1.5: Human Anatomy

Learning Objectives

1. Describe what planes specific motions happen in.
2. Differentiate between a tendon and a ligament.
3. Explain the movement of blood through the body.

Anatomy is the study of the biological tissues of the human body. This chapter will cover the basics of human anatomy focusing on the skeletal and muscular systems. As with all the chapters in this textbook, the information presented will be a basic overview of the topics in preparation for future classes and professional conversations.

Even in entirely healthy normally developed people, some slight variation in anatomy is normal. An easy way to check this is to examine the blood vessels in your forearm and the top of your hand compared to someone else. Severe anatomical abnormalities will not be covered in this chapter but could lead to serious health conditions or movement restrictions.

Many colleges will combine human anatomy and physiology together, but in this chapter, we will focus on understanding and naming the physical structures of the human body, and Chapter 6 will detail exercise physiology separately.

Remember from Chapter 1 that the scientific study of the physical structures of the human body largely started with dissecting the recently deceased. Many of the original anatomical drawings have a morbid or religious feel. These original drawings built the foundation of anatomical knowledge that much of this entire textbook is based on.

Figure 1: A black and white detailed drawing of muscle tissue and blood vessels in the upper chest and arm. "File:H. Gray, Anatomy Descriptive and Surgical. Wellcome L0028363.jpg" is licensed under CC BY 4.0.

Kinesiology and the medical field are closely related and being able to accurately and precisely describe the human body, physical orientation, and movements is critical to professional communication and treatment of patients. As kinesiologists, it is important to be able to have the anatomical knowledge to communicate with other professionals, but also be able to clearly explain the information to someone not educated in the field.

Most people will not understand “You have a grade 2 syndesmosis injury with tissue disruption in the tibiofibular joint” but if they will understand “You have a pretty serious high ankle sprain.”

In this chapter, you will learn many of the scientifically correct names and movement patterns of human biological tissue. Still, it is important to practice correctly explaining concepts in simple terms.

Anatomical Position and Terminology:

The standard anatomical position is of the body standing upright with feet at shoulder width, toes pointed forward, arms out to the side of the body, and palms of the hand facing forward, as shown in the figure below. This starting position might seem simple, but it is important to remember so that discussion of movements, injuries, or deformities can be properly communicated.

Many of the body parts are labeled with their scientific names as well as more common names.

Figure 2: A human male shown front and back in anatomical position with many labeled body parts. "Regions of the Human Body" by Leanne Dooley is licensed under CC BY-SA-4.0

Describing directionality between two relative locations is also standardized:

• 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 are 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.

Figure 3: Directional terms applied to the human body. "Directional Terms" by Leanne Dooley is licensed under CC BY-SA 4.0

Critical Thinking

Why would it be important for a surgeon and their team to communicate using these terms when operating?

Body Planes

The body and its movements can also be discussed in terms of planes, or two-dimensional surfaces passing through the body.

The sagittal plane is the plane that divides the body vertically into the 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 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.

Figure 4: The human body bisected into the planes of movement "Planes of the Body" by Leanne Dooley is licensed under CC BY-SA 4.0

In kinesiology, these body planes are used to discuss how a person is moving or rotating during activity and exercise. Imagine a person doing a regular forward lunge, they would be said to be moving through the sagittal plane, because they are moving their body front to back. Sagittal plane movements also include forward running or bench press. In contrast, a lateral lunge would be moving through the frontal plane because a person is moving left to right. Finally, the transverse plane includes twisting or rotating movements, like putting on a seatbelt.

Of course, many athletic movements performed in sports will combine motion from two or all three of the body planes.

The human body is organized into four broad categories of tissue types: Epithelial, Connective, Muscle, and Nervous.

Epithelial tissue, also referred to as epithelium, refers to the sheets of cells that cover exterior surfaces of the body, line internal cavities and passageways, and form certain glands.

Connective tissue, as its name implies, binds the cells and organs of the body together and functions in the protection, support, and integration of all parts of the body.

Muscle tissue is excitable, responding to stimulation and contracting to provide movement, and occurs in three major types: skeletal (voluntary) muscle, smooth muscle, and cardiac muscle in the heart.

Nervous tissue is also excitable, allowing the propagation of electrochemical signals in the form of nerve impulses that communicate between different regions of the body.

