regulation of blood flow and pressure Flashcards
What are the main structural layers of a blood vessel?
tunica intima, tunica media, and tunica externa
what vessel type has the greatest pressure
large systemic arteries
what vessels have lowest pressure
larger systemic veins
what type of cells are found in the tunica intima
endothelial cells
what makes up the tunic media
smooth muscle
what makes up the tunic externa
connective tissue and collagen
sympathetic nerve fibres embed in the collagen
what makes veins and venules unique
they have valves
valves are used to prevent
back flow of blood
what do veins and venules lack
elastic layers
what modulates diameter
arteries and arterioles
name the 4 hormones that regulate vasomotor tone
nitric oxide
EDHF
endothelin-1
angiotensin II
what cells produce nitric oxide
endothelial cells
is nitric oxide a vasodilator or vasoconstrictor ?
vasodilator
How is nitric oxide (NO) produced in endothelial cells?
activation of eNOS
What role does calcium play in the production of nitric oxide?
When intracellular Ca²⁺ levels rise, they bind to calmodulin, which then activates eNOS, leading to increased production of NO.
Describe the process by which NO causes vasodilation.
NO diffuses from endothelial cells into the adjacent smooth muscle cells in the vessel wall. Inside smooth muscle cells, NO activates guanylate cyclase, increasing cyclic guanosine monophosphate (cGMP) levels. cGMP then triggers a cascade that results in smooth muscle relaxation, leading to vasodilation.
What is the role of cyclic GMP (cGMP) in NO-mediated vasodilation?
activates protein kinase G to reduce intracellular Ca promoting relaxation of smooth muscle = vasodilation
What role does nitric oxide play in preventing platelet aggregation and thrombosis?
helps prevent blood clot formation
What is the impact of oxidative stress on nitric oxide function?
reactive oxygen species can reduce NO availability
What is EDHF (Endothelium-Derived Hyperpolarizing Factor)?
released from endothelial cells contribute to vasodilation
through the hyperpolarization of vascular smooth muscle cells, leading to relaxation and decreased vascular tone
What is the primary mechanism by which EDHF regulates vascular tone?
EDHF induces hyperpolarization of vascular smooth muscle cells, which inhibits calcium influx and reduces the contraction of smooth muscle cells, leading to vasodilation and decreased vascular tone.
What is Endothelin-1 (ET-1)?
potent vasoconstrictor peptide produced by endothelial cells
How does ET-1 contribute to vasoconstriction?
ET-1 induces vasoconstriction primarily through ET_A receptors on vascular smooth muscle cells, leading to calcium influx, which stimulates smooth muscle contraction and raises vascular tone.
ET-1 inhibits ______ and reduces __________ availability
eNOS
nitric oxide
What is Angiotensin II (Ang II)?
vasoconstrictor peptide part of the RAAS
How does Ang II affect vascular smooth muscle cells?
via G protein coupled receptor and intracellular Ca release
excessive levels of Angiotensin II promotes
high blood pressure and vascular inflammation
vasomodulatory hormone that’s produced in the endothelium but acts predominantly at the arteriole level within organs
endothelial derived hyperpolarizing factor (EDHF)
metabolic syndrome increases your risk for
cardiovascular disease
type 2 diabetes
signs of metabolic syndrome
obesity
dyslipidaemia
raised blood pressure
raised blood glucose
what plays a key role on the pathophysiology if metabolic syndrome
insulin resistance
what is myocardial infarction
heart attack
what is coronary ischaemia
Reduced blood flow (ischemia) in the coronary arteries, which supply the heart, can lead to angina (chest pain) or, if severe, myocardial infarction. It often results from atherosclerosis
what is renal ischaemia
reduced blood flow to kidneys can lead to chronic kidney disease
what is Carotid Artery Disease
Atherosclerosis in the carotid arteries, which supply blood to the brain, increases the risk of stroke
what is a stroke
ischemic stroke : blood flow to part if brain is blocked
hemorrhagic stroke: burst blood vessel in brain
what is the leading cause of elective amputation
peripheral arterial disease
what is atherosclerosis
plaque builds up, causes the arteries to thicken and harden, which restricts blood flow and reduces the flexibility of the vessels
risk factors of atherosclerosis
hypertension (140/90mmHg)
high cholesterol
hyperglycaemia
insulin resistance
obesity (BMI>30kg/m2)
smoking
inactivity
age
heredity
