Cardiovascular Flashcards
What does stationary blood lead to?
- Rapid depltetion of nutrients and oxygen
- Build up of waste
- Loss of transportation function
- Homrones can’t reach their targets
- Cell defense unable to perform it’s functions
How much blood does the heart pump per day?
8000 litres
What are the two circuits involving the heart?
Pulmonary and systemic
What are the 5 main heart structures?
- Great vessels
- Chambers
- Heart wall
- Pericardium
- Skeleton
What is the pericardium?
A thin fibroelastic sac composed of two layers that separate the heart from the surrounding mediastinal structures.
What is the action of the systemic circulation, which side of the heart is used to pump it and from which great vessel does the blood exit?
- Blood from heart is pumped to the organs/tissues & back
- Left hand side
- Exit via aorta
What is the action of the pulmonary circulation, which side of the heart is used to pump it and from which great vessel does the blood exit?
- Blood from the heart is pumped to the lungs and back
- Right hand side
- Exits via pulmonary trunk
What is the distribution of arteries and veins in regards to the systemic and pulmonary circuits?
Veins - always bring the blood to the heart
Arteries - always move the blood from the heart
Start: Recently oxygenated blood from the lungs.
1. Travel to the heart via the pulmonary VEINS
2. Pumped to the cells from the heart via systemic ARTERIES
3. Oxygen is used, now the blood is returned to the heart via systemic VEINS
4. Oxygen depleted blood than travels to the lungs via pulmonary ARTERIES.
What colour is oxygen rich blood on diagrams?
Red
What colour is oxygen depleted blood on diagrams ?
Blue
Where is the heart located?
- In the thorax
- Mediastinum
- Sits on diaphragm
How many chamber does the heart have?
4 total, 2 on each side
What separates upper and lower chambers?
Valves
What are the four graate vessels of the heart?
- Aorta
- Superior & inferior vena cavae
- Pulmonary artery
- Pulmonary veins
What is the function of the upper chamber of the heart?
Atria - the upper chambers of the hearts - receive blood and pump it into lower chambers. They are thin walled.
What is the function of the lower chambers?
Ventricles - the lower chambers of the herat - receive blood from atria and pump blood to the aorta or pulmonary artery
What valve separates the right atrium from right ventricle?
Tricuspid
What valve separates the right ventricle and pulmonary artery?
Pulmonary
How can we describe the pericardium?
A tipple layer sack that surrounds the heart - fibrous on either side and serous in the inner
What is a myocardium?
It is the middle heart muscle layer
What do we know about myocardial cells?
They are multinucleated cells, branched with numerous mitochondria and striations. Inbetween they have intercalated discs.
What is the function of both desmosomes and fascia adherentes?
Anchor the myocardial cells to one other
What is the function of gap junctions?
To act as direct communication between cells and propagate electrical impulses
What is the endocardium?
It is mesothelium of squamous cells that linnes inner surface of myocardium
What are the two function of heart valves?
- Prevent backflow of blood
2. Seal the chambers in response to pressure changes
What separates the two halves of the heart?
The septum
What are the coronary arteries?
They are arteries that run around the heart and provide oxygen and nutrients to the myocardial cells
What is a myocardial infraction?
It is essentially the death of muscle cells due to lack of oxygen and nutrients due to blockage in coronary arteries
What are the two major nodes?
Sinoatrial and atrioventricular
How does the impulse travel through out the heart?
- SA node - has pacemaker cells - which initiate thr impulse
- Atrial contraction is triggered
- The signal is passed through atria to a 2nd node (AV node)
- The signal travels down bundles of specialise dmuscle cells
- The main bundle than separates itno left and right
- This way the signal can reach the most distant muscle cells of the ventricles
What are the functions of the lymphatic system?
- Absorption
2. Immune cell transit
What are the 5 main types of blood vessels?
- Arteries
- Arterioles
- Capillaries
- Vanules
- Veins
What is the general feature of arteries?
They are thicker-walld and more elastic
What is the general feature of veins?
They are thinner-walled, collapse easily and communicate freely
What is the primary function of elastic arteries?
Pressure reservoir
What is the primary function of the muscular arteries?
Pressure reservoir
What is the primary function of arterioles?
Primary resistance
What is the primary function of capillaries?
Exchange of materials
What is the primary function of postcapillary venules?
Transit of immune cells
What is the primary function of venules?
Blood reservoir
What is the primary function of veins?
Blood reservoir
What are the three coats of vascular wall starting from the middle?
- Tunica intima
- Tunica media
- Tunica adventitia
What is the significance of tunica media?
It has arranged smooth muscle cells
What are the three types of capillaries?
- Continuous
- Fenestrated
- Discontinuous
How does the heart beat so rhythmically?
The heart beats rhythmically as a result of action potentials it generates by itself by use of auto rhythmic cells
Describe the electrical activity of the heart, specifically the cycle of the autorhythmic cells?
