A&P II

So I thought I would write two blogs today, to make up for the last couple of weeks. I'm not even sure that is allowed, but I thought it was worth a try.

Moving onto the heart, which is a fascinating organ to me, especially since I studied psychology for so long, and up until the 1900's, psychologists thought that the heart was actually the commanding organ...crazy I know! But it is in direct connection to the ability for our body to function, without it, nothing else works...so I guess it makes sense why the elders thought this for so long. Still, with all that we know about the heart and the circulatory system, it's crazy that we don't know very much about the developing heart in utero.

It is unknown how blood in the embryo circulates for the first 21 days in the absence of a functioning heart, although some have hypothesized that the heart is not so much a pump, as a Hydraulic Ram -- an organ built-up from cumulative peripheral activity.

When the embryonic heart begins beating -- around 21 days after conception, the human heart begins beating at a rate near the mother’s, about 75-80 beats per minute (BPM). The embryonic heart rate then accelerates linearly for the first month of beating, peaking at 165-185 BPM during the early 7th week. After peaking at about 9.2 weeks, it decelerates to about 152 BPM during the 15th week. After the 15th week the deceleration slows reaching an average rate of about 145 BPM at birth. Little is known about why it changes, how it changes, and the effect of it's changes on the baby itself. The heart is vital however to the growth and development of the child, obviously, and as it is one of the first organs to develop and function, you would think that we would have better knowledge of it's formation, and thus it's malfunctions in the womb.

I know three women who have had still born babies in the last 5 years. All three of them were told that the deaths were a direct result of the baby's heart rate fluctuating and eventually stopping. Scientists should focus energy on this subject, as the death of a child, regardless of age, is something that no one should have to bare, but especially while it's still growing inside you.

On that happy note, I hope all of you are enjoying your holiday weekend. I will see you all on Tuesday! Aimee

A&P II

While reading everyone's blogs, I noticed that almost every single person commented on the super organ, the liver. Since I missed the last two classes due to the horrible flu (I hope you are all staying healthy, cause trust me it sucks) I thought I would do a little research into what all the fuss is about. I was amazed at what I found, as it seems all of you were too.

I knew that the liver had the ability to regenerate itself, but I didn't know it could do it with as little as 25% of it left. This is predominantly due to the hepatocytes acting as unipotential stem cells. There is also some evidence of bipotential stem cells, called ovalocyte which exist in the Canals of Hering. These cells can differentiate into either hepatocytes or cholangiocytes (cells that line the bile ducts).

So with all of this regeneration ability, I was amazed that there could be so many pathologies involved with the liver itself. It seems if the crazy liver can mend itself, that it would be able to out-smart any malady it might encounter, but that's false.

Hepatitis, Cirrhosis, Haemochromatosis (a hereditary disease causing the accumulation of iron leading to liver damage), Wilson's disease (a hereditary disease which causes the body to retain copper), Primary sclerosing cholangitis, Primary biliary cirrhosis, Budd-Chiari syndrome (obstruction of the hepatic vein), Gilbert's syndrome (a genetic disorder of bilirubin metabolism), and Glycogen storage disease type II are just a few. I suppose that with the aid of surgery, the regeneration would be helpful in the recovery of any of these diseases, but even if they cut out 75% of the liver, does that mean they are cured, or will the new liver possess the same disease as before? And if so, is it really worth the surgery to begin with? I'm sure the regeneration process is slow...and the body probably does not function as well with a smaller liver...it must be a dangerous option.

A&P II

So wow, it had been awhile since I was in the A&P mode, it took a bit of time to get back in the swing of things. I have to say that I am happy to be moving forward. I think that the optional take home was a good compromise.

So in studying and reading about the Endocrine System, I feel like I have a good grasp on the concepts, so I went looking for ways that the Endocrine System screws up, cause that is what I really like...pathology. These are some of the Endocrine System disorders: diabetes mellitus (a diminished ability to create new RBC during chronic renal failure), cancer, thyroid disease, and obesity.

Endocrinopathies are classified as primary, secondary, or tertiary. Primary endocrine disease inhibits the action of downstream glands. Tertiary endocrine disease is associated with dysfunction of the hypothalamus and its releasing hormones. I couldn't find what the secondary classification was...anyone have a guess?

Cancer can occur in endocrine glands, such as the thyroid, and hormones have been implicated in signalling distant tissues to proliferate, for example the Estrogen receptor has been shown to be involved in certain breast cancers. Endocrine, Paracrine, and Autocrine signalling have all been implicated in proliferation, one of the required steps of oncogenesis. It just amazes me that with one small change in one small cell anywhere in the body, can create such chaos, such as cancer. It is especially frightening within the Endocrine System, especially because the system itself is designed to travel throughout the body, reaching every cell, so if cancer is present, it is virtually all over your body all at once...

Well, that's all for now...moving on to the blood. See you all on Tuesday! Aimee