20 PART 1 Blood Vessels Pages 588-617, 620-623

Arteries—carry blood away from the heart 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

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 Central blood-filled space of a vessel

Internal elastic membrane Figure 20.1b Generalized structure of arteries, veins, and capillaries. Tunica intima Artery Endothelium Vein Subendothelial layer Internal elastic membrane Tunica media (smooth muscle and elastic fibers) External elastic membrane Tunica externa (collagen fibers) Vasa vasorum Valve Capillary network Lumen Lumen Basement membrane Capillary Endothelial cells

Figure 20.1a Generalized structure of arteries, veins, and capillaries. Artery Vein

Elastic arteries—the largest arteries 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 Vasa vasorum Elastin Lumen Tunica externa media intima (a) Elastic artery (aorta, 12) Figure 20.2a

Muscular (distributing) arteries 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 feature Internal and external elastic laminae External elastic membrane Internal Lumen Tunica externa media (b) Muscular artery (40) Figure 20.2b

Types of Arteries Arterioles Smallest arteries Diameters range from 0.3 mm to 10 µm Larger arterioles possess all three tunics Lumen Endothelium Tunica media (c) Small arteriole (285) Figure 20.2c

Smallest blood vessels Capillaries Smallest blood vessels Diameter from 8–10 µm Red blood cells pass through single file Site-specific functions of capillaries Lungs—oxygen enters blood, carbon dioxide leaves Small intestines—receive digested nutrients Endocrine glands—pick up hormones Kidneys—remove of nitrogenous wastes

Internal elastic membrane Figure 20.1b Generalized structure of arteries, veins, and capillaries. Tunica intima Artery Endothelium Vein Subendothelial layer Internal elastic membrane Tunica media (smooth muscle and elastic fibers) External elastic membrane Tunica externa (collagen fibers) Vasa vasorum Valve Capillary network Lumen Lumen Basement membrane Capillary Endothelial cells

Figure 20.3 Red blood cells passing through a capillary (512).

Capillary Permeability Endothelial cells—held together by tight junctions and desmosomes Intercellular clefts—gaps of unjoined membrane Small molecules can enter and exit Two types of capillary Continuous—most common Fenestrated—have pores

Special Characteristics of Epithelia Cilia Narrow extracellular space Microvilli Apical region of an epithelial cell Cell junctions Tight junction Epithelium Adhesive belt Desmosome Gap junction Basal region Basal lamina Basement membrane Reticular fibers Nerve ending Connective tissue Capillary Figure 4.1

Structure of Capillaries—Cross Section Red blood cell in lumen Intercellular cleft Endothelial cell nucleus Tight junction Pinocytotic vesicles Pericyte Basement membrane (a) Continuous capillary. Least permeable and most common (e.g., skin, muscle). Figure 20.4

Structure of Capillaries—Cross Section Red blood cell in lumen Intercellular cleft Fenestrations (pores) Endothelial cell nucleus Basement membrane Tight junction Pinocytotic vesicles (b) Fenestrated capillary. Large fenestrations (pores) increase permeability. Occurs in special locations (e.g., kidney, small intestine). Figure 20.4

Wide, leaky capillaries found in some organs Sinusoids Wide, leaky capillaries found in some organs Usually fenestrated Intercellular clefts are wide open Occur in bone marrow and spleen Sinusoids have a large diameter and twisted course

Sinusoids Endothelial Red blood cell in lumen Large intercellular Nucleus of endothelial cell Red blood cell in lumen Endothelial Tight junction Incomplete basement membrane Large intercellular cleft (c) Sinusoidal capillary. Most permeable. Occurs in special locations (e.g., liver, bone marrow, spleen). Figure 20.4

Conduct blood from capillaries toward the heart Veins Conduct blood from capillaries toward the heart Blood pressure is much lower than in arteries Smallest veins—called venules Diameters from 8–100 m Smallest venules—called postcapillary venules Venules join to form veins Tunica externa is the thickest tunic in veins

Vessels interconnect to form vascular anastomoses Organs receive blood from more than one arterial source Neighboring arteries form arterial anastomoses Provide collateral channels Veins anastomose more frequently than arteries

Tunica externa of large vessels have Vasa Vasorum Tunica externa of large vessels have Tiny arteries, capillaries, and veins Vasa vasorum—vessels of vessels Nourish outer region of large vessels Inner half of large vessels receive nutrients from luminal blood

