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.

Anatomy and Physiology Week 7

This week we started discussing hormones and glands. Hormones are like chemical messangers that are carried throughout our bloodstream and go to specific receptors in specific organs. The pineal gland is the producer of melatonin which is involved in our sleep/hibernation. The pituitary gland is also known as the hypophysis, and is considered the master gland of the endocrine system. The anterior portion of the pituitary produces prolactin, FSH, LH, TSH, ACTH, and GH. The posterior pituitary produces oxytocin and ADH. Which is involved in many things from our growth to our melanin production. There are two different kinds of hormones. Protein hormones travel easily throughout our blood and have rapid changes in target cells. They also rapidly degrade and exert their effect on target cells through second messanger systems. Steroid hormones must travel through our blood bound to a transport protein which is made in our liver. They are synthesized from cholestrol.

Anatomy and Physiology Week 6

This week we discussed the autonomic nervous system. It is an involuntary part of the nervous system which carries efferent impulses away from the brain. It is made up of smooth and cardiac muscle and glands. It has two different parts, the parasympathetic(feed and breed regulator) and the sympathetic(fight or flight). Part of the parasympathetic has two neurons. Neuron number one is the preganglionic cell and it has a long axon, neuron number two is the post ganglionic cell and has a short axon. In the sympathetic there are also two neurons, but neuron number one(the preganglionic cell) has a short axon and neuron number two(the post ganglionic cell) has a long axon. The parasympathetic impulse carriers are the III(oculomotor), VII(facial), IX(Glossopharangeal) and X(vagus). We also discussed the eye and its layers. The three layers of the eye we discussed were the sclera(fibrous) which is vascular, the choroid(pigmented) which is also vascular, and the retina(visual) which is not vascular. We learned that the parasympathetic nerve responds to bright light and the sympathetic nerve responds to dim light.