Figure 5: An anatomical look inside the human body showing where various tissue types can be found. "Four Types of Tissues" by Leanne Dooley is licensed under CC BY-SA 4.0

Skeletal Muscle

The primary function of skeletal muscles is to contract and produce movement.
However, they also play a crucial role in maintaining posture by resisting gravity and making small, constant adjustments to keep the body upright and balanced. In addition, skeletal muscles prevent excessive movement of bones and joints, ensuring skeletal stability and preventing damage or deformation. By pulling on associated bones, muscles keep joints stable and prevent misalignment or dislocation. Skeletal muscles are also responsible for controlling the movement of substances through various internal tracts, such as the digestive system, urinary system, and reproductive system. This allows functions such as swallowing, urination, and defecation to be under voluntary control. Lastly, skeletal muscles protect internal organs, especially abdominal and pelvic organs, by acting as an external barrier against external trauma and supporting the weight of the organs.

Skeletal muscles play a critical role in maintaining homeostasis in the body by generating heat. The body expends more calories to maintain warmth than any other activity, including exercise. As muscles contract, they require energy, and when adenosine triphosphate (ATP) is broken down, heat is produced. During exercise, sustained muscle movement causes body temperature to rise, and in extremely cold conditions, shivering triggers random skeletal muscle contractions that generate heat. This heat production is a noticeable effect of muscle contraction and is essential for the body to maintain a constant internal temperature.

Skeletal muscles are intricate organs comprising various interdependent tissues, such as skeletal muscle fibers, blood vessels, nerve fibers, and connective tissue. These tissues collaborate to generate the intended movement.

The anatomy of a skeletal muscle consists of three layers of connective tissue that envelop and compartmentalize the muscle fibers. The outermost layer, called the epimysium, comprises dense and irregular connective tissue that imparts structural stability to the muscle. This layer enables the muscle to contract forcefully while maintaining its form and structural coherence. Furthermore, epimysium separates the muscle from adjacent tissues and organs, facilitating its autonomous movement.

Skeletal muscles comprise fascicles, which are individual bundles of muscle fibers held together by a middle layer of connective tissue known as the perimysium. This arrangement is especially prevalent in limb muscles and enables the nervous system to activate specific movements of the muscle by triggering a subset of muscle fibers within a given fascicle.

Each muscle fiber within a fascicle is enveloped by a thin layer of connective tissuecalled the endomysium, which consists of collagen and reticular fibers. The endomysium contains the extracellular fluid and nutrients necessary to support the muscle fiber, and these nutrients are provided to the muscle tissue through the blood supply.

Skeletal muscles work in tandem with tendons to pull on and move bones. The collagen fibers in the three tissue layers, or mysia, of the muscle interlock with the collagen fibers of the tendon. At the opposite end of the tendon, it blends with the periosteum, which is a thin layer of connective tissue covering the bone's surface. The tension generated by the muscle fiber contraction is transmitted via the mysia to the tendon, then to the periosteum, which pulls the bone, leading to the skeleton's movement.

Each skeletal muscle is richly supplied with blood vessels, delivering the necessary nourishment, oxygen, and waste removal to sustain the muscle's operation. Additionally, every muscle fiber in a skeletal muscle is triggered to contract by a motor neuron's axon. Unlike cardiac and smooth muscle, the sole way to stimulate a skeletal muscle contraction is through signals from the nervous system.

Skeletal Muscle Fibers

Because skeletal muscle cells are long and cylindrical, they are commonly referred to as muscle fibers. Skeletal muscle fibers can be quite large for human cells, with diameters up to 100 μm and lengths up to 30 cm (11.8 in) in the upper leg muscle tissues. During early development, embryonic myoblasts, each with its own nucleus, fuse with up to hundreds of other myoblasts to form the multinucleated skeletal muscle fibers. Multiple nuclei mean multiple copies of genes, permitting the production of the large amounts of proteins and enzymes needed for muscle contraction.

Some other terminology associated with muscle fibers is rooted in the Greek “sarco”, which means “flesh.” The plasma membrane of muscle fibers is called the sarcolemma, the cytoplasm is referred to as sarcoplasm, and the specialized smooth endoplasmic reticulum, which stores, releases, and retrieves calcium ions (Ca++) is called the sarcoplasmic reticulum (SR) (Figure 3). As will soon be described, the functional unit of a skeletal muscle fiber is the sarcomere, a highly organized arrangement of the contractile myofilaments’ actin (thin filament) and myosin (thick filament), along with other support proteins.

Here is a great video on actin and myosin.