Pulmonary Circulation Pulmonary trunk leaves the right ventricle Divides into right and left pulmonary arteries Pulmonary veins Carry oxygenated blood into the left atrium

Pulmonary Circulation Left pulmonary artery Air-filled alveolus of lung Pulmonary capillary Two lobar arteries to left lung CO2 O2 Right pulmonary Three lobar arteries to right lung veins Right atrium Aortic arch Pulmonary trunk ventricle Left Left atrium Gas exchange Figure 20.7

Systemic Circulation Systemic arteries Carry oxygenated blood away from the heart Aorta—largest artery in the body

Major Arteries Internal carotid artery Common carotid arteries Subclavian artery Aortic arch Ascending aorta Coronary artery Thoracic aorta (above diaphragm) Renal artery Superficial palmar arch Radial artery Ulnar artery Internal iliac artery Deep palmar arch Vertebral artery Brachiocephalic trunk Axillary artery Brachial artery Abdominal aorta Superior mesenteric artery Gonadal artery Common iliac artery External iliac artery Digital arteries Femoral artery Popliteal artery Anterior tibial artery Posterior tibial artery Arcuate artery (a) Anterior view Inferior mesenteric artery Celiac trunk External carotid artery Arteries of the head and trunk Arteries that supply the upper limb lower limb Figure 20.8a

Major Arteries Superficial temporal Facial artery Common carotid (b) Pulse points Common carotid artery Brachial artery Radial artery Femoral artery Popliteal artery Posterior tibial Dorsalis pedis Superficial temporal Facial artery Figure 20.8b

Ascending aorta—arises from the left ventricle The Aorta Ascending aorta—arises from the left ventricle Branches—coronary arteries Aortic arch—lies posterior to the manubrium Branches Brachiocephalic trunk Left common carotid Left subclavian

The Aorta Left internal Right common carotid artery Left subclavian Right subclavian artery Right internal jugular vein Right subclavian vein Right brachiocephalic vein Left internal Left subclavian Left subclavian vein Left brachiocephalic Left common carotid Brachiocephalic trunk Right pulmonary artery Superior vena cava Ascending aorta Right atrium Right ventricle Inferior vena cava Aortic arch Left pulmonary artery Ligamentum arteriosum Thoracic aorta Pulmonary trunk Left atrium Left ventricle Figure 20.9

Descending aorta—continues from the aortic arch The Aorta Descending aorta—continues from the aortic arch Thoracic aorta—in the region of T5–T12 Abdominal aorta—ends at L4 Divides into right and left common iliac arteries

Major Arteries Internal carotid artery Common carotid arteries Subclavian artery Aortic arch Ascending aorta Coronary artery Thoracic aorta (above diaphragm) Renal artery Superficial palmar arch Radial artery Ulnar artery Internal iliac artery Deep palmar arch Vertebral artery Brachiocephalic trunk Axillary artery Brachial artery Abdominal aorta Superior mesenteric artery Gonadal artery Common iliac artery External iliac artery Digital arteries Femoral artery Popliteal artery Anterior tibial artery Posterior tibial artery Arcuate artery (a) Anterior view Inferior mesenteric artery Celiac trunk External carotid artery Arteries of the head and trunk Arteries that supply the upper limb lower limb Figure 20.8a

Arteries of the Head and Neck Superficial temporal artery Ophthalmic artery Maxillary artery Occipital artery Facial artery Lingual artery Superior thyroid artery Larynx Thyroid gland (overlying trachea) Clavicle (cut) Brachiocephalic trunk Internal thoracic Basilar artery Vertebral artery Internal carotid artery Subclavian Axillary (a) Arteries of the head and neck, right aspect External Common Thyrocervical Costocervical Branches of the external Figure 20.10a

Common Carotid Arteries Located deep to sternocleidomastoid muscle Two branches of the common carotid artery External carotid artery Internal carotid artery

Common Carotid Arteries Internal carotid artery branches Anterior cerebral artery Anterior communicating artery Forms part of the cerebral arterial circle Middle cerebral artery

Supply the posterior brain Join to form the basilar artery Vertebral Arteries Supply the posterior brain Join to form the basilar artery Basilar artery divides into two posterior cerebral arteries Posterior cerebral arteries connect to the posterior communicating arteries

