Block 2 - Cardiac Systems (3-4) Flashcards
1
Q
Where is the right border of the heart?
What is its shape?
A
Between the 3rd and 6th costal cartilage
Parasternal line
Straight border
2
Q
Where is the left border of the heart?
What is its shape?
A
Between the 2nd and 5th costal cartilage
Midclavicular line
Oblique border
3
Q
What vertebral level does the heart run from and to?
A
T5-T8
4
Q
What are the layers of the heart?
A
Fibrous pericardium - Parietal pericardium - Visceral pericardium (Epicardium) - Myocardium - Endocardium
5
Q
What type of epithelium is the epicardium and endocardium?
A
Simple squamous
6
Q
Is the pericardial cavity a potential or real space?
A
Potential
7
Q
What are the two sinuses of the heart?
Where are they?
Which one has a blind-ending space?
A
Oblique pericardium sinus: Between pulmonary veins (blind ending)
Transverse pericardial sinus: Between aorta, pulmonary trunk and area of venous drainage
8
Q
What is the aortic knuckle?
A
The aortic arch as seen on an xray
9
Q
What are the 3 surfaces of the heart?
A
Sternocostal: Against sternum and ribs
Diaphragmatic: Contact with the diaphragm
Posterior: Against the vertebrae
10
Q
What are the 4 borders of the heart?
A
Right, left, superior and inferior
11
Q
How fast do the atria and ventricles beat?
A
Atria: 60bpm
Ventricles: 40bpm
12
Q
What is the smooth wall called in the atria?
A
Sinus venarum
13
Q
What is the rough wall called in the atria?
A
Musculi pectinati
14
Q
What does the crestiterminalis contain?
What is it seen from the outside of the heart as?
A
Contains SAN
Seen as a groove called the sulcus terminalis
15
Q
How many pulmonary veins are there?
A
4
Left and right: superior and inferior
16
Q
What is the rough area of the ventricle called?
What is its role?
A
Trabeculae carnae
Stops the heart walls from sticking together
17
Q
What is the smooth area of the ventricle called?
A
Infundibulum/ Consus anteriosus
18
Q
What is the moderator band in the right ventricle called?
Where is it found?
A
Septomarginal trabeculae
In the IV groove with the Bundle of His
19
Q
What is the path of blood in the ventricle?
A
Atria - Rough area - Smooth area - Valve
20
Q
What is the same about the size of the R and L ventricle?
A
The size of the lumen
21
Q
What are the 3 aortic sinuses?
Where are they positioned?
Which ones have a coronary artery?
A
Right aortic sinus (anterior): Right artery
Left aortic sinus (left posterior): Left artery
Posterior aortic sinus (right posterior)
22
Q
Where does the right coronary artery run?
What are its branches?
A
Runs down AV groove
MARGINAL artery branches along the inferior border to the apex
On the diaphragmatic surface this branches into the POSTERIOR DESCENDING artery which passes the IV groove in 85% of people
23
Q
What does the right coronary artery supply?
A
Right atria and ventricle
Posterior 1/3 of IV septum
SAN (60%)
AVN (80%)
24
Q
Where does the left coronary artery run?
What are its branches?
A
Bifurcates early into the:
LEFT ANTERIOR DESCENDING (widow maker) which runs down the IV septum
LEFT CIRCUMFLEX
25
What does the left coronary artery supply?
Left atria and ventricle
| Anterior 2/3 of IV septum
26
Why is coronary circulation variable?
Many vessels enatamose
27
What are the 4 main veins in the heart?
What artery do they accompany?
Where do they run?
Great cardiac vein: Left anterior descending (anterior IV septum)
Middle cardiac vein: Posterior descending (posterior IV groove)
Small cardiac vein: Marginal artery (inferior border)
Oblique cardiac vein: Descends from the left atrium
28
Which two veins do not drain into the coronary sinus?
Anterior cardiac vein: Drains blood into the right atrium from the right ventricle
Smallest (thesbian) cardiac vein: Return blood directly the heart chambers through the myocardium
29
Two ways in which cardiac muscle is similar to skeletal muscle
Striated
| Myofibrils made from actin and myosin
30
5 differences between cardiac muscle and skeletal muscle
```
Branching of myofibrils increased
Intercalated discs made from gap junctions
Mitochondria increased
Mononucleated
Shorter myofibrils
```
31
What are the gap junctions in cardiac muscle made from?