Figure 3. An artistic rendering of a skeletal muscle fiber at microscopic view with many anatomical points listed. "Muscle Fibre" by Leanne Dooley is licensed under CC BY-SA 4.0

A skeletal muscle fiber is surrounded by a plasma membrane called the sarcolemma, which contains sarcoplasm, the cytoplasm of muscle cells. A muscle fiber is composed of many fibrils, which give the cell its striated appearance.

The Sarcomere: The striated appearance of skeletal muscle fibers is due to the arrangement of the myofilaments of actin and myosin in sequential order from one end of the muscle fiber to the other. Each packet of these microfilaments and their regulatory proteins, troponin and tropomyosin (along with other proteins) is called a sarcomere.

The sarcomere is the functional unit of the muscle fiber. The sarcomere itself is bundled within the myofibril that runs the entire length of the muscle fiber and attaches to the sarcolemma at its end. As myofibrils contract, the entire muscle cell contracts. Because myofibrils are only approximately 1.2 μm in diameter, hundreds to thousands (each with thousands of sarcomeres) can be found inside one muscle fiber.

Each sarcomere is around 2 μm in length with a cylinder-like arrangement and is bordered by structures called Z-discs (also called Z-lines, because pictures are two-dimensional), to which the actin myofilaments are anchored (Figure 4). Because the actin and its troponin-tropomyosin complex (projecting from the Z-discs toward the center of the sarcomere) form strands that are thinner than the myosin, it is called the thin filament of the sarcomere. Likewise, because the myosin strands and their multiple heads (projecting from the center of the sarcomere, toward but not all to way to, the Z-discs) have more mass and are thicker, they are called the thick filament of the sarcomere.

Figure 4. An artistic rendering of a sarcomere with actin and myosin binding sites. "The Sarcomere" by Leanne Dooley is licensed under CC BY-SA 4.0

The sarcomere, the region from one Z-line to the next Z-line, is the functional unit of a skeletal muscle fiber.

Types of Body Movement

The most common type of joint in the human body is a synovial joint which allows the body a tremendous range of movements. There are two other types of joints in the human body, cartilaginous and fibrous, but they are limited in movement. Each movement at a synovial joint results from the contraction or relaxation of the muscles that are attached to the bones on either side of the articulation. The type of movement that can be produced at a synovial joint is determined by four factors:

• Orientation of the muscle. Each muscle is attached at an origin and an insertion. The origin of the muscle is its attachment to the bone that will remain relatively stable when that muscle contracts. It is the bone to which the muscle is anchored. The other end of the muscle will be its insertion, which is its attachment to the bone which will move when that muscle contracts. The orientation of the muscle – which bone it is anchored to and which bone it inserts in, will determine the movement.
• Action of other muscles that may insert and/or originate on the same bone(s) that when any particular muscle contracts, the bone will be moved in a particular direction, different from the direction any single muscle may produce. It is not uncommon to see the same muscle being involved in two or more different movements.
• Type of joint between the bones. There are several different types of joints between bones. Only the synovial joint allows for any significant movement. Each specific joint is limited in the movement it can provide because of the shape of the ends of the bones in the joint, and because of the tension in the ligaments holding the bones together.
• Muscle tension. This is a limitation that works in a similar manner to tension in the ligaments. An example of the role of muscle tension is demonstrated when touching one’s toes with the knees straight. The movement is restricted by the tension of the hamstring muscles.

While the ball-and-socket joint gives the greatest range of movement at an individual joint, in other regions of the body, several joints may work together to produce a particular movement. Overall, each type of synovial joint is necessary to provide the body with its great flexibility and mobility. There are many types of movement that can occur at synovial joints. Movement types are generally paired, with one being the opposite of the other. Body movements are always described in relation to the anatomical position of the body: upright stance, with upper limbs to the side of body and palms facing forward.

Type of Joint	Movement	Examples
Pivot	Uniaxial joint; allows rotational movement	Atlantoaxial joint (C1-C2 vertebrae articulation); proximal radioulnar joint
Hinge	Uniaxial joint; allows flexion/extension movements	Knee; elbow; ankle; interphalangeal joints of fingers and toes
Condyloid	Biaxial joint; allows flexion/extension, abduction/adduction, and circumduction movements	Metacarpophalangeal (knuckle) joints of fingers; radiocarpal joint of wrist; metatarsophalangeal joints of toes
Saddle	Biaxial joint; allows flexion/extension, abduction/adduction, and circumduction movements	First carpometacarpal joint (carpometacarpal joint of the thumb); sternoclavicular joint
Plane	Multiaxial joint; allows inversion/eversion of the foot, flexion/extension and lateral flexion of the vertebral column	intertarsal joints of foot; superior-inferior articular process articulations between vertebrae
Ball-and-socket	Multiaxial joint; allows flexion/extension, abduction/adduction, circumduction, and medial/lateral rotation movements	Shoulder joint, hip joint

For the following discussions, please take your time and physically act the movements out.