Cerebral Arterial Circle Two posterior communicating arteries join the anterior communicating artery Frontal lobe Optic chiasma Middle cerebral artery Internal carotid Mammillary body Temporal lobe Occipital lobe Cerebral arterial circle (circle of Willis) Posterior cerebral artery Basilar artery Vertebral artery Cerebellum communicating (c) Major arteries serving the brain (inferior view, right side of cerebellum and part of right temporal lobe removed) Pons Anterior Figure 20.10

Arteries of the Upper Limb Subclavian artery enters the axilla as the axillary artery Axillary artery becomes the brachial artery at the inferior border of teres major Brachial artery divides into Radial artery and ulnar artery

Arteries of the Upper Limb and Thorax Vertebral artery Costocervical trunk Thoracoacromial artery Axillary artery Subscapular artery Radial artery Ulnar artery Deep palmar arch Superficial palmar arch Digital arteries Brachial artery Suprascapular artery Thyrocervical trunk Posterior circumflex humeral artery Anterior circumflex Deep artery of arm Common interosseous artery Common carotid arteries Right subclavian artery Left subclavian artery Brachiocephalic trunk Posterior intercostal arteries Anterior intercostal artery Internal thoracic artery Lateral thoracic artery Descending aorta Figure 20.11

Arteries of the Abdominal Aorta Celiac trunk Superior mesenteric artery Suprarenal arteries Renal arteries Gonadal (testicular or ovarian) arteries Inferior mesenteric artery Common iliac arteries

Arteries of the Abdominal Aorta Hiatus (opening) for inferior vena cava Diaphragm Inferior phrenic artery Middle suprarenal artery Renal artery Superior mesenteric artery Inferior mesenteric Median sacral Common iliac artery Ureter Gonadal (testicular or ovarian) artery for esophagus Celiac trunk Adrenal (suprarenal) gland Kidney Abdominal aorta Lumbar arteries Figure 20.12

The Celiac Trunk and Main Branches (a) The celiac trunk and its major branches. The left half of the liver has been removed. Liver (cut) Diaphragm Esophagus Left gastric artery Superior mesenteric artery Left gastroepiploic Spleen Stomach Pancreas (major portion lies posterior to stomach) Splenic artery Inferior vena cava Celiac trunk Hepatic artery proper Common hepatic Gastroduodenal Right gastric artery Gallbladder Abdominal aorta Right gastroepiploic Duodenum Figure 20.13a

Distribution of the Superior and Inferior Mesenteric Arteries (b) Distribution of the superior and inferior mesenteric arteries. The transverse colon has been pulled superiorly. Celiac trunk Transverse colon Inferior mesenteric artery Aorta Descending colon Sigmoid colon Rectum Superior mesenteric Ascending colon Ileum Right common iliac artery Appendix Cecum Left colic artery Sigmoidal arteries Superior rectal artery Middle colic artery Intestinal arteries Right colic artery Ileocolic artery Branches of the superior mesenteric artery Branches of the superior Figure 20.13b

Arteries of the Pelvis and Lower Limbs Internal iliac arteries External iliac artery Femoral artery Popliteal artery Anterior tibial artery Posterior tibial artery

Internal Iliac Artery Aorta Common iliac artery Internal iliac artery (a) Anterior view Internal iliac artery External iliac artery Figure 20.14a

Arteries of the Pelvis and Lower Limbs Common iliac artery Deep artery of thigh Obturator artery Descending branch Femoral artery Adductor hiatus Popliteal artery Genicular artery Anterior tibial artery Posterior tibial artery Fibular artery Dorsalis pedis artery Arcuate artery Dorsal metatarsal arteries (a) Anterior view Internal iliac artery Superior gluteal artery External iliac artery Lateral circumflex femoral artery Medial circumflex Figure 20.15a

Arteries of the Pelvis and Lower Limbs (b) Posterior view of leg Popliteal artery Anterior tibial artery Dorsalis pedis artery (from top of foot) Posterior tibial artery Fibular artery Lateral plantar Medial plantar Plantar arch Figure 20.15b

Three major veins enter the right atrium 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

