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level: Level 1

Questions and Answers List

level questions: Level 1

QuestionAnswer
What are the 3 factors that influence rate of diffusionArea Concentration gradient Diffusion resistance
What does diffusion resistance depend onNature of the molecule --> lipophillic/hydrophillic Nature of the barrier --> pore size, number of pores Path length --> depends on capillary density
Features of the heart circulation wiseHeart is a double circulatory system and is a closed circulatory system The right heart pumps towards the lung ( pulmonary circulation ) Left heart pumps around the body ( systemic circulation )
What are the supply and demand of important tissuesBrain → constant supply , intolerant of interruptions Heart → requires increase during exercise , intolerant of interruptions Kidneys → requires high constant flow, intolerant of interruptions Gut → requires more during digestion and is tolerant of short term interruptions Skeletal muscle → requires more during exercise and is tolerant of short term interruptions Skin → not metabolically active but can increase for thermoregulation
What is SystoleThis is when the myocardium are contracting hence blood filling into the arteries
What is DiastoleThis is when the myocardium is relaxing hence blood is filling in the ventricles
What are the valves that control blood flow from atrium to ventricle and what causes it to open and shutMitral valve - prevents backflow into the atrium from the ventricle Opens when atrial pressure exceeds intra-ventricular pressure Closes when ventricular pressure exceeds atrial pressure Some backflow is needed to ensure the valves close
What are the valve that controls blood flow from ventricle to the aortaAortic valve - prevents backflow into the ventricle from the aorta Opens when intra-ventricular pressure exceeds aortic pressure Closes when aortic pressure exceeds ventricular pressure
What is the spread of excitationExcitation starts from the sino-atrial node so excitation starts in the atria to the atrioventricular node and down the muscular septum to the ventricle and it excites it on the endocardial side
Briefly what are the stages of the cardiac cycleFirst there is atrial systole which leads to the the closure of the AV valve so there is isovolumetric contraction until there is opening of the outflow valves where there is then rapid ejection phase where blood enters the arteries Then there is isovolumetric relaxation and the outflow valves close which then leads to ventricular systole and diastasis which then leads to atrial systole and the cycle repeats
What produces the sounds of the heartLup --> first sound is made by the closure of the AV valves ( start of ventricular systole ) Dup --> second sound is made by the closure of the outflow valves ( end of ventricular systole )
How can you calculate Cardiac OutputStroke volume * Heart rate Stroke volume is usually 80
Where do the impulses enter the ventriclesAt the bundle of His