Cardiovascular anatomy

Anastomoses

-A connection between two blood vessels - Serve as a back up route for blood flow if one link is blocked or otherwise compromised.

Mitral regurgitation: Cause? What happens?

-Cause often unable to be identified "idiopathic", probably a viral infection in most cases -infected muscle fibres attacked by lymphocytes, many die, others left weakened. - Left ventricle most affected due to high pressure -Left ventricle dilates, surviving fibres lengthen. -Fibrous ring support mitral valve stretches -Mitral valve flaps no longer meet during systole, causing mitral regurgitation.

Myocardial infarction

-Heart attack -Blood stops flowing to part of heart, results in damage, then death

Cardiac tamponade

-Pressure on the heart muscle when the pericardial space fills up with fluid. -ie compression of the heart by an accumulation of fluid in the pericardial sac.

Varicose veins

-Veins stretch -Valves dont meet -Pools of blood.

Aortic stenosis

-abnormal narrowing of the aortic valve -increased pressure in the LV -muscle thickens -higher pressure needed in LA -higher pressure needed in blood vessels of lungs

LV hypertrophy

-enlargement and thickening of walls -can be caused by increased blood pressure, aortic stenosis etc

Rheumatic fever

-inflammatory diseases that can occur after a group A streptococcal infection eg a sore throat. -can result in heart disease

Draw a flowchart showing the correct conduction of an action potential through the heart, with speeds and the effect it produces at each point.

1. SA Node/atrial muscle. (SA node is pacemaker of the heart, sends wave of excitation through the atrial muscle), slow - 0.5 ms. result= atrial contraction. 2. AV node. (detects wave of excitation). Conducts very slowly - 0.05m/s, result= 100ms delay between atria contracting and ventricles contracting 3. AV bundle (bundle of his) 4. Right and Left bundle branches 5. Purkinje fibres 6. Ventricular cardiac muscle 3, 4,5 and 6 have fast conduction= 5m/s result: event contraction of ventricles (systole)

What happens to mean pressures in heart with mitral regurgitation and what does this result in?

1. To maintain cardiac output, the LV must pump a greater volume (its trying to pump to 2 areas, LA and Aorta) 2. Assuming the heart rate remains the same, LV volume at the end of filling must increase. 3. in order to fill the ventricle, the LA has to work harder. 4. LA pressure increases. 5. Pulmonary venous pressure increases 6. Pulmonary capillary pressure increases 7. Pulmonary capillary leakage increases. 8. Lungs are heavier and wetter. 9. Lungs more rigid. 10. Breathing requires more muscular work (dyspnoea)

Thickness of LV wall

10-15mm

Pressure in LV

120mmHg

How many cusps does the mitral valve have?

2

How many valves are in the heart?

2 inlet and 2 outlet

Thickness of LA wall

2-3mm

Thickness of RA wall

2-3mm

Pressure in RV

27mmHg

How many cusps does the aortic outlet have?

3

How many cusps does the pulmonary outlet have?

3

How many cusps does the tricuspid valve have?

3

Thickness of RV wall

4-5mm

Total blood volume?

5L (output per pump, 5L per minute)

Pressure in RA

5mmHg

Pressure in LA

8mmHg

At anyone time what percentage of blood sits in the pulmonary circuit, systemic circuit and in the heart itself?

9% in the pulmonary circuit 7% in the heart 84% in the systemic circuit (of which 3/4 sits in veins)

What is the pericardium? What is it made out of?

A "double walled bag" that encloses the heart. Both the inner and outer wall are made of a single layer of squamous mesothelial cells. The two walls are continuous where the great vessels enter and leave the hear. The inner wall (visceral pericardium) adheres to the heart and forms the hearts outer surface (epicardium). The outer wall of the pericardium (parietal pericardium) lines a tough fibrous sac (fibrous pericardium)

Atherosclerosis

A disease of the arteries, characterised by deposition of fatty material on their inner walls.

Orientation of the heart, In the anterior view: About.. of the mass lies to the right and ... of the mass lies to the left of the midline of the body

About 1/3 of the mass of the heart lies to the right and 2/3 of the mass lies to the left of the midline of the body

LV Dilation and dilated cardiomyopathy

According to the Law of La place, the pressure the ventricle can generate is inversely proportional to radius. During dilated cardiomyopathy the radius has increased, therefore the pressure it can generate is less, so it is harder to eject blood from the ventricle. The wall thickness also stays the same, yet volume increases, making it even harder to eject the blood.

Label the following diagram and explain what each part does. Which view is this?

Answer on next card

What are the two outlet valves? What sort of valves are they?

Aortic valve and pulmonary valve. They are semilunar valves that exit the ventricle.

Coronary arteries

Arise from the aorta just downstream from the aortic valve and supply muscle of the heart. They are muscular arteries

A fibrous skeleton is present where?

