brachial artery

brachial artery is the major blood vessel of the upper arm.

It is a continuation of the axillary artery beyond the lower margin of teres major muscle. It continues down the ventral surface of the arm until it reaches the cubital fossa at the elbow. It then divides into the radial and ulnar arteries which run down the forearm. In some individuals, the bifurcation occurs much earlier and the ulnar and radial arteries extend through the upper arm. The pulse of the brachial artery is palpable on the anterior aspect of the elbow and, with the use of a stethoscope and sphygmomanometer (blood pressure cuff) often used to measure the blood pressure. The Brachial artery is closely related to the medial nerve; in proximal regions, the median nerve is immediately lateral to the brachial artery. In more distal regions, the median nerve crosses the medial side of the brachial artery and lies anterior to the elbow joint.

Blood pressure

Blood pressure (BP) is the pressure (force per unit area) exerted by circulating blood on the walls of blood vessels, and constitutes one of the principal vital signs. The pressure of the circulating blood decreases as it moves away from the heart through arteries and capillaries, and toward the heart through veins. When unqualified, the term blood pressure usually refers to brachial arterial pressure: that is, in the major blood vessel of the upper left or right arm that takes blood away from the heart. Blood pressure may, however, sometimes be measured at other sites in the body, for instance at the ankle. The ratio of the blood pressure measured in the main artery at the ankle to the brachial blood pressure gives the Ankle Brachial Pressure Index (ABPI).

Continuum mechanics

It is often appropriate to model living tissues as continuous media. For example, at the tissue level, the arterial wall can be modeled as a continuum. This assumption breaks down when the length scales of interest approach the order of the micro structural details of the material. The basic postulates of continuum mechanics are conservation of linear and angular momentum, conservation of mass, conservation of energy, and the entropy inequality. Solids are usually modeled using "reference" or "Lagrangian" coordinates, whereas fluids are often modeled using "spatial" or "Eulerian" coordinates. Using these postulates and some assumptions regarding the particular problem at hand, a set of equilibrium equations can be established. The kinematics and constitutive relations are also needed to model a continuum.

Second and fourth order tensors are crucial in representing many quantities in electromechanical. In practice, however, the full tensor form of a fourth-order constitutive matrix is rarely used. Instead, simplifications such as isotropy, transverse isotropy, and incompressibility reduce the number of independent components. Commonly-used second-order tensors include the Cauchy stress tensor, the second Piola-Kirchhoff stress tensor, the deformation gradient tensor, and the Green strain tensor. A reader of the mechanic's literature would be well-advised to note precisely the definitions of the various tensors which are being used in a particular work.

Pathology

Pathology (from Greek πάθος, pathos, "fate, harm"; and -λογία, -logia) is the study and diagnosis of disease through examination of organs, tissues, bodily fluids and whole bodies (Autopsy). The term also encompasses the related scientific study of disease processes, called General pathology.

Medical pathology is divided in two main branches, Anatomical pathology and Clinical pathology. Veterinary pathology is concerned with animal disease whereas Phytopathology is the study of plant diseases.

Ketone bodies

Ketone bodies are three water-soluble compounds that are produced as by-products when fatty acids are broken down for energy in the liver and kidney. They are used as a source of energy in the heart and brain. In the brain, they are a vital source of energy during fasting.

The three ketone bodies are acetone, acetoacetic acid, and beta-hydroxybutyric acid, although beta-hydroxybutyric acid is not technically a ketone but a carboxylic acid.a

Blood

Blood is a specialized bodily fluid that delivers necessary substances to the body's cells — such as nutrients and oxygen — and transports waste products away from those same cells.

In vertebrates, it is composed of blood cells suspended in a liquid called blood plasma. Plasma, which comprises 55% of blood fluid, is mostly water (90% by volume), and contains dissolved proteins, glucose, mineral ions, hormones, carbon dioxide (plasma being the main medium for excretory product transportation), platelets and blood cells themselves. The blood cells present in blood are mainly red blood cells (also called RBCs or erythrocytes) and white blood cells, including leukocytes and platelets. The most abundant cells in vertebrate blood are red blood cells. These contain hemoglobin, an iron-containing protein, which facilitates transportation of oxygen by reversibly binding to this respiratory gas and greatly increasing its solubility in blood. In contrast, carbon dioxide is almost entirely transported extracellularly dissolved in plasma as bicarbonate ion.

Vertebrate blood is bright-red when its hemoglobin is oxygenated. Some animals, such as crustaceans and mollusks, use hemocyanin to carry oxygen, instead of hemoglobin. Insects and some molluscs use a fluid called hemolymph instead of blood, the difference being that hemolymph is not contained in a closed circulatory system. In most insects, this "blood" does not contain oxygen-carrying molecules such as hemoglobin because their bodies are small enough for their tracheal system to suffice for supplying oxygen.

BONES

Bones are anisotropic but are approximately transversely isotropic. In other words, bones are stronger along one axis than across that axis, and are approximately the same strength no matter how they are rotated around that axis.

The stress-strain relations of bones can be modeled using Hooke's law, in which they are related by elastic moduli, e.g. Young's modulus, Poisson's ratio or the Lamé parameters. The constitutive matrix, a fourth order tensor, depends on the isotropy of the bone.