LP #107 Factors Affecting BP

Question 1

• increase P in aorta just after ventricular systole
• aorta resists stretch, which maintains increase P
• in BP readings: top value

Answer 1

Systolic P

Question 2

• decrease P in aorta- as it recoils

- in BP reading: bottom value

Answer 2

Diastolic P

Question 3

In healthy adults:

• peak P (systolic P): ~___ _ Hg
• diastolic P: ~ __- __ _ Hg

Answer 3

• 120mm

- 70-80mm

Question 4

*the rhythmical expansion or dilation of the heart and arteries correlative to systole or contraction=

Answer 4

Diastole

Question 5

*contraction of the heart=

Answer 5

Systole

Question 6

Pre-capillary sphincters control=
Smooth m contracts; pre-capillary sphincters close=
Smooth m relaxes; pre-capillary sphincters open=
Capillary BP:~ ___ __ Hg

Answer 6

• BF into capillaries
• Decrease BF into capillary bed (sympathetic)
• increase BF into capillary bed
• 40mm

Question 7

Capillaries have tunica intima only (1 cell thick)=
Decrease BF allows for adequate time for=
From venues, BP is ___ __ Hg

Answer 7

• increase P would rupture capillary
• substance exchange (nutrients & waste)
• 28mm

Question 8

• 10 mm Hg
• no blood pressure
• venous BP changes little during cardiac cycle
• venous BF: very decrease P & opposes gravity

Answer 8

Venous pressure

Question 9

Venous return is driven by alternative means:

Answer 9

1. One-way venous valves
2. Skeletal m pump
3. Respiratory pump

Question 10

• extensions of endothelium

- ensure minimal back flow

Answer 10

One-way venous valves

Question 11

• skeletal mm surround deep vv
• when mm contract: compress vv & moves blood towards heart
• valves prevent backflow when mm relax

Answer 11

Skeletal m pump

Question 12

• inspiration: diaphragm pushes on abdominal viscera
• leads to increase abdominal P & decrease thoracic P
• increase P gradient b/w abdominal & thoracic vv: pushes blood from abdomen to thoracic vv
• as blood returns to heart via vv: pick up metabolic waste (disposed of by lungs & kidneys)

Answer 12

Respiratory pump

Question 13

• volume (ml) of blood pumped out by 1 ventricle w/ each heartbeat
• correlates w/force of ventricular contraction (increase force= increase SV)

Answer 13

Stroke volume (SV)

Question 14

• amount of blood pumped out by both ventricles in 1 minute

* CO is influenced by HR & SV (CO= HR x SV)

Answer 14

Cardiac output (CO)

Question 15

Cardiac output:

• N adults total BVol is=
• an adults total BVol passes through heart each ___

Answer 15

• 5L

- Min

Question 16

• difference in CO at rest & during intense activity

- increase reserve= increase ability to engage in intense physical activity

Answer 16

Cardiac reserve

Question 17

• arterial pulsation- felt at various points in the body
• d/t increase arterial BP
• force of blood ejection from heart & ability of aa to dilate/ recoil
• increase HR & increase CO= faster & stronger pulse
• decrease CO= weak, thready pulse

Answer 17

Pulse pressure

Question 18

Variables affecting BF:

Answer 18

• CO
• PR
• BVol

Question 19

CO= ___ x ___

Answer 19

HR x SV

Question 20

BP is a fxn of?

Answer 20

CO & PR

Question 21

BP is monitored/ maintained at constant levels, ensured by:

Answer 21

• heart (CO)
• bv’s (PR)
• kidneys (vasoconstriction)
• brain (Vasomotor centres)

Question 22

Normally:

• increase CO=
• increase PR=

Answer 22

• decrease PR

- decrease CO

Question 23

Short-term & long-term mechanisms medicate?

Answer 23

BP maintenance

Question 24

Affects distribution- responds to tissue needs by altering bv lumen to maintain arterial P=

Answer 24

Neural control

Question 25

Maintaining BP short-term mechanisms (2)?

Answer 25

Baroreceptor reflexes

Chemoreceptors reflexes

Question 26

• respond to changes in arterial BP
• mediated by stretch receptors in aortic arch & carotid sinuses
• effectively mediate quick changes in BP,ex. D/t postural changes, emotional changes etc.
• do not mediate long-term BP changes

Answer 26

Baroreceptor reflexes

Question 27

• respond to changes in blood pH & other chemicals
• mediated by receptors in aortic arch & carotid sinus
• sensitive to decrease O2 levels, changing pH levels, & increase CO2

Answer 27

Chemoreceptor reflexes

Question 28

Chemoreceptor reflexes role in regulating ventilation (hypothalamus):

Answer 28

• mediate changes in blood distribution
• modify BP (via Vasomotor centre)
• emotional situations (higher brain fxns)

Question 29

Maintaining BP long-term regulation:

Answer 29

• mediated by renal & endocrine mechanisms
• kidneys
• important in maintaining BP
• regulate fluid & electrolyte balance
• affects distribution (vasoconstriction)