Homeostasis

Homeostasis is maintaining a constant state. That can be temperature, energy, gas levels, etc. All living things must maintain homeostasis. In reality, in all deaths, the cause is a loss of homeostasis. 

The body uses positive and negative feedback to adjust to its environment. These feedback mechanisms help maintain homeostasis.

Anatomical Terminology

Anatomist need to standardize the the terminology and orientation of body parts. Having a standardized language makes it possible for scientists and doctors to have productive and precise conversations about anatomy. 

The human body is divided into Regions, Planes, and Cavities

Take a few moments to read through the different regions of the human body. You will notice that many regions have both a scientific name and a more common name. In most situations the common name is appropriate. For example in the image you will notice it says Oculus or eye. Most people including doctors will know the exact region you are talking about if you say "my left eye". As you read through the different regions, notice how many of them you already knew.

The body is divided further into planes

• The sagittal plane is the plane that divides the body or an organ vertically into right and left sides. If this vertical plane runs directly down the middle of the body, it is called the midsagittal or median plane. If it divides the body into unequal right and left sides, it is called a parasagittal plane or less commonly a longitudinal section.

• The frontal plane is the plane that divides the body or an organ into an anterior (front) portion and a posterior (rear) portion. The frontal plane is often referred to as a coronal plane. (“Corona” is Latin for “crown.”)

• The transverse plane is the plane that divides the body or organ horizontally into upper and lower portions. Transverse planes produce images referred to as cross sections.

Have a look at the image of the human body divided into planes.

Body Cavities are compartments that separate organs and organ systems from each other. For example your lungs rest in the thoracic cavity. Your lungs can inflate and deflate without moving or bothering your intestines which lie in a different cavity, the abdominal cavity. 

There are many body cavities in the human body. The largest are in the dorsal (back) and ventral (front) cavities. Have a look and read each of the smaller cavities located in the dorsal cavity and ventral cavity.

Terms of direction

When we describe the human body, not only do we have to say the region or plane, or cavity we are discussing, but we often have to give directions to the exact position you are talking about. Just like in your activity where you had to guide the doctor to a location of pain. Here are the terms of direction we use.

Anterior (or ventral) Describes the front or direction toward the front of the body. The toes are anterior to the foot.

Posterior (or dorsal) Describes the back or direction toward the back of the body. The popliteus is posterior to the patella.

Superior (or cranial) describes a position above or higher than another part of the body proper. The orbits are superior to the oris.

Inferior (or caudal) describes a position below or lower than another part of the body proper; near or toward the tail (in humans, the coccyx, or lowest part of the spinal column). The pelvis is inferior to the abdomen.

Lateral describes the side or direction toward the side of the body. The thumb (pollex) is lateral to the digits.

Medial describes the middle or direction toward the middle of the body. The hallux is the medial toe.

Proximal describes a position in a limb that is nearer to the point of attachment or the trunk of the body. The brachium is proximal to the antebrachium.

Distal describes a position in a limb that is farther from the point of attachment or the trunk of the body. The crus is distal to the femur.

Superficial describes a position closer to the surface of the body. The skin is superficial to the bones.

Deep describes a position farther from the surface of the body. The brain is deep to the skull.

Student activity:

Take a moment with your neighbor or in your group of 3 to practice using Proximal and Distal correctly. You can think of it like this, if the body part is above the other body part towards the torso it is proximal to that part. If the body part is bellow the other body part away from the torso it is distal. It is a little confusing, that is why we will practice.