L3&4 - Cardiac system

Heart location

Located slightly to the left in the chest cavity

Artery

Blood vessels that transports oxygenated blood under high pressure away from the heart towards distal tissues and extremities

Vein

Blood vessels which transports deoxygenated blood under low pressure away from the distal tissues/extremities and towards the heart

Left lung

is slightly longer and narrow to accommodate the cardiac notch

Four key areas of the heart

Right and Left atrium, Right and left Ventricle

A

Superior Vena Cava - largest vein in the body that carries oxygen-poor blood into the right atrium from the upper parts of the body

J

Inferior Vena Cava - largest vein in the body that carries oxygen-poor blood into the right atrium of the heart from lower parts of the body

E

Left Pulmonary Artery

L

Right Pulmonary Artery 

Pulmonary Artery

blood vessels that carry oxygen-poor blood from the right side of the heart to the lungs for oxygenation

B

Aorta - the biggest and largest artery of the body that carries oxygen-rich blood from the left ventricle of the heart to the body

Septum

the muscular wall that separates the left and right sides of the heart

C

Right and Left Atrium

Left Atrium

the upper left chamber of the heart that receives oxygen-rich blood from the lungs via the pulmonary veins before pumping it to the left ventricle

Right Atrium

the upper right chamber of the heart that receives oxygen-poor blood from the body through the inferior and superior vena cava

D

Pulmonary Valve - the flaps that control the flow of blood between the right ventricle and the pulmonary artery

What happens when the ventricle contracts

the pulmonary valve opens allowing blood to pass into the pulmonary artery

What happens when the ventricle relaxes

the pulmonary valve closes preventing the back flow of blood from the pulmonary artery to the right ventricle

F

Left Pulmonary Veins

Pulmonary Vein

the blood vessel that carries oxygen-rich blood from the right ventricle of the heart to the lungs

H

Right and left ventricles

Left Ventricle

the thickest and lower chamber of the heart that pumps blood through the aortic valve into the aorta

Right Ventricle

the right lower chamber of the heart that pumps blood into the pulmonary artery

Two parts of the Pericardium

Fibrous Pericardium, Parietal layer of serous Pericardium

I

Papillary Muscles - extensions of the myocardium in the ventricles to which the chordae tendineae attach

K

Chordae Tendineae - string-like extensions of tough connective tissue that extend from the flaps of the tricuspid (atrioventricular) valves to the by papillary muscles

G

Tricuspid/Right atrioventricular valve - the flaps between the right atrium and the right ventricle composed of three leaf-like parts and prevents the backflow of blood from the ventricle to the atrium

Tricuspid Valve

right atrioventricular valve

Bicuspid/Mitral Valve

left atrioventricular valve between the left atrium and the left ventricle that prevents the backflow of blood from the ventricle to the atrium 

Blue star is Semi Luminar Valves (aortic and pulmonary) 

valves located at the base of the pulmonary trunk and at the base of the aorta and stops backflow/too much blood from rushing into them (and therefore into the lungs/body)

A

Tricuspid Valve (atrioventricular)

B

Pulmonary Valve

C

Mitral/Bicuspid Valve (atrioventricular)

D

Aortic Valve

Low friction environment in heart

if this is not upheld it may cause heat, pain and eventually destruction of tissue of the heart

The main layers of the heart

endocardium, myocardium, epicardium, pericardium

Endocardium

the inner thin layer of the heart made of endothelial tissue which provides a smooth inner surface for the heart so there is minimal friction as blood moves through chamber

Myocardium

The largest and thickest layer of heart that is the middle layer made of cardiomyocytes (cardiac muscle cells) with the ability to contract, generate pressure and move blood around our cardiovascular system

Cardiac Muscle Cells

striated cells with one nucleus and a branching structure that forms the walls of your heart, moving involuntarily its contractions send blood around the circulatory system

Epicardium

The dense, tough and protective outer layer of the heart made up of connective tissue also the inner layer of the pericardium 

Mediastinal

adjective to describe anything related to the mediastinum which is the space in the chest between the lungs.

