alterations of cardiovascular function Flashcards
resistance to flow is determined by
length of tube
viscosity (thickness) (low rbc volume= thin so moves quick)
radius: 1 unit change in radius results in a fourfold change
laminar flow vs turbulent flow
usually due to radius or anemia
laminar:
smooth and streamlined
turbulent:
irregular and choatic
factors regulating cardiovascular function
preload
afterload
contractility
heart rate : recall CO=HR x SV
preload
provided by the degree of ventricular filling (End-Diastolic Volume (EDV)
preload reflects myocardial muscle length before contraction
*(degree of muscle stretch and relationship between actin and myosin fibers)
why is it left venticular EDV?
how do we assess ventrular EDV?
left side of the heart has a greater workload
ventricular EDV can be assessed thru:
echocardiography
afterload
resistance to outflow from the heart
(typically the left ventricular afterload is greater concern unless pt has pulmonary vascular problem with high V/Q ratio)
determined by the degree of systemic vascular resistance (SVR)
SVR is assessed by the mean arterial pressure (MAP)
what is MAP more influenced by?
diastolic pressure more than systolic
*bc more time is spent in diastolic filling phase
*due to this MAP is not a mean average of Systolic over diastolic BPS
contractility
strength of contraction at any given end diastolic volume (EDV)
a more forcefull contraction can cause a increase SV by causing greater ejection of blood (better emptying of ventricules)
how is contractility assessed
by ejection fraction (EF) of the left ventricle
EF = SV/EDV
normal 60-75%
EF can be assessed with an echocardiogram
heart rate
measure by pulse, apical HR or HR by monitor
CO=HR x SV which means increased HR will increase CO
capillaries
the presence of multiple parallel capillary channels reduces the effect of the small radius of each individual capillary
therefore the overall resistance to flow thru the capillary bed is low
arterial disorders:
atherosclerosis
formation of an atheroma (atherosclerotic plaque) within artery
AKA: arteriosclerosis
(hardening of arteries)
patho if atherosclerosis
atheroma formation is related to:
*blood vessel injury
*inflammation
*blood lipid levels
Hyperlipidemia
Increased lipids in blood
Dyslipidemia
Abnormal lipid levels but also reflects that levels of some lipid components can also be too low:
Triglycerides
Total cholesterol
HDL cholesterol
LDL cholesterol
Lipid panel
Triglycerides
Total cholesterol:
*uses protein transporter bc it can not dissolve into the plasma
HDL cholesterol: good (return lipids to liver)
LDL cholesterol: bad (for plaque)
Both are either high or low density lipoproteins so they carry proteins
Patho how atherosclerosis occurs
Platelets and monocytes try to fix injury
If LDL is increased then they will be engulfed by macrophages
Macrophages die and inflammation increased
Macrophage accumultion and we get plaques
Common sites for atherosclerotic vascular disease
Carotid artery
Cerebral artery
Coronary arter
Abdominal aorta
Iliac artery
Thoracic aorta
Femoral
Popiteal artery
Aneurysm
Weaking of aterial wall
Usually due to atherosclerosis
Common locations of aneurysms
Same locations as atheroscleotic plaque due to them being the main cause of aneuysms
Aneurysms with increased risk for mortality
Brain (cerebral aneurysm)
*increased incidence in arterial branching locations (circle of willis)
Aorta (aortic aneurysm)
*In the arch
*Increased risk to become a dissecting aneurysm due to highest presures
*high risk for people with marfan syndrome
*abdominal aortic aneurism (AAA)
Other Arterial disorders
Arterial vasculitis Aka: arteritis (or angitis)
Acute arterial occlusion
Peripheral artery disease (chronic)
Raynaud phenomenon (raynaud syndrome)
Peripheral artery disease (chronic)
Primary cause is atherosclerosis of peripheral arteries
Primary symptom is intermittent claudication
Raynaud phenomenon (raynaud syndrome)
Arterial vasospactic disorder (caused by the vasospastic)
Characterized bu intermittent arterial spasms
Triggers include cold exposure, strong emotions
