physiology 1-external-manifestations-of-cardiac-activity
TRANSCRIPT
External manifestations of cardiac activity. Regulation
of heart work
Lecturer MD, Ph.D. Angelika V. Ivasenko
ATRIAL SYSTOLE 0,1sec
Ventricle systole 0,33sec
VENTRICLE SYSTOLE 0,33sec
VENTRICLE SYSTOLE 0,33sec
COMMON PAUSE 0,37sec
COMMON PAUSE 0,37sec
COMMON PAUSE 0,37sec
External manifestations of cardiac activity
• Mechanical (apex beat, pulse)
• Sound (heart tones)
• Electrical (ECG)
Sphygmogram
1.Anacrote2. Catacrote3. Incisure4. Dicrotic rise
FREQUENCY
MAGNITUDE
VELOCITY
rarus
altus
frequens
tardus
сеler
parvus
PULSUS CHARACTERISTICS
SYSTOLIC TONE
components:1. VALVULAR (A-V valves closure)2. MUSCULAR asynchronous contraction3. VASCULAR (aorta vibration )4. TENDON (chordae tendineae tension)
SYSTOLIC TONE. PLACES OF BEST HEARING
• heart apex projection (IV-V intercostal space on the left, 1,5-2 cm medial from the medioclavicular line)•the place of junction of sternum body and xyfoid processus
DIASTOLIC TONE
components:1. VALVULAR (semi-lunar
valves closure)
2. VASCULAR (blood rebound )
DIASTOLIC TONE. PLACES OF BEST HEARING
• II right intercostal space along the parasternal line (over aorta).
• II left intercostal space along the parasternal line (over pulmonary artery).
Right atrium excitation- ascending part of P-wave
Spreading of excitation from SA to AV node – interval PQ
Excitation of left part of intraventricular septum – Q wave
Excitation of ventricles’ apexes – R wave
Spreading of excitation from endocardium to epicardium
- QRS complex
Depoloarization in ventricles completed – ST segment
Quick final repolarization of the ventricles – T wave
MECHANISMS OF HEART REGULATION
•INTRACARDIAC REGULATION
•EXTRACARDIAC REGULATION
INTRACARDIAC REGULATION
1.Myogenic a)Geterometric (Franc-
Starling law) b)Gomeometric (Boudichi
“staircase”)2.Peripherial heart reflexes
Franc-Starling law• The more heart chambers are filled with
blood during diastole, the greater force of contraction they develop during systole
• This prevents ventricles from dilation allowing them to eject all the blood
Boudichi “staircase”• At high frequency of stimulation force of
contraction increases regardless of the cardiomyocytes length
Peripheral heart reflexes• Are performed by methasympathetic
system in the heart• They restrict Frank-Starling law so that to
readjust cardiac output to the systemic BP• The most prominent reflex is from right
atrium to left ventricle
Peripheral heart reflexes• In case of high systemic BP high threshold
receptors are activated in right atrium and via cholinergic fibers decrease heart rate & stroke volume in the left ventricle
• In case of low systemic BP low threshold receptors are activated in right atrium and via adrenergic fibers increase heart rate & stroke volume in the left ventricle
EXTRACARDIAC REGULATION
•Nervous regulation (SNS, vagus)
•Humoral regulation (Ad, Thyroxin)
HEART INNERVATION
Mechanism of sympathetic stimulation
• Adrenalin opens Na+ channels• Na+ influx depolarises myocardiocyte’s
membrane• Threshold decreases (“+” batmotrophic effect)• Time of SDD decreases (“+” chronotrophic
effect)• Conductivity increases (“+” dromotrophic effect)• Contractility increases (“+” inotrophic effect)
Influence of sympathetic nerve stimulation on AP of the pacemaker ( A – before, B – after stimulation)
ΔV1, Δ V2 – thresholds of depolarization, α1, α2 – angler, showing the steepness of depolarization, t1, t2 – time of slow diastolic
depolarization
Influence of vagus stimulation on AP of the pacemaker ( A – before, B – after stimulation)ΔV1, Δ V2 – thresholds of depolarization, α1, α2 – angler, showing the steepness of depolarization, t1, t2 – time of slow diastolic depolarization
Mechanism of parasympathetic stimulation
• Acetylcholine opens K+ channels• K+ efflux repolarises myocardiocyte’s membrane• Threshold increases (“-” batmotrophic effect)• Time of SDD increases (“-” chronotrophic effect)• Conductivity decreases (“-” dromotrophic effect)• Contractility decreases (“-” inotrophic effect)