This document discusses the structure and function of the cardiovascular system. It describes the different types of blood vessels including arteries, veins, and capillaries. It explains the layers of blood vessels and how blood flows from the heart through the arteries, capillaries and veins before returning to the heart. Key concepts covered include blood pressure, resistance, cardiac output, hormones that regulate blood pressure, and normal blood pressure readings.

1. Blood Vessels
Chapter 19

2. Types of Blood Vessels
 Arteries - vessels that transport blood
away from the heart
 Veins - return blood back to the heart
 Capillaries - microscopic blood
vessels that allow exchanges
between blood and tissues

3. Structure of a blood vessel
 Tunica externa (adventitia) - outermost layer
made of loose connective tissue. Serves to
anchor, protect and prevent overstretching
 Tunica media - middle layer composed of
smooth muscle; functions in dilation and
constriction of blood vessels
 Tunica interna(intima) - innermost layer made
of endothelium (s.squamous epithelium)

8. Blood flow through tissues
 From the heart blood flows into
 Aorta
 Arteries
 Arterioles
 Capillaries
 Venules
 Veins
 Superior/ Inferior Vena Cava
 Back to the heart

9. Arteries
 Elastic (conducting) arteries
 Larger arteries
 Muscular (distributing) arteries
 Medium arterties
 Arterioles
 Tiny, tiny arteries
 Metarteriole

11. Capillaries
 Microscopic vessels that connect
arterioles and venules
 Walls consist of a single layer of simple
squamous epithelial cells that allow the
exchange of gases
 Precapillary sphincters regulate blood
flow
 Continuous/Fenestrated capillaries

12. Veins
 Venules merge to form veins
 Have 3 distinct layers; thinner walled
than arteries due to thin tunica interna
and media
 Large lumens and posses valves
 Varicose veins
 Blood reservoir

13. Systemic Circulation
 The aorta and its major branches
 Arterial supply to neck and head
 Arterial supply to upper extremities
 Arterial supply to thorax
 Arterial supply to abdomen
 Arterial supply to pelvic region and
lower extremities

14. Systemic Veins
 Venous drainage of the head and neck
 Major tributaries of the inferior vena
cava
 Venous drainage of the upper
extremities
 Venous drainage of the lower
extremities

15. Hepatic Portal System
 Routes blood from the stomach, spleen,
pancreas, small and large intestines to
the liver
 Blood from these structures all drain
into the hepatic portal vein, then into the
liver
 Blood is returned to the inferior vena
cava via the hepatic vein

16. Fetal Circulation
 Placenta - site where exchange of
materials between fetus and mother occur
 Umbilical arteries (2) - carry fetal blood
high in CO2 / low in O2 to the placenta
 Umbilical vein - returns oxygenated blood
from the placenta to the fetus

17. Fetal Circulation
 Ductus venosus - allows blood to bypass
the liver
 Foramen ovale - opening in interatrial
septum allowing blood to bypass the lungs
Blood flows from r.atrium ->l.atrium
 Ductus arteriosus - vessel connecting
pulmonary artery to the aorta

18.  1. superior vena cava
2. inferior vena cava
3. pulmonary veins
4. pulmonary trunk (p. artery, p. aorta)
5. systemic aorta
A. Great Vessels

20. Branches of systemic aorta
 1. from ascending aorta, right and left
coronary artery
2. from aortic arch, brachiocephalic
artery
a. right subclavian artery
(1) r. axillary artery
(a) r. brachial artery
1. r. ulnar artery
2. r. radial artery

23.  3. superficial and deep
palmar arches
(anastomoses)
(b) deep brachial artery
(c) posterior circumflex
(2) r. vertebral artery
Branches of systemic aorta

24.  b. right common carotid artery
(a) r. external carotid artery
(b) r. internal carotid artery
c. (cat, not human) left common
carotid artery
(a) l. external carotid artery
(b) l. internal carotid artery
Branches of systemic aorta

27.  3. from aortic arch (human, not cat),
left common carotid artery
a. l. external carotid artery
b. l. internal carotid artery
Branches of systemic aorta

28.  4. from aortic arch, left subclavian artery
(cat and human)
a. l. axillary artery
(1) l. brachial artery
(a) l. ulnar artery
(b) l. radial artery
(c) superficial and deep palmar
arches (anastomoses)
Branches of systemic aorta

29.  (2) deep brachial artery
(3) posterior circumflex
b. l. vertebral artery
 5. from descending thoracic aorta
a. paired bronchial arteries
b. paired intercostal arteries
Branches of systemic aorta

