Medical Surgical Nursing Overview

The circulatory system consists of the heart, blood vessels, and blood.

The heart, a muscular organ, is located in the mediastinum, slightly to the left.

The epicardium is the outermost layer, containing coronary arteries, the myocardium is the thickest layer responsible for contraction, and the endocardium is the innermost layer lining the chambers.

The right atrium receives blood from the body, the right ventricle pumps blood to the lungs, the left atrium receives blood from the lungs, and the left ventricle pumps blood to the body.

The atrioventricular valves (tricuspid and bicuspid) regulate blood flow between atria and ventricles, while the semilunar valves (pulmonic and aortic) control blood flow from ventricles to arteries.

The right and left coronary arteries branch out from the aorta and supply blood to the heart muscle.

Blood flow through the coronary arteries delivers oxygen and nutrients to the myocardium.

The coronary sinus drains deoxygenated blood from the heart muscle back to the right atrium.

The circulatory system's main purpose is to transport essential substances (oxygen, hormones, nutrients) to the tissues and waste products to the excretory organs.

The conducting system of the heart controls the electrical impulses that regulate heart rhythm. It includes the SA node (pacemaker), AV node, Bundle of His, and Purkinje fibers.

S1 is the 'lub' sound caused by the closure of the AV valves, S2 is the 'dub' sound due to closure of the semilunar valves.

S3 is a heart sound heard during rapid ventricular filling, often associated with heart failure, while S4 is associated with forceful atrial contraction and stiff ventricles.

Normal heart rate is 60-100 beats per minute, tachycardia is faster than 100 bpm, and bradycardia is slower than 60 bpm.

The sympathetic nervous system increases heart rate, while the parasympathetic (vagus) nerve slows it down.

Stroke volume is the amount of blood ejected by the heart with each beat. Cardiac output is the total blood pumped per minute (stroke volume x heart rate).

Blood pressure is determined by the product of cardiac output and total peripheral resistance (the resistance blood encounters in the vessels).

Blood pressure regulation involves neural (baroreceptors) and hormonal (ADH, adrenergic hormones, aldosterone, ANF) mechanisms.

Preload refers to the stretching of the heart muscle when filled with blood before contraction.

Afterload represents the resistance the heart must overcome to eject blood into the aorta.

Arteries carry oxygenated blood away from the heart, veins carry deoxygenated blood back to the heart, and capillaries connect the two.

The lymphatic system collects excess fluid from tissues and returns it to the bloodstream.

Assessment of the cardiovascular system includes obtaining the patient's history, performing a physical exam, and utilizing laboratory and diagnostic tests.

Vital signs like blood pressure, pulse pressure, and mean arterial pressure are important indicators of cardiovascular function.

Laboratory tests like CBC, lipid profile, and cardiac enzymes help diagnose cardiovascular disorders and assess treatment effectiveness.

Cardiac catheterization, arteriography, and echocardiography are invasive or imaging tests used to visualize the heart and blood vessels.

Creatine Kinase (CK-MB) is a cardiac enzyme released in response to myocardial damage, rising within 4-6 hours of an MI.

Lactate dehydrogenase (LDH) is an enzyme that elevates in MI in 24 hours, peaking at 48-72 hours.

Myoglobin is an oxygen-binding protein released from damaged heart and skeletal muscle cells, rising within 1 hour after injury, peaking at 4-6 hours.

Troponin I and T are highly specific proteins released from damaged heart muscle, rising within 3-4 hours, peaking at 4-24 hours and persisting for 7 days to 3 weeks.