Pressures

Question 1

What is arterial blood pressure?

Answer 1

The pressure created by the interaction of blood with vascular wall
Arterial BP = CO x TPR

Question 2

Where is > 50% of TPR?

Answer 2

Systemic arterioles

Question 3

Are arteries recoiled or distended during systole?

Answer 3

Distended-arterial BP increases to a peak

Question 4

Are arteries recoiled or distended during diastole?

Answer 4

Recoiled-maintain perfusion to tissure beds

Question 5

What is happening to total blood volume in the arterial tree during diastole?

Answer 5

Decreasing = arterial BP falls

Question 6

What are the 3 auxillary pumps in the body?

Answer 6

Systole-distension of arteries
Venous pump
Respiratory pump

Question 7

What is hydraulic filtering?

Answer 7

Stretch (systole) and recoil (diastole) of the arterial tree that normally occurs during the cardiac cycle
(Saves heart work)

Question 8

With age, what happens to distensibility, and what is the consequence?

Answer 8

Decreased distensibility of the arterial tree with age = reduced hydraulic filtering = more work load for heart

Question 9

During systole, when does pressure peak?

Answer 9

As blood is ejected from the left ventricle into aorta

Question 10

During systole, is left ventricular output (SV) greater than peripheral runoff?

Answer 10

Yes = increasing arterial pressure

Question 11

What are the 2 factors that determine how low diastolic pressure falls?

Answer 11

Cycle length (inversely proportional to DBP)
Total peripheral resistance (proportional to DBP)

Question 12

Why may diastolic blood pressure not change very much during exercise?

Answer 12

Decreased cycle length is offset by decreased TPR (exercise decreases TPR causing dilation of arterioles, metarterioles, and sphincters)

Question 13

What is mean arterial blood pressure?

Answer 13

The area under the curve, and dividing it into pieces

MAP = 1/3 Pulse pressure + DBP

Question 14

Is mean arterial blood pressure the arithmetical mean between systole and diastole?

Answer 14

NO NO NO NO NO

Question 15

How does the SNS affect blood pressure?

Answer 15

Postganglionics release NE

Receptor is alpha–response is constriction of smooth muscle

Question 16

What happens with constriction of arterioles?

Answer 16

Reduced blood flow and helps raise arterial blood pressure

Question 17

What happens with constriction of arteries?

Answer 17

Raise arterial blood pressure

Question 18

What happens with constriction of veins?

Answer 18

Increases venous return

Question 19

SNS stimulation causes widespread vasoconstriction causing decreased blood flow with what 3 exceptions?

Answer 19

Brain (arterioles weakly innervated by SNS)
Lungs ( “”)
Heart (metabolic demand overrides SNS with vasodilators like adenosine)

Question 20

What is critical closing pressure?

Answer 20

Pressure required to keep arterioles from closing completely as arterial pressure falls
Proportional to vascular tone

Question 21

If cardiac output is stopped, what happens to arterial pressure and venous pressure?

Answer 21

Arterial pressure falls

Venous pressure rises

Question 22

What is mean circulatory filling pressure?

Answer 22

Equilibrium pressure where arterial BP = venous BP

need CO to stop

Question 23

What is mean circulatory filling pressure responsible fore?

Answer 23

pressure gradient driving peripheral venous return

Question 24

What may prevent equilibration pressure?

Answer 24

Closure of arterioles (critical closing pressure)

Question 25

At a given mean circulatory filling pressure (MCFP), as central venous pressure (CVP) increases, what happens to venous return?

Answer 25

Decreases

Question 26

If mean circulatory filling pressure (MCFP) = central venous pressure (CVP), what happens to venous return?

Answer 26

Goes to 0 (CO also goes to 0 because VR = CO)

Question 27

What is at the point of intersection of a vascular function curve and a cardiac function curve?

Answer 27

The point where we live physiologically--where CO = VR

Question 28

As central venous pressure (CVP) increases, cardiac output increases due to what?

Answer 28

Intrinsic and extrinsic effects

Question 29

What is central venous pressure?

Answer 29

The pressure in the central veins (superior and inferior vena cava) at the entry into the right atrium (right atrial pressure)

Question 30

Where is the vasomotor center?

Answer 30

Collection of neurons in the medulla and pons

Question 31

What are the 4 major regions in the vasomotor center?

Answer 31

Pressor center-increases blood pressure Depressor center-decreases blood pressure Sensory area-mediates baroreceptor reflex Cardioinhibitory area-stimulates CN X

Question 32

Where is the pressor (vasoconstrictor "C1") center in the vasomotor center?

Answer 32

Anterolateral portions of upper medulla | NE projections to intermediolateral horn (IML) cells

Question 33

What are the effects of the pressor (vasoconstrictor) center?

Answer 33

Vasoconstriction Stimulate cardiac activity Tonically active exciting SNS outflow

Question 34

Where is the depressor (vasodilator area "A1") center in the vasomotor center?

Answer 34

Anterolateral lower medulla oblongata

Question 35

What are the effects of the depressor (vasodilator) center?

Answer 35

Vasodilation | Decreased cardiac activity

Question 36

Where is the sensory area "A2" of the vasomotor center?

Answer 36

Posterolateral portions of pons and medulla in nucleus tractus solitarius

Question 37

Where does the sensory area recieve input from?

Answer 37

CN IX & X

Question 38

Where does the sensory area send output to?

Answer 38

Pressor and depressor centers

Question 39

What are the effects of the sensory area of the vasomotor center?

Answer 39

Mediates baroreceptor reflex - Inhibits pressor center - Lowers blood pressure

Question 40

Where is the cardioinhibitory area of the vasomotor center?

Answer 40

Medially next to dorsal motor nucleus of vagus (DMNV)

Question 41

What are the effects of the cardioinhibitory area of the vasomotor center?

Answer 41

Transmits impulses into the dorsal nucleus of vagus (DMNV) inhibiting heart activity

Question 42

What does sympathetic vasoconstrictor tone do and where does it receive input from?

Answer 42

Maintains normal arterial blood pressure | Due to pressor center input