What are the three main components of the Cardiovascular System? What are they in relation to each other?
1. Components: The cardiovascular system consists of the heart, blood vessels, and blood.
2. Relation: The heart is the pumping structure, the blood vessels serve as the network (of vessels), and the blood is the medium that is pumped.
What is the Primary Function of the Cardiovascular System? How about in relation to cells?
1. Function: Transport materials to and from all parts of the body.
- To Cells: from external environment such as oxygen, nutrients
- Between Cells within the body such as hormones, immune cells/proteins
- From Cells in which something is eliminated to the external environment such as carbon dioxide, metabolic waste.
What are some other functions of the cardiovascular system other than its primary function? (5)
- Temperature Regulation
- pH regulation
- Fluid levels maintenance
What does the word Pulmonary refer to? How about Systemic?
- Pulmonary: refers to being between the heart and lungs
- System: refers to being between heart and body tissues.
What is the difference between Pulmonary and Systemic Circulation?
- Pulmonary Circulation only circulates blood from the right ventricle to the lungs and back to the heart again.
- System Circulation circulates blood from the left ventricle to all organs and back to the heart
- Refer to page 465 for suplemental diagram
Which blood vessel carries blood to the lungs? How about the vessel that returns to the heart?
- To lungs: The blood vessels that carry blood away from the heart to the lungs are the pulmonary arteries.
- To heart: The blood vessels that carry blood to the heart from the lungs are the pulmonary veins.
For Cardiac muscle descirbe the: connections, appearence, characteristics, and how it contracts. What forms the sarcomeres?
1. Connections: intercalated discs or gap junctions join each muscle cell.
2. Appearence: Muscle cells are short, branched, and striated.
3. Characterisitc: Muscle cells are involuntary and regulated by the ANS.
4. Contraction is due to the myosin and actin cross bridges which are stimulated by calcium.
5. Sarcomeres: Are formed by myosin and actin filaments.
What are the 4 chambers of the heart? What seperates the atria from the ventricles?
1. 4 chambers
a. Right atrium -RA
b. Left atrium LA
c. right Ventricle -RV
d. Left ventricle -LV
2. Fibrous skeleton
What are the 4 valves of the heart?
1. Tricuspid or right atrioventricular valve: between right atrium and ventricle
2. Bicuspid aortic or left atrioventricular valve: between left atrium and ventricle.
3. Pulmonary semilunar valve: between right ventricle and pulmonary trunk.
4. Aortic semilunar valve: between left ventricle and aorta.
What are the two sounds produced from normal functioning and what causes them? What is the abnormal sound that can be produced and what is the cause?
1. The Lub-Dub sounds of the heart are produced by the closing of the heart valves.
a. The "Lub" is produced from the closing of the atrioventricular valves.
b. The "Dub" is produced from the closing of the semilunar valves.
2. A murmur is produced when blood flows through the heart abnormaly. This is typically caused by defective heart valves.
What are myocardial autorhythmic cells? What do these cells determine? What percent of cardiac muscles are autorhythmic?
1. Myocardial autorhythmic cells: are the pacemaker cells that set the pace or rate of heartbeat
2. They determine the heart rate -HR.
3. They account for 1% of cardiac muscles.
What are myocardial contracitile cells? What percentage of cardiac muscles are contractile?
1. Myocardial contractile cells are the typical branching cardiac cells with intercalated disks.
2. They compose of 99% of cardiac muscle cells.
How do heart cells behave as a single functional unit? How do the atria and ventricles act as a seperate unit?
1. Cells behave as a single functioning unit due to their connections via intercalated discs with gap junctions. Because of this an action potential in one myocardial cell can stiumulate all the cells in that area causing contraction.
2. Atria and ventricels are able to function as seperate units as they are electrically seperated by a fibrous skeleton.
What node is the pacemaker for the heart?
The Sinoatrial node or SA node.
What is the pacemaker potential? What happens at -60mV? What happens at -40mV? What occurs during Reploarization?
1. Pacemaker potential is the slow, spontanious depolarization of the autorythmic cells at -60mV.
2. At -60mV: the Na+ and K+ channels open
3. At -40mV: voltage gated Ca2+ channels open and triggers AP
4. During Repolarization more K+ channels open
What factors influence the heart rate? What are the three hormones that can influence the heart rate? What effect do they have on the heart rate?
1. Although the sinoatrial node depolarizes spontaneously and the autorhythmic cells determine heart rate ANS input and hormones can influence the heart rate.
