This document provides an outline and overview of the cardiovascular system, including blood flow, blood pressure, vasculature, arteries, capillaries, veins, and lymphatic circulation. It discusses the physical laws governing blood flow and pressure, factors that influence resistance and peripheral resistance. It also examines the regulation of blood flow and pressure through intrinsic controls like metabolic activity and stretch of arteries as well as extrinsic controls like neural and hormonal mechanisms. The goal is to explain how blood is circulated and pressure is maintained through the complex cardiovascular system.

1. Cardiovascular system: Blood
vessels, blood flow, blood pressure

2. Outline
• 1- Physical laws governing blood flow and blood
pressure
• 2- Overview of vasculature
• 3- Arteries
• 4. Capillaries and venules
• 5. Veins
• 6. Lymphatic circulation
• 7. Mean arterial pressure and its regulation
• 8. Other cardiovascular regulatory processes

3. Outline
• 1- Physical laws governing blood flow and blood
pressure
• 2- Overview of vasculature
• 3- Arteries
• 4. Capillaries and venules
• 5. Veins
• 6. Lymphatic circulation
• 7. Mean arterial pressure and its regulation
• 8. Other cardiovascular regulatory processes

4. Physical laws governing blood flow and blood
pressure
• Flow of blood through out
body = pressure gradient
within vessels X
resistance to flow
- Pressure gradient: aortic
pressure – central venous
pressure
- Resistance:
-- vessel radius
-- vessel length
-- blood viscosity

5. Factors promoting total peripheral resistance
(TPR)
• Total peripheral
resistance = TPR
-- combined resistance of
all vessels
-- vasodilation 
resistance decreases
-- vasoconstriction 
resistance increases

6. Outline
• 1- Physical laws governing blood flow and blood
pressure
• 2- Overview of vasculature
• 3- Arteries
• 4. Capillaries and venules
• 5. Veins
• 6. Lymphatic circulation
• 7. Mean arterial pressure and its regulation
• 8. Other cardiovascular regulatory processes

7. Vasculature

8. Arteries and blood pressure
• Pressure reservoir
• Arterial walls are able to
expand and recoil
because of the pressure
of elastic fibers in the
arterial wall
• Systolic pressure:
maximum pressure
occurring during systole
• Diastolic pressure:
pressure during diastole

9. Arterial blood pressure
Figure 14.8

10. Blood pressure values: what do they mean?
• Pulse pressure:
PP = SP-DP
• Mean arterial blood
pressure = MABP
• MABP = SBP + (2XDBP)
3
CO = MABP = SV x HR
TPR

11. • Blood flow within each organ
changes with body activities
• Reminder: The ANS controls
blood flow to the various organs
Figure 14.15

12. Outline
• 1- Physical laws governing blood flow and blood
pressure
• 2- Overview of vasculature
• 3- Arteries
• 4. Capillaries and venules
• 5. Veins
• 6. Lymphatic circulation
• 7. Mean arterial pressure and its regulation
• 8. Other cardiovascular regulatory processes

13. Capillaries
• Allow exchange of gases,
nutrients and wastes between
blood and tissues
• Overall large surface area and
low blood flow
• Two main types:
- continuous capillaries:
narrow space between cells 
permeable to small or lipid
soluble molecules
- fenestrated capillaries:
large pores between cells
large molecules can pass

14. Local control of blood flow in capillaries
• Presence of precapillary
sphincters on the arteriole
and beginning of
capillaries
• Metarteriole: no sphincter
 continuous blood flow
 controls the amount of
blood going to
neighboring vessels

15. Movement of materials across capillary walls
• Small molecules and lipid
soluble molecules move
by diffusion through the
cell membrane
• Larger molecules,
charged molecules must
pass through membrane
channels, exocytosis or in
between 2 cells
• Water movement is
controlled by the capillary
hydrostatic and osmotic
pressures

