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MCD - Cell pathology > Haemodynamic disorders > Flashcards

Haemodynamic disorders Flashcards

1
Q

Define Oedema.

where is the fluid from?

A

Abnormal increase in interstitial fluid

  • this is when the fluid moves from the plasma to the interstitium
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2
Q

What three forces determine the movement of fluid between blood vessels and the interstitial space?

A
  • Capillary hydrostatic pressure
    venous obstruction
    pushing out of the vessel
  • tissue hydrostatic pressure
    pushing into the vessel
  • Plasma oncotic pressure
    pulling in to the vessel
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3
Q

What are the four broad causes of oedema?

A
  • Increased capillary hydrostatic pressure
    congestive cardiac failure
  • Decreased capillary oncotic pressure (e.g. nephrotic syndrome)
  • Inflammation
    increased vascular permeability facilitates movement of fluid into the interstitium
  • Lymphatic Obstruction
    ymphoedema - breast cancer treatment - damage the lymph vessels leading to build up of fluid
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4
Q

What is a common cause of pulmonary oedema?

A

Increased plasma hydrostatic pressure in the pulmonary capillary bed

Left Ventricular Failure – build up of pressure in left atrium leading to back pressure into the capillaries – this pushes water into the tissues

This is cardiogenic pulmonary oedema

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5
Q

What is non-cardiogenic pulmonary oedema?

A 
Caused by increased permeability 
often seen in injecting drug users 
ARDS – Acute Respiratory Distress Syndrome 
Often caused by Sepsis, Shock and Trauma
- can be chronic or acute 
- the main symptom is dyspnea 
which is shortness of breath
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6
Q

What are the four types of cerebral oedema?

A

Vasogenic – physical breakdown of the blood-brain barrier – commonly due to trauma or tumours

Interstitial – breakdown of the CSF-brain barrier – commonly due to obstruction of the flow of CSF (Obstructive Hydrocephalus)

Cytotoxic – derangement of the sodium-potassium pumps leads to a build up of intracellular sodium causing intracellular oedema (common with ischaemic strokes)

Osmotic – increase in plasma osmolality – commonly caused by Syndrome of inappropriate ADH secretion (SIADH) that is commonly caused by small cell lung cancer

VICO

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7
Q

What are the possible serious consequences of cerebral oedema?

A

Rise in intracranial pressure, which could cause brain herniation
- (squeezing of the brain across a structure
within the skull) and death
- confusion, nausea and vomiting

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8
Q

What are two common causes of generalised oedema?

A 
Left Ventricular Failure 
dependent oedema (accumulated in areas affected by gravity)

Nephrotic Syndrome
fluid accumulates in all parts of the body

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9
Q

What is a consequence of oedema in a peripheral setting?

A

Impaired wound healing

- cellulitis

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10
Q

What are the three main factors affecting thrombus formation?

A

Hypercoagulability
Primary - Genetic Disorder
Secondary - Acquired
more likely to develop blood clots

Vessel Wall Injury
Physical Damage to Endothelium
exposes ECM and activated blood clotting cascade
- when the endothelium isn’t working properly it causes coagulants to be released

Stasis
-alteration to normal blood flow
platelets are exposed to the endothelium - more likely to form a clot
- might also change the dilution of blood clotting factors

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11
Q

What is cardiac thrombosis caused by and what is an important complication?

A

Stasis – e.g. atrial fibrillation
- Left Atrial Thrombosis is usually related to atrial fibrillation

  • Left Ventricular Thrombosis is usually related to prior myocardial infarction

Complication – systemic embolisation

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12
Q

What is arterial thrombosis caused by?

A

Vessel wall injury

- Vessel wall injury is often caused by atherosclerotic plaques

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13
Q

What is venous thrombosis caused by and what is an important complication?

A 
Stasis and Hypercoagulability 
happens in the deep veins 
- risk factors include 
age, obesity, malignancy, immobility
Complication – pulmonary embolism
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14
Q

What are the four fates of a thrombus?

A

Propagation– thrombus accumulates fibrin and grows and takes up larger part of the vessel

Embolisation– thrombus dislodges and moves somewhere else

Dissolution– thrombus is destroyed by fibrinolytics
maybe through a drug

Organisation and Recanalisation–
thrombus becomes fibrotic and is remodelled, lumen appears again allowing blood flow

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15
Q

Where do most arterial thromboemboli originate?

A

Carotid arteries

- causes stroke in cerebral arteries

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16
Q

Define haematoma

A

A localised mass of extravasated blood that is relatively or completely confined within an organ or tissue

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17
Q

What are the three classes of haemorrhage based on size?

A 
Petechiae = 1-2mm 
Purpura = >3mm 
Ecchymoses = 1-2cm
18
Q

What is shock ?

characterised by?

A
  • occurs when the tissue perfusion is inefficient to meet metabolism standards

Prolonged hypotension causes circulatory collapse leading to ischaemia of
multiple organs

Hypotension

19
Q

What two equations are used to evaluate the effects of changes in various vascular factors?

A

MAP = CO x SVR
cardiac output x systemic vascular resistance

CO = HR x SV
heart rate x stroke volume

20
Q

What are the five types of shock?

