Chapter 14 Cardiovascular system Flashcards by patricia allen

pulmonary circulation

goes from the right side of the heart to the lungs and then back to the heart

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systemic circulation

goes from the left side of the heart to the tissues and back to the heart

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Pressure gradient (^P)

blood flows down the pressure gradient

from highest pressure (aorta) to the lowest pressure (venae cavae/pulmonary veins)

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driving pressure

the pressure created when the ventricles contract

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resistance

increases as the length of the tube and the viscosity (thickness) of the fluids increase, and the radius of the tube decreases.

Radius has the greatest effect on resistance

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Relationship between resistance and flow rate

Resistance increases, flow rate decreases

inverse relationship

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fluid flow and pressure gradient relationship

fluid flow through a tube is proportional to the pressure gradient

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flow rate

the volume of blood that passes one point in the system per unit time

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velocity

the distance a volume of blood travels in a given period of time

at a constant flow rate, the velocity of flow through a small tube is faster than the velocity through a larger tube

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myocardium

cardiac muscle

striated muscle

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autorhythmic cells

generate a signal for the contraction of the heart

they are non-contractile myocardium

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intercalated disks

link myocardial cells that contain gap junctions

junctions allow depolarization to spread rapidly from cell to cell

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pacemaker potential

the unstable membrane potential of autorhythmic cells

pacemaker potential is due to I^f channels that allow a net influx of positive charge

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the sinoatrial node (SA node)

here actions potentials originate and spread rapidly from cell to cell in the heart

the potentials are followed by a wave of contraction

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path of the electrical signal

SA node (using the internodal pathway) - AV node - AV bundle - bundle branches - terminal Purkinje fibers - myocardial cells

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electrocardiogram (ECG)

surface recording of the electrical activity of the heart

readings include the P, QRS complex, and T waves

provides information on heart rate, rhythm, conduction velocity, and condition of cardiac tissues

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P-wave

represents atrial depolarization

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QRS complex

ventricular depolarization and incorporates atrial repolarization

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T-wave

ventricular repolarization

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cardiac cycle

one cycle of contraction and relaxation

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systole

contraction phase

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diastole

relaxation phase

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end-diastolic volume (EDV)

majority blood enters the ventricles while the atria are relaxed

Only 20% of ventricular filling is due to atrial contraction

the volume of blood at the end of ventricular filling is EDV

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AV valves

prevent backflow of blood into atria

Closure of AV valves during ventricular contraction set up vibrations that create the first heart sound

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Isovolmic ventricular contraction

during this, the ventricular blood volume does not change but pressure increases

semilunar valves

when ventricular pressure exceeds arterial pressure these open and ejects blood into the arteries when ventricles relax and ventricular pressure falls these valves close and create the second heart sound

end-systolic volume

the volume of blood in the ventricles at the end of the contraction

stroke volume (SV)

amount of blood pumped by one ventricle during one contraction

cardiac output

the volume of blood pumped per ventricle per unit of time = HR x SV average cardiac output at rest = 5L/min changes in cardiac output are accomplished through changes in heart rate, stroke volume, or both

parasympathetic activity

slows HR down

sympathetic activity

increase HR

Norepinephrine / epinephrine

act on B receptors to speed up the rate of pacemaker depolarization increases the force of myocardial contraction when binding to B1-adrenergic receptors they shorten the duration of cardiac contraction

acetylcholine

activates muscarinic receptors to hyperpolarize pacemakers

length of muscle fiber

the longer the muscle fiber when a contraction begins the greater the force of the contraction

Frank-starling law of the heart

increase in end-diastolic volume (EDV) results in greater stroke volume

venous return

determines EDV and preload affected by skeletal muscle contractions, the respiratory pump, and constriction of veins by sympathetic activity

contractibility of the heart

enhanced by catecholamines and some drugs

inotropic effect

chemicals that alter the contractibility have this effect

afterload

the load placed on the ventricle when it contracts reflects the preload and the effort required to push the blood out into the arterial system Mean arterial pressure is a clinical indicator of afterload

In a laboratory, students used a stimulus that decreased the distance between R waves on an ECG. This represents a _____.

decreased length of time for one heartbeat and increased heart rate

Which of the following is the correct description of myocardial infarction and what it is caused by?

A region of the heart muscle dies due to a lack of blood supply.

How does the administration of nitroglycerine help someone that might be suffering from myocardial infarction?

Nitroglycerine will dilate the coronary vessels, which will increase blood flow to the heart muscle.

Arteries are most accurately defined as blood vessels that carry __________.

blood away from the heart

Which of the following is the best definition of an artery?

A vessel that carries blood away from the heart

Which blood vessels return blood to the heart?

