Special Senses

This week we have started to look at our senses and how they can change with age. We first looked at the eye. There are 3 different layers of the eye: the Fibrous Tunic, the Vascular Tunic and the Nervous Tunic. The fibrous tunic contains the white and opaque area known as the sclera, and the cornea. The vascular tunic contains the choroid coat, the ciliary body, and the iris. The nervous tunic contains inner nervous tissue layers, robs and cones, and this is where the nerve fibers synapse to form the optic nerve. Some of the age related changes with the eye are: slight shrinkage of the eye, increase in connective tissue, degeneration of cells, reduced blood supply, skin of the eye lid thins, and there is a loss of fat and elastic tissue around the eye. Other conditions related to aging are glaucoma, diabetic retinopathy, cataracts and macular degeneration.

I found a video that further explains how light enters our eye. The link is: http://www.youtube.com/watch?v=15P8q35vNHw

Parkinson's Disease

Parkinson's Disease is one that affects the neurons that make Dopamine. It is a disorder that leads to tremors, difficulty walking and difficulity with coordination and movement. There are three genes related to Parkinson's and they aer SNCA, LRRK2, and MAPT. There are several symptoms related to this disease. Some of them include: tremors, blinking, low blood pressure when getting up, difficulty swallowing, drooling, loss of small hand movements, stiff muscles, anxiety, stress, confusion and depression. There is no cure for this disease but medications are used to increase the level of Dopamine in the brain. The two types of Parkinson's Disease are tremor dominant, and PIGD or partial instability gate of difficulty.

I found an article that discusses the life expectancy of those diagnosed with Parkinson's Disease. The article shows how the life expectancy depends on the age a person is when diagnosed. For example, if you were to get Parkinson's Disease between the ages of 25-39, you could expect to live about 38 more years. If you were to get the disease betweent the ages of 40-64, you could expect to live 21 more years. Finally, if you get the disease when you are 65 or older, you can expect to live 5 more years (Robinson, 2008).

Link: http://www.mdvu.org/emove/article.asp?ID=1013

Muscular System

We have recently been talking about the muscle system. We learned that there are four properties of muscle which are excitability, contractility, extensibility and elasticity. We also learned that there are three types of muscle: skeletal, smooth, and cardiac. Skeletal muscles are attached to bones and make up about 40% of our body weight. They are striated and are voluntary movements. It is hard to see distinct skeletal muscle cells because there is multi nuclei per cell. Smooth Muscle is found in the walls of hallow organs, in the eyes and in the skin. The cells are not striated and they have an involuntary rhythm. Cardiac muscle is striated but not as severe as skeletal muscle. Cardiac muscle has intercalated disks which is how you can tell from cell to cell. We also learned about how muscle attaches to bone through tendons and connective tissue.

I found an article that discusses smooth muscle. I found it interesting that we have over 600 muscles in our body. Muscles are even responsible for making you get sick, or throw up. The article goes into detail about the function of smooth muscle which I found very interesting.
Link: http://kidshealth.org/kid/htbw/muscles.html

Bone and Cartilage

Before break we were learning about bone and cartilage. First we looked at the two different types of bone. There is Trabecular or Spongy bone which gives strength to the end of bones. The second type is Cortical or Compact bone which forms the outside of the shaft of the bone. Dr. Hens often uses the example of the cowboy to explain how bone can reform itself because of forces acting upon it. We then looked at the different parts of the compact bone. The osteon is a unit of bone, or the central cavity. Osteocytes are cells that make up bones and they sit in the bone matrix. The Lacunae is the space between the bones. The three types of cells that are in bones are Osteocytes, Osteoblasts and Osteoclasts.

Hyaline Cartilage is located in the long bone and trachea and is mostly water. Fibrocartilage is located in the spine and meniscus and there is a lot of resistance because of dense collagen. Elastic cartilage is located in the ears and nose.

I found an article on Osteoporosis that had some interesting facts on it. It states that Osteoporosis is the most common type of bone disease and that one in five American females over the age of 50 suffer from the disease (ADAM Medical Encyclopedia). The articles also discusses risk factors as well as symptoms.

Link: http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001400/