M103 T3 L3 Flashcards
What stresses cause a blood vessel to burst?
internal stresses
Turbulent flow
Large diameter - high wall tension
Low compliance - when the blood vessel is stiff or not stretchy enough
What damage can cause a blood vessel to burst? (TAD)
Trauma
Atherosclerosis
Diabetes
What is the relationship between diameter and wall tension in a blood vessel?
The larger the vessel, the greater the wall tension
What is the difference between low and high compliance vessel graphs?
high - has a more vertical slope with a positive gradient
low - has a more horizontal slope with a positive gradient
What does a double arrow in a low / high compliance vessel graph represent?
the pulse pressure between systole and diastole turbulence
What is a feature of laminar flow?
flow is slow at the edges
most of the fluid molecules travel in a straight line
What causes turbulent flow?
if the vessel is branching
if the blood has low viscosity
high speed flow
obstacles (e.g. atherosclerosis)
How does the endothelium lining blood vessels control blood vessel tone?
the inner endothelial surface layer cells monitor the blood vessel
the ends of these cells secrete nitric oxide for vasodilation and also control vasoconstriction
lets them regulate perfusion in the local area
What activities does the endothelium regulate?
blood vessel tone fluid filtration haemostasis white cell recruitment angiogenesis hormone tracking
How is the endothelium responsible for fluid filtration?
bc it helps make different secretions via fluid filtration
What are the effects of acute myocardial infarction?
reduces the capacity of the heart to pump
if there is one large or many small infarct(s), can lead to heart failure where the pump of the heart is functioning suboptimally - doesn’t pump out enough blood
can be fatal - can trigger arrhythmia and HF
What are the symptoms of atherosclerosis?
asymptomatic but can lead to other disorders
What is atherosclerosis caused by?
hyperlipidaemia
immune action
unknown aetiology
What are the symptoms and primary cause of coronary artery disease?
Angina or asymptomatic
atherosclerosis
How is coronary artery disease treated?
drugs for hyperlipidaemia, angina or hypertension
stenting
surgically replacing clogged vessels
Are atheromas dangerous?
they are relatively safe, even if they occlude 50% of a vessel.
However, if plaque rupture occurs in a coronary artery, a thrombus or embolism - myocardial infarction
How is the sympathetic NS involves with MI’s?
releases adrenaline and noradrenaline in response to pain and to haemodynamic abnormalities
can help compensate for HF - increases heart rate, contractibility strength
increases peripheral resistance - can make it harder for the heart to pump out blood but powerful resistance can also help to maintain pressure
can lead to an increase in arrhythmia - can lead to sudden death
What are the two forces that act on water in a capillary?
Hydrostatic and Osmotic pressure
What is the usual osmotic pressure in a capillary?
25 mmHg bc there’s usually more water and protein on the inside
How does hydrostatic pressure vary through a capillary?
the arterial end will have a higher hydrostatic pressure than the venous end
in the arterial end the net pressure is driving the fluid out because the hydrostatic pressure is greater than that of the osmotic pressure
the opposite is true for the venous end
What happens to fluid moved out of capillaries’ arterial end by hydrostatic pressure?
leaks out of the vessel
finds its way to lymphatics
travels in the same direction to the blood vessel
the blood vessel will draw the liquid back out of the lymphatic further down the line
How does a Pulmonary Oedema occur?
fluid going out of the blood vessels
not brought by a lymphatic so it doesn’t return to the blood vessel
leads to net fluid accumulation in the tissue outside of the blood vessel
What effect does Pulmonary Oedema have on gas exchange?
impaired gas exchange bc the extra oedema fluid in the lungs prevents the newly breathed oxygen from getting to the blood vessels buried inside of the lung
the O2 diffusion path is lengthened
What is the most common cause of pulmonary oedema?
left heart failure - there is a net damning of blood - it can’t go into the left heart
this build up of blood in the left heart causes the blood to move back into the pulmonary vasculature / the lungs
causes a net increase in hydrostatic pressure inside the pulmonary circulation
results in a net fluid leak outward
What are the symptoms of pulmonary oedema? (DOH)
dyspnoea and / or orthopnea
both can lead to hypoxia
What are the effects of peripheral oedema?
often associated with gravitational effects
the swelling of tissues, especially the ankles
What is the main cause of peripheral oedema?
chronic low output HF
Is compensation beneficial?
it’s normal - it’s what you want to occur
If there’s a problem with a physiological function, you compensate
this prevents that there being a shortfall of something else
HOWEVER
cardiac remodelling is initially compensatory but later on, they become pathological - they cause risks to the person’s health and life
How is HF compensated for?
plasma volume is increased, which increases sympathetic activity
pressure increases, as does the net amount of pumping out of the heart
How will a patient with decompensated HF present and why?
patient will present with “not being able to breathe” usually due to the fact that there is water inside the lungs
What is cardiac modelling caused by?
injury such as MI or long term hypertension or valvular disease
occurs in response to an increase in preload or afterload
What two forms of cardiac modelling are there?
hypertrophy
changes shape
What is a consequence of Takotsubo cardiomyopathy?
weakens the heart muscle and means it doesn’t pump blood as well as it should
What treatment inhibits cardiac remodelling?
ACE inhibitors and spironolactone
From where is ADH secreted from and what type of molecule is it? (PPG)
the posterior pituitary gland
a peptide
What is the effect of aldosterone on the kidneys?
theyl’ll reabsorb more NaCl and water
directly decreases natriuresis which goes on to decrease diuresis
From where is aldosterone secreted from and what type of molecule is it?
the adrenal cortex
a steroid
What is the relationship between diuresis and blood pressure?
Decreased diuresis leads to higher bp
What does angiotensin II have an effect on?
vasoconstriction - increases bp
increased fluid retention
contributes to ventricular hypertrophy and heart remodelling
How does angiotensin II increase fluid retention?
more ALDOSTERONE < NA+ RETENTION
more ADH
it increases aldosterone secretion from the adrenal cortex which increases sodium retention
it increases ADH secretion from the posterior pituitary
When might cardiac hypertrophy be beneficial or dangerous?
beneficial - athlete and pregnancy
disadv - heart failure
What are the effects of ACE?
is extremely active and it will go to the adrenal cortex and affect reabsorption of water and salt, & compensation
LOWERS bp
What is the survival rate for Chronic low output heart failure?
a poor five year survival rate
What causes congestive HF?
the patient only have left HF failure, but not right
the right heart pumps blood into the lungs as usual, but the left atrium is too full
suddenly there is the amassing of hydrostatic pressure in the pulmonary circulation (left) because there’s damming of the blood
the blood goes into the lungs, but it can’t leave because the left heart isn’t pumping sufficiently
in the extreme, fluid starts leaking out of the blood vessels and into the lungs
leads to respiratory problems / symptoms
