Lesson 7 Human Body Systems As Related to First Aid

BESTGuard Lifeguarding Program

Unit 4: General Patient Assessment

Lesson 7 – Human Body Systems as Related to First Aid

BESTGuard lifeguards are expected to have a basic understanding of human body systems and how they relate to the first aid situations that they may encounter, including drowning. The following pages provide lifeguards with a solid foundation for understanding the basics of how the body works, and some of the terms commonly used by the EMS/ICS personnel that come after them.

Terms used in anatomy/first aid –

Body cavities: a hollow place in the body that contains organs. There are 5 cavities to remember – SPACT for spinal, pelvic, abdominal, cranial, thoracic

· Cranial – contains the brain (the skull is also called the cranium)

· Spinal – contains the spinal cord

· Thoracic – contains the heart and lungs

· Abdominal – contains the digestive organs: stomach, liver, pancreas, kidneys, intestines, spleen (the diaphragm and pelvis border this cavity)

· Pelvic – contains the rectum, bladder, and reproductive organs

The body cavities are referred to when performing a physical exam or when locating an injury or medical problem.

Quadrants: 4 sections of the abdomen that assist in location of injuries. They are divided by the navel both horizontally and vertically. The vertical line cuts through the navel and extends to the xiphoid process on the sternum. The horizontal line cuts through the navel and essentially rests on the iliac crest. –

· Upper right

· Upper left

· Lower right

· Lower left

The quadrants are each palpated during the physical exam for abnormalities.

Directional/motion terms used in anatomy: terms of locations/directions/motion (always from the reference point of the patient) –

· Medial – toward the mid-line or center

· Lateral – toward the outside or away from the mid-line

· Anterior – toward the front, or in the front

· Posterior – toward the back or in the back

· Superior – above or on top

· Inferior – below or on the bottom

· Distal – farthest from the body or midline (i.e. distal phalanges)

· Proximal – closest to the body or midline (i.e. proximal phalanges)

· Supinate – upward rotation, hands or entire body (supine)

· Pronate – downward rotation, hands or entire body (prone)

· Flexion – contraction of muscles that make limbs shorten, as in the biceps or hamstrings

· Extension – contraction of muscles that make limbs lengthen, as in the triceps or quadriceps

· Dorsiflexion – curling up the foot (anterior tibialis muscle does this)

· Plantarflexion – pointing the toes (gastrocnemius, soleus)

· Adduction – adding to the body, such as bringing an extended arm back to your side

· Abduction – moving away from the body, such as moving an arm from your side up into a horizontal position

· Process – a protrusion on a bone, such as the spinous processes on the vertebrae, or the acromion process on the scapula

· Tuberosity – another bump on a bone; one of the most notable is the ischial tuberosity – because you literally sit on the pair of them whenever seated.

· Tendon – connective tissue that connects muscle to bone

· Ligament – connective tissue that connects bone to bone

Circulatory System –

The circulatory system is involved in at least three functions vital to the human body: transportation, temperature regulation, and defense against diseases. It is failure of this system that results in heat stroke, heart attacks, strokes, and aneurysms.

The components of the circulatory system are:

· Blood – composed of platelets and plasma, as well as red & white blood cells, the blood is like a mighty river that transports products on barges to different ports along the river. Plasma is the fluid portion of the blood, and platelets are mostly solid cell fragments (fragmented white blood cells). White blood cells are the body’s tiny army. They attack anything that is considered hostile to the body, like bacteria. They are far fewer in number than the red blood cells. Red blood cells are in charge of transportation. Their main function is the transportation of iron and oxygen/CO2. Red blood cells out-number white about 1000 to 1.

· Arteries – are the high pressure blood vessels that carry blood away from the heart via the ventricles. Ventricles produce the high pressure that is measured in the systolic blood pressure. Arteries are the biggest “pipes” in the system. They divide into smaller arterioles, and end as microscopic capillaries. It is in the capillaries that all the business of the blood takes place: oxygen and carbon dioxide is exchanged in the tissues and the lungs. The tissues’ cells give off CO2 into the capillaries, while the capillaries supply fresh O2. In the lungs, blood releases CO2 into alveoli, and picks up fresh O2 that is delivered back to the cells.

