Cardiovascular system Flashcards
1
Q
Describe the gross topography of dogs rib structure (13)
A
- 13 thoracic vertebrae
- Each V articulate with 2 ribs = 13 pairs
- Intercostal muscles between each rib
- Heart sits between ribs 3 and 6
- Dorsal = thorasic spine which is bounded ventrally by sternum
- Dog has 8 sternebra from cranial manubrium to xiphoid process caudal
- Cranial aspect= thoracic inlet, caudal = diaphragm
- Costochondral junction = where bone meets cartilage
- First 9 ribs articulate with sternebra
- ribs 10-12 articulate with one another = costal arch
- rib 13 is floating
2
Q
Where to the lungs sit in reference to the heart
A
dorsally and laterally
3
Q
What is Pleura
A
Serous membrane that lines everything in the thorax- forms a potential space between 2 layers which contains a negative pressure which holds the lung against the diaphragm and chest wall
4
Q
What are the different types of pleura?
A
- Visceral pleura- serous membrane that lines the surface of lungs = inner membrane of cavity
- Parietal pleura- lines everything else: diaphragmatic, costal lines ribs,
- Mediastinal pleura = lines chest cavity in area between the lungs
5
Q
What does the mediastinum contain?
A
Middle of thorax have everything in in except from lungs. space between both lungs in thoracic cavity, defined on either side by mediastinal pleura- heart is within mediastinum
6
Q
What is the pericardium
A
Membrane that surrounds heart = an invaginated sac of serous membrane containing the heart:
- visceral pericardium = on heart wall = indistinguishable
- Parietal pericardium = bag around heart
7
Q
Name the different valves in the and describe positions
A
- AV valves inbetween atria and ventricles - LHS = mitral valve RHS = tricuspid
- Semilunar valves. LHS = aortic. RHS = pulmonic
8
Q
What are the sounds “lup” and “dup” referring to?
A
lup = START OF SYSTOLE. AV close (tricuspid and mitral), blood rebounds within ventrucles and accelarates within aorta
2. Dup = END OF SYSTOLE semilunar valves (aortic and pulmonic) close and blood decelerates in blood vessels
9
Q
How many ribs does a normal dog have
A
13 pairs
10
Q
What is the name of the most caudal sternabra
A
Xiphoid Process
11
Q
What is the manubrium
A
the most cranial sternebra
12
Q
What is the costochondral junction
A
Between bone and cartilage of rib
13
Q
What are the layers of the heart?
A
- inner endocardium
- Myocardium
- Outer Epicardium
14
Q
A dog presents with signs of heart failure and muffled heart sounds. A cardiac ultrasound shows fluid collecting in the sac around the heart. What is the outer layer of this sac referred to as?
A
Parietal Pericardium
15
Q
In order to drain fluid from the pleural cavity, a drain must be advanced through the skin and muscle of the body wall and which membrane?
A
Parietal pleura.
parietal = not on organ, specifically costal pleura
16
Q
Bacteria in the bloodstream travelling through the heart from a dental infection may colonise the heart valves causing serious disease. Which layer is infected first?
A
Endocardium - most inside
17
Q
This initiates the normal cardiac impulse.
A
Sinoatrial node
18
Q
Blockage of this would delay conduction of the impulse only to the left ventricle.
AND which could delay to ventricles
A
a) left bundle branch
b) bundle of his, AVN and left bundle branch
19
Q
Damage to the proximal interventricular septum could damage this part of the pathway.
A
proximal = top = bundle of his
20
Q
Describe the electrical pathway of AP in heart
A
Sinoatrial node (RA) generates impulses. Atria contract. Impulses pause at non-conducting tissue (anulous fibrosis surrounding valves) and AV node (interatrial septum close to tricuspid valve). Allows ventricles to fill. AP travels down Bundle of His to apex. AP travels through purkinje fibres, ventricles contract upwards.
21
Q
What is the function of valves?
A
ensure blood flows in the correct direction: close to prevent backflow
22
Q
What are the valves in the heart supported by?
A
Annulus fibrosis, a fibrous skeleton which also serves as an electrical insulation between atria and ventricules
23
Q
presented with a heart murmur that has long gaps between beats is this systolic or diastolic?
A
Systolic
24
Q
When listening to the heart what bit is diastolic and what systolic?