2. Epinephrine, norepinephrine from the sympathetic system and acetylcholine secreted from the neuorns of the parasympathetic system
3. Both epinephrine and norepenephrine act on the SA node to keep Na+ channels open to increase the heart rate. Acetylcholine opens K+ channels and decrease heart rate.
What is the resting potential of myocardial contractile muscle cells? What happens during depolarization? What causes the mebrane potential to plateu and for how long? When does repolarization occur?
1. Cardiac cells resting potential is between -85 to -90mV.
2. Depolarization caused by the SA nodes AP causes Na+ channels to open.
3. As Ca2+ enters while K+ exits, the membrane potential plateus for about 200 miliseconds.
4. Repolarization occurs as more K+ channels open.
What is the refractory period? What causes this? Why do the cardiac muscles have refractory periods?
1. The refractory period refers to the initiation of an AP to its original peak in which a muscel cell is unable to respond to additional stimulus
2. Because cardiac cells have a higher threshold and the AP is slow, the amount of time it takes for the entire AP to fire then repolarize, creates a long refractory period.
3. If cardiac muscles did not have refractory periods and were more like skeletal muscles, summation in the muscles could lead to tetanus. Tetanus being muscle fatigue. If the cardiac muscle became fatigued then we would die. :)
What are the two chemicals used in the contraction of the heart? How do they trigger a contraction?
1. Sodium and calcium
2.An AP from an adjacent cell causes Na+ to enter through voltage gated channels. This triggers voltage gated Ca2+ channels on the sarcolemma to open which acts as a second messenger. Incoming calcium throught this gate triggers the release of calcium from the sarcoplasmic reticulum. From here the Ca2+ binds to troponin and causes a contraction. (Refer to Chapter 12 muscle physiology to see how the complete contrraction process)
How does Ap spread and where does it begin? What are the nodes, bundles and fibers involved in the chemical conduction of the heart?
1. Action potential spreads via gap juntion in the intercalated discs begining from the SA node.
2. In this order: Sinoatrial(SA) node, atrioventricular(AV) node, Bundle of His, bundle branches, and Purkinje fibers.
What is the pathway of an AP in the heart?
The Sinoatrial node conducts across the atria to the Atrioventricular node. In the Atrioventriuclar node of the right atrium, the impluse transmits along to the atrioventicular bundle or Bundle of His. Here located in the interventricular septum, the bundle of His divides into bundle branches. Branch bundles then become Purkinje fibers which run along the ventricles and stimulates the contraction of the ventricles.
What is the pathway of electircal currents to ensure the most efficient means of contracting and pumoing the blood up and out of the heart?
1. SA node depolarizes
2. Electrical activity goes rapidly to AV node via internodal pathways
3. Depolarization spreads more slowly across atria. Conduction slows through AV node.
4. Depolarization moves rapidly through ventricular conducting system to the apex of the heart.
5. Depolarizing wave spreads upward from the apex
What are the three types of heart arrythmias?
1. Bradycardia: slow heart rate, under 60 beats per minute
2. Tachycardia: fast heart rate, over 100 beats per minute.
-Ok for active individuals, not for people at rest
3. Fibrilation: uncoordinated pumping between the atria and ventricles.
What is the cardiac cycle? What are the two names for the cycles of the heart? WHat is the typical heart rate at rest? How long is the cardiac cycle and why.
1. The cardiac cycle is the single contraction and relaxation of the heart.
2. Systolic: contraction and Diastolic: relaxation
. 3. At rest the heart rate is 72 beats per minute
4. Each cardiac cycle is about 0.8 seconds because it is the summation of both the systole, which takes 0.3 sec, and Diastole, whic takes 0.5 sec.
Ecxplain in detail the heart cycle between contraction and relaxation.
1. Late diastole: both sets of chambers of the heart are relaxed. This allows blood to fill the ventricles passsively.
2. Atrial systole: the contraction of the atria forces the remaining blood into the ventricles.
3. Isovolumic ventricular contraction(systole): during the First phase of ventriccular contraction(systole) pushes atrioventricular valves closed. Though not enough pressure to force the semilunar valves.
4. Ventricular ejection(systole): as the pressure of teh ventricles rise and exceeds the pressure in the arteries, the semilunar valves open and blood is ejected.
5. isovolumic ventricular relaxation(diastole): the ventricles relax and the pressure in the ventricles falls. this causes blood to fall back into the cusps of the similunar valves, forcing them to close.
What does an electrocardiogram measure? What are the waves?
1. Measures electrical activity(ion movement) of the heart
2. a. P wave: atrial depolrization
b. QRS wave: ventricular depolarization
c. T wave: ventricular repolarization
Use this chart to see check for irregularities of en ECG.