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Blood Vessels. Circulatory System Three basic components: Heart - serves as pump that establishes the pressure gradient needed for blood to flow to tissues.

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Presentation on theme: "Blood Vessels. Circulatory System Three basic components: Heart - serves as pump that establishes the pressure gradient needed for blood to flow to tissues."— Presentation transcript:

1 Blood Vessels

2 Circulatory System Three basic components: Heart - serves as pump that establishes the pressure gradient needed for blood to flow to tissues Blood - transport medium within which materials being transported are dissolved or suspended Blood vessels - passageways through which blood is distributed from heart to all parts of body and back to heart

3 Types Of Blood Vessels Arteries – carry blood away from the heart Capillaries – smallest blood vessels The site of exchange of molecules between blood and tissue fluid Veins – carry blood toward the heart arteries → arterioles → capillaries → venules → veins

4 Functions Of Blood Vessels Arteries - carry blood away from heart Arterioles - small arteries that deliver blood to capillaries Capillaries – thin walled vessels allow for exchange between blood and tissue cells Venules - collect and drain blood into veins Veins - return blood to heart

5 Structure Of Blood Vessels Composed of three layers (tunics) Tunica intima – composed of simple squamous epithelium Tunica media – sheets of smooth muscle Contraction – vasoconstriction Relaxation – vasodilation Tunica externa – composed of connective tissue Lumen - c entral blood-filled space of a vessel

6 Structural Differences Arteries have thicker tunica media and narrower lumens Veins have thicker tunica externa Arteries have more elastic and collagen fibers Veins have larger lumens and valves

7 Types Of Arteries Elastic arteries – the largest arteries Diameters range from 2.5 cm to 1 cm Includes the aorta and its major branches Sometimes called conducting arteries High elastin content dampens surge of blood pressure

8 Types Of Arteries Muscular (distributing) arteries Lie distal to elastic arteries Diameters range from 1 cm to 0.3 mm Includes most named arteries Tunica media is thick Unique features Internal and external elastic laminae

9 Types Of Arteries Arterioles Smallest arteries Diameters range from 0.3 mm to 10 µm Larger arterioles possess all three tunics Diameter of arterioles controlled by: Local factors in the tissues Sympathetic nervous system

10 Capillaries Smallest blood vessels Diameter from 8–10 µm Red blood cells pass through single file Endothelial cells – held together by tight junctions and desmosomes Routes into and out of capillaries Direct diffusion Through intercellular clefts - gaps of unjoined membrane where small molecules can enter and exit Through fenestrations - pores

11 Capillaries Site-specific functions of capillaries Lungs – oxygen enters blood, carbon dioxide leaves Small intestines – receive digested nutrients Endocrine glands – pick up hormones Kidneys – removal of nitrogenous wastes Tendons and ligaments – poorly vascularized Epithelia and cartilage – avascular, receive nutrients from nearby CT

12 Capillaries Three types of capillary Continuous – most common Fenestrated – have pores Sinusoids

13 Wide, leaky capillaries found in some organs Usually fenestrated Have large diameters Intercellular clefts are wide open Occur in bone marrow, liver, spleen and lymphoid tissue

14 Capillary Beds An interconnected network of vessels running through tissues Consists of: Collateral arteries feeding an arteriole Metarterioles Arteriovenous anastomoses Capillaries Venules

15 Capillary Beds Precapillary sphincters - regulate the flow of blood to tissues

16 Veins Conduct blood from capillaries toward the heart Blood pressure is much lower than in arteries Smallest veins – called venules Diameters from 8 – 100 µm Smallest venules – called postcapillary venules Venules join to form veins

17 Role Of Veins To return blood to the heart, veins have special adaptations Large-diameter lumens, which offer little resistance to flow Valves (resembling semilunar heart valves), which prevent backflow of blood Skeletal muscle pump - muscles press against thin-walled veins

18 Pulmonary Circulation Consists of blood vessels that take the blood to and from the lungs for the purpose of gas exchange Pulmonary Trunk: oxygen-poor blood leaves the right ventricle via the pulmonary trunk; large artery that branches to left and right pulmonary arteries Pulmonary Arteries : take the blood to the lung where oxygen is picked up and CO 2 is left off Pulmonary Veins: blood returns to the heart via four pulmonary veins that go to the left atrium

