Circulatory disorders Flashcards
Fx Endothelial
Lining all circulatory components, in a singular layer
synthesise and secrete substances which - (fluid balance, haemostasis, inflammation, immunity, angiogenesis/healing
3 components of microcirculation and their characteristics
- Arterioles
major resistance
Myocytes contract to control flow - Capillaries
enormous volume
Slow velocity
Sx= single endothelial layer
Nutrient and waste exchange lx = fluid balance maintenance - Postcapillary venules
low resistance
Store lots of blood up to 65%
Mechanisms for substance transport across the capillary wall
Direct diffusion (passive)
through endothelial cell membrane (gas and lipid soluable)
Interendothelial pores (water, ions, glucose, amino acids, waste)
What occurs to capillary wall transport during inflammation
The inter endothelial pores become large enough for large proteins (eg albumin) to escape
Three regional differences in capillary lining
- list and explain the lining on them
Continuous capillaries
complete endothelium and basal lamina
Lx muscle, Brain, thymus, skin, bone, lung etc
Allow transfer of H2O, O2 and CO2 and ion
Fenestrated capillaries
Small opening
Lx Often have a diaphragm (eg intestinal villi, kidney interstitium, choroid plexus)
Fx - can act as filter = renal glomerulus
Discontinuous capillaries
Larger gaps - discontinuous basal lamina allow large molecule or even cells to exit
Lx - hepatic and spleen
Fx -free transfer of plasma proteins, red and white blood cells, water and most molecules across endothelial cells
Fluid Distribution & Homeostasis
- explain the percentages of each one
• Total Body Water (~60% of lean body weight)
• Extracellular fluid (20%):
o Plasma (5%)
o Interstitial tissue fluid (15%)
• Intracellular fluid (40%)
Interstitium LX
Lx- space between microcirculation and the cells
interstitium Stx
Sx
made of extracellular matrix + supporting cells ( eg fibroblasts)
Has structural support and adhesive and absorptive properties
Composed of
Structural molecules: collagen, reticulin & elastin fibers.
Adhesive glycoproteins: fibronectin, laminin
Absorptive (hydroscopic) molecules: glycosaminoglycans, proteoglycan
Interstitium Fx (2)
Fx
binding cellular and structural elements into discrete organs and tissues
Medium through which all metabolic products pass through
Movement of fluids what affects it
Blood <—> intersitium <—> cells is controlled by - - physical stx
pressure gradients
Ion concentration
explain the things that move between blood and cells
In most areas, the capillary allows the free passage of water and ions and opposes the passage of plasma proteins.
what are the primary influence on the movement between compartments (blood, interstitium and cells)
Primary determinant is hydrostatic pressure end osmotic pressure
Starlings equation significance
Moving out fluid = hydrostatic pressure in the vascular system + some interstitial colloidal somatic oncotic pressure
Retaining fluid in the blood vessels
via the plasma proteins eg albumin ( most abundant) (primary way)
To a lesser extent —> Tissue hydrostatic pressure around blood vessels
explain Platlets
Primary haemostasis
Chemical and mechanical clotting contribution
For a loose plug
Cascade of coagulation factors
Secondary haemostasis
Formed in liver
Contact with damaged endothelium (among other things) = activation
Circulatory in inactive form
End result = Protein fibrin clot ( reinforcing platelet clot)
The circulatory disturbances (6)
Oedema
hyperaemia
Haemorrhage
Thrombosis
Ischaemia/Infarct
Shock
what is oedema
Imbalance in the factors controlling fluid distribution in the spaces - cellular, plasma and interstitial compartments
- the excess fluid accumulates in the interstitum
Histology oedema
Explain explain the fluid dynamics of arteriole end to venue end of capillaries and lymph significance, when everything is normal
(hydrostatic + colloidal pressure difference of vascular to interstitial compartment) ==
Art Cap end = flow out of capillary
Ven Cap end = Flow into capillary
Small net loss from vasculature = lymph
Essential that net loss = lymph drainage rate
4 basic processes that alter lymph creation and removal IMPORTANT
Decreased plasma (colloidal) osmotic pressure
Increased hydrostatic pressure
Obstruction of lymphatic drainage (least common)
Increased vascular permeability
Explain Decreased colloidal pressure in blood vessel (3)
Colloidal pressure primary = presence of albumin
Thus hypoalbuminaemia = decreased colloidal pressure
insufficient synthesis:
protein deficiency (starvation)
Liver disease (not common)
Increased loss:
Renal disease
Gastro-intestinal loss
Explain increased hydrostatic pressure
May cause oedema
can be local or generalised (generalised = eg heart failure, local = local increase in pressure)
Most common cause = local increase pressure obstruction of veins
Explain the side of heart failure
Left it causes oedema in the lungs
Right is causes oedema in the liver
(Think about the blood going backwards)
Explain lymphatic obstruction
May cause oedema (not common)
typically causes localised oedema
Mechanical pressure
Inflammation (lymphangitis)
Obstruction by neoplastic or infectious prescesses
Explain increase vascular permeability and its causes
Endothelial layer is leaking so too much water is going out to the interstitial.
Causes
-inflammation > release of inflammatory mediators > vasodilation and increased vascular permeability
-Direct endothelial damage ( eg viruses toxins)
=Localised oedema»_space;»» generalised oedema
Local(3) vs Generalised(2) causes of oedema
Localised oedema causes=
Local impaired venous drainage
Local lymphatic obstruction
Local inflammation
Generalised oedema=
Increased hydrostatic pressure (heart failure)
Decreased colloid osmotic pressure (hypoproteinaemia