Anatomy and Physiology Week 14

This week we started discussing the digestive system. It is an open portal system that is highly guarded by WBC's. There are four layers to the system. The mucosal layer is made of simple columnar epithelium. It is avascular and is constantly shed and replaced. The Submucosal layer is made up of dense irregular connective tissue. It is vascular and has specialized cells that protect from pathogens. The muscularis layer has a circular layer and a longitutinal layer. Peristalsis is regulated by the parasympathetic nervous system by the vagus nerve which constricts first the circular muscularis then the longitudinal muscularis. The last layer is the serosa layer. It is composed of areolar connective tissue and is vascular. It is really interesting thinking about the different layers that have to work together to help get rid of toxins from the body. The fact that the circular and longitudinal layer have to constrict at certain times to cause peristalsis to happen. I know I says this after every blog but I have a hard time believing and understanding everything that has to go right for our bodies to run correctly.

Anatomy and Physiology Week 13

This week we discussed the inflammation process. In response to injury, damaged tissue cells(mast cells in connective tissue, basophils in blood) release histamine, increasing blood flow to the area. Kinins then induce vasodilation and serve as chemotactic agents for phagocytes. Prostaglandins are released by damaged cells and intensify the effects of histamine and kinins. Phagocytes engulf bacteria, dead cells, and debris. Componenets of the complement system stimulated the release of histamine and the promotion of phagocytosis. The increased permeability of capillaries allows the leakage of blood clotting factors into the tissue. the clotting sequence is set into motion and fibrogen is converted to the thick meshwork of fibrin that traps invading microbes and prevents their spread. It is hard to imagine that all these things happen just to have an inflammatory response. I know next time I get a burn or something that causes inflammation I will have to think about all the things that go on to cause it.

Anatomy and Physiology Week 12

This week one of the things we talked about was Fetus Circulation. There is one umbilical vein and two umbilical arteries to the fetus. The umbilical vein carries oxygenated blood and the right and left umbilical arteries carries partially oxygenated blood. In the fetus the oxygen rich blood mixes with the oxygen poor blood through the liver to make partially oxygenated blood. The liver filters the blood coming from the mother before it circulates through the fetus' body(what a great idea). The ductus venosus dumps partially oxygenated blood from the liver into the inferior vena cava to the heart. At the right atrium a small amount of blood goes to the lungs, the other portions go through 2 other pathways. One is from the right atrium to the left atrium through the interatrial septum(through the foramen ovale of the heart). The other is from the right atrium to the right ventricle to the pulmonary semilunar valve to the pulmonary trunk through the ductus arterious to the aortic arch. 6-8 weeks after birth the ductus venosus and ductus arteriosus fills with collagen and closes. The ductus venosus then becomes the ligamentum venosum and the ductus arteriosus becomes the ligamentum arteriosum. At birth when the infants bottom is spanked to catch its first breath there are pressure changes in the thoracic cavity from the diaphram which causes the foramen ovale to close becoming the fossa ovalis. This is all very amazing to me. It is crazy to think about all the things that have to come together at the right times for us to be alive.

Anatomy and Physiology Week 11

This week we had vacation. I left friday to go down to Florida with my husband. While we were down there we looked at houses for our possible future move after I graduate and spent some time at the beach and universal/islands of adventure. It was actually a really rainy week and wasn't what I had hoped, especially since Wednesday I got sick and spend most of the rest of my vacation in Florida sleeping. Oh well! Hopefully I will have better luck the next time I have a break from school!

Anatomy and Physiology Week 10

This week we have been going over the heart and blood. We learned that the pericardial sac is attatched to the diaphram and the heart is imbedded in the mediastinum which is between the lungs and the esophagus and trachea run through it. The aortic hiatus is the hole in the diaphram in which these run through and the top of the heart is actually called the base while the bottom is called the apex. The membranes of the heart include the epithelial layer, connective layer, outermost layer, and innermost layer. The outermost layer is composed of the fibrous layer and the parietal layer which produces the pericardial fluid that reduces friction around the heart. The innermost layer(visceral layer) is also called the epicardium and is very thin and delicate. The endocardium is made of simple squamous, the myocardium is made of cardiac muscle, and the epicardium is made of areolar connective tissue. In lab I got to cut a heart in half and it is awesome seeing the different ventricles and where all the veins and arteries are connected. I really enjoy learing about the heart, it is the most interesting organ in the body to me.

Anatomy and Physiology Week 9

This week we started going over blood. We know that blood carries hormones, oxygen, etc. We found out that adult men have 6 liters of blood, adult women have 5 liters and pregnant women have 6 liters. Red Blood cells are hemoglobin proteins that transport oxygen atoms. A single Hg transports 4 oxygen atoms which is equivalent to 2 oxygen molecules. It is very difficult to get the hg molecule to bond to the first oxygen atom, once you do, shape change occurs making it easier to bind to the second then easier to bond to the third and so on. Normally 1 out of four atoms are off loaded, during strenous exercize 2 out of four are off loaded and in near death experiences 3 out of four are offloaded. RBC's(erythrocytes) are produced in bone marrow, in flat bones and the proximal epiphesis of long bones. Within 24 hours of leaving the bone marrow the blood cell ejects its nucleus which forms free floating nucleotides, and it because a reticulocyte. Within 90-120 days the cells are phagatosized.

Anatomy and Physiology Week 8

This week we went over second messanger systems. In one of the second messanger systems what happens is the protein can't get into the cell, so a message is passed through numerous other proteins in the plasma membrane. They generate a cytoplasmic molecular messanger which will be the protein that activates our protein. The cAMP pathway starts with a collection of associated proteins within the inner surface of the cell membrane. They are always anchored close to the receptor molecule and are called the G protein. There are three subunits, alpha, beta, and gamma. When the protein binds to the receptor a shape change occurs causing the G protein to change shape. This causes the alpha subunit to be released and float to the membrane where it makes contact with another second enzyme causing it to change shape. The second enzyme scoops up ATP molecule and rips off 2 phosphates, leaving one phosphate group(AMP). The enzyme, now activated, releases camp to the cytoplasm which can now bind to PKA ripping off one of its phosphates to bind to another enzyme, and over and over. It is crazy knowing that things this intricate go on in our body on a daily basis. So much has to go right for us to function right.