Connexon proteins
32
What type of chain is myosin
| What are the two chains made from?
Alpha helix chain
Heavy chain: Tail region and hinge protein
Light chain: Contains the head which is made from alkali and an ATPase
33
How many actin molecules surround one myosin?
6
34
What type of protein is actin?
| What type of protein does it also contain?
Globular protein with a tropomyosin protein which lies between 2 helical strands
35
What is troponin?
A regulatory complex that attaches to tropomyosin
36
What are the 3 parts of troponin?
TnT: Binds troponin to tropomyosin
TnC: Where calcium ions bind
TnI: Inhibits actin and myosin binding
37
Explain the sliding filament mechanism
Myosin bound
ATP binds --> detachment
Hydrolysing --> pivoting to cocked position
Myosin binds --> new cross bridge
Pi released --> power stroke
ADP released --> muscle ready for next time
38
What is excitation-contraction coupling?
An action potential triggered by the SAN spreads over the muscle --> contraction
39
What are the calcium channels found on the sarcolemma surface called?
L-type voltage gated calcium channels
40
How is cardiac muscle diad?
One sarcoplasmic reticulum for every T tubule
41
Define lusitrophy
Muscle relaxation
42
What is phospholambin?
Regulatory protein which is phosphorylated to allow the SERCA pump to increase uptake
43
Why are high levels of Calcium an issue?
It is toxic
44
Explain what happens during sympathetic control of the heart?
Noradrenaline and adrenaline to beta 1 adrenoreceptors on the SAN, AVN and muscle
Activate G-simulator --> cascade and phosphorylation of calcium channels to increase calcium release
45
Explain what happens during parasympathetic control of the heart?
Acetylchoine released from the vagus nerve and binds to M2 receptors on the SAN and AVN
Activate G-inhibitor --> inhibits calcium channels and phosphorylates K channels --> hyperpolarisation
46
Define Chronotropic
| Is it increased or decreased by increased calcium in the sympathetic system?
Heart rate
| Increased
47
Define Dronotrophic
| Is it increased or decreased by increased calcium in the sympathetic system?
Impulses
| Increased
48
Define Inotropic
| Is it increased or decreased by increased calcium in the sympathetic system?
Force and rate of contraction
| Increased
49
What is the transmission like in the nodes compared to the muscles and fibres?
Nodes: Fast transmission
| Muscles and fibres: Slower transmission
50
What is the difference in potentials between the nodes, muscles and fibres
Nodes: Pacemaker potential
| Muscles and fibres: Resting membrane potential
51
Explain how depolarisation occurs in the SAN and AVN
- Steady and unstable membrane potential gradually depolarises to reach the threshold
- Slow depolarisation (Na and Ca) = the 'funny current'
- Threshold --> rapid depolarisation
- K channels re-polarise and overshoot
52
Explain how depolarisation occurs in the muscle and Purkinje fibres
- Rapid depolarisation by fast Na channels
- Slight depolarisation when K channels open
- Plateau when Ca enters
- Re-polarisation when K leaves
- Pumps restore the ion gradients
53
What does the time from re-polarisation - depolarisation in the muscles and Purkinje fibres match with on the ECG?
The R-T interval
54
What is the purpose of the refractory period in muscles?
Stops random firing and arrhythmias
55
How long does atrial systole, ventricular systole and diastole last?
Atrial systole: 0.1 seconds
Ventricular systole: 0.3 seconds
Diastole: 0.4 seconds
56
What is the average EDV?
135ml
57
What are the two stages of ventricular systole?
Isovolumic ventricular contraction: Contract to close the AV valves but not enough to open the semi-lunar
Ventricular ejection: Pressure rises and semi-lunar valves open
58
What is he average ESV?
65ml
59
What is another term for ventricular diastole?
Isovolumic ventricular relaxation
60
How do you calculate cardiac output?
| What is the average value?
Cardiac output = Heart rate x Stroke volume
| 5 L/min
61
How do you calculate stroke volume?
| What is the average value?
