Vessels and Circulation Co 23 Chapter 23 Vessels and Circulation

Types of Blood Vessels Arteries travel away from the heart Arterioles are smallest arteries Capillaries are smallest vessels one red blood cell wide thin walls so oxygen, carbon dioxide, and water can move in or out of vessels Veins return to the heart Venules are the smallest veins

Fig. 23.1 Walls of a Blood Vessel Artery Vein Arteries and veins have 3 tunics (layers) Tunica intima is inner layer endothelium (simple squamous) areolar connective tissue in muscular arteries, includes internal elastic lamina Tunica intima Endothelium Valves Subendothelial layer Internal elastic lamina Tunica media Tunica externa Vasa vasorum

Fig. 23.1 Walls of a Blood Vessel Vein Artery Tunica media layers of smooth muscle in muscular arteries, includes external elastic lamina Valves Tunica media External elastic lamina

Fig. 23.1 Walls of a Blood Vessel Artery Tunica media in arteries thickest layer; mostly smooth muscle enables vasoconstriction and vasodilation Lumen Tunica media External elastic lamina

Fig. 23.1 Walls of a Blood Vessel Tunica externa areolar connective tissue with elastic and collagen fibers anchors vessel to other structures includes vasa vasorum, blood supply for very large blood vessels thickest layer in veins Artery Vein Tunica intima Tunica media Tunica externa Vasa vasorum

Fig. 23.1 Walls of a Blood Vessel Arteries lumen is narrow lots of elastic and collagen fibers in tunics stay open; withstand changes in blood pressure Veins lumen is wide valves within lumen prevent blood flow in wrong direction Tunica intima Endothelium Subendothelial layer Valves Internal elastic lamina Tunica media External elastic lamina Tunica externa Vasa vasorum Lumen Capillary bed Lumen Artery Lumen Vein Endothelium Basement membrane Capillary

Fig. 23.1 Walls of a Blood Vessel Artery Vein Capillaries connect arteries and veins only have tunica interna thin walls enable gas exchange Capillary bed Lumen Endothelium Basement membrane Capillary

Vein Tunica externa Tunica media Tunica intima Blood in the lumen Fig. 23.2 Vein Tunica externa Tunica media Tunica intima Blood in the lumen Artery Tunica intima Tunica media Tunica externa LM 100x

Types of Arteries Elastic arteries Ascending aorta Fig. 23.3 Types of Arteries Ascending aorta Pulmonary trunk (artery) Elastic arteries largest AKA conducting arteries— conduct blood from heart to smaller arteries ex. aorta, pulmonary, brachiocephalic, common carotid, subclavian, common iliac arteries Arteries Elastic artery Tunica intima Tunica media Tunica externa Descending aorta

Types of Arteries Elastic arteries Lumen Tunica intima Fig. 23.3 Types of Arteries Lumen Tunica intima Elastic arteries very thick tunica media with elastic fibers throughout elastic fibers enable stretching during ventricular contraction, return to original shape Tunica media Elastic fibers throughout tunica media Tunica externa LM 100x 23.4 (a) Elastic artery

Types of Arteries Muscular arteries Muscular artery Tunica intima Fig. 23.3 Types of Arteries Muscular artery Tunica intima Internal elastic lamina Tunica media External elastic lamina Tunica externa Muscular arteries AKA distributing arteries—distribute blood to body organs and tissues most named arteries, ex. brachial, anterior tibial, coronary, inferior mesentery

Types of Arteries Muscular arteries Tunica intima Fig. 23.3 Tunica intima Types of Arteries Internal elastic lamina Muscular arteries shape confined by internal elastic lamina (around tunica intima) and external elastic lamina (around tunica media) less ability to stretch; more ability to vasoconstrict and vasodilate Lumen Tunica media External elastic lamina Tunica externa LM 100x 23.4 (b) Muscular artery

Types of Arteries Arterioles Arteriole Tunica intima Tunica media Fig. 23.3 Types of Arteries Arteriole Tunica intima Tunica media Tunica externa Arterioles smallest larger arterioles have 3 tunics; small arterioles have endothelium and one layer of smooth muscle

