The Cardovascular System Flashcards
What is diastole and systole?
Diastole= heart relaxes
Systole= heart contracts
What is heart rate?
The number of times the heart beats per minute
Units= bpm
Heart rate= cardiac output/ stroke volume
70bpm at rest
What is stroke volume?
The amount of blood ejected from the left ventricle per beat
Units= ml
Stroke volume= cardiac output/ heart rate
70 ml at rest
Venous return is the volume of blood returning to the heart
What is Cardiac output?
The amount ejected from the left ventricle per minute
Units= l/ min
5 litres/ min at rest
Types of blood and what do they do?
Plasma= yellow liquid component that holds the blood cells and whole blood in suspension
Platelets= components of blood that reacts to externals bleeding by clumping and clothing
Red blood cells= made in the bone marrow. Contain haemogoblin which carries oxygen
White blood cells= the cells of the immune system to fight against disease. Also made in the bone marrow
What are the types of blood vessels and what do they do?
Artery= thick muscular walls- vasoconstriction and dilation
Smaller lumen- delivers blood faster
Elastic tissue- helps with blood pressure
Vein=thinner walls- allows a large lumen
More blood can get to the heart
Valves= prevent back flow of blood and creates less pressure
Capillary= very thin walls( 1cell thick)- more diffusion takes place
Very narrow lumen- only 1 red blood cell at a time more efficient
Very high density
Pulmonary circulation right side of the heart
Vena cava- right atrium- tricuspid valve- right ventricle- pulmonary semi-lunar valve- pulmonary artery- lungs- gas exchange
Systemic circulation left side of the heart
Pulmonary vein- left atrium- aortic semi-lunar valve- left ventricle- bicuspid valve- aorta - body tissue- diffusion
Contraction phase of the heart
Atrial systole= blood pumped into ventricles
Ventricular systole= blood pumped into pulmonary artery and aorta
Relaxation phase of the heart
Atrial diastole- blood entering the atria via the vena cava and the pulmonary vein
Ventricular diastole- blood entering the ventricles from the atria
4 components of the conduction system
SA node= in the wall of the right atrium. Starts the impulse and sends it across both atria
AV node= in the middle wall of the heart between atria and ventricles. Receives impulse from SA node, causes a delay to allow for atrial systole to finish and passes it into the bundle of his.
Bundle of his= in the middle of the heart. Transmits impulse to the bottom of the heart via bundle branches
Purkinje fibres= in the wall of the ventricles. Causes impulse to penetrate into ventricle walls causing ventricular systole. The most powerful contraction
Average values for HR, SV and Q and trained and untrained
UnTrained
HR at rest is 70 bpm, at sub-maximal 100-140 bpm and at maximal 220- age
SV is 70 ml, 100ml and 100ml but will decrease
Q is 5l/ min, 10-14 l/min and 20l/min
Trained
HR is 50 bpm, 120-160 bpm, 220-age
Sv is 100 ml , 200ml and 200ml but will decrease
Q is 5l/min, 24-32l/min and 40l/min
Heart rate changes during exercise
Sub-maximal= rest rises gradually
Exercise= straight line across
Recovery= decreases slowly
Maximal
Rest= rises slowly
Exercise= rises rapidly
Recovery= takes a very long time
Stroke volume changes during exercise
Both sub-maximal and maximal increase rapidly plateau and then decreases slowly called cardiovascular drift
Extrinsic factors of heart rate during exercise
Receptors
Chemo- chemical changes
Baro- blood pressure changes
Proprio- detecting muscle activity changes
Adrenaline released prior to exercise
Intrinsic factors
Increased temperature- increases Speed of nerve transmissions and then stimulation of SA node increases HR
Increased venous return- blood returning to the heart increases stimulation of the SA node which increases HR
Distribution of cardiac output
Most going to kidney and liver at rest whereas at exercise 87% of blood goes to the muscles
The vascular shunt mechanism
Vasodilation= the widening of blood vessels through relaxation
Vasoconstriction= the narrowing of blood vessels through contraction
Arterioles= the smaller arteries
Pre- capillary sphincters= the opening of capillaries
What is venous return?
Returning of blood to the heart during the cardiac cycle.
VR high= SV high
More blood returning= more heart is stretched= increase of Stimulation= increases HR and SV
Starlings law of the heart
Problems that slow down VR
Blood pressure in the veins are very low
Have to fight against gravity to make its way back up to the heart more blood distributed to the lower body
Solution to problems with VR
Pocket valves= stop back flow of blood
Skeletal muscle pump= muscles in the lower leg contracts squeeze the veins and force the blood back to the heart
Smooth muscle= venoconstrict and force the blood back towards the heart
Respiratory pump= diaphragm flattens, the pressure of thoracic cavity is decreased and acts as a vacuum and forces blood back to the heart.
Gravity= blood from above the heart returns via gravity
