Anatomy and Physiology Study Guide for the Medical Assistant test
Questions on a medical assistant test about anatomy and physiology will require you to have a basic understanding of the parts of the human body and their functions. Here, we have provided a basic outline of the concepts you must understand, but you should also access additional information about these concepts to be fully prepared.
The Body as a Whole
On a medical assistant test, you will find questions about how the human body is organized, including these concepts:
Structural units are building blocks of increasing complexity that, when combined, form living organisms. Each tier serves a particular purpose on its own but also interacts with other levels to perform the more intricate functions of human life. The four structural units of the human body from smallest to largest are: cells, tissues, organs, and organ systems.
Cells―The smallest unit of all life is the cell. Cells are primarily responsible for storing genetic information and carrying out microscopic processes such as metabolism and protein synthesis. However, human cells are specialized to perform specific tasks so their structure and function varies greatly.
Tissues―A group of cells with the same structure and function make up tissue. Tissues are typically arranged in layers and also differ based on their operation and location in the body. The most general tissue categories include epithelial, connective, muscle, and nervous tissues, but each division includes more precise types (such as cardiac, smooth, and skeletal).
Organs―More than one tissue arranged together into a differentiated structure is called an organ. Organs are specialized and each is responsible for a specific, vital function in the body. They can be hollow or solid but are typically self-contained. Examples of organs include the heart, lungs, brain, and liver.
Organ systems―An arrangement of organs working together to achieve a unified bodily objective (such as respiration, blood circulation, or digestion) is an organ system. There are at least 11 unique organ systems, but sometimes systems are referred to in a combined fashion based on their close interaction (such as muscular and skeletal into “musculoskeletal”).
Anatomical Divisions and Body Cavities
Each organ system can be further referenced by an anatomical zone where its function and structure differ slightly. For example, the respiratory system comprises the upper and lower respiratory tract. The nervous system includes central and peripheral subdivisions.
Most internal organs are contained within membrane-lined body cavities that protect them from damage and keep them in place. Cavities are also used for internal anatomical reference. The two body cavities are: dorsal and ventral.
Dorsal―The dorsal cavity is located at the posterior and includes the cranial cavity (which houses the brain) and the spinal cavity (which surrounds the spinal cord).
Ventral―The ventral cavity is much larger than the dorsal and is located anteriorly. The three ventral cavities are: thoracic (heart and lungs), abdominal (digestive organs, kidneys), and pelvic (reproductive organs, bladder).
Anatomical Positions and Directions
When describing the human body, all locations are oriented by a specific stance known as the anatomical position. In this position, a person is standing, facing forward, with their feet pointed forward. Their arms are at their side with the palms facing forward.
From this position, the rest of the body can be described in a standardized manner during assessment. When describing movement or directionality, medical terms are preferred.
Anterior or ventral refers to the front side; in humans this side includes our eyes and navel.
Posterior or dorsal refers to the back side; in humans this side includes our buttocks.
Distal means farther away from an attachment point; the elbow is distal to the shoulder.
Proximal means closer to an attachment point; the wrist is proximal to the fingers.
Superior or cranial means above; the neck is superior to the chest.
Inferior or caudal means below; the knee is inferior to the hip.
Medial means closer to the body’s midline; the mouth is medial to the ears.
Lateral means farther away from the body’s midline; the ears are lateral to the nose.
Superficial means closer to the surface; skin is superficial to bone.
Deep means farther from the surface; muscles are deep to the skin.
Please note that the terms dorsal and plantar refer to the top and bottom of the foot only.
Abduction is movement away from the body’s midline (just like “abduction” is taking someone away); picture raising your arm to turn on a light.
Adduction is movement toward the body’s midline (just like “adding” a piece to a whole); picture bringing your arm back to your side.
Flexion is movement that decreases the standard angle between two structures (not the same as “flexing” or tensing your muscles); picture bending your knee to sit.
Extension is movement that increases the standard angle between two structures; picture straightening your knee to stand back up. Keep in mind that the extension of one body part, especially a muscle, may simultaneously involve the flexion of another.
Elevation is moving a body part closer to the head; picture shrugging your shoulders.
Depression is moving a body part closer to the feet (not the same as the mood disorder).
Medial rotation is turning a body part toward the center of the body; picture turning your legs inward so that your toes touch―this is medial rotation of your hip.
Lateral rotation is turning a body part away from the center of the body; picture returning your feet to center.
The terms dorsiflexion and plantarflexion refer to flexion and extension at the ankle only. Inversion and eversion are also only specific to turning the sole of the foot inward and outward (picture twisting your ankle).
The terms pronation and supination are specific types of rotation of the forearm where the palm faces posteriorly (pronates) or anteriorly (supinates). However, prone and supine more often refer to the patient’s entire body. When the patients are prone, they are lying on their stomach; when they are supine, they are lying on their back (remember this by thinking that supine sounds like spine).
Body Planes and Quadrants
The human body can be divided into planes and quadrants in order to clearly reference structures and assessment findings. The three body planes are frontal, sagittal, and transverse.
Frontal ― Also known as coronal, the frontal plane faces forward and divides the body into anterior and posterior (or ventral and dorsal) portions.
Sagittal― Also known as lateral, the sagittal plane runs perpendicular to the ground and divides the body into left and right portions. Note that a midsagittal or median plane would pass directly through the spine and navel. All other lateral plans are considered parasagittal.
Transverse ― Also known as horizontal, the transverse plane runs parallel to the ground and divides the body into superior and inferior (or cranial and caudal) portions.
The body can also be separated into four quadrants with the origin at the navel and two imaginary lines projecting up/down and left/right to create the left upper quadrant (LUQ), right upper quadrant (RUQ), right lower quadrant (RLQ), and left lower quadrant (LLQ). Typically, these are only used to describe organs in the ventral cavity or superficial abdominal signs.
A more specific system often involves dividing the abdomen into nine regions with the central (umbilical) region surrounding the patient’s navel. The eight remaining zones (clockwise from the top) are the epigastric, left hypochondriac, left lumbar, left iliac, hypogastric, right iliac, right lumbar, and right hypochondriac.
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