19 Systemic Circulation Consists of blood vessels that extend to and from the heart delivers oxygen and nutrients to body tissues picks up CO2 and waste products

20 The Aorta And Vena Cava Ascending aorta – arises from the left ventricle branches to form coronary arteries Aortic arch – lies posterior to the manubrium branches to form Brachiocephalic trunk Left common carotid Left subclavian arteries Descending aorta – continues from the aortic arch Thoracic aorta – in the region of T 5 –T 12 Abdominal aorta – ends at L 4 Divides into right and left common iliac arteries Superior/Inferior vena cava returns blood from the systemic veins to the heart

21 The Hepatic Portal System A specialized part of the vascular circuit Picks up digested nutrients Delivers nutrients to the liver for processing

22 Veins Of The Hepatic Portal System Hepatic veins Liver Spleen Gastric veins Inferior vena cava Splenic vein Inferior mesenteric vein Superior mesenteric vein Large intestine Hepatic portal vein Small intestine Rectum

23 Cerebral Arterial Circle (Circle Of Willis) “Circle” equalizes blood pressure in the brain and can provide alternative channels if one vessel becomes blocked The circle is formed from : posterior cerebral arteries, posterior communicating arteries, internal carotid arteries, anterior cerebral arteries, and anterior communicating arteries (c) Middle cerebral artery Internal carotid artery Cerebral arterial circle (circle of Willis) Anterior Posterior cerebral artery Basilar artery Vertebral artery Posterior communicating artery Anterior cerebral artery Anterior communicating artery

24 Arteries Of The Right Upper Limb And Thorax (b) Vertebral artery Common carotid arteries Left axillary artery Right subclavian artery Left subclavian artery Anterior intercostal artery Descending aorta Brachiocephalic trunk Axillary artery Radial artery Ulnar artery Brachial artery Suprascapular artery

25 Arteries Of The Head And Neck, Right Aspect Brachiocephalic trunk Internal thoracic artery Internal carotid artery Subclavian artery (a) Axillary artery External carotid artery Common carotid artery

26 Major Branches Of The Abdominal Aorta Adrenal gland Celiac trunk Kidney Abdominal aorta Diaphragm Suprarenal artery Renal artery Superior mesenteric artery Gonadal artery Inferior mesenteric artery Common iliac artery

27 The Celiac Trunk And Its Main Branches (b) Liver Left gastric artery Superior mesenteric artery Spleen Splenic artery Inferior vena cava Celiac trunk Common hepatic artery Right gastric artery Abdominal aorta

28 Arteries Of The Right Pelvis And Lower Limb (a) (b) Common iliac artery Femoral artery Popliteal artery Anterior tibial artery Posterior tibial artery Fibular artery Internal iliac artery External iliac artery Popliteal artery Anterior tibial artery Fibular artery Posterior tibial artery Anterior view Posterior view

29 Flow Chart Summarizing Main Systemic Arteries Figure 19.17

30 Systemic Veins Three major veins enter the right atrium Superficial veins lie just beneath the skin Multivein bundles – venous plexuses Unusual patterns of venous drainage Dural sinuses Hepatic portal system

31 Venae Cavae and Tributaries Superior vena cava Returns blood from body regions superior to the diaphragm Inferior vena cava Returns blood from body regions inferior to the diaphragm Superior and inferior vena cava Join the right atrium

32 Major veins of the systemic circulation. Renal vein Splenic vein Basilic vein Brachial vein Cephalic vein Dural sinuses External jugular vein Vertebral vein Internal jugular vein Superior vena cava Axillary vein Great cardiac vein Hepatic veins Hepatic portal vein Superior mesenteric vein Inferior vena cava Ulnar vein Radial vein Common iliac vein External iliac vein Internal iliac vein Digital veins Femoral vein Great saphenous vein Popliteal vein Posterior tibial vein Anterior tibial vein Fibular vein Inferior mesenteric vein Median cubital vein Right and left brachiocephalic veins Subclavian vein

