Pressure & Flow in Arteries + Veins

Question 1

<p>How are asphygmomanometer and a stethoscope used to measure arterial pressure?</p>

Answer 1

<p>Cuff is inflated - constricts brachial artery</p>

<p>First audible tapping noise through stethoscope is because the peak of the systolic blood pressure is greater than the pressure of the cuff - a small blip of turbulent blood flow passes the stethoscope.</p>

<p></p>

<p>Noise becomes muffled as the cuff pressure is reduced because the flow becomes more laminar</p>

<p>The sounds disappear completely since the blood flow through the artery has returned to normal. The last audible sound is defined as the diastolic pressure</p>

<p></p>

Question 2

<p>What are the advantages/disadvantages of this method of measurement of blood pressure?</p>

Answer 2

<p>Disadvantages - Accuracy</p>

<p>Discontinuous – olny use it for instantaneous measurements</p>

<p>Needs care – constant surveillance, not automated</p>

<p></p>

<p>Advantages - Cheap and non-invasive</p>

Question 3

<p>What is the effect of high diastolic pressure on the aorta?</p>

Answer 3

<p>There is a higher total peripheral resistance so the aorta finds it harder to release blood</p>

Question 4

<p>What is the effect of elastic vessels on pressure variations?</p>

Answer 4

<p>Dampens them down</p>

Question 5

<p>What is the pressure wave affected by?</p>

Answer 5

<p>- stroke volume</p>

<p>- velocity of ejection</p>

<p>- elasticity of arteries</p>

<p>- total peripheral resistance (If TPR increases, stroke volume will go down (more energy is “wasted” building up sufficient pressure to open the aortic valve))</p>

Question 6

<p>Define pulse pressure</p>

Answer 6

<p>Pulse pressureis the difference between the systolic and diastolicpressurereadings</p>

Question 7

<p>What feature of arteries allows maintainance of high pressure during high systolic pressure?</p>

Answer 7

<p>Elastic fibres</p>

Question 8

<p>How does pressure change from arteries - arterioles - capillaries - venules?</p>

Answer 8

<p>Decreases</p>

Question 9

<p>What is name given tothe blood pressure left to bring the blood back to the heart?</p>

Answer 9

<p>Systemic filling pressure</p>

Question 10

<p>What is normalarterial pressure?</p>

Answer 10

<p>“Normal” arterial pressure</p>

<p> = 120/80 mmHg</p>

<p>Arterial pressure (especially pulse pressure) increases with age</p>

Question 11

<p>Why is flow constant throughout the systemic circulation?</p>

Answer 11

<p>Because everything is in series</p>

Question 12

<p>What is the pressure drop through the arteries?</p>

Answer 12

<p>•arteries (from ~ 95 to 90 mmHg)</p>

<p>–low resistance conduit</p>

Question 13

<p>What is the drop in blood pressure throught the arterioles?</p>

Answer 13

<p>•Large drop through arterioles (from ~ 90 to 40 mmHg)</p>

<p>– the resistance vessels</p>

Question 14

<p>Why is it good that blood pressure is low when blood reaches the capillaries?</p>

Answer 14

<p>–good, because they are thin-walled</p>

Question 15

<p>What is the small pressure difference pushing blood back through the veins?</p>

Answer 15

<p>•(from ~ 20 to 5 mmHg)</p>

<p>–the systemic filling pressure</p>

Question 16

<p>What is the pulmonary pressure in relation to the systemic pressure?</p>

Answer 16

<p>Pulmonary circulation is 1/5 th of the systemic</p>

Question 17

<p>Where is velocity fastest?</p>

Answer 17

<p>In the aorta and the vena cava - slowest in the capillaries</p>

Question 18

Look

Answer 18

Question 19

<p>Vessels of veins are distensible and collapsable what does this mean?</p>

Answer 19

<p>External influences affect flow</p>

Question 20

<p>Does gravity affect driving pressure from arteries to veins?</p>

Answer 20

<p>NO</p>

Question 21

<p>What is the effect of gravity in venous blood in the leg?</p>

Answer 21

<p>Causes venous distension - Decreased end diastolic volume, decreased preload, decreased stroke volume, decreased cardiac output and decreased mean arterial blood pressure (orthostatic hypotension)</p>

Question 22

<p>What is the effect of gravity in the neck?</p>

Answer 22

<p>Causes venous collapse in the neck - can be used to estimate central venous pressure</p>

Question 23

<p>Where in the body has -20 mmHg?</p>

Answer 23

<p>Head and neck</p>

Question 24

<p>Where in the body is +100 mmHg?</p>

Answer 24

<p>Feet</p>

Question 25

<p>If pressure in the arteries always remains constant what does this mean for the driving force of the blood?</p>

Answer 25

<p>Always remains the same</p>

Question 26

<p>What is the pressure that causes venous collapse?</p>

Answer 26

<p>Pressure of the interstitial fluid</p>

Question 27

<p>What is the purpose of valves?</p>

Answer 27

<p>Ensures directional flow</p>

Question 28

<p>What is the effect of sustained muscle contraction in the legs?</p>

Answer 28

<p>Stops blood flow due to sustain compression of the vein - less venous return (Decreased end diastolic volume, decreased preload, decreased stroke volume, decreased cardiac output and decreased mean arterial blood pressure)</p>

Question 29

<p>What is meant by the respiratory pump?</p>

Answer 29

<p>During inspiration, decreases in intrathoracic pressure draws air into the trachea, bronchi, and lungs and draw blood into the vena cava and right atrium of the heart</p>

Question 30

<p>How do varicose veins arise?</p>

Answer 30

<p>Result from poor valves – more pooling of blood and high pressure in deep veins</p>

Question 31

<p>What is meant by venomotor tone?</p>

Answer 31

<p>State of contraction of the smooth muscle surrounding the venues and veins</p>

<p>- mobilises the capacitance</p>

Question 32

<p>What are all the factors that affect venous pressure and blood flow in veins?</p>

Answer 32

<p>Gravity, skeletal muscle pump, respiratory pump, venomotor tone, systemic filling pressure</p>