Cardiac Flashcards
Percentage of blood in systemic
84%
Percentage of blood in pulmonary
9%
What does S.V.C and I.V.C stand for
Superior vena cava
Where does blood in svc/ivc come from
Inferior vena cava
Midline of heart is called
Interventricular sulcus
Right atrial pressure
5mmHg
Right ventricle pressure
27mmHg
Left atrial pressure
8mmHg
Left ventricle pressure
120mmHg
Left inlet valve
Mitral/bicuspid
Left outlet valve
Aortic valve
Right inlet valve
Tricuspid valve
Right outlet valve
Pulmonary outlet valve
Features of bicuspid/mitral value
Two cusps, Chordae tendineae, papillary muscles
Ventricular pressure ratio
5:1
Ventricular wall ratio
3:1 (12-15mm/4-5mm)
Right border comprised of
Right atrium
Inferior border comprised of
Right ventricle
Apex orrientation
Inferior, left, anterior
Left border comprised of
Left ventricle
Cardio thorasic ratio
Normally 50%, heart width:chest width
Rheumatic fever diagnosis: Issue and symptoms
Streptococcal infection, attacks/damages aortic valve, poor healing of valve (irregular, cusps fused at aortic wall). Aortic stinosus, left ventricle works harder, left ventricular hypertrophy, impeded blood supply to coronary arteries, stiff heart, small lumen volume.
Serous membrane around heart
Pericardium
Layers of pericardium and myocardium
Outside, fibrous, parietal, pericardial space (serous fluid), visceral/epicardium, myocardium, endocardium, lumen
Function and association of fibrous skeleton
Structure & support of valves, insulate electrical activity, associated with all valves other than pulmonary.
Path of action potentials in heart contraction
Sinoatrial node, myocardium muscle, atrioventricular node, bundle of his, purkinje fibres
Relative speeds of nodes/action potentials in reagards to heart conduction system
SA -> Atrial muscle (slow, 0.5m/s)
AV (Very slow, 0.055m/s)
AV bundle –> purkinje fibres (fast, 5m/s)
How long is the delay between SA and AV node action potential propagation and what is the purpose of this?
100ms, to allow for organised contraction (atrium then ventricle)
What are the stages of the cardiac cycle?
- Ventricular filling
- Atrial contraction
- isovolumetric ventricular contraction
- Ventricular ejection
- Isovolumetric ventricular relaxation
Types of vessels
- Elastic arteries
- Muscular arteries
- Arterioles
- Capillaries
- Venule
- Vein
- Coronary arteries
(Even Mum Acts Carefully, Very Very Carefully)
Structure/Function/location of elastic arteries
Thin sheets of elastin in middle tunic Aorta/pulmonary arteries Stretches to accommodate volume Elastic recoil maintains blood flow Absorb pressure pulse
Structure/Function/location of muscular arteries
Layer of smooth muscle in middle tunic, externa, media, interna tunics
Found in lungs and around body
Distribute blood, flow is proportional to radius 4th power
Structure/Function/Location of Arterioles
Areas of great pressure drops, and resistance.
1-3 layers of smooth muscle, thicker muscles wall relative to lumen (very strong)
Controls blood flow into capillary beds
CONSTRICTION DETERMINES:
total peripheral resistance which impacts mean arterial blood pressure
Structure/Function/Location of Capillaries
Located at muscle sites and everywhere
Small, thin walled, one blood cell thick, single layer endothelium, no muscle or CT
Leaky, allow gas exchange and nutrient/waste exchange
Structure/Function/Location of Venules
Small, CT & one layer of endothelium, sometimes a layer of smooth muscle
Drain capillary beds, low pressure, white blood cell migration
Structure/Function/Location of Veins
similar to muscular artery, thinner, back-flow valves also
Returns blood back to right atrium when it is compressed by neighboring muscles, acts also as volume reserve (64% total blood volume)
Structure/Function/Location of Coronary arteries
Located at the ascending aorta
Supplies myocardium with oxygenated blood, cardiac veins drain deoxygenated blood back to R.A.
Simple small muscular arteries
Average cardiac output at rest
5L/min
How to calculate cardiac output
L.V. volume * H.R.
