CARDIOVASCULAR SYSTEM

• Heart

  • hollow, muscular organ about the size of a closed fist.
  • Located between the lungs in the mediastinum, behind and to the left of the sternum.
  • The heart spans the area from the second to the fifth intercostal space.
• Pericardium

  • thin sac with an inner, or visceral, layer that forms the epicardium and an outer, or parietal, layer that protects the heart.
  • The space between the two layers (the pericardial space) contains 10 to 20 ml of serous fluid, which lubricates and cushions the surface of the heart and prevents friction between the layers as the heart pumps.
• Layers of the heart wall

  A) Fibrous pericardium

  B) Parietal pericardium

  C) Pericardial space

  D) Epicardium

  E) Myocardium

  F) Endocardium

  
• Structures of the heart

  A) Superior vena cava

  B) aortic arch

  C) Pulmonary artery

  D) Left atrium

  E) Right atrium

  F) Left ventricle

  G) Right ventricle

  
• The heart has four chambers — two atria and two ventricles — separated by a cardiac septum.
• The upper atria have thin walls and serve as reservoirs for blood. They also boost the amount of blood moving into the lower ventricles, which fill primarily by gravity.
• The left ventricle pumps blood against a much higher pressure than the right ventricle, so its wall is two and one-half times thicker.
• Vessels - Leading into and out of the heart are the great vessels:

  1. inferior vena cava
  2. superior vena cava
  3. aorta
  4. pulmonary artery
  5. four pulmonary veins
• Cardiac circulation

  1. Blood is ejected through the pulmonic valve into the pulmonary artery, then travels to the lungs to be oxygenated.
  2. From the lungs, blood travels to the left atrium through the pulmonary veins.
  3. Deoxygenated venous blood returns to the right atrium through the superior vena cava, inferior vena cava, and coronary sinus.
  4. Blood in the right atrium empties into the right ventricle, which contracts.
  5. The left atrium empties the blood into the left ventricle, which then pumps the blood with each contraction through the aortic valve into the aorta and throughout the body.
• Valves - in the heart keep blood flowing in only one direction through the heart.
• Valves between the atria and ventricles are called atrioventricular valves and include the tricuspid valve on the right side of the heart and the mitral valve on the left.
• The pulmonic valve (between the right ventricle and pulmonary artery) and the aortic valve (between the left ventricle and the aorta) are called semilunar valves.
• On the cusp

  • Each valve’s leaflets, or cusps, are anchored to the heart wall by cords of fibrous tissue.
  • Those cords, called chordae tendineae, are controlled by papillary muscles. The valves’ cusps maintain tight closure.
  • The tricuspid valve has three cusps.
  • The mitral valve has two.
  • The semilunar valves each have three cusps.
• Cardiac cycle

  • Contractions of the heart occur in a rhythm and are regulated by impulses that normally begin at the sinoatrial (SA) node.
• Locating the heart valves

  A) Pulmonic valve

  B) Aortic valve

  C) Tricuspid valve

  D) Mitral valve

  
• Cardiac conduction

  • The heart’s conduction system begins with the heart’s pacemaker, the SA node.
• • When an impulse leaves the SA node to atria along Bachmann’s bundle to internodal pathways to atrioventricular (AV) node to ventricles to the bundle of His to along the bundle branches and, to down the Purkinje fibers.

  A) Bacchman's bundle

  B) SA Node

  C) AV node

  D) Bundle of His

  E) Purkinje fibers

  
• Cardiac cycle

  • Systole - the period when the heart contracts and sends blood on its outward journey.
  • Diastole - the period when the heart relaxes and fills with blood.
• Vascular system

  • It delivers oxygen, nutrients, and other substances to the body’s cells and removes the waste products of cellular metabolism.
  • The peripheral vascular system consists of a network of about 60,000 miles of arteries, arterioles, capillaries, venules, and veins that’s constantly filled with about 5 L of blood, which circulates to and from every functioning cell in the body
• Arteries

  • It carry blood away from the heart. Nearly all arteries carry oxygen-rich blood from the heart throughout the rest of the body.
  • Pulmonary artery which carries oxygen-depleted blood from the right ventricle to the lungs.
  • Arteries are thick-walled because they transport blood under high pressure.
• Capillaries

