Cardiovascular Flashcards
1
Q
What is the pericardium? What are its layers?
A
A tough, double-layered fibroserous sac which covers the heart.
It’s layers are:
- Fibrous pericardium: this is the most superficial layer, has loose and dense connective tissue and protects the heart, fixes it and prevent over filling
- Serous pericardium: has two layers, parietal (fused to the fibrous) and visceral (part of epicardium) both have a lubricating function
2
Q
What artery supplies the Sino Atrial Node?
A
The right coronary artery (60%)
3
Q
What artery supplies the Atrioventricular Node?
A
Posterior interventricular artery.
This arises from:
70% - Right coronary artery
20% - Right & Left coronary arteries
10% - Left coronary artery
4
Q
Where can the apex beat be heard?
A
Left of the sternum, 5th intercostal space, mid-clavicular line
5
Q
What is on the right heart border?
A
1) Superior Vena Cava
2) Right atrium
6
Q
What is on the left heart border?
A
1) Aortic knuckle
2) Left pulmonary artery
3) Left auricle
4) Left ventricle
7
Q
What is the anterior border of the heart?
A
Right ventricle
8
Q
What is the posterior border of the heart?
A
Left atrium & pulmonary veins
9
Q
What is the mediastinum?
A
Area between the right and left pleura
10
Q
Where what divided the mediastinum into superior and inferior?
A
Plane between eternal angle & T4/5 vertebrae
11
Q
How is the mediastinum into anterior, middle & superior?
A
By pericardium
12
Q
Where would you find the SA node?
A
A long cresent shaped area in the crusts terminal is at the superior border of the right atrium
13
Q
Where is the AV node located?
A
A small nodule just above the septal cusp of the tricuspid value in the inter-atrial septum
14
Q
What is the thoracic duct?
A
A channel draining lump from below the diaphragm and above the diaphragm on the left side. It drains the lymph into the junction between the left subclavian vein and left internal jugular vein.
15
Q
What is the nerve root of the greater splanchnic nerve? What does it supply?
A
T5-9
Supplies the foregut
16
Q
What are the nerve roots of the lesser splanchnic nerve? What does it supply?
A
T10 & T11
Mid gut
17
Q
What is the nerve root of the least splanchnic nerve? What does it supply?
A
T12
Hindgut
18
Q
What level does the bifurcation of the aorta occur?
A
L4
19
Q
Why is heart pain referred and where to?
A
Neck, shoulders, jaw, arms and stomach.
Because the heart’s sensory supply is from the cardiac plexus made up of spinal nerves T1-T4 so pain is felt in the dermatomes supplied by these nerves
20
Q
What is involved in cardiac muscle contraction but not in skeletal muscle contraction (or to a lesser extent)
A
Calcium-induced calcium release: this is where an increase in Ca2+ in the cell causes more calcium release (part of the early plateau phase)
21
Q
What are the two main baroreceptors?
A
1) Carotid sinus
2) Aortic Arch baroreceptors
22
Q
What happens if the blood pressure decreases through baroreceptor detection?
A
Decreased pressure > decreased discharge rate > Fewer action potentials to medullary cardiovascular centre
This leads to:
- Increased hear rate (^symp)
- Increased contractibility (^symp)
- Arteriolar construction (^symp + angiotensin II & ADH release)
- Increased venous constriction (^symp)
23
Q
What are the local factors that cause vasoconstriction?
A
1) Endorhelin - peptide produced by endothelium with causes constriction
2) myogenic contraction of blood vessels
24
Q
What are the local factors for vasodilation?
A
Hypoxia Hypercapnia Decreased pH Bradykinin Increased K+ Nitric oxide Tissue breakdown products
25
What are the hormonal factors for vasoconstriction?
Angiotensin II
Vasopressin (ADH)
Adrenaline
26
What hormonal factors that cause vasodilation?
Adrenaline
| ANP
27
How is CO2 transported in the blood?
1) In blood plasma - 10% of CO2
2) By haemoglobin - 25-30% of CO2 (combines reversible to deoxyhaemoglobin to form carbaminohaemoglobin)
3) As hydrogen bicarbonate - 60-65%
28
How are the hydrogen ions, produced from the production of hydrogen bicarbonate, transported?