Around the mitral valve, and aortic valve (high pressure inlet and outlet), and partially around the tricuspid valve (lower pressure inlet)

Veins go.. Arteries go..

Arteries away from the heart veins towards towards the heart

In the pulmonary circuit, arteries carry... and veins carry..

Arteries carry deoxygenated blood. Veins carry oxygenated blood

In the systemic circuit, arteries carry... and veins carry...

Arteries carry oxygenated blood. Veins carry deoxygenated blood.

What are the 4 problems associated with coronary arteries?

Atheroma -> Degeneration of the walls of the arteries caused by accumulated fatty deposits and scar tissue. Ischemia -> When myocardium supplied by a diseased artery runs low on oxygen Angina -> chest pain caused by myocardium lacking oxygen Infarction -> Death of a local area of myocardium.

What is special about blood flow to and from the gut?

Blood to the gut is oxygenated, at the gut it becomes deoxygenated, but nutrient rich, it then travels through the hepatic portal vein to the liver, were the nutrients are taken, leaving just the deoxygenated blood to go back to the heart and lungs.

Angina

Chest pain due to lack of O2

Cardiomyopathy

Disease of the heart muscle causing the heart muscle to become enlarged, thick or rigid

Cardiac veins

Drain deoxygenated blood from the myocardium to the right atrium.

What is present where the fibrous skeleton is absent?

Fatty connective tissue.

Poiseuilles law

Flow is proportional the fourth power of radius

Venule Function: Structure:

Function: Low pressure vessels which drain capillary beds. During infection and inflammation, venules are the site where white blood cells leave the blood circulation to attack bacteria in the tissue alongside. Structure: Small venules have the usual endothelium plus a little connective tissue. Larger ones have a single layer of smooth muscle. Highly variable in size.

Elastic artery Function: Structure:

Function: They are very large arteries near the heart which have elastic walls. During systole they expand to store the bolus of blood leaving the ventricle, then during diastole they push blood out into the arterial tree by elastic recoil. Thus they smooth the pulsatile flow of blood leaving the ventricles. Structure: Made of many thin sheets of elastin in the middle tunic, about the width of a finger

Vein Function: Structure:

Function: Thin walled, low pressure vessels which drain blood back tot e atria (except portal veins which drain blood to another capillary bed). Their walls are thin and soft, they stretch easily (ie very compliant). A small change in venous blood pressure causes a large change in venous volume. Therefore veins act as a reservoir which stores blood (64% of blood in veins and venules compared to 13% in systemic arteries and arterioles). Structure: Similar to muscular artery but much thinner walled for their size (much less muscle and CT). Larger veins (esp in legs) have valves which prevent backflow.

Capillary Function: Structure:

Function: Tiny vessels which are thin walled to allow exchange of gases, nutrients and wastes between blood and the surrounding tissue fluid. Blood flow is slow to allow time for exchange to occur. Capillaries are leaky vessels; plasma escapes (but not blood cells). Most of the lost plasma is immediately recovered due to an osmotic gradient. Structure: Diameter just wide enough to admit one red blood cell. The capillary wall is a single layer of endothelium (with an external basement membrane). No smooth muscle is present within the wall, therefore no ability to adjust diameter, and no connective tissue.

Arteriole Function: Structure:

Function: To control blood flow into capillary beds. They have a thicker muscular wall relative to their size than any other blood vessel. These are the vessels in the circulation where the greatest pressure drop occurs, and where there is greatest resistance to flow. The degree of constriction of arterioles throughout the body determines Total peripheral resistance, which in turn affects mean arterial blood pressure. Structure: Between one and three layers of circular smooth muscle wrapped around the vessel in the middle tunic. Vessel has width of a single hair.

Muscular artery Function: Structure:

Function: To distribute blood around the body at high pressure (and lungs at medium pressure). Rate of blood flow is adjusted by using smooth muscle to vary the radius of the vessel. Flow is proportional to the fourth power of radius. Flow = radius^ 4 (poiseuilles law) therefore a small change in radius has a large impact on flow rate. Structure: Many layers of circular smooth muscle wrapped around the vessel in the middle tunic, about the width of a pen. Most common.

Order of blood vessels (start at the heart)

Heart Elastic artery Muscular artery Arteriole Capillary Venule Vein

Label the following diagram and explain what each part does. Which view is this?

I= Superior vena cava J= Aorta K= Pulmonary Trunk (carriers deoxygenated blood from the heart to the lungs -pulmonary circuit) L= Right auricle (appendage of the RA to increase its capacity. M= Right ventricle N= Left ventricle (pumps oxygenated blood to the body tissues. O= inferior vena Cava P= Right atrium

Orientation of the heart, In the anterior view: The apex of the heart points...., ... and to the ...

