ANP 1115 - Blood Vessels & Lymphatic System Flashcards
(38 cards)
What is Resting Vascular Tone?
in resting state, smooth muscles in walls of arterioles
somewhat contracted (sympathetic ns)
- can increase flow by vasodilation
How do Organs regulate blood flow?
organs regulate individual blood flow by varying resistance of arterioles
What are the Local, Metabolic Controls?
- declining tissue levels of oxygen
- increasing levels of CO2, adenosine, H+, K+, heat, inflammatory chemicals
What is the End Result of Metabolic Control?
immediate increased perfusion (hyperemia) of “needy” tissues
What is the Difference between Active & Reactive Hyperemia?
Active Hyperemia: blood flow response to metabolic activity
Reactive Hyperemia: redirect flow of blood; cut off blood supply to lower limbs
What are the Local, Myogenic Controls?
vascular smooth muscle responds to increased stretch with increased tone:
- stretch is resisted → vasoconstriction
- decreased stretch results in vasodilation
What is the Result of Myogenic Controls?
tissue perfusion homeostasis so cells not deprived in response to low bp and capillaries not damaged in response to high bp
What are the the Forces that act to influence Capillary Exchange?
(i) most cells in body within 0.02 mm of a capillary → diffusion works
(ii) capillary walls only 1 cell thick: support a mix of diffusional, osmotic & hydrostatic forces
What are the Capillary Bulk Mechanisms?
- Vesicle Transport
- Diffusion
- Bulk Flow
What is Vesicle Transport?
- for relatively large, lipid-insoluble molecules (protein hormones like insulin)
- shuttling via endocytosis, then exocytosis
- antibody molecules from maternal to fetal circulation
What is Diffusion?
- primary mechanism for dissolved solutes & gases (eg: O2, CO2, glucose)
- follow gradients
- heat moves via convection down a thermal gradient
- water-filled pores or fenestrations (Na+, K+, Cl-, glucose) or directly through the bilayer (O2, CO2, urea)
- pores <1% capillary SA; lipid-soluble substances have 100X more SA
What is Bulk Flow?
- this is especially important for fluid movement
- will also carry nutrients and wastes in appropriate direction, but they rely more on diffusion
What does the Overall Deficit of 1-2 mm Hg mean?
This means that some fluid (3-4 ml/min) is lost to the tissues and has to be returned by the lymphatic system
What does Increased Arteriole Pressure mean?
means increased filtration pressure = more fluid loss to tissues (edema)
What does Hemorrhage favour?
hemorrhage favours reabsorption
What is the Role of Lymphatic Vessels?
return up to 3 L of “leaked” fluid plus plasma proteins to the bloodstream
What is the Role of lymphatic tissues / organs?
essential in body to provide defense / resistance to disease
What are Lymphatic Vessels?
begin with microscopic, blind-ended lymph capillaries (called lacteals (pick up fluids & fats we digest to circ. system) when found in intestinal villi)
Where are Lymphatic Vessels found?
everywhere except bones, teeth, bone marrow, and in only limited areas (meninges) in CNS
What do the Flap-Like Minivalves provide?
flap-like minivalves provide spaces in between loosely attached endothelial cells
What is the Purpose of Collagen Filaments?
collagen filaments anchor the endothelial cells to surrounding structures
What happens when fluid pressure builds up in
tissues?
Make lymph capillaries more permeable
- open them up for a bit
- easier for fluid to go into those capillaries
Where does the Right Lymphatic Duct drain from?
Right head, shoulder area, upper limb, thorax area
Where does the Thoracic duct drain from?
Left head, shoulder area, upper limb, thorax area. abdomen
- Both lower limbs