Types of Arteries Arterioles Tunica media with few layers of smooth Fig. 23.3 Types of Arteries Tunica media with few layers of smooth muscle Arterioles <6 layers of smooth muscle vasoconstriction increases blood pressure, decreases blood flow to capillaries Lumen LM 220x 23.4 (c) Arteriole

Capillaries Connect arterioles to venules Fig. 23.3 Capillaries Connect arterioles to venules usually 1 mm long, 8-10 micometers wide diameter of one red blood cell erythrocytes must pass through one at a time Basement membrane Endothelium Capillary

Capillaries Basement membrane and endothelium only Fig. 23.3 Capillaries Basement membrane and endothelium only gases and nutrients diffuse easily across capillary wall into extracellular fluid gases then move from ECF to cells

Capillary beds True capillaries Arterial end Venous end Fig. 23.5 Capillary beds True capillaries Arterial end Venous end Metarteriole flows into capillary bed, venule flows out White blood cells travel through metarteriole, bypass capillaries Endothelium Endothelium Smooth muscle cells Thoroughfare channel Metarteriole Postcapillary venule Arteriole Relaxed precapillary sphincters (a) Sphincters relaxed; capillary bed well perfused

Fig. 23.5 (b) Sphincters contracted; blood bypasses capillary bed Contracted precapillary sphincters Capillary beds Precapillary sphincter is circle of smooth muscle around proximal end of capillary can cut off blood flow cycle on and off to meet tissue’s nutrient need

Types of capillaries Continuous capillary most common Fig. 23.6 Types of capillaries Continuous capillary most common continuous lining of endothelial cells materials pass through by diffusion or pinocytosis found in muscle, skin, lungs Basement membrane Pinocytotic vesicles Erythrocyte Lumen Nucleus of endothelial cell (a) Continuous capillary

Types of capillaries Fenestrated capillary Fig. 23.6 Types of capillaries Fenestrated capillary have pores (fenestrations) in each endothelial cell enable lots of fluid transport between blood and interstitial tissue found in small intestine, endocrine glands, kidney Basement membrane Fenestrations Erythrocyte Lumen (b) Fenestrated capillary

Types of capillaries Sinusoids AKA discontinuous capillaries Fig. 23.6 Types of capillaries Sinusoids AKA discontinuous capillaries have large gaps in epithelial membrane basement membrane discontinuous or absent often larger than other capillaries allow transport of proteins or blood cells found in bone marrow, spleen, liver Discontinuous basement membrane Large openings Erythrocyte Lumen (c) Sinusoid

Fig. 23.3 Ascending aorta Pulmonary trunk (artery) Superior vena cava Veins Arteries Large vein Elastic artery Tunica intima Inferior vena cava Valve Tunica intima Tunica media Tunica media Tunica externa Tunica externa Descending aorta Small to medium- sized vein Muscular artery Tunica intima Tunica intima Valve Internal elastic lamina Tunica media Tunica media Tunica externa External elastic lamina Tunica externa Venule Tunica intima Arteriole Tunica media Tunica intima Tunica media Tunica externa Tunica externa Basement membrane Endothelium Capillary

Veins Vein Tunica intima Lumen is wide Thick tunica externa Fig. 23.1 Vein Veins Lumen is wide Thick tunica externa Contain valves to prevent backflow of blood formed from tunica intima strengthened by elastic and collagen fibers Tunica intima Endothelium Subendothelial layer Valves Tunica media Tunica externa Lumen Vasa vasorum

Veins Large veins Small to medium-sized veins Superior Fig. 23.3 Veins Large veins Travel with and correspond to elastic arteries Small to medium-sized veins Travel with and correspond to muscular arteries Superior vena cava Veins Large vein Inferior vena cava Tunica intima Valve Tunica media Tunica externa Small to medium- sized vein Tunica intima Valve Tunica media Tunica externa

Skeletal muscle pump To heart Increased pressure Fig. 23.7 To heart Skeletal muscle pump Increased pressure opens valve Contraction of muscles squeezes veins, forcing blood through Works more efficiently when a person is active When a person is inactive, blood may pool in lower extremities Contracted skeletal muscles Valve closed (to prevent blood backflow) Blood flow from tissues Vein

