Cardiovascular Flashcards
(126 cards)
1
Q
What are the two phases that make up the blood? Give their proportions also.
A
Cellular phase 45%
Fluid phase 55%
2
Q
What makes up the majority of the cellular component of the blood?
A
RBCs (44%)
3
Q
Define heamatorcrit and give its usual value
A
The proportion of the cellular component of the blood, 0.45.
4
Q
Define serum
A
Fluid component of blood with all the clotting factors removed
5
Q
What happens to the haematocrit during acute anaemic (bleeding) and why?
A
Stays the same, 0.45. Cellular and fluid components of blood lost in the same proportion
6
Q
What happens to the haematocrit during chronic anaemia?
A
Decreases (0.2)
7
Q
Define haematopoesis
A
Production of blood cells
8
Q
Where are a haemopoetic stem cells in an adult?
A
Bone marrow at axial skeleton
9
Q
Where are haemopoetic stem cells found in a child?
A
Bone marrow at all bone
10
Q
Where are haemopoetic stem cells found in utero?
A
Yolk sac, liver and spleen
11
Q
What growth factor causes haemopoetic stem cells to proliferate into RBCs? And where is the factor secreted?
A
Erythropoetin (EPo)
Kidneys
12
Q
Where are mature blood cells found?
A
In circulation
13
Q
What growth factor causes haemopoetic stem cells to proliferate into WBCs?
A
Granulocyte-colony stimulating factor (GCSF)
14
Q
What growth factor caused haemopoetic stem cells to proliferated into platelets?
A
Thrombopoetin (TPo)
15
Q
Give the average life span of RBCs
A
120 days
16
Q
Give the average life span of WBCs
A
6 hours
17
Q
Give the average life span of platelets
A
7-10 days
18
Q
Which of the blood cells are anucleate/ have no membrane bound organelles?
A
RBCs and platelets
19
Q
Erythrocyte is the proper name for which type of blood cell?
A
RBC
20
Q
Describe the shape of RBCs and state why they are this shape?
A
Biconcave
Increases SA:V for rapid diffusion of O2/CO2
21
Q
What is a reticulocyte?
A
A young erythrocyte still containing its ribosomes (1% of circulating erythrocytes)
22
Q
What are the main sites of RBC breakdown?
A
Liver and spleen
23
Q
What is the major breakdown product of haemoglobin (and therefore RBCs)?
A
Bilirubin
24
Q
What is the function of RBCs?
A
Contain haemoglobin to allow the transport of gases O2/CO2
25
Describe the structure of Hb
4 polypeptide chains (2 alpha and 2 beta)
| 4 haem groups each with an Fe 2+ (ferrous group)
26
How does the presence of CO2 affect the binding of O2 to Hb? What is the name of the shift that results on an oxygen dissociation curve and in which direction does it occur?
```
Increase in CO2
Decrease in pH
Conformational change of Hb
Decreased affinity for O2
Increased unloading of O2
```
Bohr shift
To the right
27
What is the proper name for WBCs?
Leukocytes
28
What are the two main types of leukocytes
Granulocytes
| Agranulocytes
29
Give the normal range of Hb
12.5-15.5g/dL
30
Give the 3 types of granulocyte, give in order of most to least abundant
Neutrophil
Eosinophil
Basophil
31
State the 2 types of agranuolocyte, giving the most abundant type first
Lymphocyte
| Monocyte
32
Describe the features and role of a neutrophil
Multi-lobar (4) lobes
Phagocytic
Release cytokines in inflammatory response
33
Describe the features and role of eosinophils
2-3 lobes
Pink staining granules
Protect against parasite infection
34
Describe the structure and function of basophils
Blue staining granules
Secrete histamine and anticlotting factors that increase blood flow and therefore attracts infection fighting cells to accumulate at site of infection
35
Describe the features and role of lymphocytes
Small, darkly stained nucleus, & very little cytoplasm
Role in specific/adaptive immunity
T - thymus - cyctotoxic
B - bone marrow - antibodies/immunoglobulins
36
Describe the features and role of monocytes
Kidney shaped nucleus
Phagocytes in blood
Migrate and mature at tissue - macrophages
37
Define haemostasis
The prevention of blood loss
38
Give the 3 mechanisms of haemostasis when an injury to a blood vessel occurs
Vasoconstriction
Platelet plug formation
Coagulation/clotting cascade
39
Define what is meant by a haematoma
Accumulation of blood within tissues (increase interstitial pressure prevents continues blood loss)
40
Where are the majority of clotting factors synthesised? Which of the clotting factors are synthesised here?
```
Liver
I
II
V
VII
VII
IX
X
XI
```
41
What is clotting factor I?
Fibrinogen
42
What is clotting factor II?
