Cardiac Cycle and Conduction System of the Heart.
-
Upload
domenic-todd -
Category
Documents
-
view
235 -
download
2
Transcript of Cardiac Cycle and Conduction System of the Heart.
![Page 1: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/1.jpg)
Cardiac Cycle and Conduction System of the Heart
![Page 2: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/2.jpg)
The Cardiac Cycle
The mechanical events that take place in one heartbeat.
![Page 3: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/3.jpg)
The Cardiac Cycle
Contraction of a chamber - systole
Relaxation of a chamber - diastole
1 full contraction and relaxation - cardiac cycle
![Page 4: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/4.jpg)
![Page 5: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/5.jpg)
![Page 6: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/6.jpg)
Systole and DiastolePeak pressure of a chamber or vessel
Stroke volumeamount of blood ejected by the heart (LV) in one contraction
• aprox. 70 cc (60-100 cc)
Relaxation of a chamber
Pressure at its lowest
![Page 7: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/7.jpg)
Cardiac Output
Cardiac Outputamount of blood ejected every minute
• aprox. 5-6L
• SV X HR = CO
• The strength of contraction is directly related to venous return
![Page 8: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/8.jpg)
Starling’s Law
The more a muscle is stretched the harder it will contract (up to a certain point)
Similar to a spring
Muscle fibers will stretch and contract harder when there is a increased blood return
![Page 9: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/9.jpg)
Blood Pressure
The pressure exerted by blood against the walls of a given artery.
![Page 10: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/10.jpg)
Factors Affecting Blood Pressure
1. Blood Volume
2. Strength of heart contractions
3. Heart rate
4. Blood viscosity – thickness of blood
![Page 11: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/11.jpg)
Electrophysiology
Before the heart can contract it must be stimulated.
This is accomplished through a specialized network of cells called the conduction system.
There are numerous “pacemaker” cells to stimulate the heart to contract.
![Page 12: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/12.jpg)
Sinoatrial Node (SA)
Located in high RA
Main pacemaker of heart
Sends out regular impulses at 60- 100 times per minute
Regulated by the Autonomic Nervous System (vagus nerve)
![Page 13: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/13.jpg)
![Page 14: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/14.jpg)
Atrioventricular Node (AV)
Located on floor of TA next to septum and behind CS os
Has 2 main jobsDelay the impulse from the SA node long enough so the ventricles can fill with blood
Protect the ventricles from rapid atrial rates
Inherent rate of 40-70 bpm
![Page 15: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/15.jpg)
Bundle of His (HB)
A fibrous ring around the 4 valves
Only muscular connection between the atria and ventricles
AV node and HB collectively are called the AV junction
The AV junction can pace the heart at rate of 40-60 bpm
![Page 16: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/16.jpg)
Bundle Branches
HB branches into rt.... And lt.. Branches
Lt.. Bundle branch (LBB) then divides into anterior and posterior sections
![Page 17: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/17.jpg)
![Page 18: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/18.jpg)
Purkinje Fibers
Terminal portion of the conduction system
Located in ventricular muscle
Can pace the heart at 20-40 bpm
![Page 19: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/19.jpg)
![Page 20: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/20.jpg)
Electrical Properties of Cardiac Muscle
![Page 21: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/21.jpg)
AutomaticityProperty by which a cell can reach threshold potential (depolarize) and send an impulse without help from an external source
ExcitabilityAbility of cell to reach threshold potential in response to an outside stimulus
ConductivityThe propagation of an impulse form cell to cell through intercalated disks
ContractilityAbility of a muscle to shorten (contract) when stimulated
Electrophysiology cont.....
![Page 22: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/22.jpg)
Electrophysiology Cont.....
The end result of contraction of the heart is electrochemical in nature.
The impulse is sent along the conduction system because of changes in cellular polarity.
![Page 23: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/23.jpg)
![Page 24: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/24.jpg)
![Page 25: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/25.jpg)
![Page 26: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/26.jpg)
![Page 27: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/27.jpg)
![Page 28: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/28.jpg)
![Page 29: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/29.jpg)
![Page 30: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/30.jpg)
Cardiac Emergencies
A thrombosis or embolism may plug the arteries causing a myocardial infarction or “heart attack”
Angina pectoris is used to describe the severe chest pain
![Page 31: Cardiac Cycle and Conduction System of the Heart.](https://reader036.fdocuments.net/reader036/viewer/2022062407/56649dfe5503460f94ae6abc/html5/thumbnails/31.jpg)
infarct