19 The Cardiovascular System: Modified by Dr. Par Mohammadian

Blood Vessels Arteries: carry blood away from heart; oxygenated except for pulmonary circulation Capillaries: site of exchange; contact tissue cells; directly serve cellular needs Veins: carry blood toward heart Artery Vein

Structure of Blood Vessel Walls Lumen Central blood-containing space Three wall layers in arteries and veins tunica intima (internal) tunica media tunica externa Capillaries Endothelium with sparse basal lamina © 2013 Pearson Education, Inc.

• Internal elastic membrane • External elastic membrane Figure 19.1b Generalized structure of arteries, veins, and capillaries. Tunica intima • Endothelium • Subendothelial layer • Internal elastic membrane Tunica media (smooth muscle and elastic fibers) Valve • External elastic membrane Tunica externa (collagen fibers) • Vasa vasorum Lumen Lumen Artery Capillary network Vein Basement membrane Endothelial cells Capillary © 2013 Pearson Education, Inc.

Tunics Tunica intima Endothelium lines lumen of all vessels Tunica media Smooth muscle and sheets of elastin Sympathetic vasomotor nerve fibers control vasoconstriction and vasodilation of vessels: Influence blood flow and blood pressure Tunica externa Collagen fibers protect & reinforce; anchor to surrounding structures Contains nerve fibers, lymphatic vessels Vasa vasorum of larger vessels nourishes external layer

(depending on size & shape): Types of Arteries (depending on size & shape): Elastic Muscular Arterioles

Arterial System: Elastic Arteries Large thick-walled arteries with elastin in all three tunics Aorta and its major branches Large lumen offers low resistance Act as pressure reservoirs—expand and recoil as blood ejected from heart Smooth pressure downstream

Arterial System: Muscular Arteries Distal to elastic arteries Deliver blood to body organs Thick tunica media with more smooth muscle Active in vasoconstriction

Arterial System: Arterioles Smallest arteries Lead to capillary beds Control flow into capillary beds via vasodilation and vasoconstriction of the arterioles (influenced by hormones and other chemicals)

Capillaries Microscopic blood vessels Walls of thin tunica intima Pericytes help stabilize their walls and control permeability Diameter allows only single RBC to pass at a time

Provide direct access to almost every cell Functions Capillaries In all tissues except for cartilage & epithelia (receive nutrients from nearby blood vessels), cornea & lens of eye (receive nutrients from aqueous humor) Provide direct access to almost every cell Functions Exchange of gases, nutrients, wastes, hormones, etc., between blood and interstitial fluid Three structural types Continuous capillaries Fenestrated capillaries Sinusoid capillaries (sinusoids)

Continuous Capillaries Tight junctions connect endothelial cells Intercellular clefts allow passage of limited passage of fluids and small solutes Continuous capillaries of brain unique Tight junctions complete, forming blood brain barrier Continuous capillary. Least permeable, and most common (e.g., skin, muscle). Pericyte Red blood cell in lumen Intercellular cleft Endothelial cell Basement membrane Tight junction Pinocytotic vesicles Endothelial nucleus

Fenestrated Capillaries Some endothelial cells contain pores (fenestrations) More permeable than continuous capillaries Function in absorption or filtrate formation (small intestines, endocrine glands, and kidneys) Pinocytotic vesicles Red blood cell in lumen Fenestrations (pores) Intercellular cleft Endothelial cell nucleus Basement membrane Tight junction Fenestrated capillary. Large fenestrations (pores) increase permeability. Occurs in areas of active absorption or filtration (e.g., kidney, small intestine).

Sinusoid Capillaries Fewer tight junctions; usually fenestrated; larger intercellular clefts; large lumens Large molecules and blood cells pass between blood and surrounding tissues Found only in the liver, bone marrow, spleen, adrenal medulla In the liver, hepatic macrophages in lining to destroy bacteria Endothelial cell Red blood cell in lumen Large intercellular cleft Nucleus of endothelial Incomplete basement membrane Sinusoid capillary. Most permeable. Occurs in special locations (e.g., liver, bone marrow, spleen). Tight junction

