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Chapter 21. Blood Vessels and Circulation. Blood Pressure and Cardiovascular regulation Exercise. arteries arterioles capillaries venules veins. carry blood away from heart thicker walls (smooth muscle) branch and get narrower bifurcation (tri-, rami-) smallest vessels

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Presentation Transcript
slide1

Chapter 21

Blood Vessels

and Circulation

slide2

Blood Pressure and

Cardiovascular regulation

Exercise

slide3

arteries

arterioles

capillaries

venules

veins

carry blood away from heart

thicker walls (smooth muscle)

branch and get narrower

bifurcation (tri-, rami-)

smallest vessels

in networks (beds)

exchange with ECF

carry blood back to heart

thinner walls

small v. join to form larger veins

anastomosis

slide4

blood circuit

fig. 21-8

slide5

100 keys (pg. 725)

“It is blood flow that’s the goal, and total peripheral blood flow is equal to cardiac output. Blood pressure is needed to overcome friction and elastic forces and sustain blood flow. If blood pressure is too low, vessels collapse, blood flow stops, and tissue die; if blood pressure is too high, vessel walls stiffen and capillary beds may rupture.”

slide6

100 keys (pg. 732)

“Cardiac output cannot increase indefinitely, and blood flow to active versus inactive tissues must be differentially controlled. This is accomplished by a combination of autoregulation, neural regulation and hormone release.”

slide7

Controlling CO and bp

Autoregulation of blood flow

Neural mechanisms

Hormonal mechanisms

*

*

slide8

CO = HR x SV

neural mechanisms

(reflex control of

cardiovascular function)

slide9

Neural mechanisms

Reflex control of

cardiovascular function

baroreceptors

blood pressure

chemoreceptors

pH, [gases]

negative feedback loops

slide10

Neural mechanisms

Reflex control of

cardiovascular function

baroreceptors

monitor degree of stretch in walls of expandable organs

carotid sinuses

aortic sinuses

atrium

slide11

baroreceptors

if blood pressure climbs

  • decrease cardiac output
      • lower HR (ACh SA)
  • vasodilation
  • lowers peripheral resistance

reflex:

reduce blood pressure

slide12

baroreceptors

if blood pressure falls

  • increase cardiac output
      • NE on heart
  • vasoconstriction
  • NE inc. peri. resistance

reflex:

increase blood pressure

slide13

baroreceptors

atrial reflex

stretching the atrium

(more blood returning)

will stimulate cardiac output

(more blood leaving)

slide14

baroreceptors

Valsalva maneuver

exhale forcefully

close glottis

slide15

baroreceptors

Valsalva maneuver

brief rise in bp

pressure on lungs sends pulmonary blood to atria

bp falls

reduced venous return

low CO

reflexive vasoconstriction

increase in heart rate

slide16

baroreceptors

Valsalva maneuver

  • release pressure

expansion of vessels (bp6)

(6return, 5aortic volume)

4. restore normal

blood return up

CO is up

BP is up

slide17

graph of

bp drop and

HR increase

during Valsalva

slide20

Neural mechanisms

Reflex control of

cardiovascular function

baroreceptors

chemoreceptors

slide21

Neural mechanisms

chemoreceptors

monitor pH (H+)

[CO2]

[O2]

of blood and CSF

sensory neurons in: carotid body

aortic bodies

(med. oblong.)

slide22

Neural mechanisms

chemoreceptors

pH drops (H+5)

or 5[CO2]

or 6[O2]

reflex stimulation of cardio-

acceleratory centers (sym)

stimulate vasomotor

(vasoconstriction)

slide23

Neural mechanisms

chemoreceptors

pH drops (H+5)

or 5[CO2]

or 6[O2]

increase cardiac output

peripheral vasoconstriction

increase bp

slide24

Neural mechanisms

chemoreceptors

pH drops (H+5)

or 5[CO2]

or 6[O2]

receptors in medulla obl.

stimulate respiratory centers

more O2

and more venous return

slide25

Neural mechanisms

chemoreceptors

pH drops (H+5)

or 5[CO2]

or 6[O2]

increased bp and resp.

more O2 to cells

slide27

CO = HR x SV

hormonal control

neural mechanisms

NE, E

ADH

angiotensin II

EPO

natriuretic peptides

all regulate

blood volume

slide28

ADH

Antidiuretic hormone

made in hypothalamus

released from posterior pituitary gland

in response to 6 blood volume

vasoconstriction (5bp)

H2O recovery in kidney

slide29

angiotensin II

fall in bp

renin release from kidney

angiotensinogen (from liver)

angiotensin I

angiotensin II

renin

ACE

slide30

angiotensin II

four functions:

stimulates kidney to

produce aldosterone

stimulates secretion of ADH

stimulates thirst

stimulates CO and vasconstriction

(bp)

slide31

EPO

erythropoietin

released from kidneys

low bp

low O2 levels

stimulates bone marrow to make more RBC’s

slide32

natriuretic peptides

natrium = sodium (Na)

atrial natriuretic peptide (ANP)

brain natriuretic peptide (BNP)

released in response to stretching

reduce blood volume

reduce blood pressure

slide33

natriuretic peptides

increase Na+ excretion at kidney

increase volume of urine produced

reduce thirst

block ADH, NE, E, aldosterone release

stimulate peripheral vasodilation

reduce blood volume

and blood pressure

slide36

100 keys (pg. 732)

“Cardiac output cannot increase indefinitely, and blood flow to active versus inactive tissues must be differentially controlled. This is accomplished by a combination of autoregulation, neural regulation and hormone release.”

slide38

Summary

hormones

venous return

filling time

venous return

preload

contractility

afterload

Heart rate

EDV

ESV

SV = EDV-ESV

CO = HR x SV

slide39

Exercise

light

slight sympathetic innervation

slight increase in HR

vasodilation

get blood to tissues

resistance drops

more blood flows

slide40

Exercise

light

increase in venous return

muscle pumps

slide41

muscle activity

venous return

fig. 21-6

slide42

Exercise

light

increase in venous return

muscle pumps

increase respiratory pump

cardiac output increases

due to higher venous return

slide43

Exercise

heavy

more sympathetic stimulation

vasocontriction to “non-essentials”

(most internal organs except brain)

blood

lungs

skeletal

muscle

- heart -

- heart -

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