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Unit 9: Cardiovascular System (Cardiac cycle and the ECG; disorders of…
Unit 9: Cardiovascular System
Major functions of the
cardiovascular system
Transport of nutrients, oxygen, and hormones to cells throughout the body and removal of metabolic wastes
Protection of the body by white blood cells, antibodies, and complement proteins that circulate in the blood and defend the body against foreign microbes and toxins. Clotting mechanisms are also present that protect the body from blood loss after injuries.
Regulation of body temperature, fluid pH, and water content of cells.
Protects the body from infection and blood loss; red blood cells, white blood cells, and platelets
The heart pumps the blood around the blood vessels.
Blood circulates through a network of vessels throughout the body to provide individual cells with oxygen and nutrients and helps dispose of metabolic wastes
Anatomy of the heart (including all chambers, and valves)
Heart; The main muscle that pumps blood to all parts of the body.
Right Atrium; Chamber of the heart into which the superior and inferior vena cava empty. It pumps the deoxygenated blood to the right ventricle.
Left Atrium: The pulonary veins empty into this heart chamber. From here the blood is pumped into the left ventricle.
Right Ventricle
This chamber recieves blood from the right atrium and pumps it into the pulmonary arteries.
Left Ventricle
Chamber that recieves blood from the left atrium and pumps it into the aorta.
Tricuspid valve
Located between the right atrium and the right ventricle. Closes when the right ventricle contracts, allowing blood flow into the lungs and prevent backflow into the right atrium.
Pulmonary Valve
Prevents blood from flowing back into the right ventricle after it has entered the pulmonary artery.
Mitral Valve
Valve between the left atrium and the left ventricle; bicuspid valve.
Aortic Valve
The semilunar valve separating the aorta from the left ventricle that prevents blood from flowing back into the left ventricle.
Atrioventricular Valves
Valves located between the atrial and ventricular chambers on each side of the heart, prevent backflow into the atria when the ventricles are contracting.
Semi-Lunar Valves
Valves between the ventricles and main arteries leading out of the heart, which prevent backflow of blood.
Chordae Tendinae
The thin fibers that connect to papillary muscles and heart valves. They pull the valves open and shut.
Aorta
The largest artery in the body; it conducts freshly oxygenated blood from the heart to the tissues.
Lungs
Two large respiratory organs inside the chest where blood picks up oxygen and loses carbon dioxide.
Arteries
Blood vessels that carry blood away from the heart.
Veins
Blood vessels that carry blood back to the heart.
Arterioles
The blood vessels that branch off from the arteries into the capillaries. They offer the most restriction of blood flow and control blood pressure.
Venules
Vessels that drain blood from capillaries and then join the veins.
Capillaries
Tiny, thin-walled blood vessels that allow the exchange of gases and nutrients between the blood and the cells of the body. These vessels have nothing but the endothelium layer and are only one blood cell thick.
Blood
The thick red fluid that flows through the body's blood vessels and transports important cells and plasma throughout the body.
Layers of the
heart
Pericardium
a type of serous membrane that produces serous fluid to lubricate the heart and prevent friction between the ever beating heart and its surrounding organs.
The epicardium is the outermost layer of the heart wall and is just another name for the visceral layer of the pericardium. The epicardium is a thin layer of serous membrane that helps to lubricate and protect the outside of the heart.
he myocardium is the muscular middle layer of the heart wall that contains the cardiac muscle tissue. Myocardium makes up the majority of the thickness and mass of the heart wall and is the part of the heart responsible for pumping blood.
Endocardium is the simple squamous endothelium layer that lines the inside of the heart. The endocardium is very smooth and is responsible for keeping blood from sticking to the inside of the heart and forming potentially deadly blood clots.
blood flow through the heart and body
Step 1
Unoxygenated blood blood enters the right atrium from the superior and inferior vanae cavae.
Step 2
The blood flows through the tricuspid valve into the right ventricle.
Step 3
From the right ventricle, the blood flows through the pulmonic valve into the pulmonary artery.
Step 4
The right and left pulmonary arteries carry unoxygenated blood to the right and left lungs for gas exchange.
Step 5
The blood releases carbon dioxide as waste and picks up a fresh supply of oxygen.
Step 6
The oxygenated blood flows through fpur pulmonary veins from the lungs into the left atrium.
Step 7
From the left atrium, the blood flows through the bicuspid, or mitral valve into the left ventricle.
Step 8
Left ventricular contraction forces blood through the aortic valve into the aorta for distribution to the systemic circulation
Major arteries and veins of the body
The systemic circuit. In this pathway, oxygen-rich blood is carried away from the heart and toward tissues of the body.
the pulmonary circuit
oxygen-depleted blood is carried away from the heart and into the lungs where it can acquire fresh oxygen and get rid of carbon dioxide.
