1. Ch. 19 The Cardiovascular System: Blood Vessels

2. I. OVERVIEW OF BLOOD VESSEL STRUCTURE AND FUNCTION
Arteries and arterioles:
Capillaries
Veins and Venules

3. A. Structure of Blood Vessel Walls– 3 layers1.
Tunica intima
• Endothelium
Valve
• Subendothelial layer
Internal elastic lamina 2.
Tunica media
(smooth muscle and
elastic fibers)
External elastic lamina 3.
Tunica externa
(collagen fibers)
Vasa Vasorum
Lumen
Vein
Lumen
Artery
Capillary
network
Basement membrane
Vasodilation & Vasoconstriction
Endothelial cells
(b)
Capillary
Figure 19.1b

4. * a) Endothelium & Basement membrane Function: In veins:
1. Tunica Intima =
* a) Endothelium & Basement membrane
Function:
In veins:
* b) Areolar C.T w/ mostly elastic fibers
c) Internal Elastic Lamina (membrane) =
Type of vessels:
Artery
Vein

5. Thickest layer in arteries * a) smooth muscle:
2. Tunica Media =
Thickest layer in arteries
* a) smooth muscle:
* b) Connective tissue:
Appear wavy
c) External Elastic Lamina =
Vessels: only large arteries
Location: between T.M. & T.E.
3. Tunica Externa (adventitia) =
Thickest layer in veins
Outer boarder unclear
Artery
Vein

6. B. Arterial System Elasticity = Compliance 1. Elastic Artery
Resistance to Flow:
Pressure:
2. Muscular Artery
Smooth muscle:
Lumen diameter:
3. Arteriole
Number & Size:
resistance to flow:
Flow to capillaries: controlled by

7. 4. Vascular Anastomoses =
Arterial anastomoses =
Organs: Joints, abdominal organs, brain, and heart
Venous anastomoses = very common
BRAIN: Arterial Anastomoses =
Circle of Willis
- Internal Carotid & Vertebral Arteries

8. C. Capillaries 5-10 µm diameter
Basic Structure
Endothelium:
Some scattered smooth muscle
Function:
Three Types
Continuous capillaries =
Prevalence:
tight junctions:
Brain:

9. 2. Fenestrated capillaries Tight Junctions: Fenestrations Locations:
C. Capillaries …
2. Fenestrated capillaries
Tight Junctions:
Fenestrations
Locations:
3. Sinusoidal capillaries (sinusoids)
Flattened
Leakiest:
Pass large molecules and blood cells

10. 4. Capillary Beds
a) Metarteriole & Thourghfare Channel = Vascular Shunt
Location:
Attach Capillary beds attached ( capillaries)
b) Precapillary Spincters =
Normally closed, but open to allow O2 & nutrients
c) Function:
Thoroughfare Channel
Metarteriole
Figure 11.11a

11. Bypassed Capillary Beds
Figure 11.11b

12. D. Venous System 1. Venules 2. Veins Overall size & Lumen size:
Pressure is?
Thin walls
Capacitance Vessels: blood reservoirs
Venous Valves: foldsn in largest V
Function:
Venous Sinuses: flattened with only endothelium

13. C. Venous System … - Differences Between Vessels

14. II. PHYSIOLOGY OF CIRCULATION
TISSUES NEED ADEQUATE BLOOD– O2, CO2 NUTRIENTS… GET RID OF WASTES
Heart gets blood into Vessels, then
Vessels take over getting blood to cells
REVIEW OF CH.18
CO = SV x HR
SV = EDV - ESV
Stroke Volume Regulation- normal regulation (baroreceptors)
- Preload: Venous Return
- Contractility– Autonomic N.S. & Hormones
- Afterload– Blood Pressure
Heart Rate Regulation - Stress, Emergency, Exercise,
- Autonomic N.S. (Sympathetic Nervous System)
- Hormones
Interrelated

