Please enable JavaScript.
Coggle requires JavaScript to display documents.
Cardiovascular System Yatziri Carmona Per.1 (The intrinsic cardiac…
Cardiovascular System
Yatziri Carmona Per.1
The chambers of the heart
left atrium:the left atrium receives oxygen-rich blood from the lungs and pumps it to the left ventricle.
right atrium: Deoxygenated blood enters the right atrium through the inferior and superior vena cava
coronary sinus
inferior vena cava
superior vena cava
right ventricle:The right ventricle pumps the oxygen-poor blood to the lungs
left ventricle: The left ventricle is the thickest of the heart's chambers and is responsible for pumping oxygenated blood to tissues all over the body
Coverings of the heart
fibrous pericardium
serous pericardium
pericardium
parietal layer
visceral layer
Layers of the heart wall
myocardium
middle layer, muscular layer, involuntary, allows the heart to contract
endocardium
inner layer, provides protection to the valves and heart chambers
epicardium
outer, protective, layer- functions to protect the inner heart layers and also assists in the production of pericardial fluid.
The atrioventricular valves
tricuspid valve
mitral valve
coronary circulation
left coronary artery
anterior interventricular artery
circumflex artery
right coronary artery
posterior interventricular artery
right marginal artery
Pacemaker and action potentials of typical cardiac pacemaker cells
2.Depolarization: The action potential begins when the pacemaker potential reaches threshold. Depolarization is due to Ca2+ influx through Ca+2 channels
Repolarization is due to Ca+2 channels inactivating and K+ channels opening. This allows K+ efflux, which brings the membrane potential back to its most negative voltage
1.Pacemaker potential: This slow depolarization is due to both opening of Na+ channels and closing of K+ channels
The intrinsic cardiac conduction system
3 Atrioventricular (AV) bundle: connects the atria to the ventricles
4 Right and left bundle branches: conduct the impulses through the interventricular septum
2 Atrioventricular (AV) node: The impulses pause (0.1s)
5 Subendocardial conducting network: depolarizes the contractile cells of both ventricles
1 Sinoatrial (SA) node: generates impulses
The sequence of depolarization and repolarization of the heart related to the ECG waves.
Ventricular repolarization is complete
Ventricular repolarization begins at the apex, causing the T wave
Ventricular depolarization is complete
Ventricular depolarization begins at apex, causing the QRS complex, Atrial repolarization occurs
When atrial depolarization is complete, the impulse is delayed at the AV node
1.Atrial depolarization, initiated by the SA node, causes the P wave
The action potential of contractile cardiac muscle cells
3.Repolarization: due to Ca2+ channels inactivating and K+ channels opening. This allows K+ efflux, which brings the membrane potential back to its resting voltage
2.Plateau phase: due to Ca2+ influx through slow Ca2+ channels. This keeps the cell depolarized because K+ channels are closed.
1.Depolarization: due to Na+ influx through fast voltage-gated Na+ channels. A positive feedback cycle rapidly opens many Na+ channels, reversing the membrane potential. Channel inactivation ends this phase
Phases of the Cardiac Cycle
2 Isovolumetric contraction:ventricular pressure rises rapidly and sharply, closing the AV valves
3 Ventricular ejection:blood rushes from the ventricles into the aorta and pulmonary trunk
1 Ventricular filling: mid-to-late diastole: pressure in the heart is low,
4 Isovolumetric relaxation: early diastole; ventricular pressure drops rapidly and blood in the aorta and pulmonary trunk flows back toward the heart, closing the SL valves
Cardiac Output
CO=HR×SV==75 beatsmin×70 mlbeat5250 mlmin=5.25 Lmin
Stroke volume
SV=EDV−ESV=120 mlbeat−50 mlbeat=70 mlbeat
Chemical Regulation of the Heart
Hormones
Epinephrine, liberated by the adrenal medulla during sympathetic nervous system activation, produces the same cardiac effects as norepinephrine released by the sympathetic nerves: It enhances heart rate and contractility
Thyroxine is a thyroid gland hormone that increases metabolic rate and production of body heat. When released in large quantities, it causes a sustained increase in heart rate. Thyroxine acts directly on the heart but also enhances the effects of epinephrine and norepinephrine.
Ions
Normal heart function depends on having normal levels of intracellular and extracellular ions. Plasma electrolyte imbalances pose real dangers to the heart.