Capillary Beds: Two Types of Vessels Def.: Interwoven networks of capillaries – blood flows thru arterioles-> venules (microcirculation) Capillary Beds: Two Types of Vessels Vascular shunt (metarteriole—thoroughfare channel) Directly connects terminal arteriole and postcapillary venule True capillaries 10 to 100 exchange vessels per capillary bed Branch off metarteriole or terminal arteriole

Blood Flow Through Capillary Beds Vascular shunt Precapillary sphincters Metarteriole Thoroughfare channel True capillaries normally branch from metarteriole and return to thoroughfare channel Precapillary sphincters regulate blood flow into true capillaries Blood may go into true capillaries or to shunt Regulated by local chemical conditions and vasomotor nerves Example: Eating and relaxing – blood flow in the digestive system; abdominal cramps and indigestion when running and eating!!! True capillaries Terminal arteriole Postcapillary venule Sphincters open—blood flows through true capillaries. Terminal arteriole Postcapillary venule Sphincters closed—blood flows through metarteriole – thoroughfare channel and bypasses true capillaries.

Venous System: Venules Formed when capillary beds unite Smallest postcapillary venules: very porous; allow fluids and WBCs into tissues Consist of endothelium and a few pericytes Larger venules have one or two layers of smooth muscle cells

Veins Venules join to form veins Have thinner walls, larger lumens compared with corresponding arteries Thin tunica media; thick tunica externa of collagen fibers and elastic networks Called capacitance vessels (blood reservoirs); contain up to 65% of blood supply Blood pressure lower than in arteries (walls don’t burst!) => Adaptations ensure return of blood to heart despite low pressure Large-diameter lumens offer little resistance Venous valves prevent backflow of blood Most abundant in veins of limbs Venous sinuses: flattened veins with extremely thin walls (e.g., coronary sinus of the heart & dural sinuses of the brain)

Varicose vein

Circulatory Pathways: Blood Vessels of the Body Two main circulations Pulmonary circulation: short loop that runs from heart to lungs and back to heart Systemic circulation: long loop to all parts of body and back to heart

Pulmonary capillaries of the R. lung Pulmonary capillaries of the Figure 19.19a Pulmonary circulation. Pulmonary capillaries of the R. lung Pulmonary capillaries of the L. lung R. pulmonary artery L. pulmonary artery To systemic circulation Pulmonary trunk R. pulmonary veins From systemic circulation RA LA L. pulmonary veins RV LV Schematic flowchart. © 2013 Pearson Education, Inc. © 2013 Pearson Education, Inc.

Figure 19.19 Pulmonary circulation. RV LV Left pulmonary artery Air-filled alveolus of lung Aortic arch Pulmonary trunk Right pulmonary artery Three lobar arteries to right lung Pulmonary capillary Gas exchange Two lobar arteries to left lung Pulmonary veins Pulmonary veins Right atrium Left atrium Right ventricle Left ventricle Illustration. The pulmonary arterial system is shown in blue to indicate that the blood it carries is oxygen-poor. The pulmonary venous drainage is shown in red to indicate that the blood it transports is oxygen-rich. © 2013 Pearson Education, Inc.

Figure 19.20 Schematic flowchart showing an overview of the systemic circulation. Common carotid arteries to head and subclavian arteries to upper limbs Capillary beds of head and upper limbs Superior vena cava Aortic arch Aorta RA LA RV LV Azygos system Thoracic aorta Venous drainage Arterial blood Inferior vena cava Capillary beds of mediastinal structures and thorax walls Diaphragm Abdominal aorta Capillary beds of digestive viscera, spleen, pancreas, kidneys Inferior vena cava Capillary beds of gonads, pelvis, and lower limbs