Binds to deoxyhaemoglobin (of which it has greater affinity to than oxy), when deoxyhaemoglobin becomes oxy haemoglobin in the lungs it releases H+
This combines to bicarbonate
The carbonic acid is then catalysed by carbonic anhydrase to CO2 and H2O
CO2 then diffuses and is breathed out
29
What is the structure of the heart tube starting form aortic sac?
```
Aortic sac
Bulbus Cordis
Ventricle
Atrium
Sinus venosus
Horns of sinus venosus
Common Cardinal arteries
```
30
What happens in cardiac looping?
Cephalic portion: moves ventral, caudal and to the right
Atrial portion: moves dorsocranially and to the left
31
What is meant by preload?
The volume of blood in the left ventricle that stretches the cardiac myocytes before contraction
32
What is meant by after load?
The pressure again the wall of the left ventricle that must be overcome
33
What is meant by contractibility?
The force of contraction and change in fibre length
34
What is meant by elasticity in terms of the heart?
Ability to recover normal shape after systolic stress
35
What is Diastolic distensibility?
The pressure required to fill the ventricle to the same diastolic volume
36
What is meant by compliance?
How easily the heart chamber expands when filled with blood
37
What is formed from the 1st aortic arch?
Maxillary artery
38
What is formed from the 2nd aortic arch?
Hyoid and Stapedial arteries
39
What is formed from the 3rd aortic arch?
Common carotid artery and first part of internal carotid
40
What is formed from the 4th aortic arch?
Left: Part of the arch of the aorta
Right: Right subclavian artery
41
What is formed from the 5th aortic arch?
There isn't one
42
What is formed from the 6th aortic arch?
Left: Left pulmonary artery and ductus arteriosus
Right: Right pulmonary artery
43
What is the nernst equation?
E = 60 log (concentration outside/concentration inside)
44
What does the the nerest equation calculate?
The potential associated with ionic concentration gradients
45
What pump is responsible for the membrane potential?
Na+/K+ pump
46
What is responsible for the action potential spike (depolarisation)?
Voltage gated Na+ channels opening (influx of Na+)
47
What is responsible for the prolongation of the action potential?
Voltage gated Ca2+ channels opening (influx of Ca2+)
48
What is responsible for the repolarisation?
Voltage gated K+ channels opening (outflow of K+)
49
What happens to the voltage gated Na+ channels when the voltage alters?
They change shape
50
At what voltage do the voltage gated Na+ channels open?
Between -70mV and -50mV
51
What inactivates the Na+ channels?
They close after a short period of time - time controlled closure
52
Whta re the characteristic features of the voltage gated calcium channels?
1) Slower than the fast Na+ channels
2) Remain open longer
3) Na+ also passes through them
53
What are the voltage gated calcium channels responsible for?
The plateau phase
54
What ion/s are moving in phase 0?
Na+ - IN
55
What ion/s are moving in phase 1?
K+ and Cl- - OUT
56
What ion/s are moving in phase 2?
Ca2+ - IN
| K+ - OUT
57
What ion/s are moving in phase 3?
K+ - OUT
58
What ion/s are moving in phase 4?
K+ - IN
| Na+ - OUT
59
List the three structures that the action potential passes through into the cell in excitation contraction coupling
1) Membrane
2) Transverse tubules
3) Sarcoplasmic reticulum
60
What happens as a result of the arrival of the action potential in excitation contraction coupling?
Ca2+ is released
61
Where is the Ca2+ released from?
1) T tubules (unique to heart)
| 2) Sarcoplasmic reticulum (as in skeletal muscles)
62
Whta is the role of Ca2+ presence in the sarcoplasm?
It causes muscle contraction through allowing the binding of myosin head to actin
63
Briefly describe the propagation of the action potential in cardiac cells
1) Action potential spreads over cell membrane
2) Positive charge from Na+ affects adjacent cells
3) Depolarisation occurs
4) Newly depolarised cells also cause depolarisation
64
How do the ions travel between cardiac myocytes?