The major arteries that lifeguards should be familiar with include: the carotid – the main arteries in the neck (used for pulse check during CPR); the brachial – in the upper arm and across the elbow joint (used for pulse check in an infant during CPR, and for auscultation blood pressure); the radial – in the lower arm, next to the radius bone on the thumb side of the wrist (used for pulse rate and for palpation blood pressure); the aorta is the biggest artery in the body, ascending out of the left ventricle. The aorta’s branches form all the other major arteries of the body, except for the pulmonary arteries; the pulmonary artery branches into the right and left pulmonary artery which supply oxygen poor blood to the lungs. The pulmonary artery comes directly out of the right ventricle. It is the only artery to carry O2 poor blood. This is usually the job of the veins. The coronary arteries are the very first branches of the aorta. They supply blood directly to the heart muscle (myocardium). These are the arteries that become obstructed in an acute myocardial infarction (heart attack). An abdominal aortic aneurysm is dilation in a branch of the aorta. Arterial bleeding is often life threatening, due to the high pressure, especially if it’s to one of the main arteries.

· Veins – Veins carry oxygen-poor blood back to the heart, where they deliver it to the atria; the two chambers in the top of the heart. Veins are thinner walled than arteries, and have a series of one-way valves to prevent back-flow of blood.

They are of much lower pressure than arteries, thus don’t bleed nearly as freely. Veins start as capillaries, grow to venules, then larger veins. There are only a few veins that lifeguards need to know: the vena cava, the jugular veins, and the pulmonary veins. The vena cava is the largest vein in the body, and has both an inferior and superior component. The inferior vena cava is below the heart and brings blood back from the torso and lower body; the superior vena cava is above the heart and brings blood back from the upper body. Both deliver it to the right atrium. The jugular veins are also quite large and are adjacent to the common carotid arteries in the neck. The pulmonary veins bring oxygen-rich blood back from the lungs to the left atrium.

· Heart – The heart has four chambers: two atria and two ventricles. The atria receive blood into the heart from veins, and the ventricles push blood out of the heart through arteries. The right side of the heart is the pulmonary circuit, bringing oxygen-poor blood to the lungs to receive oxygenation. The left side is the systemic circuit, bringing oxygen rich blood to all the tissues via the left ventricle and the aorta. Atria pump the received blood down into the ventricles as commanded by the sino-atrial node located at the top of the right atrium. The atrio-ventricular node then commands the ventricles to pump the blood out. These two nodes control the pulse, and are what malfunction during V-fib or V-tach. Atrial fibrillation can also occur, which is very much like the irregular twitching characteristic of V-fib. A-fib is generally not a life-threatening, no pulse situation, as in V-fib. It creates an inefficient arrhythmia that affects the blood flow, but does not usually stop the heart from beating altogether. Blood flow through the body and through the heart works in a continuous loop: blood coming from all the body’s cells enters the heart via the right atrium, is pumped down into the right ventricle, then pushed into the pulmonary artery and into the lungs. It unloads CO2 , picks up oxygen and brings it back to the heart via the pulmonary veins. The pulmonary vein delivers this blood to the left atrium, which pumps it down into the left ventricle, then out via the aorta to all the body’s cells; where it delivers the oxygen, picks up CO2 and starts the loop over again.

O2 poor blood arrives in vena cava

O2 poor blood to lungs via

It enters right atrium pulmonary artery

O2 rich blood returns to left atrium

Is pumped to right ventricle Is pumped to left ventricle

O2 rich blood exits heart via aorta

In addition to circulating blood, which is the transportation function, the circulatory system cools the body, and helps to maintain warmth by precise distribution of blood and constriction or dilation of vessels close to the skin. When cold, these vessels constrict , slowing the release of heat to the surrounding environment. When hot, they dilate to release heat and provide cooling. The system can also regulate where blood goes to protect the vital organs first, as during hypothermia or hemorrhagic shock. The temperature regulation function works in harmony with other systems, such as the pilomotor (arrector pili) muscles in the dermis, that make hairs stand up to create a layer of dead-air.