Stroke volume = EDV - ESV
| 70ml
62
Define stroke volume
The volume of blood ejected from the ventricles per heart beat
63
Define the ejection fraction
| What is it a measure of?
Fraction of the EDV which is ejected with each beat
| A measure of ventricular performance
64
How do you calculate the ejection fraction?
| What is the average value?
(Stroke volume/EDV) x 100%
| >55%
65
What makes the 1st and 2nd heart sound?
1st heart sound: AV valves close
| 2nd heart sound: SL valves close
66
What three things did Starling discover?
- Increasing EDV increased stroke volume
- Increased venous return increased heart contractility and increased cardiac output
- Increased calcium causes increased muscle tension
67
What 3 things influence stroke volume?
| How do they affect the EDV/ESV?
Increased preload = Increased SV = Increased EDV
Increased afterload = Decreased SV = Increased ESV
Increased intropy = Increased SV = Decreased ESV
68
How does sympathetic stimulation increase stroke volume?
Increases the volume of blood coming back to the heart and increases the force generated by the heart
69
What cells are the SAN and AVN made from?
Pacemaker cells
70
What is the intrinsic rate of firing for the SAN, AVN and Purkinje fibres?
SAN: 70bpm
AVN: 50bpm
Purkinje fibres: 30-40bpm
71
What is the difference between the sympathetic and parasympathetic control of the heart in regards to membrane potentials?
Normal: Resting potential is -60mv and the threshold is -40mv
Parasympathetic: Resting potential increases to -70mv so it takes longer to reach the threshold of -40mv and heart rate decreases
Sympathetic: Resting potential decreases to -50mv so it lates less time to reach the threshol dof -40mv and heart rate increases
72
What 4 parts of the heart does adrenaline act on and what does it do?
SAN: Increases rate of contraction
Atrial muscle: Increases force of contraction
AVN: Increases the automatic response
Ventricular muscle: Increases the automatic response and increases contraction force
73
Explain how a current is generated in an ECG
Rest: Muscle polarised (+ outside and - inside) - charge of zero
Depolarisation: (- inside and + outside) dipole forms and charge moves to the electrode forming a peak
Full depolarised: No charge difference (S-T line)
Re-polarisation: Charge moves back in the opposite direction (T wave)
74
Define isoelectric
Charge of zero
75
What does the P-R interval on an ECG represent?
The time take from SAN-AVN
76
What do Q, R and S represent separately?
Q: Depolarisation of the IV septum
R: Depolarisation of the apex and walls
S: Depolarisation of the base
77
What does the S-T segment on an ECG represent?
| When is it elevated?
Between the end of ventricular depolarisation and re-polarisation
Elevated during a MI
78
What 2 things may the U wave represent?
Re-polarisation of the papillary muscles
| Pathology
79
What may an increased R-R interval mean?
Increased risk of Arrhythmia due to increased Q-T interval
80
What is the role of the Hexaxial Reference System of the ECG?
Diagnoses conditions by looking at axis deviation (direction of the hearts depolarisation)
81
What 4 things do you examine the ECG for?
Cardiac axis, rate, rhythm and waveforms
82
What is atrial fibrillation?
Abnormal electrical activity causes rapid firing of the atria
83
What 3 things can atrial fibrillation cause?
Arrhythmia (irregular heartbeat)
Heart failure
Stroke
84
What is the ECG like for someone with atrial fibrillation?
Irregular R waves
No P waves
F waves
Irregular irregularity in R-R intervals
85
Give 3 causes of atrial fibrillation?
Alcohol, Heart disease, Hypertension
86
What are the 5 types of atrial fibrillation?
```
1st diagnosed (feeling faint)
Paroxysmal (less than 7 days)
Persistent (more than 7 days)
Long-standing permanent (trying to restore)
Permanent (cannot restore)
```
87
What do the treatments of atrial fibrillation aim to do?
Control the ventricular rate to prevent thrombo-embolism
88
4 classes of drugs which can be used for atrial fibrillation treatment
Which one is only used now in the elderly?
Anticoagulants
Beta blockers
Digoxin (now only in the elderly)
Non-dihydropyran calcium channel antagonists
89
What is cardioversion?
| What is it used to treat?