Directly through gap junctions
65
What is the speed of conduction in atrial and ventricular fibres?
0.3 to 0.5 m/s
66
What is the speed of conduction in purkinje fibres?
4m/s
67
What is the role of the SA node?
Determines the rate at which the heart beats - it initiates depolarisation
68
What is the resting membrane potential for the SA node?
-55 to -60 mV
69
Describe the generation of the action potential in the SA node
1) Slow Na+ inflow
2) Membrane potential moves towards threshold for discharge
3) Fast Na+ channels close
4) Action potential driven by Ca2+ channels (inflow)
5) Repolarisation occurs through K+ Outflow
70
What does automaticity mean in relation to cardiac myocytes?
That they have the ability to genertae an action potential and depolarise themselves
71
How does automaticity vary in the heart cells?
Greatest in the SA node, rate of spontaneous discharge decreases down the heart
72
The AV node delays the impulse from the atria to the ventricles, why?
It allows atria to empty all the blood into the ventricles
73
How does the AV node delay impulses?
1) There are less gap junctions in the AV node
| 2) The fibres of the AV node are smaller than the atria fibres
74
What happens in the absolute refractory period in the heart in terms of the membrane?
The Na+ and Ca2+ channels are closed
75
What is the normal refractory period of the ventricles?
0.25s
76
What is the role of the absolute refractory period?
1) Prevents excessive contraction
| 2) Allows time for the heart to fill
77
Does the relative refractory period occur before or after the absolute?
After
78
What causes there to be a relative refractory period?
1) Some Na+ channels are still inactivated
| 2) K+ channels are still open
79
What does the relative refractory period mean?
That only strong stimuli can cause an action potential
80
What does the sympathetic input do to the heart?
1) Increases heart rate
2) Increases force of contraction
3) Increases cardiac output
81
What does the parasympathetic input do to the heart?
1) Decreases heart rate
2) Decreases force of contraction
3) Decreases cardiac output
82
What is the term used that means something increases/decreases heart rate?
Positively chronotropic
83
What is the term used that means something increases/decreases force of contraction?
Positively inotropic
84
What is involved in sympathetic stimulation of the heart?
1) Adrenaline and noradrenaline
| 2) Type 1 beta adrenoreceptors
85
What is involved in parasypathetic stimulation?
1) Acetylcholine
| 2) M2 receptors
86
By how much can the sympathetic stimulation increase cardiac output by?
200%
87
By how much can decreased sympathetic stimulation decrease cardiac output?
30%
88
By how much can increased parasympathetic stimulation decrease cardiac output?
50%
89
What are the equations for Cardiac output?
CO = SV x HR
OR
CO = BP/R
90
What is the equation for stroke volume?
SV = EDV - ESV
91
What is the equation for blood pressure?
BP = CO x R
92
What is the equation for mean arterial pressure?
Diastolic pressure + 1/3 (systolic pressure - diastolic pressure)
so
MAP = DP + 1/3PP
93
What is the equation for pulse pressure?
PP = Psystolic - Pdiastolic
94
What are the two equations for flow?
F = P/R
OR
F = Pressure gradient/resistance
95
Where is the principle site of resistance to vascular flow?
Arterioles
96
How does autoregulation differ around the body?
1) Renal/cerebral/coronary = Excellent
2) Skeletal muscle/splanchnic = Moderate
3) Cutaneous = Poor
97
What determine flow in the capillaries?
1) Arteriolar resistance
| 2) No. of open pre-capillary sphincters
98
What three mechanisms aid the movement of lymph?
1) Smooth muscle in the lymphatic vessels
2) Skeletal muscle pump
3) Respiratory pump
99
What are the long term mechanisms for blood pressure?
RAAS and ADH
100
List, in order, the top four organ systems in terms of blood flow
1) Liver
2) Kidneys
3) Muscle
4) Brain
101
What are the phases 0-4 in myocyte action potentials?
0) Rapid depolarisation
1) Partial repolarisation
2) Plateau
3) Repolarisation
4) Pacemaker potential
102
What does the size of the voltage on an ECG show?
