Cardiovascular System Flashcards
Briefly outline the cardiovascular system
Vena Cavae –> Right Atrium –> Right AV Valve –> Right Ventricle –> Pulmonary SL Valve –> Pulmonary Arteries –> Lungs –> Pulmonary Veins –> Left Atrium –> Left AV Valve –> Left Ventricle –> Aortic SL Valve –> Aorta –> Body –> Vena Cavae
What are the names of the Atrioventricular valves and where are they situated?
- Tricuspid (right AV) Valve
right atrium –> right ventricle - Bicuspid (left AV) (mitral) Valve
left atrium –? left ventricle
What do tricuspid and bicuspid mean?
Tricuspid = 3 cusps of endocardium Bicuspid = 2 cusps of endocardium
What are the names of the Semilunar valves and where are they situated?
- Pulmonary valve
right ventricle –> pulmonary artery - Aortic valve
left ventricle –> aorta
Which blood vessels supply the heart with blood?
Coronary arteries and veins
Describe the position of the heart
- In the mediastinum (between lungs in the thoracic cavity)
- Between ribs 2 and 6
What is the base of the heart called and what is significant about this area?
Apex, where the heartbeat is at maximum intensity
What is the point of maximal intensity?
The point at which the cardiac impulse can be best palpated against the chest wall
What structure divides the two halves of the heart?
Septum
What is the name of the heart covering and what is it?
Pericardium; a sac surrounding the heart
What are the 3 layers of the pericardium and what are their functions?
1 layer = Fibrous pericardium (protects the heart and anchors it to surrounding structures)
2 layers = Serous Pericardium Membranes; Parietal Pericardium (lines interior of fibrous pericardium) and Visceral Pericardium (part of the heart wall - also known as the epicardium)
What are the 3 layers of the heart wall and what are they made up of?
- Epicardium = visceral pericardium
- Endocardium = thin sheet of endothelium that lines the heart chambers
- Myocardium = thick bundles of cardiac muscle tissue twisted into ring-like structures; this is the part that contracts
What is the function of the pericardial sac/ cavity?
Collects serous fluids released by membranes which keeps the heart moist so it can beat without friction
What is the pulmonary circuit?
Right ventricle –> Lungs –> Left atrium
Low pressure
What is the systemic circuit?
Left ventricle –> Body tissues –> Right atrium
High pressure
What is the difference between the right and left walls of the heart?
The wall of the left ventricle is thicker as it needs to pump blood around the whole body
What is cardiac output?
The volume of blood pumped out of the heart from each ventricle in 1 minute
How much of the blood volume does the heart receive?
5%
What is the purpose of the blood that is supplied to the heart?
To nourish and oxygenate the myocardium
Describe the location of the coronary arteries
Branch from the aorta and encircle the coronary sulcus (AV groove)
What are the names of the 4 branches of the coronary arteries?
- Anterior interventricular artery (LEFT)
- Circumflex artery (LEFT)
- Posterior interventricular artery (RIGHT)
- Marginal artery (RIGHT)
How does the blood leave the myocardium?
Its drained by the cardiac veins which empty into an enlarged vessel called the coronary sinus
What is another name for the SAN (Sinoatrial Node) and why?
The ‘pacemaker’ because it initiates the heartbeat
Describe the process of a heartbeat
- Impulses spread across the atria from the SAN and cause them to contract
- Impulses reach the AVN which delays them by 0.1 second to allow the atria to finish contracting
- Impulses spread to the Bundle of His which conducts them to the base of the ventricles
- Purkinje fibres spread the impulses up and out, causing the ventricles to contract from the bottom up
What is the definition of a cardiac cycle?
The chain of events that occurs in one heartbeat, including pressure changes and contractions
Describe the relationship between the sounds that the heart makes
lub = AV valves closing dub = SL valves closing
Outline what happens in atrial systole
- Atria contract together
- Ventricles are relaxed
- Pressure is high in atria than ventricles
- Blood flows into ventricles through AV valves
Outline what happens in ventricular systole
- Atria relax
- Pressure is higher in ventricles than atria
- AV valves close
- Ventricles contract
- SL valves open and blood flows out of the heart
Outline what happens in Diastole
- Heart is relaxed
- SL valves close
- Pressure is higher in blood vessels and atria than ventricles
- AV valves open
- Blood slowly flows into the ventricles
- Cycle repeats
What does ECG stand for and what does it measure?
