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Introduction
The cardiovascular system consists of the heart, blood, and blood vessels. The heart pumps blood Blood vessels allow blood to circulate to all parts of the body The function of the cardiovascular system is to deliver oxygen and nutrients and to remove carbon dioxide and other waste products
The heart
The heart is relatively small, roughly the same size (but not the same shape) as your closed fist.
- Lies in the mediastinum
- Less than 1lb FUNCTIONS:
- Generating blood pressure
- Routing blood
- Ensuring one-way blood flow
- Regulating blood supply
Heart coverings
PERICARDIUM
The membrane that surrounds and protects the heart. Consists of two (2) parts: fibrous pericardium and serous pericardium. Superficial fibrous pericardium - composed of tough, inelastic, dense irregular connective tissue; The fibrous pericardium prevents overstretching of the heart, provides protection, and anchors the heart in the mediastinum. Deeper serous pericardium- thinner, more delicate membrane that forms a double layer around the heart. HEART WALL Consists of three (3) layers: Epicardium, Myocardium, and Endocardium. EPICARDIUM The epicardium contains blood vessels, lymphatics, and vessels that supply the myocardium. MYOCARDIUM It is responsible for the heart's pumping action and is composed of cardiac muscle tissue. It makes up approximately 95% of the heart. ENDOCARDIUM It provides a smooth lining for the heart's chambers and covers the heart’s valves.
External Heart Anatomy
Heart chambers
The heart has four (4) chambers The right and left side acts as separate pumps ATRIA - superior receiving chambers; receive blood from blood vessels returning blood to the heart, called veins. Right atrium - Forms the right border of the heart and receives blood from three veins: the superior vena cava, inferior vena cava, and coronary sinus (Veins always carry blood toward the heart.)
2023 11/ Left atrium - It receives blood from the lungs through four pulmonary veins. VENTRICLES- inferior pumping chambers; that eject the blood from the heart into blood vessels called arteries. Right ventricle- receives deoxygenated blood from the right atrium and pumps it to the lungs for oxygenation. Left ventricle- receives oxygenated blood from the left atrium and pumps it into the systemic circulation, delivering oxygen and nutrients to the body's tissues.
The Heart Valves
Heart valves allow the blood to flow in only one direction. Valves open as blood is pumped through and closes to prevent the backflow. FOUR (4) VALVES OF THE HEART: Atrioventricular valve- allows blood to flow from the atria into the ventricles but prevents blood from flowing back into the atria; composed of cusps and flaps.
- Bicuspid valve (left) or mitral valve
- Tricuspid valve (right) Semilunar valves- The SL valves allow the ejection ofblood from the heart into arteries but prevent the backflow of blood into the ventricles.
- Aortic semilunar valve
- Pulmonary semilunar valve
Blood flow through the heart
Associated great valves of the heart
AORTA
The aorta carries blood from the left ventricle to the body PULMONARY ARTERIES The Pulmonary arteries carry blood from the right ventricle to the lungs. VENA CAVA The superior and inferior vena cava carry blood from the body to the right atrium PULMONARY VEINS carry blood from the lungs to the left atrium
Coronary Circulation
Blood in the heart chambers does not nourish the myocardium The myocardium has its own network of blood vessels; coronary arteries and coronary veins
CORONARY ARTERIES- two arteries (left and right), branch from the ascending aorta and supply oxygenated blood to the myocardium. LEFT CORONARY ARTERY RIGHT CORONARY ARTERY - supplies small branches (atrial branches) to the right atrium CORONARY VEINS- carries deoxygenated blood and empty into the right atrium via the coronary sinus.
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The Cardiac Cycle
A single cardiac cycle includes all the events associated with one heartbeat. The cardiac cycle consists of systole and diastole. SYSTOLE- means to contract. Atrial systole- is the contraction of the atrial myocardium. Ventricular systole - is the contraction of the ventricular myocardium. DIASTOLE- means to dilate Atrial diastole - is the relaxation of the atrial myocardium. Ventricular diastole - is the relaxation of the ventricular myocardium.
Phases of the Cardiac Cycle
The Cardiac Output
CARDIAC OUTPUT (CO) - The amount of blood pumped by each side of the heart in one minute. CO (mL/min) = SV (mL/beat) x HR (beats/min) STROKE VOLUME- the volume of blood ejected by the ventricle during each contraction HEART RATE- the number of heartbeats per minute. In a typical resting adult male, stroke volume averages 70 mL/beat, and heart rate is about 75 beats/min. Thus, the average cardiac output is: CO = 70mL/beat x 75beats/min = 5250mL/min(average)
Regulation of Heart Rate
Heart rate is a measure of how fast the heart beats in a minute. A normal resting heart rate for adults is typically between 60 and 100 beats per minute. CAUSES OF INCREASED HEART RATE:
- Sympathetic nervous system
- Hormones
- Exercise
- Decreased blood volume CAUSES OF DECREASED HEART RATE:
- Parasympathetic nervous system
- High blood pressure or blood volume
The Vascular System
The vascular system- aka circulatory system; is a complex network of blood vessels that plays a crucial role in transporting blood, nutrients, oxygen, and waste products throughout the body. ANATOMY OF BLOOD VESSELS: THREE (3) LAYERS/TUNICS TUNICA INTERNA (INTIMA)- Inner lining of the blood vessel; composed of a single layer of endothelial cells that provide a smooth surface for blood to flow to prevent clotting. TUNICA MEDIA- middle layer of blood vessels; composed of smooth muscle cells and elastic fibers. TUNICA EXTERNA- outermost layer; composed of connective tissues. It provides structural support and protection to the vessel.
Capillary
The smallest and most numerous blood vessel Provides a microscopic network for the exchange of gases, nutrients, and waste products between the blood and tissues throughout the body. CAPILLARY BEDS- a network of 10 – 100 capillaries that connects the arterioles (small arteries) and venules(small veins) TWO (2) TYPES OF CAPILLARY BED VESSELS:
2023 11/ Vascular shunt- directly connects the arteriole to the venule True capillaries- act as an exchanging vessel. Oxygen and nutrients cross to the cells Carbon dioxide and metabolic waste products cross into the blood
Vital signs
It is an essential physiological measurement that provides information about the body's basic functions and overall health. PULSE RATE: It is the number of heartbeats per minute. Normal range: resting heart rate for adults is between 60-100 beats per minute. BLOOD PRESSURE: The pressure of blood pushing against the walls of the arteries. Systolic- pressure at the peak of ventricular contraction Diastolic- pressure when ventricles relax Normal range: typically around 120/80mmHg (120 is the systolic pressure and 80 is the diastolic pressure) VARIATIONS IN BLOOD PRESSURE: Hypotension- low systolic (below 110 mmHg) Hypertension: high systolic (equal to or greater than 130mmhg) RESPIRATORY RATE: The number of breaths (inhalation and exhalation) per minute. Normal range: The resting respiratory rate for adults is usually between 12 and 20 breaths per minute. BODY TEMPERATURE: The measure of the body's internal heat. Normal range: Typically around 98.6°F (37°C), but it can vary slightly among individuals.