Inferiorly, anteriorly and to the left

Inlets must be of ... diameter to let blood in at ... pressure

Inlets must be of large diameter to let blood in at low pressure

Answers to labelling the heart

Posterior view A = Aorta (carries oxygenated blood from the heart to the body tissues) B= Left Atrium (reservoir for oxygenated blood returning to the heart from the lungs) C= Inferior left pulmonary vein (carries freshly oxygenated blood from the lungs to the heart) D= Superior Vena Cava (carries deoxygenated blood from the head and arms to the RA) E= Right pulmonary artery (carries deoxygenated blood from RV to the right lung) F= Right atrium (reservoir for deoxygenated blood returning to the heart from the body) G= Inferior vena cava (carrier deoxygenated blood from abdomen and legs back to RA) H= Right Ventricle (pumps deoxygenated blood to the lungs)

Ischemia

Restriction of blood flow to areas resulting in lack of oxygen

Answers to labelling the heart

Right Lateral view. I= Superior vena cava J= Aorta K= Pulmonary Trunk (carriers deoxygenated blood from the heart to the lungs -pulmonary circuit) L= Right auricle (appendage of the RA to increase its capacity. M= Right ventricle N= Left ventricle (pumps oxygenated blood to the body tissues. O= inferior vena Cava P= Right atrium

What happens during Ventricular ejection?

Systole continues, but now ventricular pressure exceeds aortic pressure so the aortic valve cusps open quietly. Blood leaves the ventricle. Because blood is ejected into the aorta faster than it can run off into the distributing arteries, the pressure in the ventricle and aorta continues to rise steeply; but later in this phase the rate of ejection falls below the rate of run off, and aortic and ventricular pressures level off and then begin to decrease. Aortic pressure: 80mmHg - 120mmHg- 100mmHg (just a little below LV so probably 78 ish, 119 ish, 100 ish) LV pressure: 80mmHg - 120mmHg- 100mmHg LA pressure: -2mmHg - 5mmHg LV volume: 120mL - 60 mL Aortic valve open, Mitral valve closed

Mitral regurgitation and dilated cardiomyopathy

The LV is enlarge and the fibrous ring carrying the mitral valve has stretched so that the valve opening is dilated and the mitral valve cusps no longer meet when the valve attempts to close "mitral incompetence". During systole, blood regurgitates from the left ventricle into the left atrium. (Increase in atrial pressure during ventricular ejection due to mitral regurgitation)

Explain the difference in pressure drop between the systemic and pulmonary circuits

The drop in pressure across the systemic circuit is much greater than that across the pulmonary circuit. In the systemic circuit the drop is from LV (120mmHg) to RA (5mmHg) = 115mmHg, whereas in the pulmonary circuit, the drop is only 19mmHg (from RV to LA). This reflects the greater resistance in the systemic circuit

Relate the shape and wall thickness of the Atrium to the maximum blood pressure within it

The left and right atria have about 2-3mm average muscle thickness are are reservoirs for the ventricles, with auricles that increase their capacity. The atria do not contract strongly compared to the ventricles producing 5mmHg in the RA, and 8mmHg in the LA, which is enough to support the rapid refilling of the ventricles after each ventricular contraction.

What happens during atrial contraction?

The left atrium contracts to complete the filling of the ventricle. The rise in atrial pressure is small, for two reasons. Firstly the atrial muscle is small and secondly there are no valves where the pulmonary veins enter the atria to prevent back flow Aortic pressure: 90mmHg- 80mmHg LV pressure: < 5mmHg LA pressure: Around 8mmHg LV volume: 90/100mL (80% full)- 120mL (full) Aortic valve closed, Mitral valve open.

Relate the shape and wall thickness of the Left ventricle to the maximum blood pressure within it

The left ventricle is shaped like a hollow cone, which allows all sides to come in and up together in an efficient contraction, and it has the thickest cardiac muscle (10-15mm). Together these features allow it to produce 120mmHg aortic blood pressure during contraction.

Relate the shape and wall thickness of the Right ventricle to the maximum blood pressure within it

The right ventricle is cresent shaped around the left ventricle and has thinner walls resulting in a less forceful contraction that produces 27mmHg pressure, which is sufficient to problem blood to the lungs

What happens during Isovolumetric ventricular contraction?

The ventricle begins to contract. Blood within it lifts backwards towards the atrium and the mitral valve closes (first heart sound). Ventricular pressure is still below that in the aorta and so the aortic valve remains closed. For this brief period of rising pressure the ventricle is isolated from the rest of the circulation, with both its inlet and outlet valves closed. Aortic pressure: 80mmHg LV pressure: 5mmHg-80mmHg LA pressure: Around 5mmHg LV volume: 120mL Aortic valve closed, Mitral valve closed First heart sound *lub*

What happens during isovolumetric ventricular relaxation?