15. II. PHYSIOLOGY OF CIRCULATION …
A. Introduction to Blood Flow, Blood Pressure, and Resistance
1. Definition of Terms
Blood flow (F) =
if ALL blood vessels, then:
Varies with organ’s needs
Blood pressure (BP) =
Blood moves High  Low
Depends on:
Resistance NEXT SLIDE 
F = P/R

16. F = P/R Resistance Arterioles mostly Depends on: Blood Viscosity
1. Definition of Terms …
Resistance
Arterioles mostly
Depends on:
Blood Viscosity
Blood Vessel Diameter
Blood Vessel Length
Relationship between Flow, Pressure, and Resistace
 = Change in
Velocity volume
F = P/R
Arteries Capillaries Veins

17. B. Systemic Blood Pressure
1. Arterial Blood Pressure:
Elastic Arteries attached to heart: BP in elastic A. > _________ > _______ > _____________
Pulse Pressure: throbbing pulsation =
Varies
93mm = MAP
Mean Arterial Pressure: MAP = diastole + 1/3 pulse pressure
Accuracy:
Diastole is longer than systole

18. 1. Arterial Blood Pressure …
Arterioles: many & small
Steepest P drop, loose pulse
2. Capillary Blood Pressure = 35 – 15mm Hg
Venous Blood Pressure = 15mm to 0mm Hg (entering right atrium)
Respiratory Pump
Muscular Pump
C. Maintaining Blood
Pressure
REVIEW OF
CARDIAC OUTPUT

19. C. Maintaining Blood Pressure OVERVIEW:
∆P = CO X R
Interaction between heart and Blood Vessels
1. SHORT-TERM
Autonomic N.S. (EXTRINSIC)
Via Baroreceptors  Vasomotor & Cardiac Centers
Via Chemoreceptors  “ “ “
HORMONAL (EXTRINSIC)
Sym.  Adrenal Medulla: Epinephrine and NE
Kidney: Renin  Angiotensin II
Heart: Atria Natriuretic Peptide
2. LONG-TERM-- KIDNEY
DIRECT: amount of urine produced (INTRINSIC)
INDIRECT (EXTRINSIC)
Renin  Angiotensin  Aldosterone
 ADH
 thirst
3. BLOOD VESSELS OF A PARTICULAR ORGAN

20. C. Maintaining Blood Pressure … INTRODUCTION
Focus: by altering PERIPHERAL RESISTANCE And BLOOD VOLUME
Organs Involved: Heart, Blood Vessels, Kidneys
Entire circulation: Blood Flow (F) = CO = ∆P/ R
and rearrange to ∆P = CO X R
Also from before: CO = SV x HR
Homeostasis: factors affecting CO interact with those affecting Mean Arterial Pressure– if one variable changes blood pressure is compensated by changes in other variables
 Regulation of Heart functions and Blood Vessels interrelated

21. C. Maintaining Blood Pressure … Mechanisms
Mechanisms OVERVIEW:
Short-term: Normal Regulation via autonomic Ns and Hormoes
Long-term: via mostly kidneys in unhealthy, emergency states.

22. Maintaining Blood Pressure …
∆P = CO X R
1. Short-term–Neural Controls: Affect Resistance by
a. Purpose:
i) Maintain Mean Arterial Pressure (MAP)
altering vessel diameter to change R
ii) Specific organ demands
altering blood distribution via diameter
changes & vascular shunts
Mechanism–Cardivascular Center = Vasomotor (Sym), Cardioinhibitory (Para), Cardioacceleratory (Sym) of Medulla:
Vasomotor Center fibers (Sympathetic)
Vasomotor Tone:
For dialation of vessels, must inhibit this center