30.  6. from abdominal aorta
a. celiac trunk
(1) splenic artery
(2) l. gastric artery
(3) hepatic artery
Branches of systemic aorta

33.  b. superior mesenteric artery
c. paired renal arteries
d. paired gonadal arteries
e. paired lumbar arteries
f. inferior mesenteric artery
Branches of systemic aorta

35.  g. right and left common iliac arteries
(1) internal iliacs
(2) external iliacs->femorals->
popliteal->tibial->dorsalis pedis->
plantar arches
Branches of systemic aorta

38. C. Major veins
 A. coronary circulation: coronary sinus
B. pulmonary circulation: pulmonary
veins
C. hepatic portal circulation: hepatic
portal vein drains
1. inferior mesenteric which drains
splenic vein
2. superior mesenteric vein

40. D. Cranial Circulation:
 cranial venous
sinuses

41. E. Systemic Circulation:
 1. superior vena cava drains
a. azygos system
b. right and left brachiocephalic veins
c. internal jugular and subclavian vein
d. external jugular and axillary
e. cephalic vein (superficial) and brachial
vein (deep) which drains
radial, ulnar, median cubital and basilic
veins

44.  2. inferior vena cava drains
a. hepatic vein
b. phrenic vein
c. paired renal veins
d. paired gonadal veins

46.  e. paired common iliac veins which drain
(1) paired internal iliac veins
(2) paired external iliac veins which drain
(a) femoral veins which drain
1. popliteal veins which drain
a peroneal vein
b anterior and posterior tibial veins
(b) great saphenous veins

49. Capillary Exchange

51. Mechanisms of Exchange
 Diffusion - major method used to
exchange substances such as O2,
CO2, glucose, and amino acids
 Vesicular transport - endocytosis and
exocytosis of lipid-insoluble molecules
 Bulk flow - involves filtration and
reabsorption

52. Arteries Veins
 Pressures
promoting filtration
 Blood hydrostatic
pressure***
 Interstitial fluid
osmotic pressure
 Pressures promoting
reabsorption
 Blood colloid osmotic
pressure***
 Interstitial fluid
hydrostatic pressure

53. Physiology of Circulation

54. Important Terms
 Blood Flow
 Blood pressure
 Resistance

55. Blood Flow
 Blood flow - is the amount of blood flowing
through a tissue in a given period of time
 Velocity of blood flow is inversely related to
the diameter of the blood vessel
 Blood flows most slowly in areas of greatest
width

56. Blood Pressure
 Force that the blood exerts against the
walls of a blood vessels
 Factors affecting BP include cardiac
output, blood volume, viscosity, resistance,
and the elasticity of the arteries

57. Cardiac Output
 CO=Stroke volume X Heart Rate
 Any factor that increases SV or HR will
increase blood pressure

58. Peripheral Resistance
 Resistance to blood flow due to the force of
friction between vessel wall and blood
 Resistance affected by blood viscosity,
vessel length and vessel radius

59. Sources affecting Resistance
 Blood viscosity- how thick or thin the blood
is. Measured by hematocrit.
 Vessel length- longer the vessel, the
greater the resistance, the greater the BP
 Vessel radius- smaller the vessel the
greater the resistance

60. Blood Volume
 ↓ Blood volume , ↓ Blood pressure
 ↑ Blood volume, ↑Blood pressure
 Blood volume & blood pressure monitored
by the cardiovascular center in the medulla
(ANS), baroreceptors and chemoreceptors
and by hormonal regulation

61. Hormonal Regulation
of Blood Pressure
 Renin- angiotensin pathway
 Angiotensin II - powerful vasoconstrictor
thus raising resistance
 Stimulates secretion of aldosterone from the
adrenal gland promoting sodium retention
 ADH - antidiuretic hormone from the pituitary
causing the kidneys to reabsorb more water

62. Hormone lowering BP
 ANP - atrial natriutic peptide
 released by atrial cells promoting the
loss of salt and water in the urine ,
thus ↓ blood volume and causing
vasodilation which then ↓ blood
pressure
 PTH - parathyroid hormone causes
vasodilation

63.  Endothelin = potent vasoconstrictor
responds to low blood flow
 NO (nitrous oxide) = powerful
vasodilator; balances endothelin and
dilates vessels in response to high
blood flow.

64. Normal Blood Pressure
 Newborn = 90/55 mm Hg
 Adults = 120/80 mm Hg
 Old Age = 150/90
 Systolic Pressure = peak pressure during
systole
 Diastolic pressure = lowest pressure during
diastole (filling of ventricles)