objective 4

Question 1

what are the 2 main neural mechanisms control peripheral resistance?

Answer 1

MAP is maintained by altering blood vessel
diameter, which alters resistance
– Example: If blood volume drops, all vessels constrict (except those to
heart and brain)
2. Can alter blood distribution to organs in
response to specific demands
– Example: during exercise blood is shunted temporarily from
digestive organs to skeletal muscles.

Question 2

what do neural controls operate via reflex arcs that involve what?

Answer 2

Cardiovascular center (medulla)
◦ Baroreceptors (changes in pressure)
◦ Chemoreceptors (changes in chemical messengers)
◦ Higher brain centers (hypothalamus)

Question 3

composed of sympathetic neurons in medulla

Answer 3

cardiovascular center

Question 4

cardioinhibitory and cardioacceleratory
centers

Answer 4

cardiac centers

Question 5

cause continuous moderate constriction called vasomotor tone

Answer 5

vasomotor center

Question 6

what happens if MAP is high?

Answer 6

Increased blood pressure stimulates baroreceptors to
increase input to vasomotor center
– Inhibits vasomotor and cardio-acceleratory centers
– Stimulates cardio-inhibitory center
– Results in decreased blood pressure

Question 7

what are the 2 mechanisms that result in decrease in BP?

Answer 7

vasodilation
decreased cardiac output

Question 8

Decreased output form vasomotor center causes
dilation

Answer 8

vasodilation

Question 9

reduces peripheral
resistance, MAP falls

Answer 9

arteriolar vasodilation

Question 10

shifts blood to venous reservoirs, decreasing
venous return and CO

Answer 10

venodilation

Question 11

impulses to cardiac
centers inhibit sympathetic activity and stimulate
parasympathetic
Reduces heart rate and contractility; CO decrease causes
decrease in MAP

Answer 11

decreased cardiac output

Question 12

what happens if MAP is low?

Answer 12

vasoconstriction is initiated that increases CO and
blood pressure
– baroreceptors that monitor BP to ensure enough blood to brain
– maintains BP in systemic circuit
– Baroreceptors are ineffective if altered blood pressure
is sustained (i.e chronic HTN)
– Become adapted to hypertension, so not triggered by
elevated BP levels

Question 13

Aortic arch and large arteries of neck detect
increase in CO 2 , or drop in pH or O2

Answer 13

chemoreceptor reflexes

Question 14

how does chemoreceptor reflexes increase BP?

Answer 14

Signaling cardio-acceleratory center to increase
Cardiac output
– Signaling vasomotor center to increase
vasoconstriction ( so more resistance)
– This causes increase in BP that speeds return of blood
to heart and lungs

Question 15

Reflexes that regulate BP are found in medulla
oblongata
◦ Hypothalamus and cerebral cortex are not involved
in routine control of BP
◦ Hypothalamus increases blood pressure during
stress
◦ Hypothalamus mediates redistribution of blood flow
during exercise and changes in body temperature
◦ Allows modification of neural controls of BP

Answer 15

influence of higher brain centers

Question 16

how do hormones regulate BP?

Answer 16

short-term via changes in peripheral resistance
◦ long-term via changes in blood volume

Question 17

increase CO and vasoconstriction

Answer 17

Epinephrine and norepinephrine

Question 18

stimulates vasoconstriction

Answer 18

Angiotensin II

Question 19

cause vasoconstriction

Answer 19

ADH

Question 20

causes vasodilation
and promotes a decline in blood volume and
therefore BP

Answer 20

atrial natriuretic peptide

Question 21

how do kidneys regulate arterial BP?

Answer 21

Direct renal mechanism
2. Indirect renal mechanism (renin-angiotensin-
aldosterone)

Question 22

Alters blood volume independently of hormones
– Increased BP or blood volume causes elimination of
more urine, therefore reducing blood volume, thus
reducing BP
– Decreased BP or blood volume causes kidneys to retain
more water, increasing blood volume and BP rises

Answer 22

direct renal mechanism

Question 23

The renin-angiotensin-aldosterone mechanism:
– Decreased blood pressure causes release of renin from
kidneys
– Triggers formation of angiotensin II

Answer 23

indirect mechanism

Question 24

what do angiotensin II cause?

Answer 24

Release of aldosterone stimulating salt and water retention
– Vasoconstriction
– Release of ADH
– Thirst
– * all of these will lead to increased blood volume and BP

Question 25

Determines the distribution of fluids between the bloodstream and
the interstitial space
} Fluid flows out capillary bed at arteriolar end and re-enters the
capillary blood at the venous end
– Extremely important in determining relative fluid volumes in
blood and interstitial space
} Bulk fluid flows across capillary walls causes continuous mixing of
fluid between plasma and interstitial fluid; maintains interstitial
environment

Answer 25

bulk flow

Question 26

what does direction and amount of fluid flow depend on?

Answer 26

Hydrostatic pressure
– Colloid osmotic pressure

Question 27

force exerted by blood
pressing against vessel wall/chamber
◦ Primary source driving fluid transport

Answer 27

hydrostatic pressure

Question 28

BP in capillaries that forces
fluids through capillary walls; greater at arterial end

Answer 28

capillary hydrostatic pressure

Question 29

pressure pushing
fluid back into vessel; usually aim to be 0 as lymphatic
vessels drain interstitial fluid

Answer 29

interstitial fluid hydrostatic pressure

Question 30

sucking pressure created by
non-diffusible plasma proteins pulling water back into capillary

Answer 30

capillary colloid osmotic pressure

Question 31

opposes hydrostatic pressure

Answer 31

colloid osmotic pressures

Question 32

pressure is
inconsequential because interstitial fluid has very low protein
content

Answer 32

interstitial fluid colloid osmotic pressure

Question 33

Net filtration pressure (NFP) comprises all forces acting on
capillary bed
◦ Net fluid flow out at arterial end
◦ Net fluid flow in at venous end
◦ More fluid leaves at arterial end than is returned at venous end
◦ Excess interstitial fluid is returned to blood via lymphatic
system

Answer 33

hydrostatic-osmotic pressure interactions

Question 34

runs from heart to lungs and
back to heart

Answer 34

pulmonary circulation

Question 35

to all parts of body and back
to heart

Answer 35

systemic circulation

Question 36

share same name with corresponding artery

Answer 36

deep veins

Question 37

do not correspond to names of any arteries

Answer 37

superficial veins

Question 38

Veins can have more than one name, making venous
pathways harder to follow

Answer 38

venous pathways are more interconnected

Question 39

contains dural venous sinuses

Answer 39

brain

Question 40

drains into hepatic portal system, which perfuses through liver
before returning to heart

Answer 40

venous system of the digestive system

Question 41

runs behind and to right of pulmonary
trunk before becoming the aortic arch

Answer 41

ascending aorta

Question 42

branches of ascending aorta that
supply the mediastinum

Answer 42

Rt. & Lt coronary arteries

Question 43

deep to sternum. Has 3 branches that provide
arterial supply to head, neck, upper limbs, and part of
thorax:

Answer 43

aortic arch

Question 44

runs along anterior spine. Called thoracic
aorta from T5 – T12. Supplies the thorax and viscera, it enters
the abdominal cavity to become the abdominal aorta.

Answer 44

descending aorta

Question 45

supplies abdominal walls and ends at L4
where it splits into Rt. & Lt. common iliac arteries

Answer 45

abdominal aorta

Question 46

supply pelvis and lower limbs

Answer 46

Rt. and Lt common iliac arteries