Vascular 1 Flashcards
What is the normal range of Central Venous Pressure (CVP)?
0-2 mm Hg
What does Central Venous Pressure (CVP) represent?
It represents the balance between venous return (VR) and the pumping ability of the heart.
Example sentence: CVP is used to assess the patient’s fluid status in critical care settings.
What factors determine Peripheral Venous Pressure in a recumbent person?
Blood volume and venous capacity (compliance).
What is the effect of gravity on venous pressure when standing?
It increases pressure in leg veins from 12 mmHg in recumbency to 80 mmHg during standing, which can lead to edema and varicose veins.
How does increased blood volume affect venous pressure?
Increased blood volume (e.g., in renal failure) increases venous pressure.
What happens to venous return (VR) when right atrial pressure (RAP) increases?
Venous return decreases when RAP increases.
What is Mean Systemic Filling Pressure (MSFP)?
It is the pressure all over the systemic circulation if the heart stops pumping, typically 6-8 mmHg when cardiac output (CO) is zero.
How does a change in right ventricular resistance (RVR) affect the venous return curve?
Decreased RVR increases the slope of the VR curve, leading to increased venous return.
What mechanical factors help venous return against gravity?
Muscle pump, valves preventing retrograde flow, thoracic pump during inspiration, and heartbeat effects (ventricular and atrial suction).
What is the main mechanism for the exchange of materials across capillaries?
Diffusion.
What are the forces that move fluid outwards from capillaries during trans-capillary filtration?
Capillary hydrostatic pressure (Pc) and interstitial colloid osmotic pressure (πi).
What role do lymphatics play in the body?
They drain excess filtered fluid, carry proteins and large particles, remove bacteria, and transport fatty acids from the intestine.
What causes edema in dependent parts of the body?
Increased filtration pressure, decreased osmotic pressure, increased capillary permeability, and lymphatic obstruction.
What is myogenic autoregulation?
It is the mechanism by which increased perfusion pressure initially increases blood flow, causing vascular smooth muscle to stretch, leading to vasoconstriction and increased resistance to maintain constant flow.
How does nitric oxide (NO) affect vascular smooth muscle cells?
NO increases cyclic GMP, which leads to vasodilation.
What are the actions of endothelin-1 on vascular smooth muscle cells?
Endothelin-1 acts via ETA receptors to increase Ca2+ influx, causing vasoconstriction.
What is the role of the sympathetic nervous system in regulating blood vessel diameter?
It regulates total peripheral resistance (TPR) through noradrenergic vasoconstrictor fibers and changes venous capacity.
What triggers the secretion of vasopressin (ADH)?
Increased osmolarity, hypovolemia, hypotension, and angiotensin II.
How do natriuretic peptides affect blood volume and arterial blood pressure (ABP)?
They decrease blood volume and ABP by vasodilation, inhibiting renin release, and inhibiting aldosterone action.
What is the primary action of bradykinin in the vascular system?
Bradykinin causes vasodilation and decreases arterial blood pressure through NO release.
