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Muscular pump that continually replaces the cell's surrounding environment so that waste can be removed and nutrients can be supplied.
1. Size of a person's fist
2. beats and average of 72 times/minute (or 100,000 times/day)
3. Location in chest within a cavity called the mediastinum, also shifted to the left side.
4. Lower tip is the apex and it points to the left (patient's left), base is where the great vessels attach to the heart.
Covering of the heart (pericardium)-loosely fitting, fluid producing sac covering the heart, yields a frictionless environment.
Fluid producing slippery membrane that forms a Pericardial space or cavity - located between epicardium and serous pericardium and contains fluid.
Inner layer of the serous pericardium that is part of the heart wall (also called the epicardium).
Case of pericarditis in which excessive quantities of fluid actually hinder the beating of the heart - result in very low cardiac output.
Also called visceral pericardium outermost, somewhat thin covering (usually laden with fat), more fat means more effort of the heart to pump = more likelihood of heart attacks.
Chordae Tendineae / tendinous cords
Tiny white strings that anchor the flaps to the walls of the ventricles.
A term that includes mitral/bicuspid or tricuspid. Located between the atrial and ventricular chambers on each side. Prevent the backflow into the atria when the ventricles contract.
Prolapsed - incompetent valve
weakened valve, actually "leaks" results in heart repumping blood, decreases efficiency.
1. Blood supply to heart.
2.Two mains of these arteries left and right.
3. Branches off these main vessels are the circumflex and the anterior and posterior interventricular arteries.
4. Arise from the aorta just distal to the aortic vavle.
Angina or angina pectoris
Chest pain (spasms of the myocardium) due to temporary O2 deficiency)
Due to either stress induced spasms of coronary arteries or increased physical demands on the heart.
Pain of one region/area that is felt in another area. Classic location in addition to chest areas is left arm and occasionally neck and face.
Coronary (myocardial infarcation or MI)
1. Also called heart attack.
2. Death to tissue occurs due to extended lack of O2.
3. Caused by plaque buildup (arteriosclerosis) or clot formation.
4. Frequently described a crushing feeling in the chest, cold sweat, sense of doom/massive fear, nausea.
5. 1.5 million people have these a year, 1/3 die essentially immediately (within days), 1/2 will be dead within the year.
6. Symptoms of heart disease in 2/3 of males is usually heart attack or death in about 50% of females the first symptom is angina.
Blocked or damaged blood vessel is "bypassed" by a replacement which is necessary to re-establish blood flow to cardiac tissue, blood flow to cardiac tissue, blood vessels used are taken fromt he leg or chest.
A catheter with balloon a tip is inserted at site of blockage to press fatty deposit against artery wall, doesn't last long, good for weaker patients.
Properties of Cardiac Muscle
2. Lots of mitochondria
3. Intercalated disks/allows for cells to function as a unit, cells interlock
Intrinsic Innervation of the Heart
Conduction system of heart, ability of heart to contract (nerves not required); this system sets the basic rate of heartbeat.
SA Node: Also called Intrinsic rhythm produced by these modified cardiac muscle cells (no nerve impulse necessary), sets pace, usually about 70-80 beats / min without nervous system (electrical charge). Average 72 beats/min.
1. Location in septum between two atria.
2. Function: picks up stimuli from SA node and carries to AV bundle or Bundle of His
AV Bundle or Bundle of His
1. Location- bundle of fibers that extend down interventricular septum
2. Function- conducts impulses to bundle branches
Branches of bundle fibers that conduct impulses through muscles of both vertricles, contraction of the heart begins at the apex and spreads toward atria.
Electric shock (wipes slate clean), helps to restore the regularity of beat, by depolarizing the entire heart then allowing it to restart.
Damage to the AV node, essentially the entire conduction system is blocked and the ventricles must resort to contracting at an intrinsic rate which is a much slower rate.
Extrinsic Innervation of the Heart
This system acts as both the brakes and accelerators of the heart.
Located in the medulla of the brainstem; stimulates the heart to increase its rate.
The autonomic nervous system- the vagus nerve (a cranial nerve) innervates the heart.
Electrocardiogram (ECG or EKG)
Measurements of electrical charges generated and transmitted by the heart, represents conduction (not contraction) that can be record and studies.
Movement of impulse (change of electrical charge) from SA Node through atrial muscles (contraction of both simultaneously), represents atrial depolarization.
Depolarization of ventricles (contractions) spread of electrical impulses through ventricles (atria are relaxing but are masked).
1. Unusual heart sounds.
2. Blood flows silently unless it is obstructed in which case it cause turbulence and sound.
3. Common in young children and some elderly
4. Valve status, must be checked and monitored.
Why do we need to control circulation?
1. Maintain blood movement.
2. Vary Volume and distribution pattern
3. Deliver oxygen and nutrients and carry waste away.
1. Amount of blood pumped by each ventricle in one minute.
2. Cardiac output = stroke volume (amt of blood pumped in one contraction) x (# beats / minute) or (# of cardiac cycles).
3. CO=SV X HR
Condition in which the heart is compressed and critically low stroke volume results. May be caused by pericarditis.
Regulation of Stroke Volume- Frank Starling Law
1. Preload or the Frank-Starling Law of the Heart.
a. Amount the heart (ventricles) is stretched by contained blood.
b. Greater the stretch, greater the contraction
c. Venous return, volume in ventricles is determined by heart rate, exercise, and fluid loss.