Prothrombin
43
Describe the platelet plug formation
Exposure of collagen
von Willerbrand factor bind to collagen
Platelets bind to vWF by GP1b receptor
Binding causes the release of alpha and dense granules
ADP (from dense granules) binds to P2 (purinergic receptors) which activates the cell
Activation
- change in shape to psuedopodia
- change in metabolism
- change in surface membrane
* activation of GPIIb/IIIa receptor, increased affinity for fibrin
* thromboxane A2 release, derived from arachidonic acid
Thromboxane A2 and ADP stimulate platelet aggregation
Fibrinogen forms bridges between aggregating platelets
PLATELET PLUG
Surrounding non-damaged cells release prostaglandin and NO that inhibit aggregation and stop the platelet plug spreading any further
44
Define thrombosis
The formation of a clot inside a vessel
45
What is the proper name for platelets
Thrombocytes
46
Describe the features and role of platelets
```
Cytoplasmic fragment of megakaryocytes
Anucleate
Circulate in the inactive form
Alpha and dense granules (also lysosomes and peroxisomes)
Role in heamostatis
```
47
What have if the no. of platelets are decreased to less than 20% of their normal amount
Spontaneous bleeding
48
What is the importance of cascade reactions?
Bio amplification
| Tight regulation/graduated response
49
What is the penultimate step in the coagulation cascade? And what is this step catalysed by?
Prothrombin to thrombin
| Prothrombinase (Xa) (Also requires Ca2+)
50
What is the final step in the coagulation cascade? And what is it catalysed by?
Fibrinogen to fibrin
| Thrombin (Also requires Ca2+)
51
What is found in the alpha granules of platelets?
Fibrinogen
vWF
V
52
What is found in the dense granules of platelets?
ADP
Ca2+
Serotonin
53
Where does thromboxane 2 come from?
Derived from arachidonic acid which itself comes from the plasma membrane of platelet
54
Give the functions of thrombin
Converts fibrinogen to fibrin
Positive feedback on itself - activates other clotting factors
Activates platelets
55
What is the main component of a blood clot
Fibrin (forms insoluble meshwork)
56
Describe the intrinsic pathway of the clotting cascade
Slow
| Everything it requires w/i blood
57
When is the intrinsic pathway of the clotting cascade activated?
When blood comes in to contact with a negatively charged surface e.g. exposed collagen
58
At which clotting factor does the intrinsic pathway of the coagulation cascade start?
XII
59
Describe the extrinsic pathway of the coagulation cascade
Fast
| Requires cellular component - tissue factor
60
When is the extrinsic pathway of the clotting cascade activated
When tissue factor is released from damaged cells
61
What is the role of tissue factor in the extrinsic pathway of the coagulation cascade?
Tissue factor binds to and therefore activates factor VII
62
Factor VII is involved in the activation of which other clotting factors (this is the point at which the intrinsic and extrinsic pathways merge)
IX
| X
63
What is vitamin K required for (in terms of haemostasis)?
Synthesis of clotting factorsWh
64
What happens to the prothrombin (bleeding) time in someone who develops liver disease? And why?
Increased prothrombin time
| Due to decrease coagulation as most clotting factors synthesised at the liver
65
Give the 3 types of plasma proteins
Albumin
Globulins (immunoglobulins)
Fibrinogens
66
State the roles of albumin
Maintain oncotic/osmotic pressure
Transport and binding of substances
Free radical scavenging
Anticoagulant effects
67
Where are immunoglobulins produced?
B lymphocytes
68
What causes the plateau of the membrane potential in a cardiac myocyte during contraction
Slow influx of Ca2+
69
How long does the absolute refractory period last for in a cardiac myocyte? And why does it exist?
0.2 s
| Allows the heart to fill with blood
70
What does the P wave on an ECG show?
Atrial depolarisation
71
What does the QRS complex show on an ECG?
Ventricular depolarisation
72
What does T wave on the ECG show?
Ventricular repolarisation
73
What does the PR segment (not the same as PR interval) of an ECG show?
Delay at AV node
74
What does the PR interval of an ECG represent? Give the normal time range of a PR interval
The time it takes for an electrical impulse to spread from the SAN to the AVN. 0.12-0.2s
75
What does a longer PR interval indicate?
Heart block
76
At what speed do electrical impulses travel in atrial/ventricular muscle fibres?
0.3-0.5 m/s
77
At what speed to electrical impulses travel in purkinje fibres?
4m/s
78
What does the ST segment represent? How long does it last for?
State of ventricular contraction
79
When might ST segment become elevated?
Myocardial infarction
80
Why might ST segment become depressed?
Angina
81
How long does QRS complex normally last?
0.6 - 1.0 s
82
Give a reason for QRS complex widening
Bundle branch block
83
What does the QT interval represent? How long does it last for?
Ventricular depolarisation followed by ventricular repolarisation. 0.4 s
84
Why is the T wave a positive reflexion?
Repolarisation in the opposited direction of lead II (double negative)
85
In which direction does septal depolarisation occur? And what is it shown by on an ECG
Left to right
| Q of QRS
86
What does the R of the QRS complex represent?
Depolarisation of the mass of the ventricles
87
What does the S of the QRS complex represent?