23. ii) Baroreceptor-Initiated Reflexes Location: in Carotid Sinus
Short Term Neural Controls … Mechanism … b) Baroreceptors and Vasomotor Center …
∆P = CO X R
ii) Baroreceptor-Initiated Reflexes
Location: in Carotid Sinus
(Internal Carotid A) & Aortic Arch
If BP increases ↑ stretch of Baroreceptors 
Vasomotor Center: ______  vasodialation & ↓ BP
Cardioaceleratory ________
Cardioinhibitory __________
If BP decreases  _____ stretch of Baroreceptors
_______ Vasomotor Center  _______________
_______ Cardioacceloratory Center __________
_______ Cardioinhibitory Center _________
In Long-term. Problem = Baro. Adapt to higher pressures
↓ Heart Rate + Contractile Force

24. Maintaining Blood Pressure … Short-term Neural Controls …
∆P = CO X R
c. Chemoreceptor-Initiated Reflexes: for O2, CO2, & H+
i) Location: carotid & aortic bodies (Internal carotid artery + aortic arch)
ii) Stimulus: ↑ CO2, ↑ H+ (↓pH), ↓ O2,  SAME AS IF BLOOD PRESSURE IS LOW
Cardioacceleratory Center: __________
 ↑ HR & contractility
Cardioinhibitory Center: _________
Vasomotor Center: ___________
↑ vasoconstriction
Same control loop stimulated

25. 2. Short-Term Mechanisms: Hormonal Controls
Alter v. diameter
i) Adrenal Medula Hormones– During Stress: need ↑ BP and CO
Norepinephrine (NE)  mostly vessels
Epinephrine  mostly Heart
But, Vasodialation in skeletal & cardiac muscle
Kidneys release Renin: (Mostly Long- term Regulation) When BP or blood volume Low: kidneys releases renin Angiotensin II
 intense vasoconstriction
∆P = CO X R
Vasoconstrictors

26. 2. Short-Term Mechanisms: Hormonal Controls …
iii) Atria of Heart release ANP– When BP increases: stretches Atria  Atrial natriuretic peptide (ANP)
targets kidney  excrete ↑ sodium  water follows  ↓blood pressure
Inhibits renin & aldosterone release  vasodialation
iv) Antidiuretic hormone (ADH, vasopressin) =
Kidney tubules: reabsorb H2O
intense vasoconstriction in cases of extremely low BP
∆P = CO X R

27. Control of Blood Pressure … 3. Long-Term Mechanisms: Renal Regulation
Via changing: BLOOD VOLUME
a. Direct (intrinsic) independent of hormones
↑ BP in renal arteries  more urine  less blood volume  ↓ BP
b. Indirect (extrinsic) renin-angiotensin mechanism (Same as Short term mechanism)
 Angiotensin II:
↑ Aldosterone: reabsorbs Na+
↑ ADH: reabsorbs H2O
↑ Thirst via Hypothalamus
∆P = CO X R
Figure 19.10

28. OVERVIEW: Systemic BP Regulation
∆P = CO X R
Interaction between heart and Blood Vessels
1. SHORT-TERM
Autonomic N.S. (EXTRINSIC)
Via Baroreceptors  Vasomotor & Cardiac Centers
Via Chemoreceptors  “ “ “
HORMONAL (EXTRINSIC)
Sym.  Adrenal Medulla: Epinephrine and NE
Kidney: Renin  Angiotensin II
Heart: Atria Natriuretic Peptide
2. LONG-TERM-- KIDNEY
DIRECT: amount of urine produced (INTRINSIC)
INDIRECT (EXTRINSIC)
Renin  Angiotensin  Aldosterone
 ADH
 thirst
3. BLOOD VESSELS OF A PARTICULAR ORGAN

29. OVERVIEW: Control of Cardiac Output
REGULATING STROKE VOLUME
Preload (INTRINSIC)
Venous Return
Heart Rate
Contractility (EXTRINSIC)
Autonomic N.S via Baroreceptors  Cardiac Centers
Hormones: epinephrine & Thyroxin & Glucagon H+
Afterload– blood pressure
REGULATION OF HEART RATE (EXTRINSIC)
- Stressful Situations  Sympathetic Reflexes
Autonomic N.S.
Hormones: Epinephrine & Thyroxin
CO = SV x HR

