and wavelength. Now going back to the original equation, (λ)(f) = v, since v is constant, a change in (λ) or (f) will cause a change in the other.

You cause these equations to solve for distance or time. Since v=d/t, t =d/v, t = d/(λ)(f) or dT/(λ) = t. Solving for d, t(λ)/T = d or t(λ)(f) = d

Two Rules

1. When the medium changes, the velocity will change but the frequency will not. This means that velocity is directly proportional to wavelength.

2. When the medium is constant, wave speed does not depend on frequency or wavelength. It depends on the medium. More tension in a rope will lead to a higher speed. A lower density will also lead to a higher wave speed.

Magnetism

Tue, 15 Mar 2011 15:06:25 -0400

A magnetic field is produced any time an ion has a velocity. This means that’s circuits create a magnetic field (as long as there is potential), permanent bar magnets obvious have a magnetic field, and it also means that a proton or electron with a velocity will create its own magnetic field!

The equation for magnetic force is F = qvBsinθ where q is the charge, v is the velocity, and B is the magnitude of the magnetic field. Sinθ shows that at 90 degrees, the force will be the largest. If the velocity and magnetic field direction are parallel or anti-parallel, the force will be ZERO! If you solve for B you find N/A*m = Tesla (T). 1 Gauss = 10^4 Tesla

I’m not going to go into the right hand rule because that would be way to confusing to type out.

A few important points. Many times, a charged particle will end up experiencing centripetal acceleration due to a magnetic field. You can set the two equations equation to each other. mv^2/r = qvB, r=mv/qB. As the mass and velocity increase, so does the radius. As the charge and magnetic field increase, the radius decreases. Next, if a charge moves through an area that has both an electric field and a magnetic field, the net force will be the sum of both forces. F=qE and F = qvB = q(E + vB).

The Earth has it’s own magnetic field as well. We all know the geographic north and south poles. Since magnetic field lines exit the north and enter the south, a compass actually points north when referring to the geographic south pole!. Therefore, the Earth’s magnetic north is the same as the geographic north and vice-versa.

A few extra points about magnetism:

1. Iron is special and is “ferromagnetic” because it creates its own magnetic field that is constant without the influence of an external magnetic field. Refrigerator magnets are an example of ferromagnetism.

2. Diamagnetic species have full paired electron shells. For example Mg is diamagnetic because it’s 1s2 and 2s2 shells both have paired electrons. In the presence of an external magnetic field, these species will be deflected away (repelled)! (remember D for deflected)

3. Paramagnetic species have an odd number of electrons AND have an empty orbital. Li,C,N,O just to name a few. In the presence of an external magnetic field, they will be deflected towards it (attracted).

Reading Comments

Mon, 14 Mar 2011 02:55:00 -0400

Does anyone get fed up with the majority of comments posted by users/viewers of various media websites? It's absolutely absurd what some people in the United States believe.