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
What happens in the case of right HF, but not left HF?
in a normal heart, a normal central venous pressure pushes blood into the right heart, but the right heart isn’t pumping out blood
causes a backup of blood
the central venous pressure will build up fluid, but there will be no place for it to go because it can’t return to the heart because the right heart isn’t empt
causes an increase in central venous pressure
What systemic symptoms could right HF lead to?
potentially peripheral oedema
ascites
What are the symptoms of HF? (Fat People oD)
Fatigue
Peripheral Oedema
Dyspnoea
Why is fluid retention a feature of all forms of HF?
initially compensatory / homeostatic
leads to Dyspnoea, Ascites, Ankle oedema
retains too much fluid - volume overload
How does cardiogenic shock progress?
there is insufficient perfusion of tissues, especially in the heart, so it will beat less and pump with reduced strength
ends up pumping even less blood out, so the originally insufficient profusion of the heart becomes even worse
this is how insufficient perfusion progresses by positive feedback
How is cardiogenic shock treated?
Aggressive IV fluid AND Oxygen and the airway must be maintained
What are chronic HF treatments? (ADB)
ACE Inhibitors, Diuretics and Beta blockers
What is the aim that chronic HF treatments are trying to achieve?
to reverse the body’s homeostatic response to HF which are dangerous / damaging in the long term
What leads to the kidney accumulating fluid?
the normal, homeostatic response to low cardiac output
Why does the kidney accumulate fluid?
the kidney can’t recognise the difference between a haemorrhage and HF
Prehistorically, haemorrhages were much more common than HF, which only happens in people around 50 years old and many didn’t survive until that age
the kidney detects low pressure and assumes it is a haemorrage - loss of fluid - and so decides to retain fluid to try and stop the haemorrage
However, in the case that this is HF, it backfires and is dangerous
When the kidney increases plasma volume, what does it lead to?
fluid overload
the heart is already damaged so it’s unable to pump this fluid
What happens when the heart is unable to pump out extra fluid?
Fluid damming leads to increased venous hydrostatic pressures
Increased back pressure further damages heart
this positive feedback loop leads to rapid detioration
What processes occur during decompensated heart failure?
the kidney increases plasma volume
the heart is unable to pump out extra fluid
the capillaries leak fluid into the tissues
the lungs have fluid and so can’t exchange o2 and co2
What are the three treatment goals for low output HF?
prevent acute decompensated HF
counteract cardiac remodelling
minimize symptoms
What is another terms for a stroke?
cerebrovascular accident
What does RAAS stand for?
renin-angiotensin-aldosterone system
What does ACE stand for?
angiotensin converting enzyme
What is ADH otherwise known as?
vasopressin
What are the criteria for shock?
systolic bp > 90 mmHg
usually 125 mmHg
What is the role of renin?
to convert angiotensin I into II
What is an example of a diuretic drug?
thiazimide
What is the role of thiazide-like drugs?
to block reabsorption at the DCT
What are internal stresses caused by?
high pressures from high bp or downstream blockages
What does Low compliance describe?
if the blood vessel is stiff or not stretchy enough
What is an example of trauma that could cause a blood vessel to burst?
Transluminal procedures
What can pulmonary oedema lead to?
ascites
What is an example of a Transluminal procedure?
PCI
What are examples of dyspnoea that appear in HF?
orthopnoea, paroxysmal nocturnal dyspnoea
How do ACE Inhibitors work to treat chronic HF?
stops the heart from trying to remodel itself and become larger
How do Diuretics work to treat chronic HF?
stops the heart from trying to increase its ability to maintain fluid
How do Beta blockers work to treat chronic HF?
stops the heart from trying to increase pressure via heart rate and contractibility
What do murmers signify?
the improper closing of valves
What age group is Degenerative valvular disease common in?
in the elderly of the UK
Where is rheumatic fever seen globally?
not seen in the UK but in areas of poverty in 3rd world countries
What is Rheumatic valve disease caused by?
rheumatic fever
What is the most common valve disease in EU?
aortic stenosis
How are the leaflets of the bicuspid valve made?
often two of the other leaflets will be fused together making one, so instead of a tri leaflet valve, they’ll have a bi-leaflet valve
What is aortic regurgitation otherwise known as?
incompetence
What is an Early diastolic murmur caused by?
aortic regurgitation
What is a fulminant pulmonary oedema caused by?
when pressure is pushed back from the left side of the heart onto the vasculature very quickly without the body being able to accommodate
What happens during Mitral valve prolapse?
Initially valve shuts during the early part of systole but then, either because the leaflet is too ‘baggy’ or because of abnormal sub-valvar apparatus the leaflet prolapses back into the left atrium potentially allowing though a jet of regurgitation
What are other terms for Mitral valve prolapse?
click-murmur syndrome
Barlow’s syndrome
floppy valve syndrome
How does a Systemic emboli form a pulmonary embolism?
it always impacts in the lungs after passing through the right side of the heart
What are mechanical valves?
metallic valves
What are biological valves?
prosthetic valves
What is the normal pulse pressure?
approximately 40 mmHg
What sound is made for the duration of the systole and for mitral regurgitation?
pan-systolic murmur
Why does HF need to be compensated for?
needs to maintain cardiac output - can’t because of damage
What leads to the kidney accumulating fluid?
decreased GFR
increased Central Venous Pressure
increased Venous Return
increased preload in the right ventricle
What is the criteria for ascites?
more than 25 ml of fluid in the peritoneal cavity, although volumes greater than one liter may occur
Why is flow slow at the edges in laminar flow?
friction is created from the fluid moving against a non-moving surface - slows them down
What fluids is the endothelium responsible for creating via filtration?
the BBB, CSF and GI secretions (in the glomerulus in the kidney)
What is the role of the endothelium in the BBB?
it filters most molecules out of the BBB
What are examples of catecholamines?
dopamine
norepinephrine and epinephrine
What did epinephrine used to be known as?
adrenalin or adrenaline
What is the main hormone secreted by the adrenal medulla?
Adrenaline
When is epinephrine released?
when the brain perceives danger and the ANS is activated
By what process is the flight or fight response stimulated?
amygdala triggers the hypothalamus < activates the ANS < adrenal gland secretes epinephrine < fight or flight
In what conditions is epinephrine released?
low bp and stress
What are the effects of norepinephrine on the body?
vasoconstriction < increased bp
increased heart rate
increased blood sugar levels
Where is adrenaline made?
almost exclusively in the adrenal medulla
Where is noradrenaline made?
Predominantly in the symp NS
What type of biological substance is adrenaline?
acts mainly as a hormone and is released primarily by the adrenal medulla into the bloodstream
What type of biological substance is noradrenaline?
acts mainly as an NT at the synapse between neurons when released from symp neurons (stored in vesicles).
is released in small concs as a hormone in the blood circulation by the adrenal medulla
What is adrenaline synthesised from?
noradrenaline
What is noradrenaline synthesised from?
dopamine
When is adrenaline released?
at a stressful moment such as a fight/flight situation
during stress
When is noradrenaline released?
continuously as a hormone in the blood circulation at a low dose