1) If its large then the impulse is moving towards the electrode
2) If the voltage is small or negative it is going away from the electrode
103
What is the name for the arrangement of the leads in an ECG?
Einthoven's Triangle
104
ECG's show change in voltage over time. What does each small square represent?
40ms
105
What does each large square represent on an ECG?
0.2s
106
On an normal ECG the P waves are positive in all leads apart from...?
aVR
107
On a normal ECG the T wave is positive in all leads except from...?
aVR (and V1 and V2 in some races)
108
What are the branches of the left bundle branch called?
Anterior and posterior hemifasicles
109
What is the P waves representative of?
Atrial depolarization
110
What is the PR interval representative of?
Slow conduction of the impulse by the AV node
111
What is the QRS complex representative of?
Ventricular depolarization
112
What is the ST segment representative of?
The interval between depolarization and repolarisation of the ventricles
113
What is the T wave representative of?
Ventricular repolarisation
114
What are the characteristics of Right bundle branch block?
M in V1/V2
S wide lead I
```
Remember:
MoRriS
M - V1/V2
R = RBBB
S - in lead I
```
115
What are the characteristics of Left bundle branch block?
V in V1/V2
A in V6
Remember:
ViLlA
116
What are the positions of the chest leads?
V1 - 4th intercostal space, right of sternum
V2 - 4th intercostal space, left of sternum
V3 - 5th intercostal space, between V2 and V4
V4 - 5th intercostal space, at midclavicular line
V5 - 5th intercostal space, begining of axilla
V6 - 5th intercostal space, at middle of axilla
117
Platelets change shape when activated what is the shape change?
Smooth discoid to spiculated with pseudopodia
118
Why do platelets change shape when activated?
1) It increases their surface area
| 2) It increases the possibility of cell-cell intercations
119
What are the receptors on the platelets?
Glycoprotein IIb/IIIa
120
Summarize what happens to the receptors in platelet activation
1) No/ of receptors increases
2) Affinity of receptors to fibrinogen increases
3) Fibrinogen links the receptors, this binds the platelets together (platelet aggregation)
121
What substance is converted to prostaglandins by the COX enzymes?
Aracidonic acid
122
What does COX-1 do?
1) Mediates GI mucosal integrity
| 2) Mediates thromboxane A2-mediated platelet aggregation
123
What does COx-2 do?
1) Mediates inflammation
2) Mediates prostacyclin production which inhibits platelet aggregation
3) Affects renal function
124
What does low dose aspirin do in terms of the COX enzymes?
Inhibits COX-1
125
What does high dose aspirin do in terms of the COX enzymes?
Inhibits COX 1 and 2
126
ADP activates P2Y1, what does this result in?
1) Platelet activation
| 2) GPIIb/IIIa fibrinogen cross-linking and aggregation
127
ADP activates P2Y12, what does this do?
Sustains platelet activation and aggregation - amplifies
128
Platelets release dense granules, what do these contain?
ADP - this causes further activation
129
When does excitation-contraction coupling begin and end?
Begins: When the action potential depolarizes the cell
Ends: When the Ca2+ binds to its receptor on the contractile apparatus
130
What do myocytes rely on for energy production usually?
Free fatty acid metabolism
131
What happens in anaerobic conditions in terms of myocytes?
They rely on metabolising glucose anaerobically - this provides enough energy to maintain survival of muscle but without contraction
132
What is a sarcomere?
The functional unit of the contractile apparatus
133
How many I bands and how many A bands does a sarcomere contain?
Two half I bands and one A band
134
What is the sarcoplasmic reticulum?
It is a membrane network that surrounds the contractile proteins.
It consists of the sarcotubular network at the centr of the sarcomere and the subsarcolemmal cisternae (these touch the T-tubules and sarcolemma)
135
What is the T-tubule?
A membrane that is continuous with the sarcolemma, the lumen of the t-tubules carries the extracellular space towards the centre of the myocardial cell
136
What causes the sliding of actin over myosin?
