BISC 221 - Cardiovascular System Part 2 (Topic 3) - Midterm 3

What instrument is used to hear heart sounds?

a stethoscope

What are the normal heart sounds?

“lub-dub” (lana del)

What is S1 (“lub”)?

a resonating sound caused by blood pressure against the atrioventricular (AV) valves (1st AV warns)

What physical action results in the S1 sound?

the closing of AV valves

What is S2 (“dub”)?

a snapping sound when the ventricles relax and blood in the arteries flows back toward the ventricles (mini filling before dystole)

What physical action results in the S2 sound?

closing of semilunar valves (s2 is for 2 s emilunar valves)

What is the cardiac cycle?

the cycle of the heart muscle alternately contracting and relaxing

What is systole?

contraction and emptying of the chambers (sis stole from the chambers)

What is diastole?

relaxation and refilling of the chambers (dia gave to the chambers)

What is the state of the valves during diastole?

AV valves are open, semilunar valves are closed (AV can bring boxes in for refilling)

What is the state of the valves during systole?

AV valves are closed, semilunar valves are open (blood leaves through semilunar)

How is blood pressure expressed?

systolic pressure/diastolic pressure

What is systolic pressure?

the force with which left ventricle pushes blood through the circulatory system

What is diastolic pressure?

the force the blood exerts on the walls of the circulatory system while the heart is relaxed

What is the range for normal blood pressure?

roughly from 90-120 (systolic) to 60-80 (diastolic) (sys is 9 or 12, dia is 68)

What is the definition of high blood pressure?

loosely defined as 140/90mmHg above

What is the usual value for systolic pressure (SP)?

about 120 mm Hg

When does systolic pressure occur?

when ventricles are contracting

What is the usual value for diastolic pressure (DP)?

about 80 mm Hg

When does diastolic pressure occur?

when ventricles are relaxing

Is minimum pressure in the arteries ever zero?

no; there is always some pressure in the arteries

What is the formula for Pulse pressure (PP)?

SP-DP

What is the typical value for Pulse pressure (PP)?

40 mm Hg

What is Mean Arterial Pressure (MAP)?

weighted average of pressure

Why is MAP closer to diastolic pressure?

time spent in diastole is greater than time spent in systole

What is the formula to estimate MAP?

DP + (PP/3)

What is the estimated MAP if pressure is 120/80?

93 mm Hg

What is turbulent flow?

flow created when blood flow is restricted and bounces around

What creates sounds as blood hits the sides of the vessel?

turbulent flow

What is the basis for determining blood pressure with a sphygmomanometer?

turbulent flow

What is a sphygmomanometer?

an inflatable cuff attached to a pressure gauge

What is laminar flow?

blood (or any liquid) flowing smoothly

How much sound does laminar flow make?

it makes almost no sound

What happens to blood flow when the cuff pressure is above 120?

artery is pinched closed: no blood flow

What sound is heard when cuff pressure is above systolic pressure?

no sound heard

What type of flow occurs when cuff pressure is between 120 and 80?

turbulent flow

When is sound heard in the stethoscope during sphygmomanometry?

every time pressure in artery exceeds cuff pressure

What happens when cuff pressure is below diastolic pressure?

sounds are no longer heard

What is the SA (sinoatrial) node?

a group of cells at the top of the right atrium that serves as the heart’s pacemaker

How does the SA node initiate the heartbeat?

by initiating an electrical signal that passes from cell to cell through the right and left atria

What is the effect of the SA node signal on the atria?

causes both to contract

What is the function of the AV (atrioventricular) node?

slows the signal down so the ventricles contract after the atria (RVs move slowly)

Where is the AV node located?

in the base of the right atrium

What is the function of the AV bundle?

sends the signal to the ventricles

What is the function of the bundle branches?

send the signal to the two ventricles so they contract together

What is the function of the Purkinje fibers?

send the signal to all of the cells of the ventricles

Can the heart beat without neuronal input?

yes; the heart will beat and contract without any neuronal input

What is an electrocardiogram (ECG)?

the measurement of small electrical signals generated by cardiac muscle at the skin surface

Is an ECG a direct recording of the electrical activity of the heart?

no; it is a recording of that portion of the cardiac signal that actually reaches the surface of the body

Is an ECG a single electrical signal in a single cell?

no; it is the summed activity of many cells

What does the P wave represent?

the depolarization of the atria (beginning of their contraction) (dps)

What does the QRS complex represent?

the depolarization of the ventricles (qrs dps rescue)

What event occurs during the QRS complex besides ventricular depolarization?

atria also repolarizing (end of their contraction)

What does the T wave represent?

the repolarization of the ventricles (trep)

Is SA node firing visible on an ECG?

no; it is too small to be seen

What is the P-R interval?