Regulation of Stroke Volume-Heart Rate
a. Sympathetic division: epinephrine increase heart rate
b. Parasympathetic division: slows heart rate
c. Other factors: ions (electrolytes) (calcium and potassium in particular affect HR.
d. Age, gender, exercise, and body temperature.
Congestive Heart Failure /CHF
Pumping efficiency of the heart is so low that tissue needs are not met. TCan occur on either side of the heart, but weakness to one side stresses the other side. Typically a deteriorating condition due to :
a. athlerosclerosis (blockage) of coronary vessels.
b. persistent high BP
c. multiple MI's (heart attacks) hence death of tissue and replacement with scar tissue.
d. cardiomyopathy-stretched ventricles become flabby and muscle deteriorates.
Form a closed loop delivery system that begins and ends at the heart. Although somewhat "pipe-like" they are actually quite unique because they can pulse, constrict, and even spread/grow into new areas. Quanity in body about 60,000 miles.
Flow pattern of blood vessels
heart pumps>blood flows through arteries (larger than smaller then smallest)>capillaries>veins (smallest to larger to largest)>then back to the heart
Layer of blood vessel, endothelium (one cell thick layer of simple squamous epithelium) next to the opening (lumen) of the vessel.
Layer of blood vessel, circular arranged smooth muscle and elastin fibers; this layer is usually thicker in arteries then veins; sympathetic nerve fibers control this muscle layer.
Carry blood away from the heart, carry oxygenated blood (except pulmonary).
1. Innermost layer-endothelium single cell thick.
2. Thicker walls.
3. Function: transportation, also resistance and blood pressure.
Contraction of blood vessels. Relate to arteries not veins. Sympathetic nervous system.
Relaxation of blood vessels. Relate to arteries not veins.
Parasympathetic nervous system.
Smallest artery, have only a few muscle cells wrapped around them. Major site of blood pressure regulation and blood flow to body parts.
Microscopic, single cell thick layer, RBC's through one at a time.
1. Function: exchange site or point of diffusion of "food", "waste", and gases.
2. Estimated that every 2nd or 3rd cell is near a capillary although some tissues have more capillaries than others.
Surrounds the root of each true capillary and acts as a vavle to regulate the flow of blood into the capillary.
Blood flow is toward the heart, blood is deoxygenated (expect pulmonary). Function: transportation and reservoir can hold up to 65% of total blood volume.
Excessively dialated veins usuallyin the lower legs, however in the anal area called hemorrhoids.
Reconnection or alternate of blood vessels (either arteries or veins). Postive feature because it supplies alternate route to tissues thus ensuring their survival.
To keep us alive, blood must be kept circulating. We are now aware the heart is a pump, the arteries are conduits (pipes), the arterioles are resistance vessels, the capillaries are exchage sites, and the veins are conduits and blood reservoirs.
Also called Cardiac output. Measured as volume flowing through a structure in a period of time.
Force exerted (by blood) on the wall of a blood vessel, expressed in mm. of Hg. (mercury), loss of blood volume causes drop in blood pressure.
Opposition to blood flow, the amount of friction encountered by blood as it flows through the vessels.
3 Factors of peripheral resistance
1. Blood viscosity
2. Blood vessel length-longer equals more friction
3. Blood vessel diameter-a flexible/changeable factor
Systemic Blood Pressure
When fluid is driven by a pump (the heart) thru a circuit of closed vessels, there is pressure. Blood flows from high to low pressure. Blood pressure changes when blood flow encounters resistance. BP is highest in the aorta and lowest in the vena cava as blood enters the heart.
1. Alter blood distibution to respond to specific demands.
2. Controlling blood vessel diameter to maintain adequate BP (Vasomoter Center of the medulla)
Rhythmic expansion and recoil of arteries due to heart contraction, we equate it to the heart rate.
Dizziness due to sudden changes in posture (usually found in elderly), cause by slow nervous system response.
1. Lots of fluid loss, due to hemorrhage, burns, diarrhea, excessive vomiting.
2. Vasoconstriction results which returns BP to normal unless blood loss continues.
Blood volume is normal, caused by extreme vasodilation perhaps due to septicemia (blood infection).
High blood pressure, defined as 140/90 consistently or higher.
1. 30% of people over 50
2. Can result in heart failure, vascular disease, renal failure, and stroke.
3. stresses heart wall, enlarges and becomes flabby
4. Accelerates athlersclerosis, blood vessel tears
5. no cure but lots of potential to control problem
6. known as silent killer
Factors of primary hypertension
90% have this type of hypertension.
Diet, Obesity, Age, Race, Heredity, Stress, Smoking
Blood Flow changes during exercise
1. Brain remains the same.
2. Muscle lots more with exercise
3. Skin some additional with exercise
4. Abdomen less with exercise
a balloon like out pocketing of the artery wall, places an artery at risk for rupture, may be congenital (birth defect) but more likely due to hypertension or athlersclerosis, likely sites include aorta, and arteries in brain.
Inflammation of a vein with associated pain, throbbing, and redness of the skin over the inflamed area, usually cause by bacterial infection.
Intravascular clotting often follwoing phlebitis; particulary dangerous if clots become detached and form an embolus.
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