Pericardium/Pericardial Sac

the membrane that surrounds and protects the heart, separating it from other mediastinal structures and keeping it in place

Pericardium/Pericardial Sac function

it creates a sac around the heart that can fill with fluid in the pericardial cavity, creating lubrication between the outside wall of the heart and its external environment to avoid friction

Pericardial cavity

the cavity surrounding the heart filled with a lubricating seroud fluid that reduces friction as the heart contracts

Myocardial Infarction

a complete and sudden obstruction in blood flow to a coronary artery causing the death of an area of tissue due to interrupted blood supply, commonly known as a heart attack

Coronary Heart Disease

chronic condition when blockages of the coronary arteries happen over time

Journey of blood

Blood enters the right atrium heart through superior/inferior vena cava, then pumped down into right ventricle and out through the pulmonary artery to our lungs. Newly oxygenated blood is then pumped back to the heart through the pulmonary veins entering the left atrium and pushed down to the left ventricle, a high level of pressure is generated to force blood out through the aorta into the rest of the body’s systems

Valve Issues

Stenosis and Regurgitation

Stenosis

valves have become too stiff and do not properly open, causing resistance to blood flow in the cardiovascular system

Regurgitation

valves have become damaged and do not close properly allowing backflow of blood, limiting efficiency of system and can disrupt normal blood flow

1-5

Pulmonary circuit 

6-10

Systemic circuit

Blood pressure

the force on the blood vessels walls by the blood within them 

Blood is under higher pressure

when blood is leaving the heart through arteries as necessary as blood is being forced further through the body

Blood is under lower pressure

when blood returns to the heart in veins

Pulse variations 

regular, irregular, regularly irregular

Character

how strong the pulse is e.g. high/low volume, weak/thready

Cardiac cycle

period of time between the onset of atrial contraction (atrial systole) and ventricular relaxation (ventricular diastole)

Systole

period of time when the heart muscle is contracting

Diastole

period of time when the heart muscle is relaxed and the chambers fill with blood

Cardiac output

volume of blood pumped out of the ventricles per minute (heart rate x stroke volume)

Stroke Volume

the volume of blood ejected from the left ventricle per beat

Factors affecting the stroke volume

contractility; preload; afterload

Contractility 

the strength of the myocardial contraction at any given preload - increased by things like exercise

Example of Vascular occlusive disease

Peripheral Arterial Disease (PAD)

PAD

caused by fatty plaque build up in arteries narrowing them and reducing blood flow affecting the contractility of the heart

Stroke volumes relationship with contractility

increasing contractility increases stroke volume

Preload (end diastolic volume)

the degree of stretch of the ventricles before it contracts

Cause of preload

blood returning to and filling the heart - the more the heart fills with blood in the diastole the greater the contractile force in systole

Preload relationship with stroke volume

increased preload increases stroke volume

Afterload

the pressure that must be exceeded before ejection of blood from the ventricles can occur 

Relationship between afterload and stroke volume

increase in afterload decreases the stroke volume

A

Pulmonary Circulation

B

Systemic Circulation

C

Systemic Veins

D

Pulmonary Arteries

E

Pulmonary capillaries

F

Pulmonary veins

G

System arteries

H

Systemic capillaries

I

Oxygen rich blood

J

Oxygen poor blood

ECG

Electrocardiogram records the electrical activity of your heart to check its rhythm and rate

Depolarisation

when the heart cells send an electrical signal to contract

A

P-Wave - Sino-atrial node firing impulse (depolarisation)

B

QRS Complex - Atrio-ventricular node firing impulse (depolarisation) right and left ventricle contracting but only left visible (systole)

C

T-wave - ventricular repolarisation when the heart is refilling with blood and there are no electrical impulses (diastole)

VF

Ventricular Fibrillation - cardiac arrest with irregular uncoordinated rippling contractions of ventricles with no effective cardiac output

Potential side effects  and treatment of ventricular fibrillation 

loss of cerebral perfusion, unconsciousness and death treat by defibs (shock)

Atrial Fibrillation

a common arrythmia that means the heart rhythm is irregular/unsteady or rapid, common in adults and may alter a patients pulse

VT

Ventricular tachycardia - occurs when the lower chamber of the heart beats too fast to pump well and the body doesn't receive enough oxygenated blood

Pulseless Electrical Activity - (PEA)

cardiac arrest in which electrical activity is present but not strong enough to pump blood effectively around the body usually caused by hypoxia in which

Flat line

Asystole in which there is a sudden cardiac arrest and blood flow to organs stops - ROSC less likely to be achieved OHCA

ROSC

Return of spontaneous circulation