The cardiovascular system Flashcards
What makes up the cardiovascular system and what is its function
The cardiovascular system is made up of the heart and blood vessels. The heart is the pump that circulates the blood through the vessels. The vessels are the major transport system responsible for transporting nutrients and oxygen to tissues and removing urea and carbon dioxide. It also transports hormones involved in homeostasis.
What are arteries
Arteries are thick muscular blood vessels that carry high pressure oxygenated blood away from the heart.
What are veins
Veins are thin walled blood vessels which carry low pressured deoxygenated blood towards the heart
What are capillaries
Capillaries are small vessels that distribute blood and connect arteries to veins. They are usually found in capillary beds connected by venules and arterioles. They are regulated by precapillary sphincters
What colour is the blood in the arteries and the veins
Arteries have oxygenated bright cherry red blood. Veins have deoxygenated dark cherry red blood
Where is the heart located and where can you palpate it
The heart is located in the thoracic cavity behind the breastbone (sternum). With the apex projecting to the left, so you can palpate it in the 5th intercostal space to the left.
How many litres of blood does the heart pump in a day
The heart pump 9000 litres of blood a day
How big is the heart
it is 12-14cm long and 9-11cm wide but it can increase with age due to it being harder to pump the blood round the vessels which have fatty deposits.
How does the heart change during pregnancy
The heart is pushed up the chest during pregnancy and increases on size (known as hypertrophy) due to the increase in blood volume
What is the pericardium
The pericardium is a tough membrane that surrounds the heart
What are the functions of the pericardium
It anchors the heart to the sternum and top of diaphragm in position. It also produces pericardial fluid which lubricates and prevents trauma from rubbing other structures. It also acts as a shock absorber
Name the three layers of the heart
The myocardium is the thick muscle layer responsible for pumping blood
The epicardium is the outer layer
The endocardium in the inner layer and lines heart chambers
What is cardiac tamponade
Cardiac tamponade is a condition caused by either an infection or trauma to the heart causing an increased amount of pericardial fluid. This increases pressure on the heart which stops effective pumping and requires a needle decompression to remove it.
What is the role of the coronary arteries
The coronary arteries supply oxygenated blood to the myocardium
What is coronary artery disease
Coronary artery disease is caused by the arteries narrowing due to a buildup of fatty deposits which turns into plaque and limits blood flow and causes angina. Smoking, a fatty diet and some health conditions increase the risk.
When might midwives encounter coronary artery disease
Women don’t always experience the symptoms particularly those with diabetes due to damaged nerve endings because of the constantly high sugar levels. Pregnancy puts extra strain on the heart which may cause them to experience angina for the first time.
How many chambers are in the heart
The heart has four chambers. Two upper thin and elastic collecting chambers called atria and two lower thick and muscular lower pumping chambers called ventricles.
How many valves are there in the heart
Between the atria and ventricles there are two atrioventricular valves. The Tricuspid on the right and the bicuspid on the left. There are two semilunar valves to prevent backflow the pulmonary valve on the right and the aortic valve on the left.
Label a diagram of the heart
Check using notes should include 4 chambers, tricuspid valve, bicuspid valve, pulmonary valve, aortic valve, pulmonary artery, vena cava, aorta and pulmonary vein.
Explain how the pulmonary circuit works
The right side of the heart collects deoxygenated blood from the vena cava and pumps it through the pulmonary arteries to the lungs to become oxygenated. It returns through the pulmonary vein to the left side.
Explain how the systemic circuit works
The oxygenated blood is pumped into the aorta round the organs
What is systole
Systole is contraction of the heart chambers
What is diastole
Diastole is relaxation of the heart chambers
What happens during atrial systole
The atria collect blood from the vena cava and pulmonary veins and contracts forcing it through the atrioventricular valves into the ventricles.
What happens during ventricular systole
The ventricles fill with blood and contract ejecting it into the pulmonary artery and aorta and then undergo diastole as the stria contract again.
What is bradycardia
Bradycardia is when the resting HR is less than 60 bpm, it is usually in athletes and patients on beta blockers
What is tachycardia
Tachycardia is a resting HR above 100bpm usually due to stress infection or haemorrhage
What is the tunica externa
The tunica externa is the outer protective layer that anchors the vessel in place
What is the tunica media
The tunica media is the smooth muscle inner layer which allows regulation of blood flow through vasoconstriction/dilation.
What is the endothelium
The endothelium is the innermost layer which is one cell thick and easily damaged by cigarette toxins, blood sugar and raised BP. It periodically folds in on itself to form valves.
What is the skeletal muscle pump
The skeletal muscle pump helps to return deoxygenated blood under low pressure to the heart by the calf muscles compressing veins during movement which increases pressure aided by the semilunar valves to prevent backflow.
Why is thrombosis an issue during pregnancy
To prepare for bloodloss the liver produces more plasma proteins which increases risk of thrombosis as it makes the blood hypercoagulable.
What is vischows triad
Vischows triad is three factors that predispose thrombosis: hypercoagulable blood, endothelial injury and circulatory stasis
Why is it important to exercise during pregnancy and what are the risks of not
To active the skeletal muscle pump to avoid a DVT which may compromise bloodflow. The clot may become dislodged and embolise and travel to the heart to become a pulmonary embolism leading to a heart attack or stroke.
Summarise the cardiovascular changed during pregnancy
Upwards displacement of heart Hypertrophy Lower BP in 2nd trimester 50% increase in blood volume Weight gain due to increased blood volume
