Week 3 Flashcards
(77 cards)
1
Q
How many blood groups are there ?
A
43 blood groups
Most are ABO , Rhesus +/-
2
Q
What are the A and B antigens ?
A
Sugars
3
Q
What happens if a blood transfusion uses the wrong blood ?
A
Causes thrombosis as there is agglutination of RBC as the antibodies bind to the antigens
4
Q
If you have an antigens what antibodies do you have ?
A
B
5
Q
If you have b antigens what antibodies do you ahve ?
A
A
6
Q
If you have no antigens ( type o ) what antibodies do you have ?
A
A and B
7
Q
Which blood type can be a universal donor ?
A
Type O
8
Q
What blood type is the universal reciever ?
A
Type AB - no a or b antibodies so do not agglutinate donor blood
9
Q
Where is the heart ?
A
In the mediastinum with the lungs
10
Q
How many layers does the pericardium have ?
A
3 main layers :
Fibrous pericardium
Serous pericardium
Epicardium
11
Q
What is pericarditis ?
A
Problems with the pericardium which impact the movement and function of the heart
12
Q
In what ways does the pericardium support the heart ?
A
Lubrication ( serous )
Mechanical protections
13
Q
What do atrioventricular do ?
What do semilunar valves do ?
A
Prevent backflow from atria to ventricles
Prevent backflow from Aorta/Pulmonary artery into the ventricles
14
Q
What is the role of chordae tendinae ?
A
Stop valves acting like a swing door in both directions
15
Q
What are some of the potential problems with heart valves ?
A
Incompetent valves :
- do not fully close so there is regurgitation flow
Valvular stenosis :
-stiffened valves caused by repeated infection , congenital disease or calcium deposits. Opening is narrowed so insufficient blood gets through
16
Q
What are the 3 layers of arteries and veins ?
A
Tunica adventitia / externa : supportive outer
Nerves and blood vessels
Tunica media :
Muscular middle , affects resistance to blood flow
Tunica intima :
Endothelial , inner , layer creates a smooth surface and involved in communication
17
Q
What is the bag called that the heart sits in ?
A
Pericardium
18
Q
What is a cardiac cycle ?
A
One heart beat
19
Q
What is systole ?
A
Contraction , generally taken to mean ventricular contraction and ejection
20
Q
What is diastole ?
How does ECG trace the phases ?
A
Relaxation
Measuring current flow
21
Q
What are the basic stages of the cardiac cycle ?
A
Atrial contraction
Isovolumetric contraction
Ventricular ejection
Isovolumetric relaxation
Ventricular filling
22
Q
At a heart rate of 75bpm , the cycle lasts 0.8 seconds how long does each section last ?
A
Diastole - 0.4 secs
Systole - 0.1 secs
Ventricular systole - 0.3 secs
23
Q
There are 4 sounds but only 2 are loud enough to hear , what are the 2 first sounds and what causes them ?
A
LUBB - turbulence caused by the closure of the AV Valves
DUBB - semilunar valves closing
24
Q
Describe atrial systole
Give the equation for end diastolic volume
A
Atria contract, squeezing blood into the ventricles, through the valves.
AV valves open. Pulmonic and Aortic closed
Slight increase in atrial pressures
End Diastolic Volume = ventricular vol + atrial contribution (10% at rest)
EDV= 105ml +25ml = 130ml
25
Describe Isovolumetric contraction
All valves closed.
Beginning of systole.
Increase in intraventricular pressure from contraction.
Heart shape change but no blood is ejected.
Pushes AV valves closed. First sound
26
Describe rapid ejection
What does no heart sound indicate
AV valves closed , others open.
When intraventricular P is higher than the aortic and Pulmonary P, the valves open and blood is ejected.
Atria continue to fill.
L: LVP exceeds aortic P of 80mm/Hg for SL valves to open and ejection. P increase to 120mm/Hg
R: RVP exceeds pulmonary P of 20mm/Hg for SL valves to open and ejection. P increases to 25-30mm/Hg
No heart sounds in healthy patient. Ejection sounds indicate a shunt or valve disease.
27
Describe reduced ejection
Aortic and pulmonary valves stay open and AV valves stay closed. No movement of blood
Ventricular muscle relaxation. Ventricular P decreases slightly but blood still leaves the heart (kinetic energy). Atrial P increasing as atria continue to fill
28
Describe Isovolumetric relaxation
What is the equation for end systolic volume ?
Valves close ( Heart sound 2). Aortic first, then pulmonic valve. Ventricle volume remains the same as valves are closed (dicrotic wave). Atrial pressure and volume increase from venous return
Volume remaining in the ventricles after ejection ESV = (EDV) 130ml - 70ml = 60ml
29
Describe rapid filling and reduced filling
Rapid -
AV valves open, aortic and pulmonary valves close
Ventricular filling , relaxation phase
Amount of filling decreases when HR increases
Atrial P falls
Reduced -
Difficult to distinguish these phases
When filling is nearly finished, ventricles at full stretch so P rises. P in large vessels drops as blood flows into circulation
30
How do we calculate stroke volume and cardiac output ?
