Cardiovascular System Flashcards
Where does the heart lie?
In the mediastinum
What is the mediastinum?
a compartment that runs the length of the thoracic cavity between the pleural sacs of the lungs
What lies on the superior, anterior, inferior and posterior sides of the heart?
Superior: connective tissue of the neck
Anterior: Chest wall behind the sternum
Inferior: Diaphragm
Posterior: thoracic spine
Where is the superior edge of the heart situated?
beneath the 2nd rib?
Where is the apex of the heart situated?
in the 5th intercostal space
What is the Fossa Ovalis/Foramen Ovale and what are the potential complications?
hole in the heart that closes after birth - in the womb deoxygenated and oxygenated blood mixes
if this hole does not close then the following may occur: shortness of breath, cyanosis
What is the Ductus Arteriosis?
Connection between the aorta and the pulmonary artery which should also close after birth.
How is the heart divided?
by the intraventricular septum
Which ventricle has the thicker wall?
left ventricle
Which side of the heart receives oxygenated/deoxygenated blood?
oxygenated: left
deoxygenated: right
Frank Starling’s Law
the greater the preload on cardiac muscle fibres before they contract the greater the force of contraction during systole.
Atria pushes as much blood as possible down to the ventricles so that the ventricles are under a large amount of pressure, when the ventricles then contract they forcefully push blood out of the aorta
What would valve regurgitation sound like?
a trickling sound
Aortic valve
between the left ventricle and aorta
listen in the right 2nd intercostal space
Pulmonary valve
between the right ventricle and pulmonary artery
listen in the left 2nd intercostal space
Tricuspid valve
between right atrium and right ventricle
listen in the left 4th intercostal space
has 3 cusps
Bicuspid Valve
between left atrium and left ventricle
listen in the 5th intercostal space
has 2 cusps
Where is Erb’s point?
3rd intercostal space on the left
What structure prevents the valves becoming inverted
Chordae Tendineae
Main heart blood vessels and where they transport blood to and from
Aorta: from left ventricle to rest of the body
Vena Cava: from rest of the body to right atrium
Pulmonary Artery: from right ventricle to lungs
Pulmonary Veins: from lungs to left atrium
Flow of blood on the left hand side
Vena cava - right atrium - tricuspid valve - right ventricle - pulmonary valve - pulmonary artery
Flow of blood on the right hand side
Pulmonary veins - left atrium - mitral valve - left ventricle - aortic valve - aorta
systole v diastole
systole - contraction
diastole - relaxation
Atrial Diastole
Right: deoxygenated blood enters right atrium from vena cava
Left: oxygenated blood enters left atrium from pulmonary veins
Atrial systole/ventricular diastole
Right: blood flows from right atrium into right ventricle via tricuspid valve
Left: Blood flows from left atrium into left ventricle via bicuspid valve
Ventricular Systole
Right: blood leaves via pulmonary semi lunar valves into the pulmonary artery
Left: blood leaved heart via aortic semi lunar valve into the aorta
Layers of the heart from outer to inner
Pericardium
Myocardium
Endocardium
Pericardium
outermost layer
2 layers
pericardial cavity contains serous fluid to prevent friction
What is pericarditis?
a viral or bacterial infection causing inflammation of the pericardium causing adhesions that join the layers together
Myocardium
middle layer
muscle fibres organised in planes and separated by connective tissue
left ventricle is thicker
Endocardium
inner layer
epithelium and connective tissue (high in elastin and collagen)
contains blood vessels and specialised cardiac fibres called purkinje fibres
What does the left main coronary artery split into?
into 2 vessels
circumflex and left anterior descending
Sino Atrial Node
natural pacemaker
found in right atrium
electrical impulses spread through atria causing them to contract - setting rate and rhythm of the heart
What allows action potentials to spread through cardiac muscle?
intercalated discs
Atrioventricular Node
base of interatrial septum
slows impulses before they reach the septum
allows atria to empty before ventricular systole
Bundle of His
branches down into the interventricular septum and splits into left and right bundle branch
distributes electrical impulses
Purkinje Fibres
emerge from bundle branches
impulses go to myocardial cells causing ventricular systole
Average length of cardiac cycle
0.8 seconds
Stroke volume
Volume of blood expelled from the heart in every beat
Heart Rate
number of beats per minute
Cardiac Output
volume of blood expelled per minute
Arteries Overview
Blood away from heart
lots of smooth muscle - withstand pressure
elasticated - help push blood forward
Arterioles and Venules
Arterioles connect arteries and capillaries and venules connect veins and capillaries
Capillaries overview
site of exchange of nutrients and waste
squamous epithelium is 1 cell thick
Veins Overview
blood towards the heart
large lumen to support volumes of blood
less elastic tissue and muscle than arteries
valves to prevent backflow of blood
If valves do not work properly what can occur?
Varicose veins
Layers of a blood vessel
Tunica Intima: single layer of epithelial tissue
Tunica Media: smooth muscle - control of diameter
Tunica Externa: white fibrous connective tissue
What part of the brain controls the cardiovascular system
Medulla Oblongata
Plasma
water, plasma proteins and other solutes
Transports RBCs, antibodies and hormones
helps maintain blood pressure
carries clotting proteins
Thermoregulation
Red blood cells
biconcave shape, no nucleus
contains haemoglobin
flexible
White blood cells
5 different types
2 principle types: granulocytes, agranulocytes
combat inflammation and infection (neutrophils and macrophages do this through phagocytosis)
Eosinophils combat the effect of histamine in allergic reactions
can migrate out of vessels
Platelets
form clots to stop bleeding
fatty deposits = platelets get caught = clots
can also engulf viruses
How does an MI occur
unhealthy lifestyle choices/hereditary issues = atherosclerosis
plaque breaks off (atheroma) and occludes coronary arteries
prevents blood flow to that part of the heart
lack of oxygen to myocardial cells = ischaemia = cell death