Max cardiac output
20L/min
Cardiac reserve
Difference between resting CO and Maximal CO
CO formula
CO = HR x SV
Factors of stroke volume
Pre-load
Inotropy (contractility)\
After load
Define pre-load
The pressure provided by pulmonary circuit into left ventricle, causing stretch
Define inotropy
Forcefulness of contraction
Define after load
Pressure in arteries needed to overcome in order to achieve ventricular ejection
Frank-Starling Law 1920s
More blood in –> More blood out
Define positive inotropy agent and provide an example
Increases contractility of the heart via promoting inflow of CU ions into myocardium i.e. Sympathetic Nervous System
Define negative inotropy agent and provide an example
Decreases contractility of the heart via increasing potassium ions and therefore hyperpolaristion
Calculate stroke volume
difference between volume prior to ventricular filling and volume after atrial contraction
Ejection fraction
Percentage of volume pumped out of heart (60-70%)
At what ejection fraction will heart failure occur
50%
Normal and dangerous levels of BP
over 90mmHg diastolic, over 140mmHg systolic
ECG definition and function
Electrocaridogram, detects sum of electrical activity in the heart
Intrinsic rhythm of sinoatrial node
90-100bpm
Intrinsic rhythm of atrialventricular node
~50bpm
Fibrilation
Disordered/random coordination of contraction due to loss of rhythm of action potential propogation
Duration of cardiac action potential compared to standard neuron action potential
300ms vs 1-2ms
How come tetani of myocardium does not occur?
Action potential duration exceeds contraction dutration
P wave ECG graph
Depolarization of atria
R wave ECG graph
Depolarization of ventricle
T wave ECG graph
Repolarization of ventricle
P-Q & Q-T represents
Time delay between contraction of atria and ventricle
CNS involvement in heart
Cardiovascular centre in medulla
Facets of ANS
Sympathetic & Parasympathetic
Sympathetic NS on heart
Impacts SA node via spine, noreadrenaline increases heart rate and stroke volume
Parasympathetic NS on heart
Vagus nerve in neck, acetylcholine, decreases heart rate
Parasympathetic or sympathetic, which is faster acting on heart?
Parasympathetic. Sympathetic takes 3-4 seconds
Function and location of baroreceptors
Detects stretch/blood pressure increase of elastic arteries (pulmonary & aortic artery), sends information to the brain to activate SNS to increase heart rate.
Located on the arteries
Function of the heart
Supply
How do we change/stabilize BP
Change HR, SV or TPR
What vessels alter BP
Arterioles
Mean BP
Average blood pressure, MBP = CO x TPR
Systolic BP
High blood pressure (ventricular ejection)
Distolic BP
Lower blood pressure (ventricular filling)
At what vessel level does gas exchange occur
Capillary beds
What blood pressure do we measure with a pressure bag?
Arterial blood pressure, systolic/distolic
Order blood distribution from highest volume to lowest
Venules/veins, systemic arteries/arterioles, pulmonary circuit, heart, capillaries
Vascular tone at arteriole level is governed by
smooth muscle varying radius
TPR
Total peripheral resistance
Filtration pressures
Blood hydrostatic pressure, interstitial fluid osmotic pressure
Absorption pressures
Blood collide osmotic pressure, interstitial hydrostatic pressure
BHP
Blood hydrostatic pressure
IFOP
Interstitial fluid osmotic pressure
BCOP
Blood collide osmotic pressure
IFHP
Interstitial hydrostatic pressure
NFP definition & formulae
Net filtration pressure –> NFP = (BHP+IFOP)-(BCOP+IFHP)
Arterial pressure, A.K.A
Net filtration pressure
Venous pressure, A.K.A
Net reabsorption pressure
NFP-NAP
Net filtration pressure - Net absorption pressure. This will be a positive value, as more
CNS monitoring the blood pressure…
Baroreceptors, located on ascending arterial arch. Increased firing for high BP, decreased firing for low BP. Baroreceptors sned to cardiovascular center, then pack to ANS.
Functions of ANS on cardiovascular system
SNS–> noreadreniline increases HR, constricts arterioles
PSNS–> Vagus nerve to heart, acetylcholine decreases heart rate
What receptors are on the arterioles
Alpha and beta receptors
Alcohol and heat cause
vasodilation, decreased heart rate