Week 3 Hypertenstion & Heart Failure Flashcards
1
Q
- What is the tern used to describe the pressure exerted by circulating blood on the walls of the blood vessels?
HINT: COxSVR - What effect does pregnancy, meds and bradycardia have on blood pressure?
A
- Blood Pressure (BP)
2. Low BP
2
Q
- Describe what is meant by mean arterial pressure.
- What is the reference value of MAP?
- How do we increase MAP and decrease MAP?
A
- MAP is the average arterial pressure during a single cardiac cycle (SBP+ 2 x DBP)/3
- 70-100mmHg
- Increase MAP: primary HTN
Decrease MAP: cardiac failure and sepsis
3
Q
- What is the term for the volume of blood pumped by the heart per minute (mL/blood/min)?
- How can we increase this term? How do we decrease the volume of this term?
A
- Cardiac output
- Increase - increase MAP, increase circulating volume
Decrease - decrease MAP, decrease circulating blood volume or decrease strength of ventricular contraction, heart failure
4
Q
- What is the volume of blood in the ventricles immediately before contraction known as?
- What is this term directly related to?
- Stroke volume is?
- How do we increase and decrease stroke volume?
A
- End Diastolic Volume (EDV)
- Directly related to the preload; the greater the preload the greater the EDV
- SV is the amount of blood pumped by the heart per cardiac cycle
- Increase SV by increasing circulating volume + inotropes (ex. Digoxin)
Decrease SV when contractility is impaired and valve is dysfunctional
5
Q
- What is the measurement of resistance or impediment of the systemic vascular bed to blood flow?
- How do hypovolemic shock and vasoconstrictors affect the SVR?
- How do vasodilators, morphine, anaphylactic shock and late septic shock affect the SVR?
A
- Systemic Vascular Resistance
- Increase SVR
- Decrease SVR
6
Q
- Explain the Frank-Starling Mechanim.
- How does increase blood volume affect the stretch of the heart and force of contraction?
- How does increased SV affect EDV and force of the next contraction?
- When does increased SV become ineffective?
A
- The greater the stretch, the greater the force.
- Increase blood volume increases the stretch of the heart and thus increases the force of contraction
- Increased SV will increase EDV and increase the force of the next contraction
- Becomes ineffective once the heart becomes overfilled and the muscle becomes over-stretched
7
Q
- What does LAPLACE’s law state?
- What is the equation for LAPLACE’s law?
- As wall thickness increases, how does it affect wall tension?
- What type of relationship do radius and tension have?
- How does dilation affect the work of the heart?
A
- As the radius increases, so does the tension
- Wall tension = intraventricular presure x internal radius/wall thickness
- As wall thickness increases wall tension decreases (inverse relationship)
- Radius and tension have an direct relationship.
- Requires the heart to work harder to pump blood.
8
Q
- Define the term used for pressure generated at the end of diastole.
- What 2 primary factors determine the preload?
- What affect does increased preload have on cardiac output? How does this affect stretch?
A
- Preload
- A) The amount of venous return to the ventricle
B) Blood left in the ventricle after systole of end-systolic volume - Increased preload increases cardiac output (volume of blood pumped per min); Increases stretch and the force of the next contraction
9
Q
- How is preload increased?
- How is preload decreased?
- When preload is too high this may have a _____ relationship with stroke volume.
A
- Preload is increased when venous return is increased via fluid overload or structural heart defects
- Preload is decreased when venous return is decreased via hemorrhage, 3rd spacing (edema) or limited ventricular filling via constrictive pericardititis and cardia tamponade (layers of heart becoming filled with blood)
- Inverse relationship
10
Q
- Define afterload
- What does afterload depend on mainly? (2)
- What relationship do afterload and cardiac output share?
A
- The force that the contracting heart must generate to eject blood from the filled heart
- Depend mainly on a) ventricular wall tension and b) peripheral vascular resistance
- Inverse relationship; the greater the afterload the less the cardiac output
11
Q
- How is afterload increased ?
- How can increased afterload effect ventricular ejection?
- How is afterload decreased?
- What is aortic valve stenosis?
A
- Caused by increased aortic pressure (ex. Aortic stenosis) and increased SVR (ex. Severe HTN, vasoconstriction)
- May impair ventricular ejection if ventricles cannot generate sufficient pressure
- Afterload is decreased when SVR is decreased and vasodilation occurs (Ex. Sepsis, hyperthermia); decreased BP, nitrates
- Valve does not fully close and valve does not fully open
12
Q
- How do beta-blockers, Ca channel blockers and digoxin affect HR?
- How does increased HR affect CO?
- How does decreased HR affect CO?
A
- Decrease HR
- Increased HR shortens diastole and ventricular filling time, so this will decrease CO
- Decreased HR also decrease CO; even though SV is similar we are not circulating enough blood per min
13
Q
- Increasing contractility results in increased/decreased SV. This increases/decreases myocardial oxygen consumption.
- What 3 factors affect contractility?
- What factors could compromise intrinsic contractility?
- Which medication increase contractility? Which decrease contractility?
A
- Increased SV; Increased myocardial oxygen consumption
- Preload; Innervation to ventricles; O2 supply
- Poor myocardial perfusion (blockage), degenerative changes that occur with aging, necrosis that occurs from myocardial infarction, medication
- Increase: Inotropes (ex. DA, digoxin, dobutamine); Decrease: beta blockers, Ca channel blockers, anesthetic, chemotherapeutic agents
14
Q
BARORECEPTORS
- What are they?
- Where are they located?
- What is their function?
- Provide a clinical example.