A
Between beats = diastolic
Beats = systolic
25
Describe route taken by blood through heart adn why?
LA receives O blood from lungs via pulmonary vein, through to LV: atrioventricular (MITRAL) valve. Delivers to rest of body via aorta. RA receives DO blood from rest of body via vena cava, through to RV through right atrioventricular (TRICUSPID) valve. Delivers to lungs via pulm artery.
Left and right separated by interatrial septum, LRV by interventricular septum.
Moves due to pressur changes. valves = no backflow
26
What is the structure of the Mitral and tricuspid valves
1. Mitral = 2 main cusps
2. Tri = most species 3 cusps but dogs = 2 main with several small commissural cusps at the free edge
2. Muscular projections on the ventricle walls called papillary muscles are attached to chordae tendinae (fibrous muscles) attached to free edge of valve, hold it in place, anchoring to prevent prolapse
3. supported by annulus fibrosis whcih also serves as an electrical insulation between atria and ventricles
27
Structure and function of semilunar valves
1. made up of 3 cusps
2. supported by annulus fibrosis
3. function = prevent arteriol blood flowing back into V during diastole
28
What does incompetence mean in reference to valves and what does this result in?
1. failure to close properly = blood regurgitation as it flows in wrong direction which could lead to congestion and heart failure
29
What does it mean if valves are stenotic? what could this result in?
narrowed.
| Result in blood unable to pass through as easily, leading to increased work on heart and pressure in chambers
30
What stops AV valves folding back into atria?
becuase of chordae tendinae which anchor free edge of valve- allow to close then tight which stop it from pushing backwards
31
What would happen if the valve didn't close?
blood would flow back into atrium = reduced blood output and pressure in atrium increases = backwards heart failure
32
What is collateral circulation?
When arteries have side branches
33
What is an inter arterial anastomoses?
joining between arteries
34
What would happen if there was blockage in an end artery
Lead to infarction and necrosis (death) of the tissue
35
How can the volume of blood reaching a cap bed vary?
1. Pre capillary sphincter zone = pre cap arterioles that contract to decrease blood blow and relax to increase it
2. Arteriovenous anastomoses = joining between an artery and vein = bypass capillary bed completely
3. Thoroughfare channel = pre cap arteriole sends blood through one cap = minimal exchange
36
Why do tumours often spread to the lung?
as all blood that goes through lungs must pass through a capillary. Not really any arteriovenus anastomoses in lungs so blood in lungs can't bypass cap bed so easy for tumour cells to get stuck
37
Give 4 examples of when we take thoracic radiographs
1. Respiratory disease
2. Cardiovascular disease
3. staging of neoplasia (presence or formation of new, abnormal growth of tissue)
4. Trauma
38
When examining lungs what position do you want the animal and why?
Ventrodorsal - lungs closer to plate therefore more accurately represented in terms of size and shape (further away = more magnified)
39
When examining heart what position?
Dorsoventral as heart is ventral to the lungs
40
If want to look at right hand lung what position of animal and why?
Left lateral recumbency as when on LHS left lung will be collapsed
41
How does the lymphatic system maintain fluid balance in the body?
1. generally net filtration from circulation into ISF as hydrostatic pressure outweight oncotic
2. Greater pressure in ISF than lymph so fluid moves into L by bulk flow
3. Blind ending lymph favours absorption from ISF, opposes filtration = more protein uptake into lymph from ISF = lowers oncotic pressure of ISF, INC OP in lymph
4. Pressure in CV lower than in lymph so lymph flows down pressure gradient into venus
42
What are the circulatory adaptations of the foetus in the utero?
1. ductus arteriosus- as little blood flow throuhg pulmonary crculation, frow occurs from pulmonary trunk to aorta via ductus arteriosus
2. Foramen ovale allows oxygenated blood to flow from right to left atrium
3. Ductus venosus allows blood to bypass liver
43
What happens to the umbilical cord at birth?
1. Umbilical cord ruptures and U arteries contract stop bleeding, undergo elastic recoil to prevent heamorrhage
2. Umbilical vein contracts squish all blood in umbilical cord back into animal: can contribute up to 30% total blood volume
3. Umbilical artery becomes round ligament of the bladder – no longer functional artery
4. Umbilical vein becomes round ligament of the liver: not functional vein
44
How does the first breath affect resistance to flow in the pulmonary circulation
LArge drop in resistance to flow in pulmonary circulation as blood vessels pulled open (inc radius) = no longer collapsed so now blood can flow through lung. Reduced right ventricular afterload!