16. Forces controlling water movement
• Arterial side of the capillary:
– High capillary hydrostatic
pressure (BHP), lower
capillary osmotic pressure
(BOP, due to proteins and
other molecules in the blood)
 Net filtration pressure
pushes fluid from the blood
toward the tissue (but the
proteins remain in the capillary
• Venous side of the capillary:
- Lower hydrostatic pressure (due
to resistance) and higher capillary
osmotic pressure  Net filtration
pressure moves fluid back toward
the capillary
• Interstitial fluid hydrostatic
(IFHP) and osmotic pressures
(IFOP) remain overall identical

17. Fluid movement in the capillary
• Arteriole side: fluid moves
toward the tissues
• Venous side: fluid reenters the
capillary
• Overall: for every 1 liter of fluid
entering the tissues, only 0.85 l
reenter the capillary
• The remaining 0.15 l is
reabsorbed as lymph by
lymphatic capillaries and
eventually returned back to
blood circulation
• When this system fails: Edema

18. Causes of edema
• Increased hydrostatic • Increased interstitial
blood pressure hydrostatic pressure
- heart failure (left or right),
(lymphatic capillary
blockage)
- excess fluid in the blood
- breast cancer surgery,
elephantiasis
• Decreased blood osmotic • Leaking capillary wall
pressure - histamine release during
– Liver, kidney diseases,
allergic reaction
malnutrition (kwashiorkor),
burn injuries

19. Outline
• 1- Physical laws governing blood flow and blood
pressure
• 2- Overview of vasculature
• 3- Arteries
• 4. Capillaries and venules
• 5. Veins
• 6. Lymphatic circulation
• 7. Mean arterial pressure and its regulation
• 8. Other cardiovascular regulatory processes

20. Veins
• Veins are blood volume reservoir
• Due to thinness of vessel wall  less resistance to stretch = more compliance

21. Factors influencing venous return
• 1- Skeletal muscle pump
and valves 
• 2- Respiratory pump
• 3- Blood volume
• 4- Venomotor tone

22. Outline
• 1- Physical laws governing blood flow and blood
pressure
• 2- Overview of vasculature
• 3- Arteries
• 4. Capillaries and venules
• 5. Veins
• 6. Lymphatic circulation
• 7. Mean arterial pressure and its regulation
• 8. Other cardiovascular regulatory processes

23. Lymphatic circulation
• Driven by factors similar to
venous circulation:
- muscle activity
- valves
- respiration
• Lymph = plasma-proteins
• Lymphatic circulation collects
fluid not reabsorbed by the
capillaries
• Lymph is filtered in nodes
before return to blood
circulation

24. Outline
• 1- Physical laws governing blood flow and blood
pressure
• 2- Overview of vasculature
• 3- Arteries
• 4. Capillaries and venules
• 5. Veins
• 6. Lymphatic circulation
• 7. Mean arterial pressure and its regulation
• 8. Other cardiovascular regulatory processes

25. Mean arterial pressure and its
regulation
• Regulation of blood flow in arteries
- Intrinsic control
- Extrinsic control
-- Neural control
-- Hormonal control
* Control of blood vessel radius
* Control of blood volume

26. Mean arterial pressure and its
regulation
• Regulation of blood flow in arteries
- Intrinsic control
- Extrinsic control
-- Neural control
-- Hormonal control
* Control of blood vessel radius
* Control of blood volume

27. Regulation of blood flow in arteries
• It is important to adjust blood flow to
organ needs  Flow of blood to particular
organ can be regulated by varying
resistance to flow (or blood vessel
diameter)
• Vasoconstriction of blood vessel smooth
muscle is controlled both by the ANS and
at the local level.
• Four factors control arterial flow at the
organ level:
- change in metabolic activity
- changes in blood flow
- stretch of arterial smooth muscle
- local chemical messengers

28. Intrinsic control of local arterial blood flow
• Change in metabolic • Stretch of arterial wall =
activity myogenic response
– Usually linked to CO2 and - Stretch of arterial wall due to
O2 levels (↑ CO2  increased pressure  reflex
vasodilation ↑ blood flow) constriction
intrinsic control
• Locally secreted
• Changes in blood flow
chemicals can promote
- decreased blood flow  vasoconstriction or most
increased metabolic wastes 
vasodilation
commonly vasodilation
- inflammatory chemicals,
(nitric oxide, CO2)