The ventricle relaxes, as it does ventricular pressure drops suddenly, flow reverses in the aorta, and the aortic valve closes (2nd heart sound) as blood tries to reenter the ventricle. The mitral valve is closed because ventricular pressure, although falling, still exceeds atrial pressure. For a brief period the ventricle is again isolated from the rest of the circulation. When this phase is completed the heart re-enters the stage of ventricular filling Aortic pressure: 100mmHg - 105 mmHg LV pressure: 100mmHg- 5mmHg LA pressure: 5mmHg LV volume: 60mL Aortic valve closed, Mitral valve closed Second heart sound "dub"

How do veins stop backflow?

They have bicuspid valves. As leg muscles alongside the vein alternately contract and relax during walking, the system acts as a venous pump which returns blood to the right atrium

What happens during ventricular filling?

This commences when pressure in the ventricle drops below that in the atrium. The mitral valve opens quietly and blood enters the ventricle. The ventricle will fill to about 80% of its capacity during this phase. Aortic pressure: 100mmHg- 90mmHg LV pressure: < 5mmHg LA pressure: Around 5mmHg LV volume: approx 80mL - 90/100mL (80% full) Aortic valve closed, Mitral valve open.

what are the 5 parts of the cardiac cycle

Ventricular filling Atrial contraction Isovolumetric ventricular filling ventricular ejection Isovolumetric ventricular relaxation

What happens to atrioventricular valves when ventricles are relaxed vs when they are contracting?

When the ventricles arent contracting, pressure in the atria exceed the pressure in the ventricles, and the papillary muscles are relaxed (not pulling on the chordae tendinae) so the cusps are slack. Since blood always flows from high to low pressure, blood will enter the ventricles. The ventricles with then contract and increase the pressure. When this happens the high pressure pushes the cusps of the inlet valves upwards until their edges meet and close preventing back flow into the atria. Papillary muscles then contract and pull the chordae tendinae taught, stopping the valves from opening into the atria.

What happens to semilunar valves when ventricles are contracting vs when they are relaxed?

When ventricles contract pressure in the ventricle exceeds the pressure in the arteries. Blood is pushed upwards and the cusps of the valve passively open allowing ejection of blood into the arteries. However when the ventricles relax, pressure in the arteries exceeds that in the ventricles causing back flow of blood into ventricles .The back flow fills the cusps with blood causing the valves to shit, preventing blood going back into the ventricles.

Orientation of the heart, In the anterior view: The base of the heart is the most ...

superior

Orientation of the heart, In the anterior view: The left border is formed mainly by ...

the left ventricle

Orientation of the heart, In the anterior view: The right border of the heart is formed mainly by ...

the right atrium

Orientation of the heart, In the anterior view: The inferior border is formed mainly by ...

the right ventricle

What is special about the liver?

It is dual input

What does the fibrous skeleton do in the heart?

It means the wave of excitation can only leave the atria through the AV node.

The Pulmonary circut

Just consists of the lungs. It has medium resistance and medium pressure.

What are the 2 inlet valves? What sort of valves are they?

Mitral (bicuspid) and tricuspid. They are atrioventricular valves.

Components of an atrioventricular valve

Mitral valve (cusp/flap) made of fibrous CT Chordae tendinae (tendinous cord) Papillary muscle

Why is dilated cardiomyopathy and mitral regurgitation a vicious cycle?

Once mitral regurgitation has begun to occur, the LV must pump a greater volume of blood to achieve the normal volume out of the aorta (As some is lost to regurgitation). This volume increase will further increase LV dilation, which in turn will further stretch the mitral valve and therefore allow greater regurgitation. This forms a cycle of worsening disease, which is either repaired by valve replacement (if detected early) or heart transplant or eventually results in the LV failing to maintain sufficient cardiac output, causing death.

3 tunics of arteries

Outer tunic (tunica externa) Middle tunic (tunica media) Inner tunic (tunica interna/intima)

Outlets must be of.. diameter to let blood out at ... pressure

Outlets must be of small diameter to let blood out at high pressure

Descrive the travel of blood around the body, starting with oxygenated blood from the lungs.

Oxygenated blood from the lungs, travels via the pulmonary veins, to the left atrium, through the inlet (mitral) valve, into the left ventricle, through the outlet (aortic) valve), through the systemic arteries, arterioles, capillaries, to organs, through the venules, and veins, into the superior/inferior vena cava, into the right atrium, through the inlet valve (tricuspid valve), intot he right ventricle, through the outlet valve (pulmonary valve), into the pulmonary arteries and back to the lungs.

Pericardium Peri= Cardium =

Pericardium Peri= surrounding Cardium = heart

Why are there 2 "dubs"

because of the differences in pressure, the aortic valve closes slightly before the pulmonary valve closes causing turbulence at slightly different times.

The systemic circuit

is the circuit that goes to all the organ systems except the lungs. It has High Resistance and High Pressure