Types of Sensory Receptors

Sensory receptors are organized into five groups; mechanoreceptors, chemoreceptors, electromagnetic receptors, thermoreceptors, and pain receptors. Mechanoreceptors are receptors stimulated by physical stimuli. They respond to mechanical energy pressure such as pressure, touch, stretch, motion, and sound. Chemoreceptors include general receptors that monitor solute concentration and specific receptors that respond to important molecules. Response to different forms electromagnetic energy is caused by electromagnetic receptors. The forms of electromagnetic energy can be visible light, electricity, and magnetism. Thermoreceptors are found in the skin and hypothalamus. These receptors respond to either heat or cold and help maintain body temperature. Pain receptors are naked dendrites in the epidermis. They respond to excess heat, pressure, or chemicals released by injured or inflamed cells.

Conjoined Twins

I am super fascinated in human development. I actually want to pursue a career in Obstetrics. We know that a woman releases an egg, which can then be fertilized by a sperm. Sometimes women have more than one baby at a time. TWINS!!! This occurs two ways, when the fertilized egg divides and separates you have identical twins (same sex) or the woman may release two eggs at the same time that are fertilized by separate sperm, then you have fraternal twins. But there are some instances where the one egg of identical twins doesn’t quite separate equally. These children are called conjoined twins. Conjoined twins are extremely rare, they occur in one and every 200,000 births. Male conjoined twins are more likely to occur in the womb than female, but for some reason female conjoined twins are more likely to survive. About 70% of female conjoined twins born are female. And nobody knows why? Although having conjoined twins is a serious matter, their prognosis is become a lot brighter than in recent years. They can live well into their 60’s, and 200 separations have been performed, where 75% of the time one or both twins survive. Hopefully someday scientists can figure out ways to prevent the conjoining of twins, and give the children longer lives : )

Circulatory System

Diffusion alone is not sufficient enough for the transporting of substance over long distances. The time it takes for a substance to diffuse from one place to another over a long distance is proportional to the square of that distance. The circulatory system solves this problem. The circulatory system rapidly transports fluids in bulk throughout the body. This system exchanges gases, absorbs nutrients, and disposes waste. The vertebrate circulation is called the cardiovascular system. The heart pumps blood through the blood vessel channels and delivers it to various parts of the body. Arteries carry blood away from the heart. They divide up into aterioles which are small blood vessels. From aterioles capillaries are formed. They are the smallest vessel to carry oxygenated blood. Different species of vertebrates have slightly different heart forms. Fish have a two chambered heart. Amphibians and reptiles have a three chambered heart. Mammal and birds have a four chambered heart. These hearts may have different structures but they all provide basically the same function.

The path blood flows through the body !

Deoxygenated blood passes through the superior and inferior vena cava into the right atrium of the heart. Blood then flows into the right ventricle, which pumps it to the lungs via the pulmonary arteries. Oxygenated in the lungs, the blood flows through the pulmonary veins back into the left atrium of the heart, then into the left ventricle, from which it is pumped to the entire body via the aorta. Arteries carry blood away from the hear, breaking down into a network of arterioles. Veins arise from a network of venules to bring blood toward the heart. Between arterioles and venules are capillaries, tiny vessesla where cellular exchange (gases, nutrients, wastes) occurs. The lymphatic system returns lost fluid to the blood. Lymph fluid can intermingle with blood along lymph capillaries, which run alongside circulatory capillaries. Lymph nodes filter the lymph fluid by the action of white blood cells, protective cells that attack and isolate foreign bodies. Hope you enjoyed the quick overview of the circulatory system =]

I have a COLD!

When we learned about the immune system we learned that the body has many defense mechanisms in order to protect itself. For example mucus! Mucus coats your body cavities that are exposed to the environment like your GI tract, respiratory tract, and reproductive tract. This mucus can help trap particles, fight pathogens, and moisten the air that we take in. But I have a cold and I want to know why my nose doesn’t stop running! Well basically my airways are inflamed. Woooo! So like I mentioned before mucus helps fight off pathogens, like the common cold. Your immune system activates the inflammation when it detects a pathogen, and it increases its mucus production. Even though I have to use a tissue every 4 seconds, and my nose turns bright red this mucus is helping my body fight the cold. GO MUCUS!!!!

But I think I am going to go take some cold medicine : )

Storing Protein for Growth!!

We all know that our bodies require certain amounts of proteins. Certain animals like the Adelie penguin from Antarctica molt or grow new feathers yearly. Their feathers are like puffy winter coats that help them sustain a constant body temperature. So when they don’t have this insulation they cannot go into the freezing ocean to feed or swim, they must remain on land. So how do they survive the time period of about the 20 days it takes for them to restore their feathers? Before the penguin molts it amplifies its muscle mass (A JACKED PENGUIN : D ). Then during those 20 days where the feathers are growing back the penguin survives by breaking down the extra muscle protein. This extra protein provides the penguin with the amino acids it needs to grow new feathers. What an awesome adaptation!

A cool picture of a molting King Penguin : http://www.galenfrysinger.com/penguins.htm

Tropisms!!!!!!

WOOOO!!! Let's discuss TROPISMS! First, let's define what the word means.

Tropism- The growth of a biological organism, usually plants, in response to environmental stimulus. A definition never really hits it on the nail, so we'll discuss three types of tropisms.

1. Phototropism (no, there is no "h" in the word) is a plant's response to light. When the shoots grow towards the light, it's called positive phototropism. When the shoots grow away from the light, it's called negative phototropism. When the apical meristems on all sides of the plant absorb equal amounts of light the plant grows evenly; however, when light is only absorbed by apical meristems on one side of the plant, it will grow towards the light.

http://www.yksd.com/distanceedcourses/Courses09/Biology/lessons/FourthQuarter/Chapter13/13-1/images/II17phototropism1.gif

2. Geotropism is a plant's response to gravity, the roots always grow down through the soil from the seed no matter how you plant it.

http://www.omegagarden.com/images/photos/geotropism.jpg

In this image you will see 3 types of Geotropism.

• The first seed, which is planted sideways shows Transversal Geotropism, where the root extends sideways and pushes down through the soil due to gravity.
• The second seed, which is planted upside down shows Negative Geotropism, where the root pushes up and then pushes back down into the soil due to gravity.
• The third seed is planted normally, it shows Positive Geotropism, where the root grows straight down and pushes through the soil due to gravity once again.

3. Thigmotropism is the plant's response to touch or contact.

http://www.alphadictionary.com/images/flytrap.gif

I thought this image was a very good example of thigmotropism. As you can see, once the insect makes contact with the plant, the plant traps the insect for some good old NUTRITION!
That's really as simple as it gets. Some other plants use thigmotropism to protect themselves from predators who feed on their surfaces by closing their leaves.

Success!