SV = EDV - ESV
CO = SV / HR
ML/min ML / beat. Beats / min
31
32
Cardiac output is affected by control of heart rate ?
Neural control : physical or emotional stress
Sympathetic nervous system stimulates heart rate (SA node ) up to 100-200%
Parasympathetic nervous system steadies HR
Ion levels :
-Calcium: too little : weak . Too much : long contractions
Potassium : involved in muscle contraction and nerve conduction
Heart rate can increase CO to a point
CO increase not proportional to HR increase
33
Describe the skeletal muscle pump
Lack of muscle in veins limits the force of venous return.
Contraction of skeletal muscle in the tissue surrounding the veins compresses them.
Compression closes upstream valves and opens downstream valves.
Compressed veins = increased pressure
Venous return increases during exercise.
Valves prevent backflow
34
What is blood pressure ?
Equation ?
Related to cardiac output
CO = HR x SV
HR related to age , exercise , health
SV related to venous return
Cardiac output x total peripheral resistance
35
What is peripheral resistance ?
What causes friction ?
Degree of friction encountered by blood
Constriction or narrowing - initiated by action of the sympathetic nervous system or atherosclerosis or stiffening
Increased blood volume
Viscosity
I
36
When does pulse pressure ( PP) increase ?
What is the equation for pulse pressure ?
Increases as arteries become less stretchy
Pp = systolic BP - Diastolic BP
37
What is mean arterial pressure ?
Equation ?
Pressure at which blood is actually delivered to tissues
MAP = DP + (PP/3)
38
What do baroreceptors detect ?
Changes in blood pressure
Baroreceptors in the Arterial carotids and aortic arch
Each receptor is sensitive to a different pressure.
Small changes in therefore increase firing frequency
A decrease in P is also detected (via decreased frequency)
39
Describe chemoreceptors
1. Peripheral chemoreceptors : carotid bodies in carotid artery. No receptors in veins
2. Central chemoreceptors: medulla
Detect changes in PO2, PCO2, pH
Low PO2 is associated with changes in pulmonary pressure, so changes in lung stretch receptor activity will also respond to low O2 levels.
40
Describe vasoconstriction
Contraction of smooth muscle in the vessel walls, also precapillary sphincters in arterioles
Activation of Sympathetic Nervous activity
Causes narrowing of the diameter of the blood vessel
Increases the resistance of blood vessels to blood flow
Increases Blood Pressure
41
Vasodilation
Relaxation of smooth muscle in the vessel walls, also precapillary sphincters in arterioles
Causes widening of the diameter of the blood vessel
Caused by withdrawal of sympathetic nerve activity and locally released chemicals e.g. nitrous oxide and lactic acid
Decreases the resistance of blood vessels to blood flow
Decreases Blood Pressure
42
Why would you need to raise Blood Pressure ?
Counteract the pressure change from getting up too quickly (orthostatic hypotension)
Haemorrhage can cause problems medically
Stress or exercise
43
How can you decrease blood pressure ?
Low salt diet ( regulation of blood volume )
Decrease stress and effects of sympathetic nervous system
Therapeutically with ACE inhibitors- interacting with the renin angiotensin aldosterone system ( RAAS) that regulates blood volume and BV constriction
44
What is Frank-Starling’s law and stroke volume ?
Bigger stroke volume ejected if there is a larger degree of filling at the end of diastole
45
Exercise increases venous return how ?
Rapid breathing forcing reoxygenated blood into heart quicker
Skeletal muscle pump forcing venous return Cardiac
46
What is preload ?
What is after load?
What is contractility ?
How stretchy is the heart at max fill
The pressure at which the heart needs to pump,to expel blood
The ability of the muscle to produce a force
47
What are the different types of capillaries ?
Continuous - no gaps except between endothelial cells (tight junctions _ , skin , CNS , muscle
Fenestrated - 70-100nm , in choroid plexus , kidneys , endocrine glands , villi and ciliary processes of the eye
Sinusoid capillaries - wider gaps in the vessel walls ( lets blood cells through ) - bone marrow endocrine glands , placenta
48
49
What are the 3 systems through which blood flow is distributed after leaving the heart ?
1. Pulmonary circulation
2. Systemic circulation
3. Coronary circulation
50
Where is pulmonary circulation positioned ?
Towards the back of the heart
Blue ( deoxygenated ) at back
Crescent shaped
Blood in through vena cava and back out through pulmonary artery
51
Where is systemic circulation ?
At front and apex
More circular ( thicker walls )
In through pulmonary veins
Out through Aorta to aortic arch
52
Describe coronary circulation
L and R coronary arteries from the base of the Aorta, shut during contraction
Coronary arteries branch to supply the heart
Arteries supply the capillaries for gas and nutrient transfer before draining into the veins
53
After severe blood loss , what happens locally within tissues ?