Flexion and extension are movements that take place within the sagittal plane and involve anterior or posterior movements of the body or limbs. For the vertebral column, flexion (anterior flexion) is an anterior (forward) bending of the neck or body, while extension involves a posterior-directed motion, such as straightening from a flexed position or bending backward. Lateral flexion is the bending of the neck or body toward the right or left side. These movements of the vertebral column involve both the symphysis joint formed by each intervertebral disc, as well as the plane type of synovial joint formed between the inferior articular processes of one vertebra and the superior articular processes of the next lower vertebra.

In the limbs, flexion decreases the angle between the bones (bending of the joint), while extension increases the angle and straightens the joint. For the upper limb, all anterior-going motions are flexion, and all posterior-going motions are extension. These include anterior-posterior movements of the arm at the shoulder, the forearm at the elbow, the hand at the wrist, and the fingers at the metacarpophalangeal and interphalangeal joints. For the thumb, extension moves the thumb away from the palm of the hand, within the same plane as the palm, while flexion brings the thumb back against the index finger or into the palm. These motions take place at the first carpometacarpal joint. In the lower limb, bringing the thigh forward and upward is flexion at the hip joint, while any posterior-going motion of the thigh is extension. Note that extension of the thigh beyond the anatomical (standing) position is greatly limited by the ligaments that support the hip joint. Knee flexion is the bending of the knee to bring the foot toward the posterior thigh, and extension is the straightening of the knee. Flexion and extension movements are seen at the hinge, condyloid, saddle, and ball-and-socket joints of the limbs (Figure 5a-d below).

Hyperextension is the abnormal or excessive extension of a joint beyond its normal range of motion, thus resulting in injury. Similarly, hyperflexion is excessive flexion at a joint. Hyperextension injuries are common at hinge joints such as the knee or elbow. In cases of “whiplash” in which the head is suddenly moved backward and then forward, a patient may experience both hyperextension and hyperflexion of the cervical region.

Abduction and Adduction: Abduction and adduction motions occur within the coronal plane and involve medial-lateral motions of the limbs, fingers, toes, or thumb. Abduction moves the limb laterally away from the midline of the body, while adduction is the opposing movement that brings the limb toward the body or across the midline. For example, abduction is raising the arm at the shoulder joint, moving it laterally away from the body, while adduction brings the arm down to the side of the body. Similarly, abduction and adduction at the wrist moves the hand away from or toward the midline of the body. Spreading the fingers or toes apart is also abduction, while bringing the fingers or toes together is abduction. For the thumb, abduction is the anterior movement that brings the thumb to a 90°perpendicular position, pointing straight out from the palm. Adduction moves the thumb back to the anatomical position, next to the index finger. Abduction and adduction movements are seen at condyloid, saddle, and ball-and-socket joints (Figure 5e).

Circumduction is the movement of a body region in a circular manner, in which one end of the body region being moved stays relatively stationary while the other end describes a circle. It involves the sequential combination of flexion, adduction, extension, and abduction at a joint. This type of motion is found at biaxial condyloid and saddle joints, and at multiaxial ball-and-sockets joints (Figure 5e).

Rotation can occur within the vertebral column, at a pivot joint, or at a ball-and-socket joint. Rotation of the neck or body is the twisting movement produced by the summation of the small rotational movements available between adjacent vertebrae. At a pivot joint, one bone rotates in relation to another bone. This is a uniaxial joint, and thus rotation is the only motion allowed at a pivot joint. For example, at the atlantoaxial joint, the first cervical (C1) vertebra (atlas) rotates around the dens, the upward projection from the second cervical (C2) vertebra (axis). This allows the head to rotate from side to side as when shaking the head “no.” The proximal radioulnar joint is a pivot joint formed by the head of the radius and its articulation with the ulna. This joint allows for the radius to rotate along its length during pronation and supination movements of the forearm.

