Blood flow and control of blood pressure Flashcards
(40 cards)
Describe the functional model of the cardiovascular system
What are vessels and the progressive branching?
What is vascular smooth muscle?
What are arteries and arterioles?
What are capillaries?
-Smallest vessels in the cardiovascular system, where the majority of exchange between the blood and interstitial space occur
-Single thin endothelial layer surrounded by a basal lamina (extracellular matrix)
-Gases can normally passively diffuse across the endothelial cells
-Linked by interendothelial junctions that also aid in the transport of small solutes and water
-Some cells contain fenestrations, membrane lined conduits running through them to allow the transport
-capillaries are often surrounded by pericytes (BBB)
What are the 3 types of capillaries?
Continuous capillary:
-Thicker endothelial cells that do not contain fenestrations
-Only allow passage of water and small ions through intercellular junctions
Fenestrated capillary:
-Thin endothelial cells that are perforated with fenestrations that often have a thin diaphragm (small molecule passage)
Discontinuous (sinusoidal) capillary:
-Lack a basal membrane, have large open fenestrations as well as gaps between the endothelial cells (liver and spleen)
What are the methods of transport in capillaries?
Transcellular transport:
-Diffusion or osmosis across the endothelial cell membrane
-Gases, small lipid soluble molecules, water (aquaporin channels)
paracellular transport:
-Diffusion through interendothelial junctions, pores or fenestrations (water, small water soluble and small polar molecules)
Transcytosis:
-The combination of endocytosis, vesicular transport, and exocytosis that transports macromolecules across endothelial cells
What are venules and veins?
What is angiogenesis?
necessary part of the process in the progression of cancer from small, localized neoplasms to larger, growing and potentially metastatic tumors
Describe blood pressure
what is hypotension?
-Represents when the blood pressure falls too low (<90/60)
-This can cause the driving force for blood flow to be inadequate to overcome the opposition by gravity
what is hypertension?
-represents when the blood pressure is chronically elevated (>140/90)
-high pressure on the vessel walls can cause them to become weakened or even rupture and leak
-If this occurs in the brain it is called a cerebral hemorrhage and may cause a loss of neurological function, commonly referred to as a stroke
What is mean arterial blood perssure?
-Driving force for blood flow
-Balance between blood flow into the arteries and blood flow out of the arteries
-Mean arterial pressure is proportional to cardiac output x peripheral resistance
-Eg. If cardiac output increases and peripheral resistance does not change, then blood is pumped into the arteries faster than it is removed from the arteries, increased volume in arteries = increased arterial blood pressure
-Most cases of hypertension believed to be due to increased peripheral resistance without changes in cardiac ouput
What are the factors that influence mean arterial pressure?
How do changes in blood volume affect blood pressure? How does the body respond?
What vessel has the highest resistance?
-Resistance is highest within arterioles due to arrangement in series
Explain myogenic autoregulation (local control of arteriol resistance)
Explain how paracrines alter vascular smooth muscle (local control of arteriol resistance)
Explain sympathetic control of vascular smooth muscle
-The secondary mechanism invovles release of epinephrine from the adrenal medula in response to sympathetic activation
-Epinephrine has a low affinity for alpha receptors that cause vasoconstriction and a high affinity for b2 adrenergic receptors which lead to vasodilation
-Depends on relative amount of each receptor (eg. muscles more beta than alpha, GI more alpha than beta
-Norepinephrine on a1 receptor constricts vessel
-Epinephrine on b2 receptor causes dilation
Explain the distribution of blood to the tissues
Describe the regulation of cardiovascular function
What is the baroceptor reflex?
Describe the pathways in which the CVCC integrates sensory information and initiates an appropriate response
Explain the negative feedback loop on the baroreceptor reflex in response to an increase in mean arterial pressure