- Funny channels permit the inward NA+ uptake and reduced K+ outlow (initial slow depolarisation)
- Transient type Ca2+ channels open causing depolarisation until the threshold potential is reached
- After threshold potential is reached, rapid depolarisation is caused by opening of long-lasting Ca2+ channels
- After peak depolarisation, the repolarisation occurs due to opening of K+ channels
Describe the electrical activity of the heart in regards to the nodes?
- SA node initiates action potential
- First spreads in both atria through interatrial pathway - than moves through the internodal pathway
- Internodal pathway leads to the AV node
- AV node is a point where action potential can spread to ventricles rapidly - bundle of His is used - than Purkinje fibers
Describe the electrical activity of the heart with refrence to the potential of cardiac contractile muscle?
- Rapid entry of Na+
- Brief repolarisation due to limited K+ efflux
- Proogned plateu due to slow Ca2+ entry
- Opening of voltage gated K+ and rapid repolarisation
- Maintenance by keeping K+ channels leaky
What is the refractory period?
It is the shortest interval between 2 input impulses
What is the intrinsic firing rate of the SA node?
60-100 bpm
At rest, what is the average heart rate?
60 - 200 bpm
At rest, which is the dominant influence on heart rate and how would you test your answer?
Parasympathetic influence
What would happen to cardiac output if one has bradycardia an arrhythmia that reduces heart rate?
Reduction of heart rate = reduction of cardiac output
Describe how this may influence blood pressure?
MAP = CO x TPR, meaning blood pressure will be reduced
Use flow chart or mind map to outline how having a wakened heart may result in low blood pressure?
Weaker heart = less cardiac output lower MAP
Other than Martti’s example can you think of one other cause that may lead to a weakened heart?
Myocardial infraction = low oxygen supply to contractile cells = death of contractile cells = less contraction
What is the formula for cardiac output?
Cardiac output = Stroke volume x heart rate
What is the typical cardiac output for males and females?
5 L min-1
4.5 L min-1
What happens to the stroke volume and heart rate during sympathetic stimulation?
They both increase, thus increasing cardiac output.
What influence does the parasympathetic stimulation have on the heart rate?
It slows the heart rate
What is an important part of cardiac output that could lead to potentially life threatning events?
During exercise, CO increases significantly. This increases must coincide with increase in blood pressure and/or volume distribution otherwise pressure becomes life threteningly high.
How does volume distribution help with maintenance of appropriate blood pressure?
It is though that not all blood vessels are used in normal events, but during sympathetic stimulation these blood vessels could uptake the access volume of blood.
Describe the events of the cardiac cycle starting with diastole.
- Diastole
- Repolarisation
- Refractoriness
- Relaxation
- Contraction
- Spread of action potential
- Depolarisation
- Systole
What is tachycardia?
Rapid heart rate
What is bradycardia?
Slow heart rate
What is arrhythmia variation?
Changes from normal rythm of the heart
Why might deviation from the normal range of rate and rhythm of the heart be bad for your patient?
This alter the cardiac output meaning the patient could potentially have some sympathetic stimulation, caused by dental anxiety or anxiety in general and not produce enough c
What is diastole?
It is essentially the passive filling of theheart chamber
What is the systole?
It is the pushing of the blood out of the ventricles
What is the bainbridge reflex?
When venous return increase - it increases atrial stretch which increases heart rate
What is normal BP?
120/80
What is hypotensive BP?
90/60
What is hypertensive BP?
140/90
What is the formula for calculation mean arterial blood pressure?
Mean Arterial Pressure = Heart Rate x Stroke Colume x Total Peripheral Resistance
What causes orthostatic hypotention?
Orthostatic hypotension happens when gravity causes blood to pool in the lower extremities, which in turn compromises venous return, resulting in decreased cardiac output and subsequent lowering of arterial pressure.
What are the main blood pressure sensors?
- Carotid sinus baroreceptor
2. Aortic arch baroreceptor
What the kidney ding with Blood Pressure Sensoring?
The kidneys sense blood pressure via the volume of sodium and chloride moving across macula densa
What type of hormone is released by macula densa cells in order to change renal perfusion?
Renin and it is regulated by detection of Na+ and Cl-
Describe the cascade of the renin angiotensin aldosterone system.
- Kidneys detect the decrease in blood pressure
- Renin is released by the kidneys
- Angiotensinogen is released by the liver
- Renin and Angiotensinogen combine to creat angiotensin I
- ACE is released by the lungs
- ACE and angiotensin I combine to create Angiotensin II
- Angiotensin II is able to: increase sympathetic drive, cause an increase of water retention by the kidneys, increase aldosterone secretion, cause arteriolar vasoconstriction and cause the release of AHD which increases the amount of aquporins in the collecting duct wall.
What is an example os SNS output on heart pressure?
- Release of adrenaline and noradrenaline
- Adrenaline and noradrenaline binds to beta 1 recepotrs of cardiac muscle causing increased heart rate and contractility
- Adrenaline and noradrenaline binds to alpha 1 receptors on vascular smooth muscle causing vasoconstriction
- Adrenaline binds to beta 2 receptors on vascular smooth muscle or bronchiolar smooth muscle