Fig. 23.7 Respiratory pump Respiratory pump Thoracic cavity Abdominopelvic cavity contraction of diaphragm compresses abdominal cavity, squeezes vessels, pushes blood through relaxation of diaphragm decreases pressure in abdominal cavity, draws blood into vessels of abdomen Inhalation Increases blood flow into thoracic veins Exhalation Increases blood flow into heart and abdominal veins Decreased intrathoracic pressure Increased intrathoracic pressure Diaphragm contracts Diaphragm relaxes Blood moves superiorly Compression Release of compression Decreased intra-abdominal pressure Increased intra-abdominal pressure (b)

Types of Veins Venules smallest veins Fig. 23.3 Types of Veins Venules smallest veins travel with and correspond to arterioles smallest are postcapillary venules drain capillaries similar to capillaries but slightly wider lumen largest venules have all 3 tunics Tunica intima Tunica media Tunica externa Venule Postcapillary venule

Fig. 23.3 Ascending aorta Pulmonary trunk (artery) Superior vena cava Veins Arteries Large vein Elastic artery Tunica intima Inferior vena cava Valve Tunica intima Tunica media Tunica media Tunica externa Tunica externa Descending aorta Small to medium- sized vein Muscular artery Tunica intima Tunica intima Valve Internal elastic lamina Tunica media Tunica media Tunica externa External elastic lamina Tunica externa Venule Tunica intima Arteriole Tunica media Tunica intima Tunica media Tunica externa Tunica externa Basement membrane Endothelium Capillary

Varicose veins Varicose veins Veins with nonfunctional valves Page 688 Varicose veins Varicose veins Veins with nonfunctional valves Blood pools in one area, vein swells Causes: genetics, aging, long periods of standing, obesity, pregnancy Compression stockings prevent the vessels from swelling Treatment: sclerotherapy—irritant injected into vein; vein scars and seals off phlebectomy—vein removal

Pulse and Blood Pressure Blood pressure (mm Hg) Aorta Arteries Arterioles Capillaries Venules Veins Venae cavae 80 60 40 20 Systolic pressure 120 100 Diastolic pressure Pulse and Blood Pressure Pulse = blood ejected from left ventricle Blood pressure = force that blood places on inside wall of blood vessel Highest in aorta, lowest in vena cava

Pulse points Positions on body where pulse can be felt Page 691 Superficial temporal artery Pulse points Facial artery Common carotid artery Positions on body where pulse can be felt Located where artery can be compressed against bone or solid structure Pulse felt with fingers, not thumb (has its own pulse) Brachial artery Radial artery Femoral artery Popliteal artery Posterior Posterior tibial artery Dorsalis pedis artery

Systemic circulation From heart, blood pumped through ascending aorta Left common carotid artery Systemic circulation Right common carotid artery From heart, blood pumped through ascending aorta Right and left coronary arteries branch off first Brachiocephalic trunk is first of 3 large branches on aortic arch Branches into right common carotid: supplies right side of head and neck right subclavian: supplies right arm and some thoracic structures Right subclavian artery Left subclavian artery Brachiocephalic trunk Right coronary artery Left coronary artery

Left common carotid artery Systemic circulation Right common carotid artery Left common carotid is next branch off aortic arch supplies left side of head and neck Left subclavian is last supplies left arm and some thoracic structures After arch, aorta becomes descending aorta Right subclavian artery Left subclavian artery Brachiocephalic trunk Aortic arch Ascending aorta Descending aorta Right coronary artery Left coronary artery

Head and neck circulation Fig. 23.10ab Head and neck circulation Common carotid artery splits above thyroid cartilage internal carotid artery supplies internal skull structures external carotid artery supplies external skull structures Branches of common carotid artery Internal carotid artery External carotid artery Common carotid artery (a) Arteries, right lateral view

Systemic circulation External carotid artery has many branches Fig. 23.10ab Systemic circulation External carotid artery has many branches Names match places they supply (facial: face; lingual: tongue, etc.) Branches of external carotid artery Superficial temporal artery Maxillary artery Posterior auricular artery Occipital artery Facial artery Lingual artery Ascending pharyngeal artery Superior thyroid artery Thyroid cartilage Brachiocephalic artery Common carotid artery Subclavian artery (a) Arteries, right lateral view