A
- Pressure-sensitive (or stretch) receptors
- Primarily in the carotid sinus and aorta
- Respond to changes in the stretch of vessel wall by sending impulses to cardio-centers in the brain stem -> appropriate changes in HR and vascular smooth muscle tone
- Blood loss due to trauma -> decreased BP -> increased HR+vasoconstriction and increased contractility
15
Q
CHEMORECEPTORS
- What are they?
- Where are they located?
- What is their function?
- Provide a clinical example
A
- Sensory receptors
- Located in the medulla oblongata, carotid and aortic bodies
- Detect changes in the concentration of O2, CO2 & pH in arterial blood -> send messages to cardioregulatory/vasomotor centres (medullary oblongata) -> SNS and PNS responses in the vessels and heart
- Respiratory illnesses (ex. Pulmonary edema) -> decreased arterial O2 concentration/increase in PaCO2 -> increased HR, increased SV and Increased BP
16
Q
- How do kidneys control arterial pressure?
- Where is renin released from? What type of molecule is renin? When is it released? What does it act on?
- What affect does angiotensin 1 have on the body?
- How is angiotensin II formed? Where is it formed? What does angiotensin II do? How is it deactivated?
A
- Through changes in ECF volume and the renin angiotensin system
- Renin is released from the kidneys; it is protein enzyme; it is released when the arterial pressure falls too low; it acts on angiotensinogen to release angiotensin 1.
- Has mild vasoconstrictor properties but not enough to cause significant changes in circulatory function
- Formed by ACE enzyme; formed in the lungs; extremely powerful vasoconstrictor; deactivated by angiotensinases;
17
Q
- What are the two principle effects that can elevate arterial pressure?
- What does increased SVR do to arterial pressure?
- How does aldosterone secretion manifest?
- How does aldosterone work in the body?
A
- Vasoconstriction in many area of the body (arterioles and veins)
And decrease excretion of both salt and water by the kidneys - Increased SVR increases arterial pressure
- Aldosterone is secreted by the kidneys and is initiated by angiotensin II
- Increase Na reabsorption; increase H2O reabsorption; increased blood volume; increase CO
18
Q
- What effect does increased sodium and water levels have on BP?
- Over production of aldosterone has been implicated in _______.
- What is vascular auto regulation?
- Increased metabolism causes a build up of ___________. This results in ________ of smooth muscle encircling the vessel.
A
- Increased BP
- HTN
- Intrinsic ability of arteries to adjust blood flow according to tissue needs.
- Vasodilatory chemicals in the vessels; relaxation
19
Q
- What occurs when MAP gets too high or too low?
2. Which organs require the most effective ability to auto-regulate blood flow?
A
- Body loses its ability to auto-regulate
2. BRAIN, HEART and KIDNEYS
20
Q
- What is HTN?
- What are the values for prehypertension?
- What are the values for Stage 1 hypertension? What are the values for Stage 2 hypertension?
A
- A persistent elevation of systemic arterial blood pressure
- Systolic: 120-139 or Diastolic: 80-89
- Stage 1: Systolic: 140 to 159 or Diastolic 90 to 99
Stage 2: Systolic: 160 or higher Diastolic: 100 or higher
21
Q
- What are some of the risks of primary HTN?
- What is the equation for BP?
- Anything that effects ___,____ or ____ will effect BP.
- Primary HTN is the result of a complicated interaction between _______ and the _________ leading to ______ vascular tone and blood volume.
A
- Advancing age, cigarette smoke and heavy alcohol consumption, diabetes melllitus, obesity, ethnicity, family history, psychosocial stress, socioeconomic status, excessive dietary sodium
- BP = COxSVR
- SVR, heart rate and stroke volume
- Genetics and the environment leading to increased vascular tone and BV
22
Q
SNS
- Where is the sympathetic vasomotor centre located?
- Which NT is released from the sympathetic nerve endings?
- Which receptor does this NT activate?
- What do alpha-adrenergic receptors control? Beta-adrenergic receptors?
- When SNS is activated how does this affect a) the heart b) SVR c) kidneys d)arterial pressure?
A
- Located in the medulla
- NE
- Receptors in the SA node, myocardium and vascular smooth muscle
- Alpha - peripheral vasoconstriction, pupil dilation; beta - HR and contractility
- A) Increased HR and contractility b)increased SVR c) release of renin by kidneys d)increased arterial pressure
23
Q
- Increased SNS activity causes _______ insulin release.
- Increased SNS causes vascular ________ which _________ blood vessels.
- Angiotensin II stimulates which hormone? Where is this hormone released from?
- Increased renin secretion has been investigated as a cause of _______ peripheral vascular resistance in primary HTN.
A
- Increased insulin release
- Vascular remodeling; narrows the BV
- Stimulates aldosterone; released from the adrenal cortex
- Increased peripheral vascular resistance
24
Q
- What do natriuretic peptides modulate?
- How does tissue ischemia affect glomeruli & tubules?
- Which ions can affect the function of natriuretic peptides?
A
- Modulate renal sodium excretion
- Tissue ischemia causes dysfunction in the glomeruli and tubules which promotes additional sodium retention
- Excessive Na intake, inadequate dietary intake of K, Mg and Ca
25
Q
- How does inflammation affect the endothelial tissue and HTN?
- How does endothelial dysfunction affect HTN?
- How does obesity influence HTN?
- How does insulin resistance affect endothelial tissue and HTN?
A
- Causes endothelial injury and tissue ischemia which damages the kidneys causing increasedNa retention and sustained HTN
- Endothelial dysfunction causes decreased production of vasodilators and increased production of vasoconstrictors
- Obesity contributes to endothelial dysfunction and renal Na retention
- Insulin resistance is associated with endothelial dysfunction