blood pressure summary

8/17/2019 Blood Pressure Summary

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BLOOD PRESSURE

1. Integrate ideas from the heart and the circulatory system todescribe the determinants of mean arterial ressure- Mean arterial pressure is the main driving force for propelling blood to

the tissues- It must be closely regulated so that it is high enough to ensuresucient driving pressure. Also the pressure must not be too high thatit creates extra work for the heart and increases the risk of vasculardamage- The primary determinants for mean arterial pressure are cardiacoutput and total peripheral resistance

The mean arterial pressure is constantly monitored by barorecetorspressure sensors! within the circulatory system. "hen deviations are

detected# multiple re$ex responses are initiated to return meal arterialpressure to its normal value.

%hort term& occur within seconds!'! Ad(ustments made by alterations in cardiac output and totalperipheral resistance. It is mediated by means ofautonomic nervous system in$uences on heart# veins# andarterioles



)ong term& re*uire minutes to days!'! Involve ad(usting total volume blood by restoring normal salt

and water balance through mechanism that regulate urine output andthirst

!. Describe ho" mean arterial ressure is sensed and identifythe re#e$ resonse that "ould occur "hen stimulating theseressure sensors- Any change in meal arterial pressure triggers an automaticbarorecetor re#e$.- The most important receptors involved in the moment-to-momentregulation of blood pressure# the carotid sinus and aortic archbarorecetors# are mechanoreceptors sensitive to changes in bothmean arterial pressure and pulse pressure.

+ ,luctuations in pulse pressure enhance their sensitivity aspressure sensors because changes in diastolic or systolic pressure may

alter the pulse pressure without changing the mean pressure+ )ocated about the common carotid arteries and in the ma(or

arterial trunk- "hen arterial pressure increases# the receptor potential of thebaroreceptors increases# this increasing the rate of ring in thecorresponding aerent neurons. And vice versa.- The integrating center that receives the aerent impulses is thecardio%ascular control center& located in the medulla within thebrain stem.- The eerent pathway is the autonomic system. The cardiovascularcontrol center alters the ratio between sympathetic and

parasympathetic activity to the eector organs heart and bloodvessels!



There are other re$exes and responses that in$uence thecardiovascular system even through they primarily regulate other bodyfunctions'. )eft atrial volume receptors and hypothalamic osmoreceptors areimportant in water and salt balance in the body/ they aect long-termregulation by controlling plasma volume

0. 1hemoreceptors located in the carotid and aortic arteries aresensitive to low 20 or high acid levels in blood. Their main function isto increase respiratory activity but also increase blood pressure butsending excitatory impulses to the cardiovascular center.

'. Di(erentiate bet"een rimary and secondary hyertension3ypertension is when the blood pressure is too high. Above '45675mm3g!



%econdary 3ypertension&

- Accounts for about '58 of hypertension cases- 2ccurs secondary to another known primary problem- 9x! :enal hypertension# 9ndocrine hypertension. ;eurogenic

hypertension<rimary 3ypertension&- Is a catch-all category for blood pressure elevated by a variety of

unknown causes rather than by a single disease entity- <eople show a strong genetic tendency to develop primary

hypertension# which can be hastened by contributing factorssuch as obesity or smoking

- <otential causes=o >efects in salt management by the kidneys

o 9xcessive salt intake

o >iets low in fruits# vegetables# and dairy products

o <lasma membrane abnormalities# such as defective ;a?-@? pumps

o ariation in the gene that encodes for angiotensinogen

o Abnormalities in ;2# endothelin# or other locally acting

vasoactive chemicalso 9xcess vasopressin

+ the baroreceptors do not respond to bring the blood pressure back tonormal during hypertension because they BresetC to operate at ahigher level.

1omplications

- 1ongestive heart failure- %troke- 3eart attack- %pontaneous haemorrhage- :enal failure- :etinal damage

Treatment- >ietary management- A variety of drugs that manipulate salt and water management- Autonomic activity on the cardiovascular system

+ Agents that reduce plasma volume or total peripheral resistance willdecrease blood pressure toward normal

). Integrate the heart and circulatory sections to determineho" the body "ould comensate in resonse to a decrease inblood %olume *shoc+,



3ypotension is when the blood pressure is below '556D5 mm3g. Itoccurs when there is too little blood to ll the vessel of when the heartis too weak to drive the blood. The most common situation where hypotension occurs is orthostatichyotension. 2rthostatic hypotension is a condition resulting from

insucient compensatory responses to gravitational shifts in bloodwhen a person moves from horiEontal to vertical position.

1irculatory shock occurs when blood pressure falls so low thatade*uate blood $ow to the tissues can no longer be maintained.1irculatory shock is categoriEed into four main types'! 3ypovolemic low volume! shock F occurs through severehaemorrhage or indirectly though loss of $uids derived from theplasma diarrhoea# sweating! 0! 1ardiogenic heart produced! shock F sue to a weakened heartGs

failure to pump blood ade*uately

H! asogenic vessel produced! shock F caused by widespreadvasodilation triggered by the presence of vasodilator substances. Thereare two types of asogenic shock& septic and anaphylactic. %epticshock is due to vasodilator substances released from infective ages.%imilarly# extensive histamine release in severe allergic reactions cancause widespread vasodilation in anaphylactic shock.

4! ;eurogenic nerve produced! shock F involves generaliEedvasodilation but not by means of the release od vasodilator

substances. )oss of sympathetic vascular

blood pressure summary

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