| What are the 3 factors that influence rate of diffusion | Area
Concentration gradient
Diffusion resistance |
| What does diffusion resistance depend on | Nature 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 wise | Heart 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 tissues | Brain → 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 Systole | This is when the myocardium are contracting hence blood filling into the arteries |
| What is Diastole | This 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 shut | Mitral 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 aorta | Aortic 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 excitation | Excitation 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 cycle | First 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 heart | Lup --> 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 Output | Stroke volume * Heart rate
Stroke volume is usually 80 |
| Where do the impulses enter the ventricles | At the bundle of His |
