Cardiovascular System Flashcards
Function of CVS
Transport of oxygen and nutrients, removal of metabolic waste
Transport hormones
Maintains constant body temp
Infection and injury
Regulation of fluid and ph
Chordae tendineae function
Stringy tissue that connect papillary muscles to value cusps
Does NOT open or close the valves, only prevent it from flapping about/ backflow
Cause of third heart sound
Heart defects like valve regurgitation (valve not tight)
Valve stenosis (thickening and stiffening of valve cusps)
Congenital heart defects (valves do not form properly
What phase is often masked on an ECG
Atrial diastole masked by ventricular systole
Vascular compliance
Change in vol / change in pressure
Ability of vessels to PASSIVELY stretch and recoil in response to changes in pressure
Functions of endothelial cells
Inner lining (tunica intima)
Local blood pressure control
Permeability
Platelet and fibrinolysis
Angiogenesis and Bessel remodeling
What is the tunica media made of
Layers of elastin fibres and smooth muscle cells
What is the tunica Adventitia/externa made of
Thick connective tissue with elastic and collagen fibres
Which tunica layer controls the total peripheral resistance? TPR
Tunica media has smooth muscle
Vasodilators and vasoconstrictors
Vasodilators - Beta 2 adrenoreceptors, ANP, Nitric oxide, Prostagladin l2
Vasoconstrictors - alpha-1, RAAS, thromboxane A2, endothelin-1
Describe RAAS (Renin Angiotensin Aldosterone System)
Angiotensin II Causes vasoconstriction
Shear stress
Force that blood exerts on the vessel walls, due to blood travelling at different velocities
Are blood vessels under constant mechanical load
Yes
3 types of capillary systems
Continuous (tight intercellular clefts)
Discontinuous (highest permeability due to large clefts and large gaps in basement membrane )
Fenestration
Metarterioles
Do not contain smooth muscle, smooth muscle encircles the vessel at intermittent points along its length , pre-capillary sphincter to control blood entering capillaries
Can lymph vessels contract
Yes
What does lymphatic system do
Maintain fluid volume, moving absorbed fat into circulation , return excess fluid volume from tissue slaves to the circulation
What does lymph system control
Conc of proteins in interstitial fluid
Volume of interstitial fluids
Interstitial fluid pressure
Colloid pressure and hydrostatic pressure in the systemic vs pulmonary circulation
Hydrostatic pressure higher in systemic than pulmonary
Colloid osmotic pressure same
Pulmonary Oedema
Excess fluid in lungs that collects in the alveoli
3 mechanisms of intrinsic control (blood flow matches metabolic requirement of that particular tissue)
Autoregulation
Reactive hyperemia
Active hyperemia
What is active hyperemia
Blood flow is proportional to tissue’s metabolic activity like increased blood flow to skeletal muscles during exercise
Reactive hyperemia
Oxygen debt accumulates and greater post blood flow above pre-vessel occlusion levels until oxygen debt is reversed
Factors that determine resistance to blood flow
Vessel diameter, length and viscosity of blood
What does Poiseulle’s equation assume
It assumes that
1 tube is straight uniform pipe
2 fluid is non-pulsatable
3 flow is smooth (laminar flow)
What aids venous return to the heart?
Skeletal muscles contracting , compressing veins.
Intra thoracic pressure becomes more negative , pressure gradient between abdominal and thoracic veins becomes bigger?
Chronotropy inotropy lusitropy dromotropy
Chronotropy - hr
Inotropy - strength
Lusitropy - rate of relaxation
Dromotropy - conduction speed through AVN
Clinical relavance of circle of Willis
Preserve cerebral perfusion if carotid artery obstruction occurs
Tonic sympathetic vasoconstriction function
Ensure that TPR does not decrease excessively due to too much vasodilation during exercise
Local vasodilators in muscle
Lactate adenosine potassium
As viscosity increases, does the velocity of flow increase or decrease to a maximum at the centre?
Flow in the middle is maximum
What is a normal blood pressure
85-100mmhg
Does hypocapnia stimulate vasoconstriction or vasodilation
Hypocapnia is the lack of CARBON DIOXIDE. (Think too much oxygen even tho it’s wrong concept). Too much oxygen so vasoconstriction
Molarity vs osmolarity
Molarity is the number of molecules in solution and osmolarity depends on the number of particles (IONS AND MOLECULES) in solution
Ions are the dissociations of the molecules
What is often referred to as a physiological or isotonic saline
0.9% NACL solution
RBC haemolyse in what type of solution
Detergent
Hypotonic
How to tell if haemolysis has occured?
If the solution turns coloured and transparent because the red pigment that is released absorbs the light and does not disperse the light
Do ruptured erythrocytes disperse light ?
NO THATS WHY Transparent, coloured solution
Urea isotonic and osmotic related to blood plasma
Urea is isosmotic but not isotonic that’s why rbc swell and burst
For a solution to be isotonic with blood plasma, what conditions must be fulfilled
- Isosmotic
- Solutes must be impermeable (like urea crystals and surf rose )
The magnitude of DBP fall is dependent on what 3 variables (think about the arterial pressure waveform graphs)
- Systolic BP
- Rate of fall of BP
- Time before next heart beat
Does venous return rise or fall when standing up abruptly
Falls due to venous pooling at legs due to gravity
What artery do you pulpate and what artery do you look for for shygometry
Radial
Bronchial
Does ecg tell you about the rhythm regularity and force of contraction
Not for contraction only for rhythm, regularity and total electrical activity
When does the heart receive blood
Diastole because the blood is compressed during systole and unable to reach myocardium
What is the aortic knuckle
It is the prominence as the aorta changes direction in the chest
What type of artery is the aorta
Elastic
