Week 3 Flashcards
Superior and Inferior vena cava function
Carries deoxygenated blood back to the heart
Superior - Head, neck, arms and chest
Inferior - Legs, feet, organs in abdomen
Pulmonary artery function
Delivers deoxygenated blood to the lungs
Pulmonary vein function
Returns oxygenated blood back to the heart from the lungs
Aorta
Delivers oxygenated blood to the body
Right atrium
Deoxygenated blood enters via the vena cava
Right ventricle
Deoxygenated blood enters from the right atrium and is forced up the pulmonary artery to the lungs
Left atrium
Oxygenated blood enters via the pulmonary vein
Left ventricle
Oxygenated blood enters via the left atrium and is forced out of the aorta
Atrioventricular valves
Prevent backflow from the ventricles back into the atrium
Layers of the heart
Epicardium - Lubricative outer layer
Myocardium (cardiac muscle) - Provides muscular contractions that eject blood from the heart chambers
Endocardium - Serves as protective inner lining of the chambers and valves
Pro and con of heart hypertrophy
pro - Benefits exercise
con - high blood pressure
How does contraction of the myocardium occur?
1.Action potential spreads rapidly along myocardial sarcolemma.
2.Calcium enters the cell by the dihydropyridine receptors in the T-tubules.
3.Unlike skeletal muscle, calcium entering the T-tubules is not sufficient to cause muscle contraction, instead triggering another receptor -> Ryanodine receptor.
4.This receptor releases calcium from the sarcoplasmic reticulum to aid contraction.
Where does the parasympathetic nervous system originate?
Medulla oblongata
Reaches the heart through the vagus nerve
Parasympathetic nervous system function
Decrease heart rate
Releases acetylcholine which causes hyperpolarisation and therefore slower depolarisation
Sympathetic nervous system function
Increase heart rate
Increases rate of depolarisation as well as conduction speed therefore increasing heart rate
