9. Cardiovascular system Flashcards
What are the main components of the cardiovascular system?
The heart - to pump blood
The blood vessels
> arteries - carry blood away from heart
> veins - carry blood back to the heart
> capillaries - allow gas exchange
Explain systemic circulation and pulmonary circulation.
Systemic - carries blood from heart to all other parts of body and back again.
Pulmonary - short loop from heart to lungs and back again.
List 3 functions of the cardiovascular system.
Deliver oxygen + nutrients
Remove waste products
Regulate body temperature
Explain the location of the heart
- Located centrally and inferiorly within thoracic cavity
- Boarded laterally by the lungs
- Anteriorly within the mediastinum
- Boarded superiorly by the great vessels
- Inferiorly by the diaphragm
- Anteriorly by the sternum
- Posteriorly by oesophagus and aorta
Hearts blood supply
watch vid?
Layers of heart
watch vid?
Explain how the heart’s electrical activity functions.
- The sinoatrial node propagates the electrical impulse, the atria the contract from the base to apex.
- The atrioventricular node precipitates the signal down the bundle of his.
- The bundle of his carry the signal to the apex
- Purkinje fibres radiate out, transmitting the impulse to the ventricles.
- Ventricles contract from apex to base.
Regulates by the vagal nerve (teeth cranial nerve)
What do electrocardiograms (ECG’s) do?
Record the electrical activity of the heart.
Explain an ECG graph.
Each part of the wave function relates to discrete part of the cardiac cycle.
P wave = Atrial depolarisation + contraction
QRS complex = ventricular depolarisation and contraction
T wave = ventricular repolarisation and relaxation.
Cardio pulmonary circulation
check vid?
Why is atrial repolarisation not visible on ECG’s?
Because it occurs at the same time as the ventricular depolarisation.
Explain location of the great vessels - aorta.
- Arises from the left ventricular outflow tract
- Coronary arteries emanate from aortic root
- It ascends to form an arch before descending
- Lies centrally + anterior to the vertebral column
- Perforates the diaphragm at T12
- Continues caudally through the abdomen
- Bifurcating at L4 into left and right iliac arteries.
What is the location of the pulmonary artery?
The main pulmonary artery (trunk), arises from the right ventricular outflow.
Bifurcating inferiorly to the aortic arch at T5.
The left and right pulmonary artery perforate the lung at the hilus.
Explain how the great vessels vena cava functions. - How blood travels
Venous blood is returned to the heart via the superior and inferior vena cava
The jugular and brachiocephalic veins fill the superior vena cava.
Tributaries from the abdominal organs and lower limbs fill the inferior vena cava.
A decrease in thoracic pressure during inspiration, helps draw the blood back to the heart.
What are the major blood vessels?
- Carotid arteries and jugular veins
- Subclavian arteries and veins
- Main abdominal arteries
- Common iliac arteries and veins
- The main vessels of the upper and lower limbs
What are the 3 layers that blood vessels consist of?
- Tunica interna/intima - endothelium
- Tunica media - smooth muscle and elastic membrane
- Tunica externa/adventitia - collagenous and elastic fibres
What are arteries composed of?
Thick walls to absorb the pressure generated by the heart.
What are capillaries composed of and why?
Basement membrane and endothelium only
> permeable to allow for gaseous and nutrient exchange
What are veins composed of and why?
Thinner walls, particular at tunica media with valves in order to prevent backflow.
What is blood pressure?
The measurement of peripheral arterial pressure.
What are the 2 components of blood pressure results?
- diastolic - pressure measured at the end of the cardiac cycle ‘rest phase’
- systolic - pressure during ventricular contraction
What are the units of blood pressure results?
Normal: 120/80mmHg
High: 140/90mmHg
millimetres of mercury
What is a pulse?
A palpable difference between systolic and diastolic pressure.