Head and neck circulation Fig. 23.10ab Head and neck circulation Vertebral artery emerges from subclavian travel through transverse foramina of cervical vertebrae, through foramen magnum, to form basilar artery; becomes posterior cerebral arteries Paired arteries to head and neck Thyrocervical trunk Costocervical trunk Vertebral artery Brachiocephalic artery Common carotid artery Subclavian artery (a) Arteries, right lateral view

Fig. 23.10ab Systemic circulation Veins of neck and superficial head structures Veins from head and neck drain into subclavian, then brachiocephalic vein Occipital vein Superficial temporal vein Maxillary vein Posterior auricular vein Major veins draining head and neck Retromandibular vein Facial vein Vertebral vein Lingual vein External jugular vein Internal jugular vein Superior thyroid vein Right subclavian vein Right brachiocephalic vein (b) Veins, right lateral view

Cerebral arterial circle Fig. 23.11 Anterior Anterior communicating artery (connects right and left anterior cerebral arteries) Internal carotid artery Anterior cerebral artery Anterior cerebral arteries (R/L) Ophthalmic artery Internal carotid artery (R/L) Posterior communicating arteries (R/L) Middle cerebral artery Posterior cerebral arteries (R/L) Circle of Willis Cerebral arterial circle (circle of Willis) Posterior cerebral artery Anastomosis (arteries that join to supply one area) around sella turcica Basilar artery Vertebral artery Posterior (a) Arteries of the brain, inferior view

Venous draining from head Fig. 23.11 Superior sagittal sinus Inferior sagittal sinus Cavernous sinus Superior petrosal sinus Inferior petrosal sinus Ophthalmic veins Straight sinus Occipital sinus Marginal sinuses Transverse sinus Sigmoid sinus Internal jugular vein (b) Cranial and facial veins, right superior anterolateral view Facial vein Venous draining from head Dural venous sinus system drains into internal jugular veins

Major arteries Descending thoracic aorta Fig. 23.12 Major arteries Descending thoracic aorta Descending thoracic aorta becomes descending abdominal aorta below diaphragm Left renal artery Right renal artery Descending abdominal aorta Common iliac artery Left internal iliac artery Left external iliac artery Left femoral artery

Major arteries Descending thoracic aorta Renal arteries supply kidneys Fig. 23.12 Major arteries Descending thoracic aorta Renal arteries supply kidneys Left renal artery Right renal artery Descending abdominal aorta Common iliac artery Left internal iliac artery Left external iliac artery Left femoral artery

Major arteries Common iliac artery Fig. 23.12 Major arteries Common iliac artery Above sacrum, aorta splits into common iliac arteries Common iliac branches into internal and external iliac arteries Below inguinal ligament, external iliac artery renamed femoral artery Left internal iliac artery Left external iliac artery Left femoral artery

Thoracic arteries Branches into: Anterior intercostal Fig. 23.12 Thoracic arteries Branches into: anterior intercostal arteries, supply anterior intercostal spaces musculophrenic artery, divides into anterior intercostal arteries 7-9 Anterior intercostal arteries Musculophrenic artery

Thoracic and abdominal veins Fig. 23.13 Thoracic and abdominal veins Superior vena cava Lumbar veins and posterior intercostal veins drain into azygos system along posterior thoracic wall Hemiazygos drains left-side veins Azygos vein drains right-side veins, drains into superior vena cava Azygos vein Posterior intercostal veins Hemiazygos vein

Bronchial circulation Bronchial arteries branch off descending thoracic aorta supply blood to bronchi, bronchioles and connective tissue of lungs Bronchial veins drain in to azygos system

Pulmonary circulation Pulmonary circulation oxygenates blood Bronchial circulation supports lung tissues branches off aorta

Digestive System

Fig. 23.15 Celiac trunk Liver celiac trunk branches off aorta, supplies stomach, part of duodenum, liver, part of pancreas, spleen Esophagus Stomach Spleen Duodenum Pancreas

Fig. 23.15 Celiac trunk Liver Left gastric artery Esophagus Splenic artery Stomach Common hepatic artery Spleen celiac trunk branches into left gastric, splenic, and common hepatic arteries Duodenum Pancreas

Abdominal Arteries Celiac trunk Celiac trunk branches from abdominal aorta, branches into: Left gastric artery supplies stomach Splenic artery supplies spleen Common hepatic artery supplies liver Liver Common hepatic artery Left gastric artery Hepatic artery proper Stomach Splenic artery Spleen Right gastric artery Superior mesenteric artery Descending abdominal aorta Inferior vena cava