Coordinates the heart beat through electricity or drugs
| Atrial fibrillation
90
What are 4 other names for ventricular ectopic beats?
Ventricular extrasystoles
Ventricular premature complexes
Ventricular premature beats
Ventricular contractions
91
What 3 things happen during ventricular ectopic beats?
Beats occur earlier
There is a compensatory (longer) pause between beats
Impulse is not conducted well down the purkinje fibres causing slower depolarisation
92
What is the ECG like for ventricular ectopic beats?
Wide QRS complex
No P wave
An inverted T wave
93
How can you increase the removal of toxins from the body?
Increase the blood pressure
94
What does a decrease in peripheral resistance cause?
The blood runs away faster
| The pulse collapses faster
95
What is the equation for flow?
Flow = pressure gradient / resistance
96
What is resistance provided by?
Capillaries
97
What happens to pressure and flow when resistance increases?
Pressure and flow decrease
98
What is the difference between systemic and pulmonary vascular difference?
Systemic vascular difference is greater than pulmonary vascular difference
99
Why does the brain need a constant pressure?
So that the tissues can draw whatever blood they need
100
Explain how tissues get more blood during exercise
Cardiac output increases
| Resistance decreases and pressure remains constant so flow increases
101
What happens to the heart if the blood pressure gets to high?
It continues to pump
102
What controls blood flow at rest?
| What will altering blood pressure during this time do?
Tissues control blood flow at rest by adjusting peripheral resistance
Altering blood pressure does little to control flow
103
Explain how small levels of vasodilation increases blood flow
Tissue flow is proportional to the radius^4
| Dilate the tube from 1-2 = dilate the flow from 1-16
104
Where are precapillary sphincters found?
| What are they made from?
At the site of arterial bifurcation
| Smooth muscle
105
What causes relaxation of the precapillary sphincter?
Metabolic products
| e.g. CO2, H+, Hypoxia, NO
106
What are the 4 short term controls of blood pressure?
| How long is short term?
Arterial stretch, autonomic nervous system, baroreceptors, chemoreceptors
Seconds - hours
107
Where do sympathetic fibres run to?
The vasomotor centre in the medulla
| All blood vessel
108
How is blood pressure slightly increased at rest?
Increased sympathetic outflow
109
Where do nor-adrenergic fibres run to?
What receptor do they work on?
How do they cause vasoconstriction/dilation?
Smooth muscle alpha receptors
Agonise noradrenaine --> vasoconstriction
Block noradrenaline --> vasodilation
110
What happens to the muscles, tissues and heart if you stimulate the CNS?
Muscles vasodilate
Tissues vasoconstrict due to an increase in peripheral resistance, blood pressure, venous return and CO
Increased contractility, rate and relaxation of the heart
111
How do baroreceptors transmit impulses to the brain?
Cranial nerves 9 and 10
112
What do baroreceptors do when the pressure increases and decreases?
Increased pressure: Increased impulses to medulla so a decrease in sympathetic tone
Decreased pressure: Decreased impulses to the medulla so an increase in sympathetic tone
113
Why are baroreceptors important when you stand up?
Standing up changes gravity and thus circulation
Resting vasomotor tone causes a decrease in blood pressure and vasoconstriction so arteries increase increase blood pressure and increase venous return
114
What happens if there are no baroreceptors?
The mean blood pressure stays the same but it is all over the place
115
Which baroreceptors are the most important?
The ones in high pressure circulation
| Low pressure ones are still needed
116
When is long term control of blood pressure needed?
When blood pressure is persistently high
117
What are the four methods of long term blood pressure control?
ADH, Natriuretic peptides, Pressure diureses, RAAS
118
What happens in pressure diureses if you have a high salt diet or kidney disease?
High salt: Increased blood pressure needed to get rid of the salt
Kidney disease: Increased blood pressure is needed to get rid of the same amount of salt and water (causes hypertension)
119
What are Natriuretic Peptides?
| What do they do?
Hormones
Increased fluid stretches the cardiac muscle causing production of Natriuretic Peptides which increases salt and water removal by the kidney
120
What is renin?
An enzyme released from the kindey's juxtaglomerular apparatus
121
What is the RAAS system's pathway?