29. Mean arterial pressure and its
regulation
• Regulation of blood flow in arteries
- Intrinsic control
- Extrinsic control
-- Neural control
-- Hormonal control
* Control of blood vessel radius
* Control of blood volume

30. Extrinsic control of blood pressure
• Two ways to control BP:
- Neural control
- Hormonal control
** Use negative feedback

31. Control of blood pressure
• Importance: Blood pressure is a key factor for
providing blood (thus oxygen and energy) to organs.
SBP must be a minimum of 70 to sustain kidney filtration
and adequate blood flow to the brain
• CO= HR X SV = MABP/TPR 
MABP= HRxSVxTPR  heart rate, stroke volume
and peripheral resistance affect MABP
• Main factors controlling BP: - Blood volume
- Blood vessel radius

32. Neural control of BP - 1
• Baroreceptors: carotid
and aortic sinuses
sense the blood
pressure in the aortic
arch and internal
carotid  send signal
to the vasomotor
center in the medulla
oblongata
• Other information are
sent from the
hypothalamus, cortex


33. Neural control of BP - 2
• The vasomotor center
integrates all these information
• The vasomotor sends decision
to the ANS center:
- Both parasympathetic and
sympathetic innervate the S/A
node  can accelerate or slow
down the heart rate
- The sympathetic NS
innervates the myocardium
and the smooth muscle of the
arteries and veins  promotes
vasoconstriction

34. Hormonal control of BP
• Control of blood vessel radius
• Hormones can control blood - Epinephrine
vessel radius and blood - Angiotensin II
volume, stroke volume and - Vasopressin (?)
heart rate
• On a normal basis, blood
• Control of blood volume
vessel radius and blood
volume are the main factors - Anti-diuretic hormone
(vasopressin)
• - Aldosterone
If there is a critical loss of
pressure, then the effects on
HR and SV will be noticeable
(due to epinephrine kicking in) • Control of heart rate and
stroke volume
- Epinephrine

35. Control of blood vessel radius
• Epinephrine: secreted by the
adrenal medulla and ANS reflex 
increase HR, stroke volume and
promotes vasoconstriction of most
blood vessel smooth muscles. • Angiotensin II secretion:
- Decreased flow of filtrate in kidney
• Angiotensin II  promotes tubule is sensed by the
vasoconstriction Juxtaglomerular apparatus (a
small organ located in the tubule)
 secretion of renin
- Renin activates angiotensinogen,
a protein synthesized by the liver
and circulating in the blood 
angiotensin I
- Angiotensin I is activated by a lung
enzyme, Angiotensin-Activating
Enzyme (ACE),  angiotensin II
- Angiotensin II is a powerful
vasoconstricted of blood vessel
smooth muscles

36. Control of blood volume
• Anti-diuretic hormone =
ADH
- Secreted by the posterior
pituitary in response to ↑blood
osmolarity (often due to
dehydration)
- Promote water reabsorption by
the kidney tubules  H2O
moves back into the blood 
less urine formed

37. Control of blood volume
• Aldosterone:
- Secretion by the adrenal
cortex triggered by angiotensin
II
- Promotes sodium reabsorption
by the kidney tubules (Na+
moves back into the blood)
- H2O follows by osmosis
- Whereas ADH promotes H2O
reabsorption only (in response
to dehydration), aldosterone
promotes reabsorption of both
H2O and salt (in response to ↓
BP)

38. Clinical application: Shock
• Stage I: Body reacts to
• Stage I: reversible, maintain BP  ↑HR,
compensated shock vasoconstriction.. BP remains
within normal range
• Stage II: reversible,
noncompensated shock • Stage II: Body reacts to
maintain BP  ↑HR,
• Stage III: irreversible shock vasoconstriction.. BP drops
below adequate range (SBP 70).
Can be reversed by medical
• Death treatment
• Stage III: Body is fighting to
maintain adequate BP without
success  HR is very high  not
enough O2 for cardiac, brain cells
to survive  damages. Cannot
be reversed by medical treatment