THE Heart:

Ø  The heart is completely divided into a right half and a left half

Ø  These 2 sides of the heart act as separate pumps

Ø  There is no mixing of blood between them.

Ø  Each is in charge or pumping blood into one of the two blood vessel circuits

Ø  Has 2 major fluid transportation systems, the cardiovascular system and the lymphatic system.

 

Ø  Cardiovascular System consists of:

Ø  Heart and blood vessels

Ø  Closed system

Ø  Transports blood to all parts of the body

Ø  Blood flowing through the circuit formed by the heart and blood vessels

Ø  Brings oxygen, food, and other chemical elements to tissue cells 

Ø  Removes carbon dioxide and other waste products resulting from cell activity.

Ø  Lymphatic System:

Ø  Drainage for tissue fluid

Ø  Auxiliary part of the circulatory system

Ø  THE HEART :

Ø  Efficient pump

Ø  Four-chambered muscular organ lined with endocardial tissue

Ø  Lies within the chest

Ø  2/3 of its mass to the left of the midline

Ø  Lies in the pericardial space in the thoracic cavity between the two lungs.

THE Heart Layers:

Ø  The pericardium is a double walled sac enclosing the heart.

Ø  The outer fibrous surface gives support, and the inner lining prevents friction

Ø  The lining surfaces of the pericardial sac produce a small amount of pericardial fluid needed for lubrication to facilitate the normal movements of the heart.

Ø  Three distinct layers 

Ø  Epicardium – Outer layer

Ø  Corresponds to the visceral pericardium

Ø  Protects the heart by reducing friction

Ø  Myocardium – Middle layer

Ø  Cardiac muscle tissue

Ø  Pumps blood out of the heart chambers

Ø  Endocardium -Inner layer

Ø  Epithelium and connective tissue

Ø  Elastic and collagenous fibers.

Heart Chambers

Ø  There are four chambers in the heart.

Ø  The Atria

–        Upper chambers (right and left atria)

–        Smaller upper chambers

Ø  The Ventricles

–        Lower chambers (right and left ventricles)

Ø  Right atria communicates with Right Ventricle

Ø  Left atrium communicates with the left ventricle.

The Septum

Ø  The septum is a partition which divides interior of the heart into right and left sides

Ø  Prevents direct communication of blood flow from right to left chambers or left to right chambers.

Ø  Right side of the heart receives un-oxygenated blood returning from the systemic (body) circulation.

Ø  Left side of the heart receives oxygenated blood returning from the pulmonary (lung) circulation.

The Heart Valves

Ø  Heart valves allow the blood to pass from a chamber but prevent its return.

Ø  The atrioventricular valves

Ø  Between the upper and lower chambers

Ø  Within the heart

Ø  The semilunar valves

Ø  Are within arteries arising from the right and left ventricles

Ø  Atrioventricular valves:

Ø  The Tricuspid valve

Ø  Between the right atrium and right ventricle.

Ø  3 flaps or cusps.

Ø  The Bicuspid valve or Mitral valve

Ø  Between the left atrium and left ventricle

Ø  2 flaps or cusps.

Ø  Semilunar Valve

Ø  The pulmonary Semilunar valve

Ø  half-moon shaped

Ø  Located at the opening into the pulmonary artery that arises from the right ventricle.

Ø  The aortic semilunar valve

Ø  Located at the opening into the aorta that arises from the left ventricle

Ø   

Ø  Blood Flow

Ø  The heart is the pump

Ø  The heart is the connection between the systemic circulation and pulmonary circulation.

Ø  All blood returning from the systemic circulation must flow through the pulmonary circulation for exchange of carbon dioxide for oxygen.

Ø  Blood from the upper part of the body enters the heart through the superior vena cava and blood from the lower part of the body enters through the inferior vena cava.

Ø  Blood from the superior vena cava and inferior vena cava enters the heart at the right atrium.

Ø  The right atrium contracts, and blood is forced through the open tricuspid valve into the relaxed right ventricle.

Ø  As the right ventricle contracts, the tricuspid valve is closed, preventing back flow into the atrium.

Ø  The pulmonary semilunar valve opens as a result of the force and movement of the blood, and the right ventricle pumps the blood into the pulmonary artery.

Ø  The blood is carried through the lung tissues, exchanging its carbon dioxide for oxygen in the alveoli.

Ø  This oxygenated blood is collected from the main pulmonary veins and delivered back to the left side of the heart to the left atrium.

Ø  As the left atrium contracts, the oxygenated blood flows through the open bicuspid (mitral) valve into the left ventricle.

Ø  As the left ventricle contracts, the bicuspid valve is closed.

Ø  The aortic semilunar valve opens as a result of the force and movement of the blood, and the left ventricle pumps oxygenated blood through the aortic semilunar valve into the aorta, the main artery of the body.

Ø  Oxygenated blood now starts its flow to all of the body cells and tissues. The systemic circulation starts from the left ventricle, the pulmonary circulation from the right ventricle.

Ø  Coronary Arteries

Ø  The heart gets its blood supply from the right and left coronary arteries

Ø  These arteries branch off from the aorta just above the Aortic Valve, then subdivide into many smaller branches within the heart muscle.

Ø  If any part of the heart muscle is deprived of its blood supply through interruption of blood flow through the coronary arteries and their branches, the muscle tissue deprived of blood cannot function and will die.

Ø  This is called myocardial infarction (MI). Blood from the heart tissue is returned by coronary veins to the right atrium via the coronary sinus.

Ø  The Pulse

Ø  Each time the heart beats the left ventricle contracts and sends blood through the arteries.

Ø  The pulse is the rhythmic expansion of the arteries that results from each heartbeat.

Ø  When the pulse is being counted, the rate, rhythm, and volume (force) should be noted.

Ø  The Pulse Rate

Ø  Rate may be noted as normal, fast (tachycardia), or slow (bradycardia).

Ø  An average pulse rate for a resting adult is 70-80 bpm.

Ø  Tachycardia: rates faster than 100 bpm

Ø  Bradycardia: rates slower than 60 bpm 

Ø  A well-trained athlete may have a resting pulse of less than 50 bpm.

Ø  Blood Pressure

Ø  Blood pressure is defined as the pressure exerted by the blood on the walls of the blood vessels.

Ø  Systolic pressure is the maximum pressure occurring during systole, or contraction, of the ventricles.

Ø  It is the higher of the two numbers.

Ø  Normal systolic pressure for the average resting adult is between 100-150 mmHg.

Ø  Diastolic pressure is the pressure occurring during diastole, the period of relaxation and filling of the ventricles.

Cardiac System

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