Angiotensin --> ANG 1 (Renin)
| ANG 1 --> ANG 2 (ACE)
122
4 roles of ANG 2
Aldosterone release
Increases vasopressin from the posterior pituritary
Vascular hypertrophy
Vasoconstriction
123
What does aldosterone do?
| Where is it released?
Sodium and water retention
| Adrenal cortex
124
What is contraction of the aorta?
| Why is it a problem?
A congenital defect where the aorta is occluded
Descending aorta has a LOW blood pressure --> RAAS activation
Ascending aorta is fine --> too high bp in the brain
125
Explain, in detail, how the RAAS system works if salt intake is high
Increased volume - Increased blood pressure - Decrease RAAS - Decrease salt and water retention - Decreased volume - Decreased blood pressure
126
What is hypertrophy?
An enlarged heart
127
What is the difference between Angina Pectoris and Myocardial Infarction?
Angina Pectoris: Marginally blocked coronary artery causing a weaker muscle and chest pain
Myocardial Infarction: Completely blocked coronary artery causing the death of a muscle
128
What does the tunica externa include?
Collagen for protection
129
What does the tunica media include?
Layers of smooth muscle supported by connective tissue
130
What is the epithelium in the tunica intima?
| What else does it contain?
Simple squamous
| Layers of connective tissue
131
What are the three types of capillary?
Continuous: Least permeable; small space between the capillary and cell
Fenestrated: Increased pores
Einusoid: Super increased pores
132
When does the heart tube begin to form?
Where?
What form?
21 days
The pericardial cavity
From cardiogenic mesoderm
133
What three things happen at 23 days?
Blood vessel formation
Heart begins to beat
Folding of the heart tube
134
What is the heart tube?
| What is is made from?
A pair of blood vessels folded together to produce a kink
| This kink is formed from 2 sheets of endoderm and makes up the foregut
135
What is the left common cardial vein formed by?
Formed by the fusion of two blood vessels and nerves either side of the lungs
Form the pleural and pericardial cavities
136
What does the 1st pharyngeal arch form?
Maxillary artery
137
What does the 2nd pharyngeal arch form?
Corticotympatic artery
138
What does the 3rd pharyngeal arch form?
Common and internal carotid
139
What does the 4th pharyngeal arch form?
Left part of the aortic arch
| Right part of the right subclavian
140
What does the 6th pharyngeal arch form?
Left part of the left pulmonary
| Right part of the right pulmonary
141
When are the pharyngeal arches symmetrical?
29 days
142
What is it called when the heart loops to the left instead of the right?
Dextrocardia
143
Explain how the heart tube develops
2 tubes filled with cardiac jelly stick together forming a single chamber with 2 vessels exiting out of the top and bottom.
The heart then loops to the right
144
What are the 3 chambers of the heart during early development?
Right and left ventricle
| TRUNCUS ARTERIOSUS
145
What is the first wall to partition the atria?
Septum primum wall grows from the top and bottom of the endocardial cushion and form a hole known as the foramen ovale
146
What is the second wall to partition the atria?
Septum secundum grows adjacent to the first wall and covers the foramen ovale forming a flap
147
What are the 4 defects in tetrology of farrot?
Enlarged aorta
Enlarged ventricle
Pulmonary valve constricted
Ventricular septum incomplete
148
How does the truncus arteriosus form 2 tubes from 1?
Walls grow from the outside of the tube and fuse in the midline
The walls grow in different orientations forming a spiralling tube
The tubes then separate
149
What two vessels does the truncus arteriosus create?
Aorta and pulmonary artery
150
Explain how blood enters the foetus?
Umbilical artery --> Ductus venosus --> Inferior vena cava --> Liver --> Heart
151
What are the 2 bypasses in a foetus which prevent blood going to the lungs?
Foramen oval in atria
| Ductus arteriosis from the pulmonary trunk to the aorta
152
What does the ductus arteriosus form in the adult?
Ligamentum arteriosusm
153
What does the foramen oval form in the adult?
Fossa ovalis
154
What does the ductus venosus form in the adult?
Ligamentum venosum
155
What does the umbilical vein form in the adult?
Round ligament of the liver
156
What does the umbilical arteries form in the adult?
Medial umbilical ligament