30. III. Blood Flow Through Body Tissues
A. Blood Flow to particular tissues
Capillaries have greatest affect
Independent of MAP (systemic pressure)
Flow = ∆P X R
To specific Organs: Flow is right for proper function
B. Autoregulation INTRINSIC
Modifies via diameter of arterioles
Mechanisms next slide
Brain
Heart
Skeletal
muscles
Skin
Kidney
Abdomen
Other
Total blood
flow at rest
5800 ml/min
Total blood flow during strenuous
exercise 17,500 ml/min

31. Metabolic: INTRINSIC To ↑ Flow to Active Tissues
B. Autoregulation …
Metabolic: INTRINSIC To ↑ Flow to Active Tissues
Active Tissues: have increased CO2, H+, NO
trigger dilation
Precapillary Spincters open
Inflammatory chemicals (tissue damage)  dilation
2. Myogenic: INTRINSIC To protect against inadequate perfusion and high of pressure that would rupture vessels
↑ Pressure ↑stretch  damage to small vessels: so compensate by constricting to reduce flow to organ
↓ Pressure ↓stretch  tissue not adequately oxygenated: so compensate by dilating
Long-term Regulation
Angiogenesis: ↑ blood vessels

32. C. Blood Flow in Specia Areas
1. Blood Flow: Lungs
Pulmonary circuit is short and Arteries/arterioles structurally like veins/venules
Arterial resistance and pressure are low (24/8 mmHg)
Autoregulation opposite of most tissues at capillaries
Low O2 levels = blocked/damaged air sacs  bypass with vasoconstriction;
High O2 levels means that air sacs are functional, so send blood to them  dilation

33. D. Blood Flow Through Body/Tissue Capillaries and Capillary Dynamic
1. Capillary Exchange of Respiratory Gases and Nutrients– how they get from blood to tissues
Gases Diffusion of O2 and CO2
TO TISSUES:
FROM TISSUES:
a. Lipid-soluble molecules diffuse directly through membranes
b & c. Water-soluble solutes pass through clefts/fenestrations
d Larger molecules, such as proteins, actively transported
SEE NEXT SLIDE FOR DIAGRAM

34. Caveolae Pinocytotic vesicles Intercellular cleft Endothelial
fenestration
(pore) 4
d. Transport
via vesicles or
caveolae (large
substances) 3
c. Movement
through
fenestrations
(water-soluble
substances)
Basement
membrane 2
b. Movement
through intercellular
clefts (water-soluble
substances)
a. Diffusion
through
membrane
(lipid-soluble
substances) a

35. High Pressure End
Low Pressure End

36. Arterial End—Hydrostatic Pressure dominates:
2. Fluid Movement: Bulk Flow maintains fluid balance b/n blood and tissues
At Capillaries, movement of water depends on opposing forces: hydrostatic and colloid osmotic pressures
Arterial End—Hydrostatic Pressure dominates:
HPc=capillary blood pressure greater than
HPif=interstitial pressure
So Fluid is forced out of capillaries
NFP at Arterial End = 10 mmHg = net outward pressure

37. At Venule End: Osmotic Pressure dominates
OPc=capillary osmotic pressure at venule end is high because solute concentration of plasma is > that of Interstitial fluid (OPif)) due to blood proteins (albumins …) which stay in blood and do not filter out.
So H2O moves from high concentration in interstitial fluid to blood
NFP at Venule End = --8 mmHg = net inward pressure

38. NFP at Arterial End = 10 mmHg = net outward pressure
NFP at Venule End = --8 mmHg = net inward pressure
“--” means osmosis moves water into capillaries at venule end

39. IV Disorders of the Blood Vessels
Students Do Following:
Atherosclerosis
Types of Circulatory Shock
Hypo- and Hypertension