Arrector pili muscles

creating layer of dead air over

the skin

As mentioned earlier, the third function is to transport the army of white blood cells and anti-bodies that fight diseases. The blood transports everything else to the cells as well, drugs, nutrients, etc.

Respiratory System –

This system works in tandem with the circulatory system to provide oxygen to the body’s cells and to release carbon dioxide from the cells. Breathing is accomplished through a change in chest cavity pressure: when inspiring (breathing in) the pressure is lowered in the lungs relative to the outside air so the air rushes in. When expiring (breathing out) the pressure in the lungs is greater than the outside air, and the air in the lungs is pushed out. Because it takes effort to expand the chest volume by the diaphragm and intercostal muscles, inspiration is the “active” part of breathing. Expiration is accomplished by merely relaxing the muscles of inspiration.

The components of the respiratory system are:

· Lungs – Located inside the rib cage, and separated by the descending aorta and the vena cava, the lungs are the main component of the system, where O2 is exchanged with CO2.

· Mouth – Air is inhaled and exhaled through the mouth and/or nose. OPAs are inserted into the mouth, and NPAs into the nose to the pharynx, to provide a clear passage of air and prevent the tongue from obstructing the airway.

· Nose - Breathing is mostly through the nose, except during exertion when more oxygen is needed, and the mouth is used as well.

· Pharynx – Is the back of the throat. The area that becomes obstructed by the tongue when the tongue falls back on an unconscious patient; or during anaphylaxis when the tongue is swelling into the pharynx.

· Larynx – The voice box, located near the top of the trachea. Sounds and pitch are formed in the larynx, while words are formed by the tongue and lips.

· Trachea – The wind-pipe. Air comes through the pharynx into the trachea where it branches off into the right and left bronchi. These two pipes supply the right and left lungs.

· Epiglottis – The small flap over the opening to the trachea. It is a valve that prevents food or liquids from entering the trachea. Only air should be allowed in there! During a seizure, the epiglottis may be twitching along with other muscles in the body, allowing water to flood the lungs and disable alveoli.

· Bronchioles – Smaller divisions of the bronchi that eventually end in the microscopic alveoli. COPD patients suffer from chronic inflammation, mucous production, and obstruction of these passages.

· Alveoli – The microscopic sack-like structures that exchange oxygen and carbon dioxide.

Respiratory distress refers to difficulty breathing. Breathing rates that are outside the normal ranges for resting rate constitute respiratory distress: Respirations of less than 12 or more than 20 (adult), less than 15 or more than 30 (child), less than 25 or more than 50 (infant). Respiratory arrest means breathing has stopped.

Note: The esophagus is NOT a component of the

respiratory system. It is the tube directly behind the trachea

through which food is transported to the stomach.

Musculo-skeletal System –

Bones, muscles, tendons, and ligaments, along with cartilage, and other specialized tissues comprise this system. Its functions are support and movement. Some of the major components are:

· Bones – There about 206 bones in the body. Many have duplicates or numbers, so most of the bones can be identified by a lifeguard. A list of the major bones follows:

o Bones of the skull/cranium – frontal: the forehead; parietal: the sides of the head above the temporal; temporal: the temples or sides of the head; occipital: the bone in the back of the head; zygomatic: the cheek bone; maxilla: upper lip (houses upper teeth); mandible: the jaw bone (houses lower teeth). The zygomatic and mandible are the two bones that are grasped by guards during the head/chin support position. The nasal bones are at the top of the nose and are quite thin & delicate. The vomer and lacrimal bones are also at the top of the nose: the vomer is in the center, and the lacrimal bones are just superior to the nasal bones. These bones are again quite thin and delicate. One other bone that is prominent on the skull is the mastoid process, just behind the ear (part of the temporal bone). There are other bones in the skull not in clear view: ethmoid, sphenoid, hammer (malleus), anvil (incus), stirrup (stapes).