Figure 19.21a Major arteries of the systemic circulation. R. external carotid artery R. internal carotid artery L. external carotid artery L. internal carotid artery R. common carotid – right side of head and neck L. common carotid – left side of head and neck R. vertebral L. vertebral R. axillary R. subclavian – neck and R. upper limb Brachiocephalic – head, neck, and R. upper limb L. subclavian – neck and L. upper limb L. axillary Aortic arch Arteries of L. upper limb Arteries of R. upper limb Ascending aorta – L. ventricle to sternal angle L. and R. coronary arteries Thoracic aorta T5–T12 (diaphragm) L. ventricle of heart Visceral branches Parietal branches Mediastinal – posterior media- stinum Esophageal – esophagus Bronchial – lungs and bronchi Pericardial – pericardium Posterior intercostals – intercostal muscles, spinal cord, vertebrae, pleurae, skin Superior phrenics – posterior and superior diaphragm Diaphragm Abdominal aorta T12 (diaphragm)–L4 Visceral branches Parietal branches Gonadal – testes or ovaries Suprarenal – adrenal glands and Renal – kidneys Superior and inferior mesenterics – small intestine – colon Celiac trunk – liver – gallbladder – spleen – stomach – esophagus – duodenum Inferior phrenics – inferior diaphragm Lumbars – posterior abdominal wall Median sacral – sacrum – coccyx R. common iliac – pelvis and R. lower limb L. common iliac – pelvis and L. lower limb Arteries of R. lower limb Arteries of L. lower limb

Aorta Ascending artery Aortic Arch Descending aorta Major arteries of the systemic circulation. Aorta Ascending artery Aortic Arch Descending aorta Left coronary artery Right coronary artery Thoracic aorta Abdominal aorta Left & right common iliac arteries brachiocephalic Left common carotid artery Left subclavian artery Right common carotid artery Right subclavian artery

Arteries of the head and trunk Internal carotid artery Figure 19.21b Major arteries of the systemic circulation. Arteries of the head and trunk Internal carotid artery External carotid artery Arteries that supply the upper limb Common carotid arteries Subclavian artery Vertebral artery Axillary artery Subclavian artery Brachiocephalic artery Brachial artery Aortic arch Radial artery Ascending aorta Ulnar artery Coronary artery Celiac trunk Deep palmar arch Abdominal aorta Superficial palmar arch Superior mesenteric artery Digital arteries Renal artery Arteries that supply the lower limb Gonadal artery External iliac artery Inferior mesenteric artery Femoral artery Common iliac artery Popliteal artery Internal iliac artery Anterior tibial artery Posterior tibial artery Arcuate artery Illustration, anterior view © 2013 Pearson Education, Inc.

Brachiocephalic trunk Figure 19.22a Arteries of the head, neck, and brain. R. and L. anterior cerebral arteries R. Middle cerebral artery Anterior communicat- ing artery Cerebral arterial circle R. and L. Posterior communicat- ing arteries Ophthalmic artery R. posterior cerebral artery Basilar artery Superficial temporal artery Maxillary artery R. and L. vertebral arteries Occipital artery R. and L. internal carotid arteries Facial artery Lingual artery R. and L. external carotid arteries Superior thyroid artery R. and L. common carotid arteries R. and L. subclavian arteries Brachiocephalic trunk Aortic arch © 2013 Pearson Education, Inc. © 2013 Pearson Education, Inc. Schematic flowchart

Arteries of the head and neck, right aspect Figure 19.22b Arteries of the head, neck, and brain. Ophthalmic artery Branches of the external carotid artery Basilar artery Vertebral artery • Superficial temporal artery Internal carotid artery • Maxillary artery • Occipital artery External carotid artery • Facial artery • Lingual artery Common carotid artery • Superior thyroid artery Thyrocervical trunk Larynx Costocervical trunk Thyroid gland (overlying trachea) Subclavian artery Clavicle (cut) Brachiocephalic trunk Axillary artery Internal thoracic artery Arteries of the head and neck, right aspect © 2013 Pearson Education, Inc. © 2013 Pearson Education, Inc.

Colorized arteriograph of the arterial supply of the brain Figure 19.22c Arteries of the head, neck, and brain. Colorized arteriograph of the arterial supply of the brain © 2013 Pearson Education, Inc. © 2013 Pearson Education, Inc.