Veins

# Choose the correct order in which blood would make contact with the following structures as it traveled from the left atrium through the blood vessels and back to the right atrium. 1) Abdominal aorta 2) Ascending arteries 3) Inferior vena cava 4) Hepatic artery 5) Superior vena cava 6) Left ventricle 7) Ascending veins

``` 6, left ventricle 1, Abdominal aorta 4, Hepatic artery 7, ascending veins 3 inferior vena cava ```

The first branch off the aorta represents which blood vessel(s)?

Coronary arteries

A patient is given a β1 receptor agonist. What would you expect to find?

Increased heart rate and increased cardiac output

Mr. Cortez takes his blood pressure for two weeks and gets an average of 160/100. Normal blood pressure should be slightly lower than 120/80 what is the term used to describe Mr. Cortez's condition?

hypertension

Which of the following conditions can result from chronic hypertension?

heart failure, stroke, and kidney failure

Which parameter associated with mean arterial blood pressure will angiotensin II directly affect? How will this parameter change? What will it do to MAP?

total peripheral resistance; increase; increase

Beta-blockers and Ca++ channel blockers can both be prescribed to Mr. Cortez in order to help with his hypertension. What ONE parameter will both of these medicines have a common effect on?

cardiac output

Which tissue in the walls of blood vessels allows for regulation of vessel diameter?

Smooth muscle

Which blood vessels allow blood to move directly from the arterial to the venous circulation?

Metarterioles

During exercise, cardiac output may increase by more than 170% to meet the body’s increased O2 demands. This increase in cardiac output increases blood pressure. But the accompanying increase in arterial pressure is relatively small—only about 40%. What limits this increase in blood pressure so that it doesn’t reach dangerously high levels during exercise?

Vasodilation causes arterial diameter to increase in the exercising skeletal muscle.

A patient is vomiting and has diarrhea. Which would you expect?

Decreased blood volume and decreased blood pressure

What maintains the driving pressure on blood while the heart is NOT contracting (ventricular diastole)?

Recoil of the elastic arteries

Which is the correct relationship among pressure, flow, and resistance?

Flow is directly proportional to change in pressure and inversely proportional to resistance.

Using a sphygmomanometer, a nurse measures a patient's blood pressure as 134/86. What are the patient's pulse pressure and mean arterial pressure?

PP = 48 mm Hg and MAP = 102 mm Hg

A patient has a hemorrhage and loses a large volume of the blood. Which compensatory mechanisms would you expect?

Vasoconstriction and decreased kidney fluid output in the urine

What effect would an increase in blood volume have on the resistance to blood flow?

There would be no effect; blood volume and resistance to blood flow are not directly linked.

Hours after a surgery, a patient is taken for a walk around the hospital floor. What effect would an increase in venous return have on mean arterial pressure?

It would increase it, by shifting blood from the veins into the arteries.

Which type of vessel changes most to regulate resistance to blood flow? Why?

Arterioles, because of the large amount of smooth muscle in their walls

What is the mechanism behind myogenic autoregulation in vascular smooth muscle?

When cells stretch, mechanically gated cation channels open, depolarizing the cell, resulting in contraction.

What causes active hyperemia?

Increased metabolism results in a local increase in CO2.

A patient takes a beta2 receptor antagonist. Which of the following would you expect?

Vasoconstriction in blood vessels supplying the liver

Where are the sensors for the arterial baroreceptor reflex located?

carotid sinus and aortic arch

If blood pressure is increased at the arterial baroreceptors, what would happen with the activity level of the parasympathetic nervous system (PNS) and sympathetic nervous system (SNS)?

increased PNS activity and decreased SNS activity

Which of the following would cause vasodilation of arterioles?

decreased activity of the sympathetic nervous system

Stimulation of the adrenal medulla would result in which of the following?

an increase in heart rate and contractility

A decrease in blood pressure at the arterial baroreceptors would result in which of the following?

an increase in heart contractility

If increased blood pressure stimulated the baroreceptor reflex, which changes would occur?

Increased vessel diameter, decreased resistance, and decreased cardiac output

If there were a sudden increase in blood volume, what would the baroreceptors do, and what would be the effect of that reflex?

Increase firing rate; decreased myocardial contractility

In the capillaries, hydrostatic pressure (HP) is exerted by __________.

blood pressure

The net hydrostatic pressure (HP) is the hydrostatic pressure in the __________ minus hydrostatic pressure in the __________.

capillary; interstitial fluid

The colloid osmotic pressure in the capillary is caused by __________.

proteins in the blood

Which net pressure draws fluid into the capillary?

net osmotic pressure

Reabsorption of fluid into the capillary takes place at the arterial end or venous end of the capillary?

venous

Chapter 14 Cardiovascular system Flashcards

(78 cards)