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

Major Veins of the Systemic Circulation Renal vein Splenic vein Basilic vein Brachial vein Cephalic vein Dural venous sinuses External jugular vein Vertebral vein Internal jugular vein Superior vena cava Right and left brachiocephalic veins 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 Small saphenous vein Dorsal venous arch Dorsal metatarsal veins Inferior mesenteric vein Median cubital vein Subclavian vein Veins of the head and trunk Veins that drain the upper limb Veins that drain the lower limb Figure 20.16

Veins of the Head and Neck Venous drainage Internal jugular veins External jugular veins (a) Veins of the head and neck, right superficial aspect Vertebral vein Ophthalmic vein Superficial temporal vein Facial vein Occipital vein Superior and middle thyroid veins Posterior auricular vein External jugular vein Internal jugular vein Brachiocephalic vein Subclavian vein Superior vena cava Figure 20.18

Veins of the Head and Neck Dural sinuses Superior sagittal sinus (b) Dural venous sinuses of the brain Superior sagittal sinus Falx cerebri Inferior sagittal sinus Straight sinus Cavernous sinus Transverse sinuses Jugular foramen Confluence of sinuses Sigmoid sinus Right internal jugular vein Figure 20.17

Veins of the Upper Limbs Deep veins Follow the paths of companion arteries Have the same names as the companion arteries Superficial veins Visible beneath the skin Cephalic vein Basilic vein Median cubital vein

Veins of the Thorax and Right Upper Limb Right subclavian vein Brachiocephalic veins Axillary vein Brachial vein Cephalic vein Basilic vein Median cubital vein Median antebrachial Internal jugular vein External jugular vein Left subclavian vein Superior vena cava Azygos vein Inferior vena cava Ascending lumbar vein Accessory hemiazygos Hemiazygos vein Posterior intercostals Ulnar vein Deep palmar venous arch Superficial palmar Digital veins Radial vein Figure 20.19

Superficial Veins of the Right Upper Limb Form anastomose frequently Median cubital vein is used to obtain blood or administer IV fluids Cephalic vein Biceps brachii Pronator teres Basilic vein Brachioradialis Medial cubital vein Cephalic vein Median vein of the forearm (a) Surface view, right upper limb (b) Cadaver dissection of same view Figure 20.20

Veins of the Thorax Azygos vein Hemiazygos vein

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

Tributaries of the Inferior Vena Cava Inferior phrenic vein Left suprarenal vein Left ascending lumbar vein Lumbar veins Left gonadal vein Common iliac vein Internal iliac vein Renal veins Hepatic veins Inferior vena cava Right suprarenal vein Right gonadal vein External iliac vein (a) Tributaries of the inferior vena cava; venous drainage of the paired abdominal organs. Figure 20.21

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

The Basic Scheme of the Hepatic Portal System (b) The veins of the hepatic portal system Hepatic veins Liver Spleen Gastric veins Inferior vena cava (not part of hepatic portal system) Splenic vein Right gastroepiploic vein Inferior mesenteric vein Superior Large intestine Hepatic portal vein Small intestine Rectum Figure 20.22

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

Veins of the Right Lower Limb and Pelvis Popliteal vein Common iliac vein Fibular vein Anterior tibial vein Dorsalis pedis vein Dorsal venous arch Dorsal metatarsal veins (a) Anterior view Internal iliac vein External iliac vein Inguinal ligament Great saphenous vein (superficial) Small saphenous vein Femoral vein Figure 20.23

Veins of the Right Lower Limb and Pelvis Great saphenous vein Popliteal Anterior tibial vein Fibular Small (superficial) Posterior tibial Plantar veins Deep plantar arch Digital veins (b) Posterior view of leg Great saphenous vein Small (superficial) (c) Superficial veins of leg, posterior view Figure 20.23

Blood Vessels Throughout Life Fetal circulation All major vessels in place by month three of development Differences between fetal and postnatal circulation Fetus must supply blood to the placenta Very little blood is sent through the pulmonary circuit

Vessels to and from the Placenta Umbilical vessels run in the umbilical cord Paired umbilical arteries Unpaired umbilical vein Fetal vessels and structures Ductus venosus Ligamentum venosum

Shunts Away from the Pulmonary Circuit Foramen ovale Ductus arteriosus

Figure 20.25 Fetal Circulation. (1 of 2)

Figure 20.25 Fetal Circulation. (2 of 2)