40. PART 3 CIRCULATORY PATHWAYS: BLOOD VESSELS OF THE BODY
Two Main Circulations
V. Systemic Arteries & Veins
Arteries: Left Ventricle  AORTA
Arch
Thoracic Aorta
Abdominal Aorta
Pelvic Cavity: Common Iliac Arteries
Figure 11.12

41. Veins: entering Right Atrium
V. Systemic … …
Veins: entering Right Atrium
Superior Vena Cava
- Circle of Willis (a.k.a. cerebral arterial circle) keeps blood flowing to brain
Figure 11.13

42. 2. Inferior Vena Cava
a) Digestive organ Veins do not directly take blood back to Inferior Vena Cava, but to Liver: food eaten may have toxins in it, so must be processed by Liver before toxins are spread to the rest of the body

43. b. Hepatic Portal System Digestive Organ Capillaries drain into
Veins: entering Right Atrium …
2. Inferior Vena Cava
b. Hepatic Portal System
Digestive Organ Capillaries drain into
 Digestive Organ Veins: Superior & Inferior Mesenteric and Splenic
Do not directly empty into the Inferior Vena Cava
Hepatic Portal Vein  drains into
 Liver Sinusoids for processing of digested food
Hepatic Veins then take processed blood
 Inferior Vena Cava
Figure 11.13

44. b. Hepatic Portal System …
Digestive Arteries  Digestive Capillaries  Digestive veins
 Hepatic Portal V.  Liver sinusoids  Hepatic Veins
 Inferior Vena Cava  Right Atrium

45. 2. Superior Vena Cava - Circle of Willis (a. k. a
2. Superior Vena Cava - Circle of Willis (a.k.a. cerebral arterial circle)
The Internal Carotid Arteries form an Anastomosis with the Vertebral Arteries to keep blood flowing to brain
Result—blood moves to brain despite damage to internal carotid or vertebral arteries

46. VI. Pulmonary Arteries & Veins
Arteries– Pulmonary Trunk from Right Ventricle
Left and Right Pulmonary Arteries
B. Veins– 4 Pulmonary Veins enter Left Atrium

47. END PPT
Review Questions
Extra Slides

48. precapillary sphincters
Review Questions
What type of capillaries are found in the liver and bone marrow?
What type of vessel maintains the lowest pressure and highest blood volume?
One mechanism of blood flow control through capillary beds is via __________ ___________ that can bypass beds by routing blood through vascular shunts.
Sinusoid
Veins
precapillary sphincters

49. Review Questions
Alternative routs for blood flow that develop from interconnecting vessels are known as _____________.
What type of vessel provides the major source of resistance to blood flow?
Blood pressure depends on what 3 major variables?
anastomoses
Arterioles
CO, R, and Blood Volume

50. Baroreceptors and Chemoreceptors
Review Questions
Short term neural control of BP is controlled by reflex arcs involving what types of receptors?
________ is the only hormone that reduces blood volume and is produced by the __________
Which short term hormonal control is initiated by renin release from the kidneys?
Baroreceptors and Chemoreceptors
ANP
heart
Angiotensin II

51. CO, Resistance, and Blood Volume Blood Volume – which is regulated by?
Review Questions …
Blood pressure depends on what 3 major variables?
Short term control of BP is regulated by which of the above?
Long term control is regulated by changing which variable?
CO, Resistance, and Blood Volume
Resistance (and CO)
Blood Volume – which is regulated by?

52. Via intercellular clefts or fenestrations
Participate
Localized adjustments made to ensure blood flow according to tissue needs = __________________
_________ autoregulation occurs when arterioles are stretched if systemic BP increases
How do water soluble solutes pass through capillary walls?
autoregulation
Myogenic
Via intercellular clefts or fenestrations

53. Net Filtration Pressure
Review Questions
What does NFP stand for?
When net hydrostatic pressure (HP) is less than net osmotic pressure (OP), which way do fluids flow?
What vein delivers blood TO the liver?
Net Filtration Pressure
Into capillaries
Hepatic portal vein