CV VI Flashcards
(48 cards)
How can we tell difference between capillaries and venules
Capillaries begin to converge
What is the volume reservoir
Veins
Very distensable, can add significant volume without adding pressure
Angiogenesis
Formation of new blood vessels
When is microcirculation not constant
Wound healing, endurance training, inflammation, tumour growth, endometrium during menstrual cycle
What drives angiogenesis
Angiogenic growth factors (pro-mitotic) activate receptors on endothelial cells
How does angiogenesis work after endothelial cells are activated
- Acted cells produces proteases that degrade basal lamina so it moves from parent vessel
- Cells proliferate into surrounding matrix and grow sprouts toward stimulus
- Sprouts form loops to become full-fledged vessel lumen
How is angiogenesis a part of progression of cancer
Progresses from small, localized neoplasms to larger, growing and potentially metastatic tumours
How is angiogenesis a possible treatment option for CV diseases
Instead of artificial vessel, speed up growth of natural ones to bypass damage
What is blood pressure
Ventricles creating enough force to propel blood through the CV system
What does ventricular contraction cause
Semilunar valves open
Blood ejected
Aorta and arteries expand and store pressure in elastic walls
What does ventricular relaxation do
Semilunar valve shuts
Preventing flow back
Elastic recoil of arteries send blood forward into rest of circulatory system
Elastic recoil allows blood to continually move
What sustains driving pressure during ventricular diastole
Aorta and large arteries
Where is pressure the highest
Aorta and decreases throughout the circuit
When is aortic pressure the highest and lowest
Highest during ventricular contraction (systole)
Systolic pressure (120mmHg)
Lowest during ventricular relaxation (diastole)
Diastolic pressure (80mmHg)
What is pulse pressure
The difference between systolic and diastolic pressure
In aorta: 120mmHg - 80mmHg
= 40mmHg
Normally only exists on arterial side
Where is pressure measured
In a major artery (brachial) as reflection of ventricle (driving pressure)
Why do we look at a single value of arterial blood pressure
Mean arterial blood pressure as driving pressure
- because pressure is pulsatile
Why is mean arterial pressure not an average
Because equal amounts of time are not spent in systole and diastole
Cardiac cycle time
~ 800ms
250ms ventricular systole
550ms ventricular diastole
What is the MAP equation
Diastolic pressure + 1/3 (pulse pressure)
= 80mmHg + 1/3 (120 - 80mmHg)
= 93 mmHg
Hypotension
BP falls too low (<90/60)
Can cause driving force for blood flow to be inadequate to overcome opposition of gravity
Hypertension
BP is chronically elevated (>140/90)
High pressure on vessel walls can cause them to weaken or even rupture and leak
What can rupture or leak of vessel in brain do
Cerebral hemorrhage
Cause loss of neurological function, stroke
How is blood pressure estimated
Sphygmomanometry
Blood pressure cuff