  • The exchange of fluid, nutrients, and metabolic wastes between blood and cells occurs here.
  • It occurs because it is thin-walled and highly permeable.
• Arterioles constrict and dilate to control blood flow to the capillaries.
• Venules gather blood from the capillaries.
• Veins

  • It carries blood toward the heart. Most carry oxygen depleted blood.
  • Pulmonary veins which carry oxygenated blood from the lungs to the left atrium.
  • It serves as a large reservoir for circulating blood.
  • The wall of a vein is thinner and more pliable than the wall of an artery. Veins contain valves at periodic intervals to prevent blood from flowing backward.
• Atrial systole

  • The atria contract, emptying blood into the ventricles. As pressure within the ventricles rises, the mitral and tricuspid valves snap shut, producing the first heart sound, S1.
• Ventricular systole

  • Shortly after atrial systole, the ventricles contract, ejecting blood from the heart to the lungs and the rest of the body. At the end of ventricular contraction, the aortic and pulmonic valves snap shut, producing the second heart sound, S2.
• Diastole

  • Atria and ventricles relax and blood refills each chamber.
• Arterial pulses - pressure waves of blood generated by the pumping action of the heart. All vessels in the arterial system have pulsations, but the pulsations can be felt only where an artery lies near the skin.
• You can palpate for these peripheral pulses:

  • temporal
  • carotid
  • brachial
  • radial
  • ulnar
  • femoral
  • popliteal
  • posterior tibial
  • dorsalis pedis
• Clubbing - sign of chronic hypoxia caused by a lengthy cardiovascular or respiratory disorder.
• If the patient is dark-skinned, inspect his mucous membranes for pallor.
• Inspection

  • Inspect the vessels in the patient’s neck.
  • The carotid artery should appear to have a brisk, localized pulsation.
  • The internal jugular vein has a softer, undulating pulsation. Unlike the pulsation of the carotid artery, pulsation of the internal jugular vein changes in response to position and breathing. The vein normally protrudes when the patient is lying down and lies flat when he stands.
• Evaluating jugular vein distention

  • Locate the angle of Louis (sternal notch). To do so, palpate the clavicles where they join the sternum (the suprasternal notch). Place your first two fingers on the suprasternal notch. Then, without lifting them from the skin, slide them down the sternum until you feel a bony protuberance—this is the angle of Louis.
  • Arterial pulsations continue, whereas venous pulsations disappear with light finger pressure.
  • Also, venous pulsations increase or decrease with changes in body position; arterial pulsations remain constant.
• Inspecting the neck vessels can provide information about blood volume and pressure in the right side of the heart.
• Palpation

  • To palpate the carotid artery, lightly place your fingers just medial to the trachea and below the angle of the jaw. The pulse should be regular in rhythm and have equal strength in the right and left carotid arteries.
  • You shouldn’t be able to detect any palpable vibrations, known as thrills.
  • Don’t palpate both carotid arteries at the same time or press too firmly. If you do, the patient may faint or become bradycardic
• Auscultation

  • Normally, you should hear no vascular sounds over the carotid arteries upon auscultation using the bell of the stethoscope.
  • If you detect a blowing, swishing sound, this is a bruit that results from turbulent blood flow.
  • A bruit can occur in patients with arteriosclerotic plaque formation.
• Apical impulse: the point of maximal impulse, located in the fifth intercostal space at or just medial to the left midclavicular line.
• Cardiovascular landmarks 1

  A) Midclavicular line

  B) Midsternal line

  C) axillary line (anterior)

  D) midaxillary line

  E) axillary line (posterior)

  
• Cardiovascular landmarks 2

  A) Aortic area

  B) Pulmonic area

  C) Tricuspid area

  D) Mitral area

  
• Palpation

  • Maintain a gentle touch when you palpate so that you won’t obscure pulsations or similar findings.
  • Follow a systematic palpation sequence covering the sternoclavicular, aortic, pulmonic, tricuspid, and epigastric areas.