CVS physiology 3 Flashcards
What 2 methods can be used to measure arterial pressure?
Sphygmomanometer and stethoscope oscillatory blood pressure measurement
What is the systemic filling pressure?
Pressure difference that pushes blood back to the heart from the capillaries (from 20 to 5mmHg)
What is velocity of blood flow related to?
Total cross section area (fastest in aorta and slowest in capillaries)
What is the pressure of blood when they arrive at the capillaries?
40mmHg
What is the drop in pressure of blood from the start of arterioles until they reach the capillaries?
90 to 40mmHg
What is the values of pressure at the start of the arteries compared to the end?
95 to 90mmHg
What can venous collapse in the neck be used to estimate?
Central venous pressure
What effect does skeletal muscle pump have on blood flow?
Increases venous return and EDV
What effect does respiratory pump have on blood flow?
Increased respiratory rate and depth increases venous return and EDV
What is venomotor tone?
Smooth muscle tension in the veins
Name 5 things that can impact venous return?
Gravity
Skeletal muscle pump
Respiratory pump
Venomotor tone
Systemic filling pressure
What is the role of thrombin?
Converts fibrinogen to fibrin
What is the role of prostacyclin?
Inhibits platelet aggregation
What is the role of tissue factor pathway inhibitor (TFPI)?
Stops thrombin production
What is the role of thrombomodulin?
Binds to thrombin and inactivates it
What is the role of heparin?
Inactivates thrombin
What is the role of plasminogen activator (t-PA)?
Converts plasminogen to plasmin which digests clots
What are 3 types of capillary?
Continuous
Fenestrated
Sinusoid
What feature of capillaries in the brain creates the blood brain barrier?
No clefts or pores
On average, how much fluid is drained into the lymphatic system per day?
3L
Name 4 causes of oedema
Lymphatic obstruction
Raised CVP due to ventricular failure
Hypoproteinemia
Increased membrane permeability due to inflammation
What is mean arterial pressure equal to?
Cardiac output x total peripheral resistane
What is the mechanism of active hyperaemia in blood flow?
Increase metabolite production stimulates the production of EDRF, Which causes arteriolar dilation - Increasing blood flow
What is the mechanism of pressure autoregulation in blood flow?
A decrease in mean arterial pressure causes decrease in flow, this stimulates production of EDRF causing arteriolar dilation - increasing blood flow
What effect does the sympathetic nervous system have on blood pressure?
Noradrenaline is released and binds to alpha 1 receptors, this causes arteriolar constriction which increases TPR - Increasing MAP
What effect does the parasympathetic nervous system have on blood pressure?
Usually no effect (genitalia and salivary glands are an exception)
What features of coronary blood flow allow the heart to have sufficient blood supply?
Shows excellent active hyperaemia expresses many beta 2 receptors
What features of cerebal blood flow allow it to maintain stable conditions that is requires?
Shows excellent pressure autoregulation
What features of renal blood flow allow it to maintain stable conditions that is requires?
Shows excellent pressure autoregulation
What is the arterial baroreflex?
Short term blood pressure regulation