ATP hydrolysis on the head of the myosin molecule
137
What connects the myosin heads with the actin?
Crossbridges
138
What is myosin composed of?
2 heavy chains - responsible for the dual heads
| 4 light chains
139
What is actin?
A globular protein
G-actin = single globule
F-actin = many G-actin
Two F-actins form Double-stranded macroolecular helix
140
What is tropomyosin?
1) An alongated molecule made of two helical peptide chains
| 2) It occupies the longitudinal grooves between the two actin strands
141
What does Troponin I do?
Along with tropomyosin it inhibits actin and myosin intercation
142
What does troponin T do?
Binds the troponin complex to tropomyosin
143
What does troponin C do?
Is a high affinity calcium binding site, it signals contraction
144
What does the bonding of calcium to Troponin C do?
Drives Troponin I away from actin - this allows the interaction of actin and myosin to occur
145
what is titin?
A protein that acts as a molecular spring and is responsible for muscles passive elasticity
146
What two stages occur in LV contraction?
1) Isovolumetric contraction
| 2) Maximal ejection
147
What five stages occur in LV relaxation?
1) Reduced ejection
2) Isovolumetric relaxation
3) Rapid LV filling and LV suction
4) Slow LV filling (diastasis)
5) Atrial booster
148
Describe the process of systole
1) Wave of depolarisation arrives
2) L-calcium tubules open
3) Ca2+ arrive at the contractile proteins
4) contraction causes LVp to rise
5) LVp>LAp - MV closes
6) Isovolumetric contraction - LVp>Aop
7) AoV opens and ejection occurs
149
Describe the process of diastole
1) LVp decreases after peak
2) Cystolic calcium is taken up into SR
3) Reduced ejection
4) Ao flow maintained by aortic distensibility
5) LVp
150
Describe the process of ventricular filling
1) LVp
151
What percentage of the blood is cellular?
45%
152
What percentage of the blood is plasma?
55%
153
What is haematocrit?
It is a measure of the viscosity of the blood - it is the volume of red blood cells in the blood (usually 45% in men, 40% in women)
154
What is haematopoiesis?
The formation of the blood cellular components
155
What is the life span of red blood cells?
120 days
156
What is the lifespan of white blood cells?
6 hours
157
What is the lifespan of platelets?
7-10 days
158
Precursor cells for mature blood cells are present in different places in development, where are they found?
Adult - axial bones
Children - all bones
In utero - yolk sac then liver and spleen
159
Whta hormone stimulate red blood cell proliferation and differentiation?
Epo
160
What hormone stimulates the proliferation and differentiation of white blood cells?
C-CSF
161
What hormone stimulates Platelet proliferation and differentition?
Tpo
162
What is the structure of haemoglobin?
It has four subunits, each subunit is composed of a molecular group called heme and a polypeptide. The polypeptides are collectively known as globin.
It is a tetramer - it has two alpha and two beta chains
Each heme group has a Fe2+ onto which one molecule of oxygen can bind
163
What is the name for low haemoglobin?
Anaemia
164
What is the name for high haemoglobin?
Polycythaemia
165
How can anaemia occur?
1) Iron deficiency
2) B12.folate deficiency
3) Haemolysis
4) Bone marrow failure
166
What does iron deficiency anaemia lead to?
1) Reduced production of red blood cells
2) Low haemoglobin
3) Small red blood cells
167
What is haemolysis?
Normal or increased red cell production but decreased lifespan
168
What happens if haemolysis occurs?
1) Increased haem turnover leads to jaundice and anaemia
| 2) Increased reticulocytes
169
What are reticulocytes?
Immature red blood cells - shouldn't be present in blood
170
What are neutrophils?
```
White blood cell
Most common type
Lifespan - 10 hours
Phagocytose and kill bacteria
Release chemotaxins and cytokines in inflammatory response
```
171
What are B lymphocytes?
White blood cell
(Named after bone marrow)
Differentiate into plasma cells that produce immunoglobulins when stimulated by foreign antigen
172
What are T lymphocytes?