3 unpaired arteries branching from abdominal aorta Fig. 23.15 Celiac trunk and branches Left gastric artery Splenic artery Liver Common hepatic artery Esophagus Hepatic artery proper Stomach Left hepatic artery Left gastro-omental artery Right hepatic artery Spleen Right gastric artery Right gastro-omental artery Gastroduodenal artery Duodenum Pancreas Superior mesenteric artery Descending abdominal aorta Inferior vena cava 3 unpaired arteries branching from abdominal aorta celiac trunk supplies stomach, part of duodenum, liver, part of pancreas, spleen

Superior mesenteric artery located inferior to celiac trunk Transverse colon Fig. 23.15 Superior mesenteric artery Celiac trunk Descending colon Superior mesenteric artery located inferior to celiac trunk supplies most of small intestine, pancreas, proximal large intestine Inferior mesenteric artery

Transverse colon Fig. 23.15 Superior mesenteric artery Celiac trunk Descending colon Inferior mesenteric artery branches from aorta superior to common iliac arteries supplies inferior colon and rectum Inferior mesenteric artery

Hepatic portal vein receives blood from GI tract; formed from inferior mesenteric vein drains from distal large intestine splenic vein drains spleen superior mesenteric vein drains small intestine and part of large intestine Liver Hepatic portal vein Splenic vein Superior mesenteric vein Inferior mesenteric vein Fig. 23.16

Page 702 The configuration of the veins of the hepatic portal system resembles the side view of a chair. Hepatic portal vein Splenic vein Inferior mesenteric vein Superior mesenteric vein

Fig. 23.16 Blood leaves liver through hepatic veins, drains into inferior vena cava Inferior vena cava Diaphragm Hepatic veins Liver Hepatic portal vein Splenic vein

Renal arteries supply kidneys Gonadal arteries supply gonads Fig. 23.12 Left renal artery Right renal artery Right gonadal artery Left gonadal artery Renal arteries supply kidneys Gonadal arteries supply gonads

Blood returns through veins with same names Fig. 23.13 Right renal vein Left renal vein Right gonadal vein Left gonadal vein Blood returns through veins with same names Renal veins drain kidneys Gonadal veins drain gonads

Supply to pelvis and perineum from internal iliac artery Fig. 23.18 Supply to pelvis and perineum from internal iliac artery Branches supply gluteal region, medial thigh muscles, lower rectum and anus, perineum, uterus, and vagina Common iliac artery Internal iliac artery External iliac artery

Subclavian arteries supply blood to upper limbs Fig. 23.19ab Subclavian artery Subclavian arteries supply blood to upper limbs After passing over first rib, becomes axillary artery After passing teres major muscle, becomes brachial artery Axillary artery Brachial artery

Fig. 23.19ab In cubital fossa, brachial artery splits into radial artery and ulnar artery anastomose into two arches in palm: superficial palmar arch and deep palmar arch digital arteries supply fingers Brachial artery Radial artery Ulnar artery Deep palmar arch Superficial palmar arch Digital arteries (a) Arteries of right upper limb

Median cubital vein connects cephalic and basilic veins Fig. 23.19ab On hand dorsal venous network drains into basilic vein and cephalic vein basilic veins becomes axillary vein in armpit cephalic vein joins inferior to subclavian Median cubital vein connects cephalic and basilic veins usual site for blood donations or samples Cephalic vein Basilic vein Ulnar veins Radial veins Dorsal venous network Superficial veins Deep veins (b) Veins of right upper limb

Radial and ulnar veins merge at cubital fossa to form 2 brachial veins Fig. 23.19ab On hand superficial and deep palmar venous arches drain into 2 radial veins and 2 ulnar veins (deep) Radial and ulnar veins merge at cubital fossa to form 2 brachial veins Brachial veins Cephalic vein Basilic vein Ulnar veins Radial veins Deep venous arch Superficial venous arch Superficial veins Deep veins

Brachial veins merge to form axillary vein Fig. 23.19ab Subclavian vein Brachial veins merge to form axillary vein Basilic vein joins at about level of teres major Cephalic vein joins near clavicle After passing lateral border of first rib, renamed subclavian vein Axillary vein Cephalic vein Basilic vein Brachial veins Median cubital vein Cephalic vein Basilic vein Ulnar veins Radial veins Dorsal venous network Deep palmar venous arch Superficial palmar venous arch