Depolarisation of the ventricles at the base of the heart
88
Describe the features of cardiac muscle
```
Striated
Sarcoplasm
T-tubules
Single nucleus
Branched
Intercalated discs w/ gap junctions and desmosomes
```
89
What is the purpose of gap junctions between cardiac muscle cells and T-tubules within cardiac muscle cells
To allow the rapid propagation of action potentials throughout the entire heart allowing simultaneous contraction of cells
90
Where is calcium stored within a cardiac myocyte?
Terminal cisternae of the sarcoplasmic reticulum
91
What impact does an increase in cytosolic Ca2+ have on the strength of contraction in skeletal muscle?
None, a single action potential releases sufficient Ca2+ to fully saturate troponin sites
92
What impact does an increase in cytosolic Ca2+ have on the strength of contraction in cardiac muscle?
Increases
93
Give the 3 subunits of troponin and their roles
Troponin C - binds with Ca2+
Troponin I - with tropomyosin inhibits actin/myosin interaction
Troponin T - binds troponin complex to tropomyosin
94
Describe the excitation part of excitation-contraction coupling
Pacemaker potential arrives at cardiac myocyte
Action potential at cardiac myocyte w/ slow influx of Ca2+ through L-type channel
Ca2+ binds to ryanoide receptors at sarcoplasmic reticulum, releases Ca2+ into cytoplasm
95
Describe the contraction phase of excitation-contraction coupling
Ca2+ released into cytoplasm binds to troponin C which induces a conformational change in troponin I
Tropomyosin moves and exposes action-myosin binding sites
(At rest) ATP bound to myosin head is hydrolysed to ADP + Pi. Myosin head is energised
(Ca2+ present) Energised myosin heads form cross bridges with actin
Binding causes the release of ADP + Pi + ENERGY from myosin head, ratchet/angular movement occurs
ATP binds to myosin head and breaks cross bridge
ATP bound to myosin is hydrolysed to ADP + Pi. Myosin head re-energised.
Cycle repeats for as long as Ca2+ remains bound to troponin (C)
96
Describe the composition of myosin
2 heavy chains
| 4 light chains
97
Define a sarcomere
A functional unit of the contractile apparatus
98
What is used for myocardial metabolism during:
a) aerobic respiration
b) anaerobic respiration
a) FAs
| b) Glucose
99
In a sarcomere what does the A-band show?
Myosin and actin (thickest/dArkest)
100
In a sarcomere what does the I-band show?
Actin only (thinest/LIghtest)
101
In a sarcomere what does the H zone represent
Myosin only
102
Describe the composition of actin
Double helix of F(ilament) actin
| F actin made up of polymerised globular actin molecules
103
State the equation for Mean Atrial Pressure
MAP = Total Peripheral Resistance X CO
104
Which vessels are main determinant of TPR and therefore MAP?
Arterioles
105
What law describes resistance in a vessel? State it's equation
```
Poiseuille's law
R= 8nl/πr^4
R= resistance
n=viscosity
l=length
r=radius
```
106
Where are the traberculae carnae located? What are they?
RV & LV
| Ridges of muscle
107
Where are the musculi pectinati found? What are they?
RA
| Ridges of muscle
108
What is the cristae terminalis and where is it found?
Crest of muscle in the RA dividing the smooth and ridged parts of the atria wall
109
What is the surface marking of the tricuspid valve?
Right 4th IC
110
What is the surface marking of the aortic valve?
Left 3rd IC
111
What is the surface marking of the pulmonary artery?
Left 3rd CC
112
What is the surface marking of the mitral valve
Left 4th CC
113
Where would you listen for the mitral valve?
Apex
| Left 5th IC mid-clavicular line
114
Where would you listen for the tricuspid valve?
Right 5th IC
115
Where would you listen for the aortic valve?
Right 2nd IC
116
Where would you listen for the valve of the pulmonary artery
Left 2nd IC
117
In the fetus, where is the ductus arteriosus found? What does it become?
Between the PA ->aorta
| Ligamentum arteriousus
118
In the fetus where is the ductus venosus found? What does it become?
Between placenta - IVC
| Ligamentum venosus
119
Where is the foramen ovale found? What does it become?
Between right atrium -> left atrium
| Fossa ovalis
120
Where do the coronary arteries arise from?
Aortic sinus
121
What branches does the RCA usually give
- nodal
- posterior interventricular
- marginal
122
What branches does the LCA usually give?
- left anterior descending (interventricular)
| - circumflex
123
In what percentage of the population does the posterior interventricular artery arise from the RCA (only) (RIGHT DOMINANCE)
70%
124
In what percentage of the population does the posterior interventricular artery arise from the RCA and LCA (circumflex branch) (CODOMINANCE)
20%
125
In what percentage of the population does the posterior interventricular artery arise from the LCA (circumflex branch) (only)
10%
126
In what percentage of the population is the SAN supplied by the RCA
60%
