The Heart And Cardiac Cycle Flashcards
Mass transport systems
Bulk movement of substances through transport systems used to supply materials to all cells in large organisms mass transport system linked with substance exchange systems for example lungs the leaves kidneys the gut the roots
The mammalian heart
Arteries carry blood away from heart veins carry blood into the heart valves prevent back flow
2 separate pumps right side pumps to lungs
Left side pumps to body
4 chambers atria and and ventricles
Vena cava
Brings deoxygenated blood back from the body
Pulmonary artery
Carries deoxygenated blood to lungs
Aorta
Carries oxygenated blood to the body
Pulmonary vein
Carries oxygenated blood into the heart
Right a trio ventricular valve
Stop back flow of blood into atrium also known as tricuspid
Chordae tendineae
Tendons heart strings stop valves from inverting under pressure
Semi lunar valves
Found between arteries and ventricles prevent back flow into ventricles
Left atrioventricular
Bicuspid or mitral valve
Order of blood flow
Vein atrium ventricle artery
First stage of cardiac cycle
Heart is relaxed diastole blood at low pressure in veins flow into atria the pressure increases in the aria as they fill this blood pushes against atrioventricular valves causing them to open and blood flows into ventricles below
2nd stage cardiac cycle
When the atria are full atria systole blood is pushed through the atrioventricular valves into into ventricles pressure in the atria is increased due to contractions and pressure is increasing in ventricles as they fill with blood
3rd stage of cardiac cycle
When the atria contract blood cannot flow into the vein beacause pressure of the bloood pushes on pocket valves in veins to shut them
4 stage of cardiac cycle
After short delay the ventricles contract from the base upwards pressure inside the ventricles increases. The atria relaxes
5th stage of cardiac cycle
Ventricular pressure reaches higher level than that in atria blood pushing against atrioventricular valves shut them giving the first heart sound Lub preventing back flow
Stage 6 in cardiac cycle
Semilunar valves open under pressure and blood leaves heart through arteries
7 stage of cardiac cycle
Ventricles relax pressure in aorta pulmonary artery exeedsbthat of the ventricles and blood pushes on semilunar valves which snap shut the second heart sound dub preventing back flow into heart
How do we measure how efficient heart is
Cardiac output=HRxstroke volume
How is the heartbeat controlled
Cardiac muscle cells are surrounded by capillaries and up to 35% of content is mitochondria
Heart beat is myotonic
How is heart beat controlled
Pacemaker cells from intrinsic cardiac conduction system cause contractile cells in atria then ventricles to contract as impulses spread out through this system
Made of pacemaker cells send depolarising auothythmic produce action potentials like nerve cells without the need for an external stimuli
Leaky ion channels allow sodium ions to trickle in at a constant steady rate so eventually threshold is reached and the cell depolarises
SA node
Is crescent shaped collection of myocytes found between upper wall of right atrium. And opening of vena cava is the primary pacemaker
AV node
Secondary pacemaker
Bundle fibres
Tertiary pacemaker
Spread of nerve impulses
San avio bundle of his purkinji fibres