45
How does the foramen ovale close on first breath?
1. reduced right ventricular afterload so easier for blood to leave heart adn enter pulmonary circulation
2. this increases return of blood to left atrium
3. pressure in LA increases = closure of foramen ovale "flaps" closed by pressure of foramen ovale. over time this becomes permanent. = fossa ovalis
46
What is the process by which blood flows through the CV system
BULK FLOW
47
Arterial pressure =
CO X total peripheral resistance
48
Cardiac output =
SV XHR
49
What is Produced by endothelial cells to cause vasodilation as an intrinsic response to an increase in blood flow velocity.
Nitric Oxide
50
What is A product of cell metabolism which causes vasodilation in tissues
Cardon dioxide
51
What is Created in the lung, causes vasoconstriction, stimulates production of a hormone from the adrenal gland, one from the pituitary and causes increased thirst.
Angiotensin 2
52
How will constricting arteriole affect pressure of BV upstream and downstream
Capillary downstream pressure will decrease- constriction = reduced blood flow through arteriole :. capillary. Upstream = inc pressure as effectively inc blood volume there
53
What is the perfusion pressure
pressure needed for blood to move through blood vessels, generated by the pumping action of the ventricles = difference in pressure between 2 points in a BV.
PP = pressure inlet - pressure outlet
54
What is transmural hydrostatic pressure
the pressure across the vessel wall. TP = Pressure inside - pressure outside
55
What does osmosis depend on
presence of:
1. semipermeable membrane
2. osmotic pressure difference
56
What is the difference between oncotic and osmotic pressure
```
oncotic = the pressure exerted by plasma proteins
osmotic = the drive for water to move into a solution by osmosis
```
57
what does oncotic pressure favour in terms of reabsorption?
reabsorption of water from the ISF into the capillary as there are ususally a lot more plasma proteins inside the cap than in the ISF
58
What does the starling equation quantify
the net movement of water between the caps and the ISF is decided by the balance between osmotic and hydrostatic pressures across the capillary wall
59
What does a neg / and positive answer mean with starling equation
```
positive = water filtered out of cap
negative = water reabsorption
```
60
What is starlings law of capillaries
the balance of hydrostatic and oncotic pressures across a capillary wall determines the amount and direction of fluid transported across the wall
61
How is oedema caused
if the amount of fluid filtered into the ISF exceeds the ability of the lymphatic system to remove it it builds up. caused wither problem with lymphatic system or volume is excessive
62
What is diapedesis and where does it occur?
in Post capillary venules. where WBC moves out of the circulation and into tissues to fight infection
63
Name and say a bit about different vessels found in a cap bed
1. arteriole
2. thoroughfare channel/ metarterioles/ arteriovenous caps = contain smooth muscle:. not true caps = A road of capillary.
3. Pre cap sphincter = smooth muscle cells that can squeeze down to stop blood flowing through a true cap
4. arteriovenous anastomosis = vesses that can shut off/ open cap bed entirely.
5. post cap venules drain into venules, into veins
64
How is blood returned to the heart
passively by the action of valves preventing backflow due to gravity and pressure differences
65
What are artery and veins walls made up of
1. Tunica intima = internal with endothelial lining
2. tunica media = varying amounts of smooth muscle adn elastic tissue
3. tunica adventitia = layer of connective tissue
66
identify the great vessels of the heart
aorta, pulmonary trunk, cranial and caudal venae cavae, pulmonary veins, coronary arteries and veins
67
When left atrial pressure exceeds left ventricular pressure which valve will open
Left AV/ mitral
68
Which phase of cardiac cycle creates the pressure difference that causes the aortic valve to open?
