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Blood Vessels.

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Presentation on theme: "Blood Vessels."— Presentation transcript:

1 Blood Vessels

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


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 r. ulnar artery r. radial artery



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

24 Branches of systemic aorta
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



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

28 Branches of systemic aorta
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)

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

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



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


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



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
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
e. paired common iliac veins which drain (1) paired internal iliac veins (2) paired external iliac veins which drain (a) femoral veins which drain 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 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)







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