ESSENTIALS: ANATOMY & PHYSIOLOGY

When we teach about the heart, we differentiate between the structures and functions of its right and left sides. The major functional difference is that the right side of the heart delivers blood to the lungs and the left side delivers blood to the rest of the body. The right side’s purpose is pulmonary circulation, and the left side is responsible for systemic circulation.

Coronary circulation includes important arteries and veins that perfuse the heart. The blood inside the atria and ventricles does not directly support the heart muscle; the heart has to deliver and drain blood as it does for any other muscle.

Blood vessels are adaptable to stress. If there is hypoxic stress (low oxygen content present) that results in tissue hypoxemia (low oxygen in the tissue), a cascade of local hormonal and anabolic events occurs that produces new capillaries and new arterioles. This process is called angiogenesis and is considered to be an endurance-friendly anatomical adaptation, improving the body’s capacity to deliver oxygen to working skeletal muscle.

The flow of blood through the heart follows the same general pattern as the electrical conductive pathway if we begin tracing it from its entry into the right ventricle. However, the blood flow system includes both inflow and outflow.

An explanation of the anatomical features that conduct the electrical impulses in the heart, driving muscle contraction and setting the heart’s rhythm

The wall of the heart is composed of three distinct layers: the epicardium, myocardium, and endocardium.

The heart’s upper segment contains two atria, and the lower segment includes the ventricles. The heart also may be divided into left and right segments, each containing one atrium and one ventricle. The right side serves pulmonary circulation, the left side systemic circulation.

The human heart is a muscular organ, not too large in size, tipping the scales at between half a pound and three-fourths of a pound (250 to 350 grams). It pumps blood 24/7, from birth to death. On average, this corresponds to roughly 2,796,192,000 pumping actions over the course of a lifetime.

Fat cells, also known as monovacuolar cells or adipocytes, are essentially large lipid droplets surrounded by a thin cell layer. Fat cells and fat tissue are adaptive entities that can be affected by nutritional habits and exercise.

Inside metabolically active cells, you will find little droplets of fat (more properly called lipid) that can be used as an energy source. Fat carries out many crucial roles in the body apart from being a pretty effective energy storage medium. Adipose cell accumulations, or adipose tissues, are located subcutaneously (under the skin), viscerally (surrounding internal organs), in bone marrow, in streaks along fascicular spaces in muscle, and in breast tissue.

To keep the body in line during a push-up or plank, muscles all along the body — ankle to head, anterior and posterior — isometrically contract. Weakness or lack of endurance on one side or the other induces sagging or rounding.

The meaning of the anatomical core has become confused over time. Originally used as a word added to modify the phrase “body temperature," in the 1990s and 2000s, it became associated with lumbar and abdominal exercises designed to address lower back pain. In reality, a far greater number of muscles are part of the core's structure, and these contribute to what we refer to in CrossFit as midline stability.

Ligaments connect bone to bone, and as there are 26 bones in the foot, there are numerous ligaments connecting and crisscrossing the foot’s interior. The foot receives quite a bit of support from the simple interlocking of the tarsal bones via their shape and via the intertarsal ligaments.

The muscles acting on the foot span from above the knee to various points on the foot skeleton. The muscles with proximal attachments at points outside the foot are referred to as extrinsic muscles of the foot. Another set of muscles, the intrinsic muscles of the foot, have both proximal and distal attachments within the foot’s bony architecture, from calcaneus to distal phalanx.

The many ligaments of the ankle complex hold 14 bones in close proximity, including the tibia, fibula, and tarsals.

The anterior and lateral muscles of the ankle equip the joint for various movements and functions, including plantar flexion, dorsiflexion, extension of the toes, and the inversion and eversion of the foot.

The muscles of the ankle, like its skeletal architecture, are essential to function. There are a number of muscles that dorsiflex, plantar flex, evert, and invert the foot at the ankle. Together, these muscles can also act to stabilize the joints they cross during locomotion.

The posterior knee muscles are more numerous and expansive than those in the anterior musculature. Four cross the hip and knee, and two cross the knee and ankle. There are larger, more powerful muscles in this group as well as smaller weaker muscles.

The muscles acting at the knee are generally categorized into two groups: anterior extensors and posterior flexors. The anterior muscles — the vastus medialis, vastus lateralis, vastus intermedius, tensor vastus intermedius, and rectus femoris — are commonly known as the quadriceps.

A virus is structurally and functionally different from a cell. Viruses are most frequently categorized according to morphology. The most pressing epidemiological virus we currently face is SARS-CoV-2, a variant of the envelope virus that includes spike proteins scientists believe exploit complementary proteins on the membranes of target cells.