A 
Cardiogenic   
Hypovolaemic 
Anaphylactic 
Neurogenic 
Septic

CHANS

21
Q

Describe each of the five types of shock and its causes and effects

A

Cardiogenic -impaired cardiac function,
- Causes include cardiac tamponade
fluid in the pericardium
- heart doesn’t work so lowered stroke volume leading to shock

Hypovolaemic– loss of blood volume,
- Causes include: trauma, haemorrhage
low volume - Low SV- Low MAP - Body tries to compensate with tachycardia

Anaphylactic– IgE mediated hypersensitivity,
- Causes vasodilation and increased permeability, Reduced SVR leads to Reducer MAP

  • Neurogenic– injury to sympathetic pathways, Normally happens after trauma
  • Widespread vasodilation and reduced SVR
  • Septic– result of inflammatory response,
    • Causes vasodilation.
  • Reduced SVR leads to Reduced MAP
22
Q

Define infarction.

A

Tissue necrosis due to unresolved ischaemia

23
Q

What are the two types of infarction and how are they different?

A

Red – haemorrhagic – affects organs with a dual blood supply
- normally caused by venous blood supply

White – anaemic – affects solid organs that have one blood supply

24
Q

How can the rates of development of the occlusion affect the infarction?

A

If the occlusion develops slowly then there may be enough time for collateral vessels to form

25
Q

What are the two types of myocardial infarction?

A

Transmural – across the whole wall of the heart
- occurs when there is a complete blockage of the vessel and complete cessation of the blood supply

Subendocardial – some myocardial tissue -just the layer under the endocardium

26
Q

Describe the process of atherosclerosis.

A

1) Endothelial damage
2) Macrophage infiltration and release of cytokines
3) Cytokines recruit LDLs
4) LDLs become oxidised and hence become pro-inflammatory and drive progression of plaque
5) Smooth muscle cells migrate from the tunica media to the lesion and deposit a collagen-rich matrix, which forms a protective fibrous cap

27
Q

What are the two types of atherosclerotic plaque and how are they different?

A

Stable – thick fibrous cap – less likely to rupture
less inflammation

Unstable – thinner fibrous cap – more likely to rupture
more inflammation

28
Q

what is generalised oedema?

A

Severe Generalised Oedema = Anasarca
- It is the widespread accumulation of fluid in subcutaneous tissues and serous cavities
-

29
Q

what is the mechanism of heart failure causing oedema?

A
  • Low Renal Blood Flow
  • Release of Renin from kidneys
  • Formation of angiotensin II
  • Release of aldosterone from adrenal gland
  • Absorption of sodium and water from kidneys Generalised oedema
30
Q

what are the consequences of arterial thrombosis ?

A
  • Stenosis = narrowing of the artery by the thrombus
  • Stenosis causes ischaemia of the tissue supplied by the artery
    • Occlusion = complete blockage of the artery by the thrombus
    • Occlusion causes infarction of the tissue supplied by the artery
31
Q

what is an embolism?

A

A detached intravascular solid, liquid or gaseous mass that is carried by the blood to a site distant from its point of origin.

32
Q

where do venous thromboembolism originate from?

A
  • Most originate in Deep Veins

- Most Significant Consequence - pulmonary (thromboembolism)

33
Q

what are the consequences of a pulmonary embolism?

A
  • Consequence depends on the size of the embolus and where it gets lodged.
  • major pulmonary artery can cause instantaneous death
  • lodged at the bifurcation of one pulmonary artery into two, it is called a saddle embolus
  • medium arteries = breathlessness
  • small arteries = non-specific symptoms
34
Q

where do cardiac Thromboemboli start?

A
  • Most originate on the LEFT SIDE OF THE HEART
  • ## might lodge in the cerebral artery, mesenteric artery, lower limb artery
35
Q

what is a Haemorrhage and what are the causes?

A

Extravasation of blood due to vessel rupture.

causes include trauma and intrinsic disease of the vessel

36
Q

what does the rupture of a major vessel result in?

A
  • Hypovolaemia
  • Shock
  • Death
37
Q

what will a solid haematoma result in?

A
  • can be fatal

- causing a rise in intracranial pressure and tonsillar herniation

38
Q

what are factors influencing the development of the infarction?

A
  • the nature of the blood supply
    single blood supply (kidney and spleen) or double blood supply ( lung and liver)
  • the rate of development of occlusion
    if the occlusion develops slowly there might be time for collateral vessels to form
  • vulnerability to hypoxia
    different types of cells are vulnerable eg. neurones are very vulnerable
  • Oxygen content of the blood
    patients who have anaemia and chronic heart failure will have reduced levels of oxygen in their blood - more prone to developing infarctions
39
Q

what are other consequences of myocardial infarction?

A
  • pericarditis
    (inflammation of the pericardium)
  • Cardiac Rupture
40
Q

what is cerebral infarction?

A
  • Wedge shaped area in the right middle cerebral artery (MCA) area
  • the MCA area is a common area to get affected by infarction
41
Q

what is atherosclerosis?

A
  • complex chronic disease underlying cause of most vascular disease
  • accumulation of lipids and fibrous tissue associated with smooth
    muscle proliferation
  • medium and large vessels are affected
  • it develops from a fatty streak into plaque within the intima

MCD - Cell pathology (6 decks)

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