Cardiovascular Flashcards
Cardiac output can be defined as…..
stroke volume x heart rate
Cardiac output =
the amount of blood pumoed by the heart in 1 minute
What is another name for the pacemaker of the heart?
SA node
What shape is the heart and what size is it roughly?
cone shaped
about the size of your fist
WHeres does the heart sit?
within the mediastinum
location of the heart is….
slightly left of the midline
What are the lateral, posterior, anterior and inferior borders of the heart?
Lateral = lungs Posterior = Vertebral column Anterior = Sternum Inferior = Diaphram
How many chambers are there in the heart?
4
2x atria
2x ventricles
What are the left and right atria seperated by?
the interatrial septum
What are the left and right ventricles seperated by?
interventricular spetum
What are valves?
Prevents the backflow of blood
How many valves are there?
4
2 each
What are the valves called?
bicuspid and tricuspid
aortic and pulmonary
Biscuspid and tricuspid are what kind of valves?
Atrioventricular valves
Aortic and pulmonary are what kind of valves?
Semilunar valves
What is the overal function of the heart?
Pumps deoxygenated blood into the lungs and pumps Oxygenated blood to the body.
What is the mediastinum?
it is what is found in the midline of the thorax.
What is the pericardium?
a layer that surrounds the heart.
What are the layers of the pericardium called?
Fibrious layer Parietal layer ( outer serous layer) Visceral layer (inner serous layer)
What is the space between the heart and the pericardium called?
The pericardial cavity
What is the heart made up of?
Myocardium
Endocardium
Epicardium (also known as visceral layer)
What is in the percardial cavity and whats its function?
Contains fluid
and allows lubrication of the heart so the heart can expand when it beats.
What are the main arteries involved with the heart?
Aorta Pulmonary arteries Left Subclavian Left common Carotid Brachiocephallic
What are the main veins involved with the heart?
SVC
IVC
Pulmonary veins
What is the main difference between the TRIcuspid valve and BIcuspid valve?
TRIcuspid has three pappilary muscle attachments via chordae tendaniae
and the other one has 2
What is chordae tendinae?
referred to as the heart strings.
It attaches to pappilary muscles which allows contraction and also allows the heart to open and close.
What is the blood flow of the heart?
- blood comes into the SVC + IVC
- Then right atrium through the TRICUSPID valve
- into the right ventricle
- then out through the Pulmonary ateries to the lungs
- then oxygenated blood comes back in from the lungs through pulmonary veins
- into the left atrium through the BICUSPID valve
- Left ventricle
- Aorta to the body
Why is the left ventricle so much thicker than the right?
Left pumps blood to the WHOLE body where as right is only to the lungs
Innervation of the heart is dominated by two types of cells. What are they?
Nodal cells and cardiomyocytes
What are nodal cells?
They are responsible for initiating the wave of excitation which passes through the cells by gap junction, into the myocytes, allowing contraction of the heart.
The excitiation of nodal cells are dominated by?
L- type Ca2+ channels
What are cardiomyocytes?
muscles cells (myocytes) that make up the cardiac muslce
The excitiation of cardiac muscles are dominated by?
voltage gated Na+ channels
In nodal cells the resting potential is ____ _____ than most somatic cells
less negative (-60/-70)
Why do nodal cells have a less negative resting potential?
due to the opening of the L-type Ca2+ channles, leading to rapid influx of Ca2+
What happens when the membrane in nodal cells become positive?
slow voltage gated K+ channels open causing gradual repolarization of the nodal cell.
Ca2+ channels close here too
What leads to hyperpolarization in nodal cells ?
a slight overshoot of the K+
What channels activated in nodal cells due to hyperpolarization?
HCN channels. This allows Na+ to come into the cell and K+ to leave the cell so allowing cycle to start again (insert pic)
What happens when action potential arrives in cardiomyoctes?
voltage gated Na+ channels open, leading to rapid influx and
depolarization of the cardiac myocyte.
What happens when the membrane potential in caridomyocytes reach +20mV?
- K+ channels
open and the efflux of K+ leads to reduction in membrane potential. At
the same time, the voltage gated Na+ channels close
What balances ou the K+ efflux in cardiomyocytes?
the L-type Ca2+ channel opening , leading to Ca2+ influx
How is resting potential restored in cardiomyoctes?
. The resting membrane potential is restored by Na+/K+ ATPase, in
preparation for the next AP regeneration.
AUTONOMIC NERVOUS SYSTEM =
PARASYMPATHETIC & SYMPATHETIC
PARASYMPATHETIC =
REST AND DIGEST
SYMPATHETIC =
FIGHT OR FLIGHT
What does it mean by innervatio of the heart?
it means a group of structures that send impulses through the heart
What is the SA node?
The pacemaker. (generates impulse and sets speed in wall of the right atrium)
What is the AV node?