Rotation can also occur at the ball-and-socket joints of the shoulder and hip. Here, the humerus and femur rotate around their long axis, which moves the anterior surface of the arm or thigh either toward or away from the midline of the body. Movement that brings the anterior surface of the limb toward the midline of the body is called medial (internal) rotation. Conversely, rotation of the limb so that the anterior surface moves away from the midline is lateral (external) rotation (Figure 5f). Be sure to distinguish medial and lateral rotation, which can only occur at the multiaxial shoulder and hip joints, from circumduction, which can occur at either biaxial or multiaxial joints.

Figure 5. Multiple drawings of physical human movements and their names. "Joint Movement" by Leanne Dooley is licensed under CC BY-SA 4.0

Synovial joints give the body many ways in which to move. (a)–(b) Flexion and extension motions are in the sagittal (anterior–posterior) plane of motion. These movements take place at the shoulder, hip, elbow, knee, wrist, metacarpophalangeal, metatarsophalangeal, and interphalangeal joints. (c)–(d) Anterior bending of the head or vertebral column is flexion, while any posterior-going movement is extension. (e) Abduction and adduction are motions of the limbs, hand, fingers, or toes in the coronal (medial–lateral) plane of movement. Moving the limb or hand laterally away from the body, or spreading the fingers or toes, is an abduction. Adduction brings the limb or hand toward or across the midline of the body or brings the fingers or toes together. Circumduction is the movement of the limb, hand, or fingers in a circular pattern, using the sequential combination of flexion, adduction, extension, and abduction motions. Adduction/abduction and circumduction take place at the shoulder, hip, wrist, metacarpophalangeal, and metatarsophalangeal joints. (f) Turning of the head side to side or twisting of the body is rotation. Medial and lateral rotation of the upper limb at the shoulder or lower limb at the hip involves turning the anterior surface of the limb toward the midline of the body (medial or internal rotation) or away from the midline (lateral or external rotation).

Supination and pronation are movements of the forearm. In the anatomical position, the upper limb is held next to the body with the palm facing forward. This is the supinated position of the forearm. In this position, the radius and ulna are parallel to each other. When the palm of the hand faces backward, the forearm is in the pronated position, and the radius and ulna form an X-shape.

Supination and pronation are the movements of the forearm that go between these two positions. Pronation is the motion that moves the forearm from the supinated (anatomical) position to the pronated (palm backward) position. This motion is produced by rotation of the radius at the proximal radioulnar joint, accompanied by movement of the radius at the distal radioulnar joint. The proximal radioulnar joint is a pivot joint that allows for rotation of the head of the radius. Because of the slight curvature of the shaft of the radius, this rotation causes the distal end of the radius to cross over the distal ulna at the distal radioulnar joint. This crossing over brings the radius and ulna into an X-shape position. Supination is the opposite motion, in which rotation of the radius returns the bones to their parallel positions and moves the palm to the anterior facing (supinated) position. It helps to remember that supination is the motion you use when scooping up soup with a spoon (Figure 6g).

Dorsiflexion and plantar flexion are movements at the ankle joint, which is a hinge joint. Lifting the front of the foot, so that the top of the foot moves toward the anterior leg is dorsiflexion, while lifting the heel of the foot from the ground or pointing the toes downward is plantar flexion. These are the only movements available at the ankle joint (Figure 6h).

Inversion and eversion are complex movements that involve the multiple plane joints among the tarsal bones of the posterior foot (intertarsal joints) and thus are not motions that take place at the ankle joint. Inversion is the turning of the foot to angle the bottom of the foot toward the midline, while eversion turns the bottom of the foot away from the midline. The foot has a greater range of inversion than eversion motion. These are important motions that help to stabilize the foot when walking or running on an uneven surface and aid in the quick side-to-side changes in direction used during active sports such as basketball, racquetball, or soccer (Figure 6i).

Protraction and retraction are anterior-posterior movements of the scapula or mandible. Protraction of the scapula occurs when the shoulder is moved forward, as when pushing against something or throwing a ball. Retraction is the opposite motion, with the scapula being pulled posteriorly and medially, toward the vertebral column. For the mandible, protraction occurs when the lower jaw is pushed forward, to stick out the chin, while retraction pulls the lower jaw backward. (Figure 6j.)

