HLB Case 1

amymed's version from 2015-10-06 19:09


Question Answer
What acts to regulate a change in pressure in the first few seconds?CNS, Baroreceptors, Chemoreceptors
What happens in a vasovagal syncope?Clammy, dizzy, transient loss of consciousness, slow thready pulse
What are the vasomotor centre's influences?Pons (reticular substance). Hypothalamus, Cerebral cortex, Cingualate. Hippocampus
How does the nervous system raise arterial pressure?SNS release NA from nerve terminals. which acts of alpha receptors of VSMC. Arterioles constrict and heart directly stimulated. NE--> G protein --> calmodulin --> Calcium -->constricts arterioles.
Layers of a resistance artieriole from inside to outside.Endothelium, internal elastic lamina, VSMC(tunica media), tunica adventia
Where are nerve terminals in artierolesRest on outside layer.
How do baroreceptors decrease BP?Activate on stretch, send signals to tractus solitarius in brainstem, inhibit vasoconstrictor centre and excite vagal parasympathetic area
Which type of receptors are important in maintaining postural BPBaroreceptors
What happens in a carotid sinus massage?BP monitored. Stimulates baroreceptors within carotid body - may find cardioinhibitory Carotid sinus hypersensitivity. BP will drop.
What long term systems regulate BP?RAAS and vascular remodelling and contractility.
How does RAAS cause an increase in BP?Renin converts angiotensinogen (released by liver) to angiotensin I. ACE converts it to angiotensin II. Angiotensin II increases sympathetic activity, releases aldosterone (NaCl resorbed), is a vasoconstrictor, causes ADH secretion - resorption of water from collecting duct.
What is the atrial volume reflex?Atrial stretch due to pressure - reflex dilation of renal afferent arteriole, increased glomerular capillary pressure - increased filtration of fluid into renal tubule. Reduced secretion of anti-diuretic hormone from hypothalamus - reduced water resorption from renal tubule. Fluid loss from kidneys
How does an decrease in arterial pressure lead to fluid resorption?Glomerula hydrostatic pressure drops, GFR drops, floor rate in loop of Henle drops leading to NaCl reabsorption and less delivery of NaCl to macular densa. Mac densa cells detect this - renin is released. efferent arteriole resistance increases and afferent decreases.
Problem with too much aldosterone?Can cause loss of too much potassium. Hypokalaemia
What is small artery remodelling?Increase in wall thickness, reduction in lumen, preservation or mild impairment of endothelial function
What happens in diabetic arteries in terms of remodelling?Increased wall thickness, no change to lumen and impaired endothelial function.
True or false, adipose tissue releases factors that can relax small arteries? True - adiponectin does this, however it is reduced in obesity.
What microscopic changes would you expect to see in small arteries and arterioles as a result of chronic hypertension?Hyaline deposits in walls. Thickened walls, narrowed lumen.