Delayes impulse slightly ( sits between atria, just above the ventricles)
Bundle of His=
two branches that sit between ventricles and distributes to purkinje fibres
Purkinje Fibres =
Lateral walls of the ventricles, distribute impulse from bottom upwards
Where is the SA node located?
walls of the right atrium
The Action Potential
Stage 1: Resting
3Na+ out and 2K+ in (against conc. gradient)
The Action Potential
Stage 2: Depolarisation at threshold
Na+ influx into the cell
The Action Potential
Stage 3: Peak
Na+ channels close
K+ channels open
The Action Potential
Stage 4: Repolarisation
K+ efflux out of the cell
The Action Potential
Stage 5: Hyperpolarisation/Refactory period
K+ channels are closing, but slowly
What are failed initiations?
If the threshold isnt reached for depolarisation an action potential will not occur.
What does the parasympathetic (vagus) do to the heart?
- DECREASE THE HEART RATE
- DECREASE THE FORCE OF CARDIAC CONTRACTIONS
- DILATE THE CORONARY RESISTANCE VESSELS
What does the sympathetic do to the heart?
INCREASE THE HEART RATE
- INCREASE THE FORCE OF CARDIAC CONTRACTIONS
- CONSTRICT THE CORONARY RESISTANCE VESSELS
What is your normal blood pressure?
120/80 mmHg
systolic/diastolic
What does it mean when arteries vasoconstrict?
Increased contraction around the artery
- Increased resistance/pressure
- Decreased blood flow
RESULTS IN INCREASED BP
What does it mean when arteries vasodialate?
- Decreased contraction around the artery
- Decreased resistance
- Increased blood flow
RESULTS IN DECREASED BP
How does arteries vasoconstrict?
INC SYMPATHETIC NERVOUS SYSTEM = RELEASE OF VASOPRESSIN AND ANGIOTENSIN 2 = VASOCONSTRICTION
How does arteries vasodialate?
DEC SYMPATHETIC NERVOUS SYSTEM = RELEASE OF HISTAMINE = VASODILATION
What are baroreceptors?
Sensors located in the blood vessels. They sense BP and relay the information to the brain to tell the heart to change the BP.
Where can baroreceptors be found?
- internal carotid
- aortic arch
What are chemoreceptors?
Chemoreceptors are special sensors that detect changes in chemicals present and responds appropriately by generating a biological signal
Chemoreceptoes respond to changes in….
paO2, paCO2, pH
hyPERtension=
blood pressure too high
hyPOtension=
blood pressure too low
What are blood made out of?
plasma, RBC, WBC. platelets
Properties of RBC/Erythrocytes
- Large Surface area
- Has no nucleus (more space to carry O2)
- Contains Haemoglobin which binds to and carries oxygen (also gives red colour)
- Bi-concave disk shape
What are the three branches of the aortic arch?
Braciocephalic trunk
L. Commin Carotid
L. Subclavian
Braciocephalic trunk has two branches called?
R. Subclavian
R. Common Carotid
The R common carotid branches into?
R. external and internal carotid
The L common carotid branches into?
L. external and internal carotid
Your L subclavian goes into
L axillary and then L brachial
What do the coronary arteries do?
they supply th emyocardium of the heart
What does the left coronary artery branch into?
Circumflex artery
What does ECG stand for?
Electrocardiogram
What does P wave stand for?
Atrial depolarisation
What does QRS complex stand for?
Ventricular depolarisation (masks atrial repolarisation)
What does T wave stand for?
Ventricular repolarisation
What does the U wave stand for?
idk its unknown lol
What does systole mean?
The phase of the heartbeat when the heart muscle contracts and pumps blood from the chambers into the arteries.
What does Diastole mean?
The phase of the heartbeat when the heart muscle relaxes and allows the chambers to fill with blood.
The cardiac cycle in order
- Atrial Systole
- Isovolumetric Contraction
- Rapid Ventricular Ejection
- Reduced Ventricular Ejection
- Isovolumetric relaxation
- Rapid Passive filling
- Reduced Passive filling
What happens in Atrial Systole?
The left and right atria contract and blood is ejected into the
ventricles via the AV valves.
What happens in Isovolumetric Contraction?
The pressure in the ventricles now exceeds the pressure in the
atria, causing the closure of the AV valves. The cardiac muscles begin to contract and the pressure in the ventricles begin to rise further.
What happens in Rapid Ventricular Ejection?
The pressure in the ventricles exceeds the pressure in the aorta/pulmonary vessles and the aortic valves open to allow the blood to be rapidly ejected from the ventricles.
What happens in Reduced Ventricular Ejection?
The ejection velocity begins to decline and the closure of the semi-lunar valves marks the end of this phase
What happens in Isovolumetric Relaxation?
The ventricles begin to relax and the AV and SL valves are both closed.
What happens in Rapid Passive Filling? (diastaisis)
The blood that has been accumulating in the atria causes the pressure in the atrium to rise above the ventricles so the AV valves open again, causing rapid movement of the blood into the ventricles. Approx 70%
What happens in Reduced Passive Filling?
The period is also known as diastasis and might not occur when the heart rate is increased i.e. in tachycardia.
Tachycardia=
fast resting heart rate
Bradycardia=
abnormally slow heart rate
What is the remnant of the fetal shunt betwenn the aorta abd the pulmonary artery?
Ligamentum Arteriosum
What ion is primarily responsible for repolarisation of an action potential?
Potassium ions.