Depression and elevation are downward and upward movements of the scapula or mandible. The upward movement of the scapula and shoulder is elevation, while a downward movement is depression. These movements are used to shrug your shoulders. Similarly, elevation of the mandible is the upward movement of the lower jaw used to close the mouth or bite on something, and depression is the downward movement that produces opening of the mouth (Figure 6k).

Figure 6. Multiple drawings of physical human movements and their names. "Joint Movement" by Leanne Dooley is licensed under CC BY-SA 4.0

(g) Supination of the forearm turns the hand to the palm forward position in which the radius and ulna are parallel, while forearm pronation turns the hand to the palm backward position in which the radius crosses over the ulna to form an “X.” (h) Dorsiflexion of the foot at the ankle joint moves the top of the foot toward the leg, while plantar flexion lifts the heel and points the toes. (i) Eversion of the foot moves the bottom (sole) of the foot away from the midline of the body, while foot inversion faces the sole toward the midline. (j) Protraction of the mandible pushes the chin forward, and retraction pulls the chin back. (k) Depression of the mandible opens the mouth, while elevation closes it. (l) Opposition of the thumb brings the tip of the thumb into contact with the tip of the fingers of the same hand and reposition brings the thumb back next to the index finger.

Figure 7. Anatomical overview of most major human muscles. "Human Muscles" by Leanne Dooley is licensed under CC BY-SA 4.0

On the anterior and posterior views of the muscular system above, superficial muscles (those at the surface) are shown on the right side of the body while deep muscles (those underneath the superficial muscles) are shown on the left half of the body. For the legs, superficial muscles are shown in the anterior view while the posterior view shows both superficial and deep muscles.

The Heart!

The pump that keeps oxygen flowing to all parts of the body while also removing metabolic by-products and circulates different hormones and other nutrients. Over a lifetime, the heart can beat nearly 3 billion times, while never taking a break. This ability to not fatigue is one of the main differences between cardiac muscle tissue and skeletal muscle tissue.

Figure 8: A drawing of the heart and its anatomical structures named with a crude example of the systemic and pulmonary circuits. "Heart and Position" by Leanne Dooley is licensed under CC BY-SA 4.0

The heart has four chambers (two atria and two ventricles) and pumps blood throughout the body by contracting and squeezing those chambers to force the blood to move forward by utilizing one-way valves. The right atrium receives deoxygenated blood from the body the left atrium receives oxygen-rich blood from the lungs. The atria contract to pump the blood into their corresponding ventricles which then contract to pump the oxygenated blood out to the body and the deoxygenated blood to the lungs. These two intermixing circulations are the systemic and pulmonary systems. The pulmonary system is the circulation of blood from the heart to the lungs and back. This system is smaller; therefore the right side of the heart is less muscled. The systemic system is the circulation from the heart to the body and back to the heart, so the left side of the heart is much larger to create the required force to push the blood through the body.

Blood pressure measurements using a sphygmomanometer (blood pressure cuff) is a common kinesiology lab test. How the heart physically beats and circulates blood through a double chambered pump makes it possible to hear the classic “lub dub” heart beat sound and measure the internal pressure of the arteries. A blood pressure cuff works by collapsing an artery completely blocking all of the blood flow. As the pressure of the cuff is reduced, the heart will be creating enough force to push the blood through the now partially open artery. Listening with a blood pressure cuff will allow determination of systolic and diastolic pressures, which are reported in mmHg.

Systolic blood pressure is the first number (or number on top) reported in a blood pressure reading, this pressure reading is from when the heart is fully contracted and pushing the blood through the arterial system.

Diastolic pressure readings show the pressure in the arteries between heart beats when the heart is relaxed. An average blood pressure reading for a healthy adult is 120/80mmHg.

The heart needs the lungs for respiration, removing carbon dioxide from the blood and providing new oxygen. The respiratory system is made up of the nose, pharynx, larynx, trachea, bronchi, and the lungs. As the lungs expand air travels down the respiratory system to the alveoli in the lungs. The alveoli are very small thin membrane sacs in the lungs that allow for gas exchange from the outside air to the blood.

The lungs are much less adaptable compared to the heart for exercise and fitness improvements. It is possible to make some small improvements but cardiovascular fitness adaptations are primarily made in the heart.

The muscles, joints, heart, and lungs all work together to allow humans to move and exercise. Focused training over a period of time will bring fitness adaptations and improvements to these systems which will be discussed in more detail in Chapter 10.

The information in this chapter is relevant to all fields of kinesiology and it is recommended to review the common terminology describing body placement and movement often.