Breathing is something an organism can do consciously or sub-consciously.  It’s not questioned, you simply must breathe in order to get oxygen to your body, and you must get oxygen to your body in order to survive.  The advanced mechanisms of breathing, and the gas exchange of oxygen and carbon dioxide, are more detailed and complex than just letting air in and out..

When a human first inhales, the air enters through the trachea, which is located behind the esophagus.  The trachea is lined with various cilia and mucus, the mucus traps dust particles, while the cilia transfer particles to the pharynx, so that they may be swallowed into the esophagus.

The trachea divides into two bronchi, which then separate into bronchioles.  Like the trachea, bronchi are also lined with cilia and mucus to pick up any remaining particles.  the division continues; the bronchioles are divided into even smaller tubes.  Ultimately the division stops in tiny air sacs called alveoli.

The alveoli are lined with the capillaries for the actual exchange of gases.  The oxygen rich air that was just inhaled, is dissolved into the moist lining within the alveolus.  The surrounding capillaries contain blood with low oxygen (O2) and high carbon dioxide (CO2).  The difference in partial pressure causes the O2 to diffuse into the blood capillaries and the CO2 to diffuse out of the blood capillaries and into the alveoli. exhalation releases CO2 from the body and allows for inhalation of more oxygen.

This advanced mechanism takes place every time you breath.  There are many levels of organization that must function properly in order for this whole process to work.

It’s natural to feel hungry when you need to refuel your body, or to feel satisfied when you are refueled.  But think deeper, how are we able to feel hunger and satiety?  Various organs, chemicals and mechanisms contribute to the feeling you get when either hungry or satisfied.

Hormones signal the satiety (satisfied)  part of the brain, depending on whether the body needs nutrition, or whether it’s satisfied.  The hormone called Ghrelin, sometimes known as the “hungry hormone” is the chemical released by the stomach when the stomach is empty, and it is continued to be released until the stomach is stretched out or satisfied.  When you miss a meal, and begin to feel hungrier and hungrier, it is when ghrelin is collectively released by the stomach.

What about the feeling of satiety?  The hormone insulin, is released by pancreas when blood sugar is too high, and it actually suppresses the appetite.  Figuratively, insulin is telling the brain that it has consumed too much sugar for now, and sending signals for it to not consume anymore until further notice.

There is another hormone called Leptin.  Leptin is released by adipose (fat) tissue, and this chemical also suppresses appetite.  Levels of leptin are actually decreased with loss of weight, which could explain why it is hard to maintain a diet with the intent to lose weight.

Another important hormone is Peptide YY, or PYY.  PYY is secreted by the small intestine when the organism finishes consuming a meal.  PYY counteracts the effects of ghrelin, and suppresses the appetite.

In conclusion, hunger and satiety are much more than just a growl  in the stomach.  There are a lot of chemicals and mechanisms that signal the brain and tell it what the body needs.

On a general day-to-day basis, you encounter a variety of people, each who have a different impact on you.  One of the main factors that determines this impact is their overall intelligence.  What is meant by intelligence?

According to the Oxford dictionary, intelligence is defined as, the ability to acquire and apply knowledge and skills.  So thus, for a creature to be intelligent, that creature must possess the ability to acquire knowledge and skills, and apply them in relevant circumstance.  There are many different classes of animals that have intelligent behavior, and it is a fascinating topic.

One of the most intelligent group of animals are elephants.  Elephants are known for their incredible memory, and they are also known to show sympathy when members of their herd die.  Their sympathetic nature is very human-like.  It is incredible that these animals possess that kind of caring nature.  They are able to learn and use creative skills, such as painting.  They have been significant in agriculture, especially in Africa in ancient times.  They possess unique strength and intelligence, which is fascinating to mankind, but also helpful in the wild.

And probably the most intelligent group in the animal kingdom, are primates, specifically the clade simians.  This group includes monkeys and apes, some of which have similar DNA to humans.  Some species of simians can actually teach each other basic skills, that vary among their different tribes.  Some apes are able to recognize individuals in their group, and they understand the levels of authority within their own community.  They are able to utilize tools in the wild, and also while in captivity.  Most apes are able to communicate to humans, via sign language, which is truly an amazing ability.

The intelligence of animals is a topic that we do not, and really cannot fully understand, but it has been studied for centuries, and will continue to amuse us as we make new discoveries.

Arthropoda is the largest phylum in the world, with over 1,000,000 known species.  This group of creatures possess multiple common characteristics that justify them to be classified in the same group.

On the Linnaean scale of classification, phylum is the classification directly below the kingdom classification.  Among arthropods, there are multiple different classes and sub-phyla. Some of these include: crustaceans, insects, and arachnids.  Some common classes of arthropods are lobsters, crabs, beetles, winged insects, etc. Sub-phylum, chelicerata, contains the class arachnid, which includes spiders, ticks and scorpions.

