Cardiovascular Physiology Flashcards
Through which veins does de-oxygenated blood enter the right atrium?
Superior and inferior vena cava
Through which artery does blood leave the right atrium?
Pulmonary artery
Through what veins does blood enter the left ventricle?
Pulmonary veins
Through which artery does blood leave the left ventricle?
aorta
what separates the two sides of the heart?
Septum (cardiac muscle)
What is the command centre of the heart?
Sinoatrial node
What is the pathway of electrical signals in the heart?
1) Sinoatrial node causes action potentials
2) spreads through the atria causing contraction
3) fibrous skeleton delays the action potential from reaching the ventricles
4) reaches the bundle of his
5) action potentials spread through the purkinje fibres, causing contraction of both ventricles
What valves are present in the right side of the heart?
tricuspid valves
What valves are present in the left side of the heart?
mitral valves
What systems cause innervation of the heart?
Parasympathetic and sympathetic
What effect does the parasympathetic system inflict on the heart?
Dominant at rest and controls the reduction of HR and reduction of force on contraction
What effect does the sympathetic system have on the heart?
increases both HR and force of contraction, releases noradrenaline
Through which nerve does the parasympathetic system effect the heart?
Vagus nerve
what features are common in all blood vessels?
Lumen, single layer of endothelial cells
what features are common in veins and arteries?
Tunica intima, smooth muscle, tunica adventitia
What are the differences between veins and arteries?
Veins have larger lumen, Lumen more elastic in veins, majority of blood volume held in veins, less smooth muscle in veins, smaller tunica adventitia
what nervous system effects blood vessels?
Sympathetic
how does the sympathetic nervous system effect the blood vessels?
releases noradrenaline which constricts blood vessels. Circulating adrenaline also constricts most blood vessels but dilates the vessels to the heart, lungs and skeletal muscle.
What occurs in capillaries?
They are the site for solute and fluid transfer
What are the four types of artery?
elastic, muscular, resistance, arteriole
How do low pressure veins still manage to return blood to the heart against gravity?
Muscles either side of the veins contract to help push the blood through the valve system that veins also have in order to prevent back-flow
What differences does smooth muscle have over cardiac and skeletal?
1) is smooth- no striations
2) phosphorylation dependant constriction rather than calcium
3) autonomic nerve control
what are the different types capillaries?
Continuous, Fenestrated, discontinuous
What is the most common form of capillaries and where are they found?
Continuous, they are found in most tissues and organs
where are fenestrated capillaries found and what is their main feature?
mainly found in the liver, glands and kidney glomeruli.
main feature is fenestrae which are small windows in teh capillaries that allow the movement of water and salts
what four pressure gradients effect the fluid movement in capillaries?
capillary pressure
interstitial pressure
oncotic osmosis pressure
oncotic pressure interstitium
what is normally the greatest pressure in the capillaries?
hydrostatic pressure
what is the purpose of the lymphatic system?
connects circulatory and immune system, removes fluid that diffused through capillaries and into the interstitial liquid and returns it back to the venous system
what type of capillaries are found in the lymphatic capillaries?
discontinuous, in order to allow the diffusion of solutes in the interstitial liquid
what are the 3 main layers of the heart itself?
Epicardium (outer layer of serous pericardium, myocardium (muscle layer, cardiac myocytes), endocardium (inner layer lining chambers)
what is stroke volume?
volume of blood ejected from the heart
define end diastolic volume
volume of blood in the ventricle just before it contracts
define ejection fraction
fraction of the end diastolic volume pumped
what is cardiac output and how can it be calculated?
cardiac output is the blood pumped from a ventricle and it can be calculated by multiplying the heart rate by stroke volume
what is intrinsic control?
forces which are controlled by the heart itself e.g., force of contraction, venous return (mechanical)
what is extrinsic control?
Factors outside of the heart e.g., autonomic nerve, circulating hormones
how can you calculate stroke volume?
end diastolic volume x ejection fraction
what is preload?
the force exerted by the volume of blood entering the ventricles and exerting a force on the myocardium
what are the phases of the cardiac action potential?
0- depolarisation 1- repolarisation 2- plateau 3- repolarisation 4- baseline
What are the regions of an ECG?
P wave QRS complex T wave PR interval QT interval
What ion is the cause of depolarisation in pacemaker cells?
Ca++ ions