Isovolumetric contraction = build up of pressure
69
Which structures and what are they attached to, prevent the AV valves from prolapsing into atria?
chordae tendinae attached to papillary muscles
70
Describe the positioning of the heart
1. left chambers sit caudally
2. right sit cranially
3. base sits dorsally and cranially to apex
4. apex sits ventrally and caudal to base
71
what is cardiac output.
| SV
vol of blood pumped by 1 ventricle in a minute. CO = HR X SV
| Strok vol = volume blood pumped out of V per caridac cycle. Calculated by SV = EDVV - ESVV
72
Why is the arterial supply to systemic organs arranged in parallel?
so blockage of one system doesn't influence supply to others and all the capillary beds receive oxygenated blood
73
what is the difference in vol of blood pumped out of left and right ventricles?
NO DIFFERENCE! = same volume
74
What is ESVV
end systolic ventricular volume: residual volume remaining after V contract
75
What is EDVV
end diastolic ventricular volume:after diastolic filling, the volume in ventricle
76
what is ejection fraction
the fraction of the end diastolic volume that constitutesthe stroke volume. EF = SV/EDVV
77
What factors affect EDVV and ESVV
preload, afterload, contractility
78
How is CO altered
by changing either SV or HR.
| To increase SV either INCREASE EDVV or DECREASE ESVV
79
What affects EDVV?
1. Ventricular preload (filling pressure)
2. compliance of ventricular wall (stretchiness)
3. Diastollic filling time
80
What affects ESVV?
1. Afterload
| 2. contractility
81
What are fairly equivalent measures of ventricular preload
1. EDVV
2. Atrial pressure
3. venous pressure
because preload is approx equal to atrial pressure which is about the same as venous, therefore diastolic V pressure
82
how does preload increase?
1. inc pressure in atria and veins by inc overall blood vol or reducing space blood needs to occupy
83
How is prelaod affected by exercise and why?
INCREASES
due to increases action of respiratory and skeletal muscle pumps which compress veisn and thereby inc venous return to heart
84
What is heterometric autoregulation?
becuase systemic and pulmonary systems exist in series, an inc in SV on one side of heart leads to inc blood flow through tissues, inc in venous return, hence preload to other side of heart therefore inc SV on that side too!
85
Why is heterometric autoregulation important?
necessary to balance the SV of the left and RHS otherwise blood would accumulate in either the pulmonary or systemic circulation
86
What is compliacne and how do you measure it
measure of how readily the V walls stretch during diastolic filling
. C= change in volume/ change in pressure
87
What to the SAN and AVN possess that means the heart deosn't need neurological stimulation?
Automaticity = they produce action potentials spontaneously
88
what role does innervation (nerves) of the heart play?
can change contractility and HR (rate and strength.) not needed to make heart beat but deos change how effective
89
what type of nerves supply heart?
autonomic
90
How can we define the systematic nervous system?
Fight or flight or freeze
91
How can we define the parasympathetic nervous system
rest and digest
92
What effect does the sympathetic nervous system have on blood vessels?
cause them to dilate to (brain,) working skeletal muscle, heart.
Vasoconstrict gut, kidney, skin etc
93
What effect will a generalised vasodilation have on cardiac output?
what about if just arteries dilate?
1. decrease preload - vessel wider = reduce hydrostatic pressure in = reduce pressure leading into heart = preload = reduce CO as dec EDVV = less V filling = reduce SV.
2. Dec afterload = inc CO as reduce ESVV = bigger pressure gradient (P in A lower than p in V) so more blood moves out = less left in V at end of systole = higher ejection fraction, more of available blood out = higher SV = higher CO
94
how would a generalised vasoconstriction inc CO
1. inc preload as dec size of container so inc Hydrostatic presure = inc pressure supplying V
95
How could generalised vasoconstriction decrease CO
1. inc afterload = reduced V emptying as bottom end of pressure gradient is higher, less blood can move out
96
how to measure blood pressure
Pa= CO X TPR
97
Where do the preganglionic fibres of the parasympathetic and sympathetic nervous system arise?
```
Craniosacral = para
thoracolumbar = sympathetic
```
98
Fight or flight response has what effect on the blood supply to non essential organse?
Vasoconstriction
99
The effect of beta 1 adrenergic activation on cardiac myocytes
Inc contractility and faster conduction
100
The effect of beta 2 adrenergic activation on coronary arterioles
vasodilation
101
What is the effect of the respiratory pump on the ehart
increase preload
102
What is the effect of metabolic autoregulation on exercising skeletal muscle
Vasodilation of afferent arterioles (afferent = towards)