There is tremendous diversity within this phylum, however, they all share a basic body plan. There are variations among different classes and species (and especially the sub-phylum arachnids), but they all follow one basic blueprint.  Each further classification is specialized with different vices, but still share basic characteristics.  What is this body plan? Arthropods have a full body exoskeleton, and jointed limbs, and three separate body cavities: a head, a thorax, and an abdomen. –With the exception of arachnids, that have a joined head and thorax, called a cephalothorax.

As many species as there are within this phylum, one can imagine the incredible diversity of arthropods.  There is so much detail we already know, and there are so many details mankind has yet to discover.

All these species being classified into one group poses the question: should they all be classified in just one group?  Yes, they should all be classified together.  Why?  Because they all share the same basic structure, and engage in similar behaviors.  This body plan gives them similarity, and even though the basic structure varies tremendously, the species all have similar behaviors and metabolic processes.  The body blue print of arthropods preserves the relationship between all the species within the phylum.

What is a chordate? How are vertebrates different from chordates?

A chordate is a member of the animal kingdom, and categorized in the phylum Chordata.  Chordates have several characteristics that define them, and set them apart from all other animals.  Some of these traits are only present during embryonic development, but nonetheless, they do serve a crucial purpose within the organism.

Chordates have a notocord, which is essentially a long, flexible rod placed within the organism between dorsal nerve cord and the digestive tract.  The notochord serves many purposes, as it is built out of stiff, fibrous tissues.  Aquatic animals push muscle against this to help them swim, for example.

Chordates also have a dorsal nerve cord, which is a hollow nerve cord.  This dorsal nerve cord, in a human, becomes the spinal cord and brain after the process of embryonic development.

Another characteristic of chordates is the pharyngeal cleft.  The pharynx is the head/neck region of the animal right behind the mouth.  The pharyngeal cleft is a cleft, or pouch like structure in the pharynx region.  The form the pharyngeal cleft takes, and the function it carries out, depends on whether the animal is terrestrial or aquatic.

Chordates also have a muscular tail.  This tail may only be visible during embryonic development, but it is an essential trait during embryonic development.  Depending on the species, it may shrink if the species no longer depends on it.  The muscular tail extends beyond the digestive tract, and for aquatic chordates especially, this tail is important to propel the animal.

How are chordates different from vertebrates?  The vertebrate definition is a craniate with a backbone.  What is a craniate?  Craniates are all the members of the phylum chordata that have a head.  A head contains a brain at the front end of the dorsal nerve chord, as well as the common sensory organs such as nose, eyes, ears, mouth.  There are actually many invertebrates that have a head, however, a craniate is exclusively a chordate with a head.

To conclude, a vertebrate is a chordate, if, and only if, the chordate is a craniate with a backbone.  A chordate must possess a head and backbone in order for it to be a vertebrate.

(Biology, Lesson 100 essay.)

“Soil is just dirt to hold the plant up.”  — This is a statement that I, and many other individuals can easily disagree with.  However, it seems that a majority of the population agrees with this statement. It is actually fairly easy to adopt the idea of soil being just dirt, intended only to support the plant, but soil is much more than that.

It is easy to overlook soil, and how crucial it is to all levels of life, because it’s not something we notice on a day-to-day basis.  Plants, bodies of water, animals, etc., perform events crucial to the environment that we can, for the most part, see and feel.  The soil, however, is essentially just the dirt under our feet.  If an individual does not want to go into the details of the complexity of soil,  it is easy to adopt the opinion of it being simply dust underfoot.

Soil has so much complexity, that someone could dedicate their entire life to studying it through pedology, or edaphology, and still only cover a small portion of study.

Why is soil so important?  Aside from water, what do animals and humans need for survival? Nutrition. Some of their nutrition comes from other animals, but those animals have to eat something.  Plants support the entire animal kingdom,either by primary or secondary consumption.

What feeds the plants? Plants utilize energy from the sun to perform photosynthesis, and this is their main nutrient, but there are nutrients in the soil that act as supplements for the plant, and affect the production of the plant. Like people, plants benefit from supplements in their nutrition.

There are several biotic and abiotic factors that affect the characteristic of the soil and will determine the plants ability to grow.  Soil supports plants, that’s a mutual opinion, but soil does more than just that.

There are many layers of soil that perform important functions, however the most important of these is the layer of top soil.  The top soil is the layer from which plants absorb minerals and receive benefits from other living organisms.

The soil in an ecosystem is important, it affects plant growth, which then significantly affects the population of other animals and organisms. Soil also supports many organisms such as earthworms, that need the soil environment to survive.  Soil does not just support plants, it supports the entire ecosystem.