What contributes to venous return
- Intermittent skeletal contraction
- increase and decrease in thoracic pressure
- diaphragm compressing abdnomla veins with each breath
- Increase in blood veins closer to heart
Name the different valves and their function
function: stop backflow of blood via papillary muscles preventing opening in the wrong direction
AV: Tricuspid (right atrium- right ventricle)
mitral valve (left atrium- eft ventticle)
pulmonary: aortic
briefly describe the contraction of the heart
- SAN node in right atrium- cels intrinisc timer (dictated by ion permeability
- SAN sends signal to AVN
- Short delay due to fiborous tissue (allow atria to contract into ventrice)
- AVN slows down spread, propogate to left ventricle via purkinje fibres
- depolarisation of atria causing contraction
- delay of av node
How is Cardiac output measured
CO= HR x SV
What is circulation affected
use of tissue in exercise
increased metabolsim
How can cardiac output be increased?
- constrict sphelanic circulation so increases redistribution
- respiratory and skeletal pump (change in thoracic pressure)
How is blood pressure measured
Blood pressure= TPR x CO
What is the short term balance of blood pressure
parasympathetic & sympathetic nervous sysem
What is long term balancing blood pressure controlled by?
Renin-angiotensin system
- blood flow to kidneys & hormone regulation
Describe the renin-angiotensin system
persistently low blood pressure causes arteriole constriction & reduced blood flow to kidneys (reduction in sodium and water excretion)
Kidney response:
1. Produce renin
renin converts angiontensin-> angiotensin 1
2. angiotensin 1-> angiotensin 2 (ACE)
3. Angiotensin 2: aldosterone is produced
- bradykinin release
How does cardiopulmonary resuscitation work
Heart stops: CPR pumps blood around 1/3 chest, 30:2
- 30: 2- 1/3 of chest compressions
- creates pressure & each recoil relieves pressure & gives time for heart ro fil
contract: blood taken away from brain : due INCREASE PRESSURE (thorax & head)
Recoil: negative pressure in thorax- perfusion & protects brain
What is a ‘high’ blood pressure
135+/ 85mmHg
What are the consequences of hypertension
- damage to walls so epithelium thickens
- chronic kidney disease
- retinopathy
- atheromas, aneurysms,
- peripheral vascular disease
- Heart failure
Causes for hypertension
non modifiable: age, gender, ethnicity
Modifiable: obesity, alcohol, sodium, smokin,g, stress, low control of kidney/ endocrine disease, drugs
What do diuretics do?
- side effects (oral)
Increase secretion of fluid from kidneys( by reducing sodium absorption)- reducing Circulatory volume = Reduced SV
What drugs are ACE inhibitors, what do they do
Side effects (oral)
ramipril, apil
- Inhibit ACE enzyme, prevent angiotensin 2 forming
- prevent vasodilation & bradykinin breakdown
Side effects: Dry mouth, glossitis, erythema multiforme, lichenoid reactions
What are calcium channel blockers role & oral side effects
Prevent vasoconstriction & reduce contractility (force & rate HR)
- Calcium dependent
side effects: gingival hyperplasia, taste distrubances
What is the mechanism of atherosclerosis
- Endothelial destruction
- Fatty streaks: accumulate in tunica intima- lopi d contained with macrophages (foam cells)
- Fibrolipid plaque- smooth muscle proliferation & migration covering fratty plaques form fibrolipid plaque caps over
- Complicated plaque: cap is damaged
What is an atheroma and why do they form
Mass of platelets, red blood cells, fibrin
- form virchows triad: blood consittutents, turbulent flow of blood, stiff vessel wall
How does ACS differ to ACI
ACS: Reduced perfusion via coronary artery
ACI: No perfusion to coronary artery
diffferentiate the drs
what are the symptoms of ACS
- Hypoxia
discomfort
breathlessness
nausea
clammy
lightheadedness
arrythmias
What is the mx of ACS
- Clot breakdown: thrombolysis, angioplasty,place a stent
- removal of blood clot
- replace vessel with another vein
mx: statins(reduce LDL), Beta blockers & ACE inhbitior (reduce BP & strain on the heart), antiplatelets, anticoagulant
What is the cause of peripheral vascular disease
atheroscleorsis- reduced perfusion: causing pain
What is meant by claudication
symptom of peripheral vascular disease
- pain in legs, worsen on elevation
- better with rest
in severe: can cause ulcers, gangrea
