Normal blood pH is about 7.4 in most tissues (it is a bit lower in veins since they carry waste products, which are acidic). To get back to the physiological set point of pH = 7.4, we want to remove the acid from the blood. The major blood buffer system is shown in the following equation: 

As we know, carbon dioxide is one of the major byproducts of respiration, and is considered waste for our bodies. Combined with water and catalyzed by carbonic anhydrase, it is converted into carbonic acid. Carbonic acid is a weak acid and will partially dissociate into hydrogen ions and bicarbonate ions. Thus, overall, carbon dioxide and water yields acid (hydrogen ions). As a result, excess carbon dioxide in the blood will lower the pH.

In order to increase the pH, we must stop this equation from proceeding in the forward direction; thus, (remember Le Chatelier's principle) we must remove carbon dioxide from the left side. This will push the reaction in the reverse direction, quenching hydrogen ions (acid) and removing them from the blood, increasing blood pH back to normal.

Since we want to get rid of excess carbon dioxide, we breathe faster. Oxygen does not have any effect on blood pH. Furthermore, the atmospheric oxygen level (21%) is plenty for our bodies to utilize, as when we exhale there is about 15% oxygen left over, meaning we only use about 25% of the oxygen we breathe (this is why CPR works!).

In anatomical position, the thumbs are pointed away from the body. In order to have this orientation, the palms must be facing up. 

"Mental" is associated with the most anterior point of the mandible (chin). There is also a somatic nerve called the mental nerve located in the chin.

The skull is associated with the term "cranial", and the navel is associated with "umbilical." The physiological term for the ear is the otic, and the term for nose is nasal.

The cervical region refers to the neck, which contains the seven cervical vertebrae. This region of the spine is the most flexible, allowing for anterior, posterior, and lateral deviations as well as twisting.

The coxal region refers to the hip joint, which is located lateral to the pelvis, but on the same level of the body as the coccyx. The term "occipital" refers to the back of the head, which houses the occipital lobe of the cerebrum and the occipital bone of the skull. Structures in the knee often contain the term "patellar" in reference to the patella bone located in this region.

There are holes and cavities in many bones of the body, with a large number located in the skull. These holes allow nerves, arteries, and veins to enter and pass through the bones. These holes are called foramen, and range in size depending on what passes through them. For example, the foramen magnum in the skull is where the spinal cord exits.

The skin, hair, and nails are associated with the integumentary system. The integumentary system is an organ system whose purpose is to protect the body from infectious diseases and bacteria.

The skeletal system gives us structure, support, protection, and leverage. Muscle gives us movement. Together, these elements form the musculoskeletal system. The endocrine system keeps our hormones leveled (prevents over or underproduction) and regulates metabolism. The immune system protects our bodies agains bacteria and viruses. The difference between the integumentary and immune systems is because the integumary system is for the first line of defense (i.e. a minor cut) and immune system is for the second line of defense (i.e. if bacteria from a cut infects your body).

Epithelial is a general tissue classification, and is not considered an organ system. Much of the integumentary system is composed of epithelial tissue.

The wrist is distal to the elbow simply because it is farther from the appendage attachment (in this case the shoulder). Proximal means that the structure is located closer to the appendage attachment. Lateral indicates that the structure is farther from the midline, while medial indicates that a structure is closer to the midline, relative to a point of comparison. In anatomical position, the wrist is lateral to the elbow; however, this is not always the case, depending on mostion of the arm. Horizontal means that if a horizontal line were cut through the middle of the body that both the elbow and the wrist would be on the same plane; this is not the case.

Enzymes are not consumed during the reaction. The enzymes are instead used to speed up a reaction by lowering activation energy. Enzymes are proteins, which are made up of amino acids. They are not consumed because they attach to the substrate and are released after the reaction is complete. As a catalyst's purpose is to speed up reactions, enzymes are classified as biological catalysts.

The mediastinum is an area found in the thorax that is contained by the pleural cavities laterally, by the sternum and the abdomen muscles anteriorly, and the vertebral column in the back. It has four main divisions: the superior, anterior, middle, and posterior. The different regions that make up the mediastinum contain important structures, vessels, and nerves. It is important to note that the mediastinum does not contain the lungs.

The spinal cord passes through a large hole in the base of the skull called the foramen magnum. Foramen are holes that vessels or nerves pass through. Nerves and veins can line grooves as well, but grooves are not enclosed. Fossa are small depressions in bones. Tubercles are raised projections on bones such as the tibial tuberosity that can be felt on the anterior portion of the leg just inferior to the knee.