External iliac becomes femoral artery inferior to inguinal ligament Anterior view Fig. 23.20a External iliac becomes femoral artery inferior to inguinal ligament deep femoral artery supplies hip joint via medial and lateral femoral circumflex arteries Femoral artery becomes popliteal artery in popliteal fossa supplies knee joint and muscles Common iliac artery External iliac artery Internal iliac artery Inguinal ligament Obturator artery Lateral femoral circumflex artery Femoral artery Medial femoral circumflex artery Deep femoral artery Popliteal artery

Popliteal artery branches anterior tibial artery supplies anterior lower leg posterior tibial artery supplies posterior lower leg Fibular artery is branch of posterior tibial artery – supplies lateral compartment leg muscles Fig. 23.20a Popliteal artery Anterior tibial artery Posterior tibial artery Fibular artery Dorsalis pedis artery Digital arteries

Fig. 23.20b Popliteal vein Dorsal venous arch drains into great saphenous vein and small saphenous vein great saphenous vein drains into femoral vein small saphenous vein drains into popliteal vein Small saphenous vein Great saphenous vein Dorsal venous arch Deep veins Superficial veins

Digital veins and deep veins of foot drain into lateral plantar veins Fig. 23.20b Digital veins and deep veins of foot drain into lateral plantar veins drain into posterior tibial veins Fibular veins drain into posterior tibial veins Anterior tibial veins collect from deep veins on dorsum of foot Anterior and posterior tibial veins merge into popliteal vein Popliteal vein Small saphenous vein Anterior tibial veins Posterior tibial veins Fibular veins Lateral plantar veins Medial plantar veins Digital veins

Fig. 23.20b Popliteal vein curves to anterior thigh, becomes femoral vein, becomes external iliac vein above inguinal ligament External iliac vein Femoral vein Great saphenous vein Popliteal vein Small saphenous vein Posterior view

Left and right common iliac veins merge to form inferior vena cava Fig. 23.13 External iliac vein and internal iliac vein merge into common iliac vein Left and right common iliac veins merge to form inferior vena cava Inferior vena cava Left common iliac vein Left external iliac vein Left internal iliac vein Left femoral vein Inguinal ligament

Blood in narrowed lumen Page 706 Blood in narrowed lumen Atherosclerosis Affects elastic and muscular arteries Tunica intima thickens; lumen narrows Causes: injury to tunica intima: infection, trauma, or hypertension injury attracts white blood cells and immune response cholesterol proteins (LDL and VLDL) enter tunica intima, stick to vessel wall other cells attracted, create foam cells, which develop into plaques Atheroma occluding lumen Lumen LM 20x LM 50x Normal artery Atherosclerotic artery

Treatment: angioplasty Page 706 Catheter Atheroma Artery Treatment: angioplasty Stent inserted into artery and expanded Stent compresses plaques, becomes new wall of artery, expanding artery 1 An uninflated balloon and compressed stent are passed through a catheter to the area of the artery that is obstructed. Stent Balloon 2 Balloon inflates, which expands the stent and inserts it in place and also compresses the atheroma. 3 The stent remains in the vessel as the balloon is deflated and the catheter is withdrawn.

Aneurysm Localized, abnormal dilation of blood vessel Page 713 Aneurysm Localized, abnormal dilation of blood vessel May be caused by atherosclerosis Felt as pulsating mass if in abdominal aorta Visualized by x-ray or ultrasound If ruptures, rarely survived Abdominal aneurysm

Aneurysm Treatment possible for abdominal aneurysm Page 713 Aneurysm Aorta Blood flows through stent graft Treatment possible for abdominal aneurysm Stent graft replaces inner artery Stent graft released from catheter Endovascular stent graft in place Abdominal aortic aneurysm Plaque Abdominal aneurysm Catheter insterted into femoral artery Common iliac artery

Fig. 23.25 Fetal circulation Inferior vena cava Oxygenated blood comes from placenta through umbilical vein Ductus venosus sends blood directly to inferior vena cava (passes under liver) After birth, transforms into round ligament of liver Ductus venosus Umbilical vein