White blood cell
(Named after Thymus)
Some are helper cells (CD4)
Some are cytotoxic cells (CD8)
They aid B cells in antibody generation and are responsible for cellular or cell mediated immunity
173
What are platelets formed from?
Megakaryocytes in the bone marrow
174
How do platelets form from megakaryocytes?
Cytoplasm buds off the polyploid cells to form the platelets
175
What does polyploid mean?
The cell has more than two paired sets of chromosomes
176
What is the name for reduced platelets?
Thrombocytopenia
177
What is the name for increased platelets?
Thrombocytosis
178
What happens with reduced platelets?
Increased or spontaneous bleeding
179
What happens with increased platelets?
Arterial and venous thrombosis
180
What are coagulation proteins?
A series of proteins that circulate in an inactive form, they function to make a blood clot.
They do this by converting fibrinogen to insoluble fibrin
181
What are the main plasma proteins?
1) Albumin
2) Carrier proteins
3) Immunoglobins
4) Coagulation proteins
182
What is albumin?
A major plasma protein
Produced in the liver
Determines oncotic pressure
Keeps intravascular fluid intravascular
183
What happens as a result of low albumin?
Oedema
184
What are the four main types of immunoglobulin?
IgG
IgM
IgA
IgE
185
Blood is usually fluid inside blood vessels, why?
1) The coagulation proteins are in an inactive state when circulating
2) The endothelial cells, natural anticoagulant pathway and fibrinolytic pathway actively keep it fluid
186
What is haemostasis?
Stopping the flow of blood
187
Why is the coagulation cascade complex with many steps?
1) Allows biological amplification
| 2) Allows for regulation - not an all or nothing response, can vary in response to severity
188
What is the consequence of liver disease in terms of blood?
It is associated with bleeding and prolonged prothrombin time due to less coagulation factors and fibrinogen
189
Vitamin K deficency has an impact on coagulation, why?
Vitamin K is required for the correct synthesis of coagulation factors II, VII, X and XI
190
What drugs can affect blood clotting?
Aspirin - affects platelet function
| Heparin and warfarin - affect coagulation cascade
191
What happens in sickle cell anaemia?
- A mis-sense mutation occurs in the beta-globin gene
- Nucleotide change means Glutamic acid is swapped to valine
- This causes the red blood cell to change shape and become deformed, inflexible and sticky upon deoxygenation
192
Is the genetic mutation for sickle-cell anaemia dominant or recessive?
Recessive
193
What happens if you are heterogeneous with one recessive allele?
You may appear normal but at low levels of oxygen the red blood cells can still deform and become sticky
194
What issues can result in sickle-cell anaemia?
1) Reduced blood flow due to cells being sticky
2) Pain due to lack of oxygen to bones
3) Lack of oxygen leads to damage of organs - notably lungs, kidneys, spleen and brain
195
What part of the heart is at its anterior surface?
Right ventricle
196
What part of the heart is at the posterior (base) of the heart?
Left atrium
197
What part of the heart is at the inferior (diaphragmatic) surface of the heart?
Left and right ventricles
198
What structure is at the right pulmonary surface of the heart?
Right atrium
199
What structure is at the left pulmonary surface of the heart?
Left ventricle
200
What region of the heart does the right coronary artery supply?
Inferior
201
What region of the heart does the Left anterior descending supply?
Anteroseptal
202
What region of the heart does the distal end of the Left anterior descending supply?
Anteroapical
203
What region of the heart does the left circumflex artery supply?
Anterolateral
204
What region of the heart does the Right coronary artery supply?
Posterior
205
Why would occlusion of the LAD be significantly bad?
The LAD supplies a large proportion of the heart, supplying the anteroseptal region of the heart which equates to the majority of the heart below the AV node
206
Where are the main two peripheral chemoreceptors located?
1) Carotid body (bifurcation of the common carotid artery)
| 2) Aortic body (in aortic arch)
207
Where are the central chemoreceptors located?
In the medulla
208
What do the peripheral chemoreceptors detect?
1) Decreases in PO2
| 2) Increases in H+
209
What do the central chemoreceptors detect?
1) Increased H+ concentration