Secondary shock , tissues need blood , open up the vessels , blood flows in very quickly, perhaps causing more damage
54
What does myogenic mean ?
What does the heart need to regulate contraction ?
Cells contract spontaneously
Pacemaker
55
What links muscle cells together ?
What does gap junctions allow ?
Intercalated disks which contain desmosomes and gap junctions
Passage of action potentials from one cell to the next - function together as a syncytium
56
57
What is the cardiac resting potential ?
If cardiac cells are hypoxic how does this change ?
-90mV
Higher ( less negative ) , inactivates some Na channels
58
Is the refractory period longer with nerve cells or cardiomyocytes ?
Cardiomyocytes = longer refractory period
59
Describe cardiac action potentials
1.Rapid depolarisation , Na+ inflow when voltage-gated fast Na+ channels open
2.Plateau ( maintained depolarisation) due to Ca2+ inflow when voltage gated slow Ca2+ Channels open and K+ outflow when some K+ channels open
3. Depolarisation due to closure of Ca2+ channels and K+ outflow when additional voltage - gated K+ cahennls open
60
What is the nodal system ?
Network of structures sets up a conduction system to control heart rate
Sinoatrial (SA) node : pacemaker
Atrioventricular node
Bundle of His (and branches ) in septum
Purkinje fibres in ventricular walls
61
Describe the depolarisation and action potential generation of cardiac pacemakers
SAN cells slowly depolarize spontaneously (funny channels)
Causes the resting membrane potential to decrease (pacemaker potential)
Once the threshold is reached, an AP is stimulated
AVN cells also spontaneously depolarize slowly. BUT they are usually triggered by SAN activity before they can depolarize on their own.
Co-ordination
SAN activity can be influenced by the Autonomic Nervous System
62
Describe neural control of heart rate
Sensory information from sensors (eg chemo and baro etc) is processed in the medulla oblongata
Triggers an ANS response
Sympathetic NS (cardiac accelerator nerves) increase HR and contractility. Physical and emotional stress will increase HR
Parasympathetic NS (Vagus nerves) decrease HR
Result is maintenance of internal environment.
63
What factors increase SA node firing ?
Sympathetic stimulation
Muscarinic receptor antagonist
β Adrenergic receptor agonists
Circulating catecholamines
Hyperkalaemia*
Hyperthyroidism
Hyperthermia
64
What factors decrease SA node firing ?
Parasympathetic stimulation
Muscarinic receptor agonist
β blockers
Ischaemia/hypoxia
Hypokalaemia*
Sodium and calcium channel blockers
Hypothermia
65
Are cardiac muscle cells multinucleated or mononucleated ?
Striated or non-striated ?
Mononucleated
Striated - crossbands of the muscle contraction apparatus are visible ( z-bands )
66
What does AP allow calcium to do in the control of contraction ?
Stimulate excitation contraction coupling : the contraction of the Cardiomyocytes
67
Describe the cardiac conduction system
Cells in the SAN produce electrical impulses at a rate of 100 per minute
Impulses spread through the atria - contraction
Impulse moves through AV node towards ventricles. Delay of siganl here to allow time for the atria to completely depolarise, contract and empty
Impulse transmitted to ventricular muscle via Purkinje fibres to stimulate contraction
68
What are the other regulators of heart rate ?
Thyroid hormone , adrenaline
Age: new born vs old
Fitness : fitness lowers resting HR , efficient pumping. Maximum filling
Sex: females have higher heart rate
Body temperature : increased body temperature increases heart rate
Decreased body temperature decreases both heart rate and contarcility
69
Describe pacemaker potentials
Influx of Calcium through L-channels
Potassium (K+) channels open, repolarising cell
2-step process:
Funny current of Na+ enters through funny channels (pacemaker current)
T-channels let Ca++ in until the threshold is reached
Phase 4 is the pacemaker potential and mediated by movement of Ca++ and Na+
70
What does AP allow calcium to do in the control of contraction ?
Stimulate excitation contraction coupling : the contraction of the Cardiomyocytes
71
What is Tachycardia ?
Increased heart rate (>100bpm) through stress, drugs , heart disease
72
What is fibrillation ?
Rapid, regular and uncoordinated contraction , differences in different section of the heart
73
What is Bradycardia ?
<60bpm, low temperature, drugs , endurance training . If not an athlete leads to poor circulation. Indicative of head trauma
74
Which valves have chordae tendinae ?
AV valves
75
Are semilunar valves bicuspid or tricuspid ?
Tricuspid but not the tricuspid valve as this is between the right atrium and ventricle
76
Regarding movement of a substance what is the difference between efflux and influx ?
Efflux - movement of a substance out of a cell
Influx - movement of a substance into a cell
77
The three muscle types share some characteristics, but what features are unique to cardiac muscle?
Spontaneous contractions,
Intercalated discs,
Branched cell