33 Dural Sinuses In The Cranium Superior sagittal sinus Falx cerebri Inferior sagittal sinus Straight sinus Cavernous sinus Junction of sinuses Transverse sinuses Jugular foramen (b) Right internal jugular vein Sigmoid sinus

34 Veins of the head and Neck Ophthalmic vein Superficial temporal vein Facial vein Occipital vein Posterior auricular vein External jugular vein Vertebral vein Internal jugular vein Superior and middle thyroid veins Brachiocephalic vein Subclavian vein (a) Superior vena cava

35 Veins Of The Right Upper Limb And Thorax Wall Right subclavian vein Axillary vein Brachial vein Cephalic vein Basilic vein Median cubital vein Median vein of the forearm Basilic vein Internal jugular vein External jugular vein Left subclavian vein Superior vena cava Azygos vein Inferior vena cava Ascending lumbar vein Accessory hemiazygos vein Hemiazygos vein Posterior intercostals Brachiocephalic veins Ulnar vein Deep palmar venous arch Superficial palmar venous arch (a) Digital veins Cephalic vein Radial vein

36 Antecubital Fossa Form anastomese frequently Median cubital vein is used to obtain blood or administer IV fluids Figure 19.22

37 Veins Of The Right Upper Limb And Thorax Wall Brachiocephalic veins Left superior intercostal vein Azygos vein Accessory hemiazygos vein Hemiazygos vein Intercostal veins Ascending lumbar vein Renal vein Superior vena cava Intercostal veins (b) Inferior vena cava

38 Veins of the Abdomen Lumbar veins Gonadal (testicular or ovarian) veins Renal veins Suprarenal veins Hepatic veins

39 Tributaries Of The Inferior Vena Cava Right suprarenal vein Right gonadal vein Hepatic veins Inferior vena cava External iliac vein Inferior phrenic vein Renal veins Lumbar veins Left ascending lumbar vein Left gonadal vein Common iliac vein Internal iliac vein Left suprarenal vein

40 Dissection of the posterior abdominal wall Diaphragm RightLeft Inferior vena cava Hepatic veins Renal veins Common iliac veins Abdominal aorta

41 Veins of the Pelvis and Lower Limbs Deep veins Share the name of the accompanying artery Superficial veins Great saphenous vein empties into the femoral vein Small saphenous vein empties into the popliteal vein

42 Veins Of The Right Lower Limb And Pelvis (b) Popliteal vein Common iliac vein Fibular (peroneal) vein Anterior tibial vein Dorsalis pedis vein Dorsal venous arch Metatarsal veins Internal iliac vein External iliac vein Inguinal ligament Femoral vein Great saphenous vein (superficial) Great saphenous vein Popliteal vein Anterior tibial vein Fibular (peroneal) vein Small saphenous vein (superficial) Posterior tibial vein Plantar veins Plantar arch Digital veins (a)

43 Flowchart Summarizing The Main Veins R. External jugular – superficial head and neck R. vertebral – cervical spinal cord and vertebrae R. brachiocephalic – R. side of head and R. upper limb Superior vena cava – runs from union of brachiocephalic veins behind manubrium to R. atrium Inferior vena cava – runs from junction of common iliac veins at L 5 to R. atrium of heart R. atrium of heart Diaphragm L. brachiocephalic – L. side of head and L. upper limb Intracranial dural sinuses R. internal jugular – dural sinuses of the brain R. subclavian – R. head, neck, and upper limb Same as R. brachiocephalic R. axillary Azygos system – drains much of thorax L. and R. hepatic veins – liver Veins of L. lower limb L. and R. renal veins – kidneys Lumbar veins (several pairs) – posterior abdominal wall R. suprarenal (L. suprarenal drains into L. renal vein) – adrenal glands R. gonadal (L. gonadal drains into L. renal vein) – testis or ovary Veins of R. lower limb Veins of R. upper limb R. common iliac – pelvis and R. lower limb L. common iliac – pelvis and L. lower limb (a)


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