Elastic arteries
are closer to the heart where blood pressure is highest
contain more elastic fibers, which allows them to both expand and contract with the surges of blood that occur when the heart beats
Muscular arteries
are further from the heart where blood pressure is lower
contain more smooth muscle tissue and less elastic fibers
Artery wall layers
Tunica intima. The innermost layer that’s made up of cells called endothelial cells as well as elastic fibers.
Tunica media. The middle, and often the thickest layer, that’s made up of smooth muscle cells and elastic fibers that can help control the diameter of the blood vessel.
Tunica externa. The outermost layer that’s made up of elastic fibers and collagen. This layer predominantly provides structure and support.
The aorta branches off into two main coronary blood vessels . These coronary arteries branch off into smaller arteries, which supply oxygen-rich blood to the entire heart muscle.
The right coronary artery supplies blood mainly to the right side of the heart. The right side of the heart is smaller because it pumps blood only to the lungs.
The left coronary artery, which branches into the left anterior descending artery and the circumflex artery, supplies blood to the left side of the heart. The left side of the heart is larger and more muscular because it pumps blood to the rest of the body.
Superior Vena Cava
drains the head, neck, upper limbs, and thoracic region; takes deoxygenated blood to the right atrium
Inferior Vena Cava
drains the organs below the diaphragm; takes deoxygenated blood to the right atrium
structural and
functional differences between blood vessel types
The Systemic Capillaries
-Located in the body tissues
-Point of exchange of various materials
The Systemic Veins
-Carry Blood low in O2 back toward the heart
-The Venous blood flows into the right atrium through the superior & inferior vena cava
Structure of the Arteries
-Contain thick walls because they need to be strong enough to receive blood pumped under pressure from the ventricles
-Elastic tissue between the arterial walls, allow them to stretch when receiving blood & then return to their regular size
Structure of Arterioles
-Contain thin walls with little elastic connective tissue but more smooth muscle (controlled by the ANS)
-The vessel lumens (openings) constrict when the muscle contracts & dilates when the muscle relaxes, regulating how much blood enters the tissues at a given time
-Changes in the arterioles diameter is a major factor in blood pressure
Structure of Capillaries
-Reach a maximum diameter of 10 mcm, just wide enough for a blood cell to pass through
-One layered
-Contain thin, transparent walls, allowing for the exchange between blood & the body cells & between lung tissues & the outside air
Structure of Veins
-The walls of veins are the same as those of arteries except the middle tunic (smooth muscle) is relatively thin
-Contain less elastic tissue between the layers so they expand easily & carry blood under much lower pressure
-Collapse easily because their walls are so thin
-Most are equipped with valves to allow blood to flow only toward the heart. valves are most numerous in the heart
Structure of Venules
-Tiny veins formed by the union of capillaries
-Walls are only slightly thicker than those of capillaries
-When merged to form veins, the middle tunic becomes thicker & the venules begin to acquire the additional layers found in the larger vessels
Cardiac cycle and the ECG;
disorders of the cardiovascular system
sinoatrial (SA node)
group of specialized cardiac cells located in the wall of the right atrium that depolarize spontaneously, SETTING HEART RATE
atrioventricular (AV) node
group of specialized cardiac cells that depolarize and pass the impulse through the Bundel of His, down the bundle branches and to the purkinje fibers.
P wave
wave on ECG, associated with atrial depolarization
QRS complex
wave on ECG, associated with ventricle depolarization
T wave
wave on ECG, associated with ventricle repolarization.
Systole on ECG
initiated by the depolarization of contractile cells
Diastole on ECG
on ECG represents contractile cells relaxing
cardiac cycle
period of time from the start of one heart beat to the beginning of the next
ventricular diastole
phase when ventricles are relaxing
ventricular systole
phase when ventricles are stimulated to contract
blood pressure
measurement of the pressure that the blood exerts on walls of artery
radial pulse
pulse detected in radial artery
refractory period
period following effective stimulation of heart muscle
Coronary artery disease
Damage or disease in the heart's major blood vessels.
High blood pressure
A condition in which the force of the blood against the artery walls is too high.
Cardiac arrest
Sudden, unexpected loss of heart function, breathing, and consciousness.
Congestive heart failure
A chronic condition in which the heart doesn't pump blood as well as it should.
Arrhythmia
Improper beating of the heart, whether irregular, too fast, or too slow.
Peripheral artery disease
A circulatory condition in which narrowed blood vessels reduce blood flow to the limbs.
Stroke
Damage to the brain from interruption of its blood supply.
Congenital heart disease
An abnormality in the heart that develops before birth.