Major arteries serving the brain (inferior view, right side Figure 19.22d Arteries of the head, neck, and brain. Anterior Cerebral arterial circle (circle of Willis) Frontal lobe Optic chiasma • Anterior communicating artery Middle cerebral artery • Anterior cerebral artery Internal carotid artery • Posterior communicating artery Mammillary body • Posterior cerebral artery Temporal lobe Basilar artery Vertebral artery Pons Occipital lobe Cerebellum Posterior Major arteries serving the brain (inferior view, right side of cerebellum and part of right temporal lobe removed)

Superficial palmar arch Figure 19.23a Arteries of the right upper limb and thorax. R. common carotid artery L. common carotid artery R. vertebral artery Thyrocervical trunk L. vertebral artery Suprascapular artery L. subclavian artery R. subclavian artery. Axillary artery Thoracoacromial artery Thoracoacromial artery (pectoral branch) Aortic arch Costocervical trunk Anterior and posterior circumflex humeral arteries Brachiocephalic trunk Internal thoracic artery Brachial artery Anterior intercostal arteries Deep artery of arm Lateral thoracic artery Thoracic aorta Posterior intercostal arteries Subscapular artery Anastomosis Common interosseus artery Radial artery Ulnar artery Deep palmar arch Metacarpal arteries Superficial palmar arch Digital arteries © 2013 Pearson Education, Inc. © 2013 Pearson Education, Inc. Schematic flowchart

Thoracoacromial artery Superficial palmar arch Figure 19.23b Arteries of the right upper limb and thorax. Vertebral artery Common carotid arteries Thyrocervical trunk Right subclavian artery Costocervical trunk Suprascapular artery Left subclavian artery Thoracoacromial artery Brachiocephalic trunk Axillary artery Subscapular artery Posterior intercostal arteries Posterior circumflex humeral artery Anterior intercostal artery Anterior circumflex humeral artery Internal thoracic artery Brachial artery Deep artery of arm Lateral thoracic artery Thoracic aorta Common interosseous artery Radial artery Ulnar artery Deep palmar arch Superficial palmar arch Digital arteries Illustration, anterior view © 2013 Pearson Education, Inc. © 2013 Pearson Education, Inc.

L. gastroepiploic artery Figure 19.24a Arteries of the abdomen. Diaphragm Abdominal aorta L. gastric artery Inferior phrenic arteries R. gastric artery Common hepatic artery Hepatic artery proper L Celiac trunk Gastro- duodenal artery Splenic artery R R. gastroepiploic artery Middle suprarenal arteries L. gastroepiploic artery Intestinal arteries Middle colic artery Superior mesenteric artery R. colic artery Renal arteries Gonadal arteries Ileocolic artery Sigmoidal arteries Inferior mesenteric artery L. colic artery Superior rectal artery Lumbar arteries Median sacral artery Common iliac arteries Schematic flowchart. © 2013 Pearson Education, Inc. © 2013 Pearson Education, Inc.

Liver (cut) Diaphragm Inferior vena cava Esophagus Celiac trunk Common Figure 19.24b Arteries of the abdomen. Liver (cut) Diaphragm Inferior vena cava Esophagus Celiac trunk Common hepatic artery Left gastric artery Hepatic artery proper Stomach Splenic artery Gastroduodenal artery Left gastroepiploic artery Right gastric artery Spleen Gallbladder Right gastroepiploic artery Pancreas (major portion lies posterior to stomach) Duodenum Superior mesenteric artery Abdominal aorta The celiac trunk and its major branches. The left half of the liver has been removed. © 2013 Pearson Education, Inc. © 2013 Pearson Education, Inc.

Major branches of the abdominal aorta. Figure 19.24c Arteries of the abdomen. Diaphragm Hiatus (opening) for inferior vena cava Inferior phrenic artery Hiatus (opening) for esophagus Adrenal (suprarenal) gland Middle suprarenal artery Celiac trunk Renal artery Kidney Superior mesenteric artery Abdominal aorta Gonadal (testicular or ovarian) artery Lumbar arteries Inferior mesenteric artery Ureter Median sacral artery Common iliac artery Major branches of the abdominal aorta. © 2013 Pearson Education, Inc. © 2013 Pearson Education, Inc.

Distribution of the superior and inferior mesenteric arteries. Figure 19.24d Arteries of the abdomen. Celiac trunk Transverse colon Superior mesenteric artery Aorta Branches of the superior mesenteric artery Inferior mesenteric artery • Middle colic artery Branches of the inferior mesenteric artery • Intestinal arteries • Right colic artery • Ileocolic artery • Left colic artery • Sigmoidal arteries Ascending colon • Superior rectal artery Right common iliac artery Ileum Descending colon Cecum Sigmoid colon Appendix Rectum Distribution of the superior and inferior mesenteric arteries. The transverse colon has been pulled superiorly. © 2013 Pearson Education, Inc. © 2013 Pearson Education, Inc.