AV nodal delay (pr boxes come late)

What is the Q-T interval?

Time during which ventricles are contracting and emptying (qt but sys stole)

What is the T-P interval?

Time during which ventricles are relaxing and refilling (relax)

What are the three types of blood vessels?

arteries, capillaries, and veins

What are the three layers in the walls of arteries and veins?

endothelium, smooth muscle and elastic tissue, and connective tissue (esec)

What is the inner layer of a blood vessel?

endothelium

What makes up the middle layer of a blood vessel?

smooth muscle and elastic tissue

What makes up the outside layer of a blood vessel?

connective tissue

What feature do veins have that is similar to the heart?

one-way valves

How thick are the walls of capillaries?

one-cell layer thick

What happens to blood pressure as it flows through the systemic circulation to the veins?

the pressure drops

What is the pressure in the veins as blood is returned to the heart?

almost zero

What forms the pores in capillary walls?

small gaps between adjacent endothelial cells

How are small water-soluble substances exchanged across capillaries?

by passing through the water-filled pores

How are lipid-soluble substances exchanged across the capillary wall?

by passing through the endothelial cells

How are proteins moved across the capillary wall?

by vesicular transport

Can plasma proteins escape from the plasma across the capillary wall?

no

What vessels lead to capillaries?

Arterioles

What are networks of capillaries called?

capillary beds

What is ultrafiltration?

process at the arteriole end where high blood pressure forces water into the tissues

Why do large plasma proteins not leave the blood during ultrafiltration?

they cannot pass through the pores

What is the relationship between pressures at the arteriole end of a capillary?

Blood pressure > Osmotic pressure (blood is thicker than water)

What is reabsorption?

process at the venule end where water flows back into the blood

What happens to pressures as blood passes through capillaries to the venule end?

the pressure drops and the osmotic pressure increases

What is the relationship between pressures at the venule end of a capillary?

Osmotic pressure > Blood pressure

In what vessels does blood collect after leaving capillaries?

venules and veins

How does blood pressure in veins compare to arteries?

blood moves through the veins under lower pressure

What is the first reason blood continues to flow toward the heart despite low pressure?

fluids flow more easily from a smaller vessel to a larger one

What is the second reason blood continues to flow toward the heart despite low pressure?

venous valves prevent backflow of blood

What is the third reason blood continues to flow toward the heart despite low pressure?

skeletal muscles surrounding veins “push” blood toward heart

What is the fourth reason blood continues to flow toward the heart despite low pressure?

respiratory pump enhances venous return

How does respiratory activity establish a pressure gradient for venous return?

pressure surrounding the chest veins is lower than the pressure surrounding the veins in the extremities and abdomen (blood always move from high to low pressure)

What are the two main portions of blood?

plasma (liquid) and formed elements (solid)

What are the formed elements in blood mainly composed of?

cells

How does blood prevent blood loss at injuries?

it forms clots

What is the role of blood cells in the immune system?

they patrol the body to destroy pathogens

What does plasma transport?

hormones, nutrients, and gases

Where does blood transport heat?

between the body core and the skin

What percentage of total blood volume is plasma?

46 to 63%

What are the components of plasma?

92% water, 7% dissolved proteins, and 1% electrolytes, nutrients, and wastes

What is the function of albumin in the plasma?

maintain blood’s osmotic pressure so water remains inside vessels

What are examples of electrolytes in plasma?

sodium and potassium

What are examples of nutrients in plasma?

carbohydrates and amino acids

What are examples of wastes in plasma?

urea, CO2 and lactic acid

What are the formed elements in blood?

cells and cell fragments