Electrocardiograph
Measures the electrical currents in the heart
What are the 3 parts of an ECG monitor?
Sensor, Transducer and Monitor
What does the P wave represent?
Atrial depolarisation
impulses from SAN sweep over atria
What do the QRS waves represent?
Ventricular Depolarisation
impulses spreading through the AV node, Bundle of His and Purkinje fibres and cause the ventricles to contract
What does the T wave represent?
Ventricular Repolarisation
relaxation of ventricular muscle
What is stroke volume?
The volume of blood pumped out of the heart by each ventricle with each heartbeat
What is heart rate?
The number of times the heart beats per minute
What is the equation for cardiac output? (include units)
Cardiac Output (ml) = Heart Rate (bpm) x Stroke Volume (ml/beat)
Name 4 factors that increase heart rate
- Trauma
- Low/ high blood pressure
- Hormones
- Exercise
Name a factor that decreases heart rate
Decreased blood volume
What system allows the heart rate to increase and decrease?
Sympathetic Nervous System increases HR
Parasympathetic Nervous System decreases HR
What is venous return?
Volume of blood which returns to the heart
What factors affect venous return?
Exercise increases VR
Blood loss decreases VR
What is blood pressure?
The pressure exerted on the walls of the blood vessels as blood passes through them
What is peripheral resistance?
The amount of friction blood encounters as it flows through blood vessels
Name 4 factors that increase blood pressure?
- Decreased blood volume
- Exercise
- Chemicals (e.g. nicotine)
- Increased blood viscosity
What are the names of the 3 layers that make up the blood vessel walls?
- Tunica externa
- Tunica media
- Tunica intima
What is the tube through which the blood flows called?
Lumen
What are the differences between the walls of arteries and veins?
- The tunica media and externa are much thicker in arteries than veins
- Arteries also have an internal elastic lamina (between tunica intima and media) and an external elastic lamina (between tunica media and tunica externa)
What is the tunica intima made up of?
Endothelium and loose connective tissue
What is the tunica media made up of?
Smooth muscle and elastic fibres
What is the tunica externa made up of?
Collagen fibres
Give 4 characteristics of veins
- Contain valves (except hepatic, superior vena cavae etc)
- Carry deoxygenated blood (except pulmonary)
- Split into smaller branches called venules and then capillaries
- Have a larger lumen than arteries to carry more blood and reduce resistance
Outline the blood flow of deoxygenated blood
Capillaries –> Venules –> Veins –> Vena Cavae
Give 2 characteristics of arteries
- Carry oxygenated blood (except pulmonary)
2. Split into smaller branches called arterioles and then capillaries
What is mean arterial pressure?
Average pressure in arteries (mmHg)
Outline the blood flow of oxygenated blood
Aorta –> Arteries –> Arterioles –> Capillaries
Give the equation for Mean Arterial Pressure (include units)
MAP (mmHg) = diastolic pressure + ((systolic pressure + diastolic pressure) divided by 3)
e.g. BP = 120/90
90 + ((120-90) divided by 3) = 100mmHg
How is MAP significant in pregnancy?
If pregnant women have a MAP over 120mmHg they can have a placenta eruption and there is a risk of them having a stroke
What are the formed elements in blood?
Erythrocytes
Leucocytes
Platelets
What is the function of salt in blood plasma?
Maintains osmotic balance, pH buffering and regulation of membrane permeability
What is the function of plasma proteins?
Maintain osmotic balance, pH buffering, blood clotting, defence and lipid transport
What are the 3 types of leucocytes?
- Lymphocytes (produce antibodies) - agranulocyte
- Monocytes (undergo phagocytosis) - agranulocyte
- Granulocytes:
- neutrophils
- eosinophils
- basophils
What is haemostasis?
Stopping a flow of blood (e.g. coagulation)
What is a granulocyte?
White blood cell with secretory granules in its cytoplasm
What is an agranulocyte?
White blood cell with a one-lobed nucleus