Figure 19.25a Arteries of the right pelvis and lower limb. Abdominal aorta Superior gluteal artery Internal iliac artery Inferior gluteal artery Common iliac artery Internal pudendal Obturator artery Medial circumflex femoral artery Deep artery of thigh External iliac artery Lateral circumflex femoral artery Femoral artery Adductor hiatus Arterial anastomosis Popliteal artery Anterior tibial artery Posterior tibial artery Fibular artery Dorsalis pedis artery Lateral plantar artery Lateral plantar artery Medial plantar artery Arcuate artery Plantar arch Dorsal metatarsal arteries Plantar metatarsal arteries Schematic flowchart © 2013 Pearson Education, Inc. © 2013 Pearson Education, Inc.

Superior gluteal artery Figure 19.25b Arteries of the right pelvis and lower limb. Common iliac artery Internal iliac artery Superior gluteal artery External iliac artery Deep artery of thigh Lateral circumflex femoral artery Medial circumflex femoral artery Obturator artery Femoral artery Adductor hiatus Popliteal artery Anterior tibial artery Posterior tibial artery Fibular artery Dorsalis pedis artery Arcuate artery Dorsal metatarsal arteries Anterior view

Figure 19.26b Major veins of the systemic circulation. Veins of the head and trunk Dural venous sinuses Veins that drain the upper limb External jugular vein Vertebral vein Subclavian vein Internal jugular vein Axillary vein Right and left brachiocephalic veins Cephalic vein Brachial vein Superior vena cava Basilic vein Great cardiac vein Hepatic veins Splenic vein Median cubital vein Hepatic portal vein Ulnar vein Renal vein Radial vein Superior mesenteric vein Inferior mesenteric vein Digital veins Inferior vena cava Common iliac vein Veins that drain the lower limb Internal iliac vein External iliac vein Femoral vein Great saphenous vein (longest vein; issue from dorsal venous arch) Popliteal vein Posterior tibial vein Anterior tibial vein Small saphenous vein Dorsal venous arch Dorsal metatarsal veins Illustration, anterior view. The vessels of the pulmonary circulation are not shown. 

Veins of the head and neck, right superficial aspect Figure 19.27b Venous drainage of the head, neck, and brain. 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 Superior vena cava Veins of the head and neck, right superficial aspect

Brachiocephalic veins Internal jugular vein Right subclavian vein External jugular vein Left subclavian vein Axillary vein Brachial vein Superior vena cava Azygos vein Cephalic vein Accessory hemiazygos vein Basilic vein Hemiazygos vein Posterior intercostals Inferior vena cava Median cubital vein Ascending lumbar vein Median antebrachial vein Basilic vein Cephalic vein Ulnar vein Radial vein Deep venous palmar arch Superficial venous palmar arch Digital veins Anterior view Figure 19.28b Veins of the thorax and right upper limb.

Tributaries of the inferior vena cava. Figure 19.29b Veins of the abdomen. Inferior phrenic vein Hepatic veins Inferior vena cava Left suprarenal vein Right suprarenal vein Renal veins Left ascending lumbar vein Right gonadal vein Lumbar veins Left gonadal vein Common iliac vein External iliac vein Internal iliac vein Tributaries of the inferior vena cava. Venous drainage of abdominal organs not drained by the hepatic portal vein.

The hepatic portal circulation. Figure 19.29c Veins of the abdomen. Hepatic veins Gastric veins Liver Spleen Inferior vena cava Hepatic portal vein Splenic vein Right gastroepiploic vein Inferior mesenteric vein Superior mesenteric vein Small intestine Large intestine Rectum The hepatic portal circulation.

Common iliac vein Internal iliac vein External iliac vein Figure 19.30b Veins of the right lower limb. Common iliac vein Internal iliac vein External iliac vein Inguinal ligament Femoral vein Great saphenous vein (superficial) Popliteal vein Small saphenous vein Fibular vein Anterior tibial vein Dorsalis pedis vein Dorsal venous arch Dorsal metatarsal veins Anterior view