EMT 1114 - Ch 5: The Human Body (The Circulatory System: A&P)

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The Circulatory System: Anatomy

A complex arrangement of connected tubes, including the arteries, arterioles, capillaries, venules, and veins. Also known as the cardiovascular (heart/blood vessels) system. Entirely closed, with capillaries connecting arterioles and venules.

Two circuits in the body

- Systemic circulation
- Pulmonary circulation

Systemic Circulation

The portion of the circulatory system outside of the heart and lungs.

Pulmonary Circulation

The flow of blood from the right ventricle through the pulmonary arteries and all of their branches and capillaries in the lungs and back to the left atrium through the venules and pulmonary veins; also called the lesser circulation.

Heart

A hollow muscular organ approximately the size of the patient's clenched fist. It is made of a specialized muscle tissue called cardiac muscle, or myocardium, and actually works as two paired pumps, the left side being more muscular. Each side is divided into an upper chamber (atrium) and a lower chamber (ventricle).The left side is a high-pressure pump; the right side supplies blood to the lungs and is a low-pressure pump.

Myocardium

The heart muscle.

Atrium

One of the two upper chambers of the heart.

Ventricle

One of the two lower chambers of the heart.

Pulmonary Veins

The four veins that return oxygenated blood from the lungs to the left atrium of the heart.

Chordae Tendineae

Thin bands of fibrous tissue that attach to the valves in the heart and prevent them from inverting.

Systole

The ventricle contracts.

Diastole

The ventricle relaxes.

Heart Rate (HR)

The number of heartbeats during a specific time.

Normal Heartbeat

In a normal adult, the resting heartbeat may range from 60 to 100 beats/min. During vigorous physical activity, the heart rate may rise to as fast as 180 beats/min. At each beat, 70 to 80 mL of blood is ejected from the adult heart. This is called the stroke volume (SV). In 1 minute, the entire blood volume of 5 to 6 L is circulated through all the vessels. This is the cardio output (CO).

Stroke Volume (SV)

The volume of blood pumped forward with each ventricular contraction.

Cardio Output (CO)

The amount of blood moved in 1 minute.

Calculated: CO = HR x SV

Arteries

Carry blood from the heart to all body tissues. Branch into smaller arteries and then into arterioles, which then branch into the vast network of capillaries.

Tunica Media

The middle and thickest layer of tissue of a blood vessel wall, composed of elastic tissue and smooth muscle cells that allow the vessel to expand or contract to response to changes in blood pressure and tissue demand.

Aorta

The principle artery leaving the back left side of the heart; it carries freshly oxygenated blood to the body.

Pulmonary Artery

Begins at the right side of the heart and carries oxygen-depleted blood to the lungs. It divides into finer and finer branches until it meets with the pulmonary capillary system located in the thin walls of the alveoli.

Arterioles

The smallest branches of arteries leading to the vast network of capillaries.

Pulse

The wave of pressure created as the heart contracts and forces blood out of the left ventricle and into the major arteries. Can be palpated most easily at the neck, wrist, or groin.

Carotid Artery

The major artery that supplies blood to the head and brain.

Femoral Artery

The principle artery of the thigh, a continuation of the external iliac artery. It supplies blood to the lower abdominal wall, external genitalia, and legs. It can be palpated in the groin area.

Radial Artery

The major artery in the forearm; is palpable at the wrist on the thumb side.

Brachial Artery

The major vessel in the upper extremity that supplies blood to the arm.

Posterior Tibial Artery

The artery just behind the medial malleolus; supplies blood to the foot.

Dorsalis Pedis Artery

The artery on the anterior surface of the foot between the first and second metatarsals.

Capillary Vessels

The tiny blood vessels between the arterioles and venules that permit transfer of oxygen, carbon dioxide, nutrients, and waste between body tissues and the blood.

Sphincters

Muscles arranged in circles that are able to decrease the diameter of tubes. Examples are found within the rectum, bladder, and blood vessels.

Veins

Carries oxygen-depleted blood back to the heart through the network of capillaries, venules, and larger and larger veins. Have much thinner walls than arteries and are generally larger in diameter.

Superior Vena Cava

Carries blood returning from the head, neck, shoulders, and upper extremities.

Inferior Vena Cava

Carries blood returning from the abdomen, pelvis, and lower extremities.

Systemic Vascular Resistance (SVR)

The resistance to blood flow within all of the blood vessels except the pulmonary vessels.

Flickr Creative Commons Images

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