The Heart Flashcards
The pulmonary circulation
Heart –> lungs
Pulmonary artery
Pulmonary vein
Systemic circulation
Heart –> rest of body
Aorta (artery)
Vena cava (vein)
Complete steps in circulation
Vena cava–> RA–> RV–> pulmonary artery–> lungs–> pulmonary veins–> LA–>LV–> aorta –> rest of body (…vena cava–>..)
What do arteries do?
Carry oxygenated blood away from heart (except pulmonary artery)
What veins do?
Return deoxygenated blood to heart (except pulmonary vein)
Capillaries are..?
Sites of nutrient, metabolic products and fluid exchange
They connect arterial to veins
Precapillary sphincters control…
… Blood flow by expanding to allow flow through artery
Also restricts and directs blood for physical demands
Location of tricuspid?
Between RA & RV
Location of bicuspid?
Between LA & LV and is sometimes called the mitral hat.
Blood flow to brain at rest? ml/min
650 (13%)
Blood flow to kidneys at rest? ml/min
950 (20%)
Chordae tendineae and papillary muscles play important role in… By…?
… In preventing back flow to atria by contraction of papillary muscles tenses chordae tendineae, holding cusps closed
First half of the pacemaker potential (initial phase of slow depolarisation to threshold) is the result of…
… Simultaneous opening of unique funny channels (If) which permits inward Na+ current and closure of K+ channels which reduces outward K+ current
Second half of the pacemaker potential is the…
…result of opening of Transient-type Ca2+ channels. Once threshold reached the rising phase of action potential is the result of opening Long-lasting Ca2+ channels
Third part of pacemaker potential…
Is the repolorisation by K+ permeability increases
Electrical system of the heart:
Begins in sino-atrial node
Then spreads throughout both atria (depolarises-contracts) spread facilitated by internodal fibres
Atrio-ventricular node waits till ventricles fill before contract
From AV node action potential spreads to AV bundles (bundle of His & purkinje fibres) left and right branches
What is an ECG recording of?
Electrical activity present in body fluids from the cardiac impulse that reaches the body surface
( not direct recording of actual electrical activity of the heart)
Normal ECG has 3 distinct waves: P wave, QRS complex, T wave. What does each waveform represent?
O wave: atrial depolarisation
QRS complex: ventricular depolarisation
T wave: ventricular repolarisation
What is the first recorded wave? How? Why is that the first?
P wave
Impulse/wave of depolarisation spreads across the atria
First because firing of SA node not generate enough electrical activity to reach body surface so no wave recorded
There’s no visible separate wave for atrial repolarisation in a normal ECG because?
Because atrial repolarisation occurs simultaneously with ventricular depolarisation and masked by the QRS complex
Position of the heart?
Between sternum and vertabrae
Most important changes in ion movement that give rise to the pacemaker potential are..?
1) increased inward Na+ current
2) decreased outward K+ current
3) increased inward Ca2+ current
