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Chapter 15

Blood Vessels and Blood Vessels and Blood CirculationBlood Circulation

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The Vascular SystemThe Vascular System

• Closed system• Blood vessels• Four heart chambers

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Blood VesselsBlood Vessels

Five types of blood vessels• Arteries• Arterioles• Capillaries• Venules• Veins

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Checkpoint 15-1: What are the five types of blood vessels?

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Blood Circuits

Two groups of blood vessels• The pulmonary circuit

• Pulmonary artery and its branches• Capillaries in lungs• Pulmonary veins

• The systemic circuit• Aorta• Systemic capillaries• Systemic veins

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Blood flow in a closed system of vessels. Oxygen content changes as blood flows through the capillaries.  Zooming InJudging from color coding, which vessels pick up oxygen? Which vessels release oxygen?

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Checkpoint 15-2: What are the two blood circuits and what areas does each serve?

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Vessel Structure

Three tunics (coats) of arteries and veins• Inner (endothelium)• Middle (smooth [voluntary] muscle)

• Controlled by autonomic nervous system• Thinner in veins

• Outer (supporting connective tissue)

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Sections of small blood vessels. Drawings show the thick wall of an artery, the thin wall of a vein, and the single-layered wall of a capillary. A venous valve also is shown. The arrow indicates the direction of blood flow.  Zooming InWhich vessels have valves that control blood flow?

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Checkpoint 15-3: What type of tissue makes up the middle layer of arteries and veins, and how is this tissue controlled?

Checkpoint 15-4: How many cell layers make up the wall of a capillary?

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Systemic ArteriesSystemic Arteries

The aorta• Largest artery• Receives blood from left ventricle• Branches to all organs

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The Aorta and Its Parts

• Ascending aorta• Aortic arch• Thoracic aorta• Abdominal aorta

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 The aorta and its branches.  Zooming InHow many brachiocephalic arteries are there?

Principal systemic arteries.

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Branches of the Ascending Aorta and Aortic Arch

• Ascending aorta• Left and right coronary arteries

• Aortic arch• Brachiocephalic artery

• Right subclavian artery• Right common carotid artery

• Left common carotid artery• Left subclavian artery

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Branches of the Thoracic Aorta

• Branches to chest wall, esophagus, and bronchi• Intercostal arteries

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Branches of the Abdominal Aorta

• Celiac trunk• Left gastric artery• Splenic artery• Hepatic artery

• Superior mesenteric artery• Inferior mesenteric artery• Paired lateral branches

• Phrenic arteries• Suprarenal arteries• Renal arteries• Ovarian and testicular arteries• Lumbar arteries

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Checkpoint 15-5: What are the subdivisions of the aorta, largest artery?

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The Iliac Arteries and Their Subdivisions

• Internal iliac arteries• External iliac arteries

• Femoral artery• Popliteal artery

• Tibial arteries• Dorsalis pedis

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Arteries That Branch to the Arm and Head

• External carotid artery• Internal carotid artery• Subclavian artery

• Vertebral artery• Axillary artery

• Brachial artery• Radial artery• Ulnar artery

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Checkpoint 15-6: What arteries are formed by the final division of the abdominal aorta?

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Anastomoses

Communication between two vessels• Circle of Willis• Superficial palmar arch• Mesenteric arches• Arterial arches

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Arteries that supply the brain. The bracket at right groups the arteries that make up the circle of Willis.

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Checkpoint 15-8: What is an anastomosis?

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Systemic VeinsSystemic Veins

• Superficial veins• Cephalic, basilic, median cubital veins• Saphenous veins

• Deep veins• Femoral and iliac vessels• Brachial, axillary, subclavian vessels• Jugular veins• Brachiocephalic vein

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The Venae Cavae and Their Tributaries

• Superior vena cava• Head, neck, upper extremities

• Azygos vein• Chest wall

• Inferior vena cava• Right, left veins from paired parts, organs• Unpaired veins from spleen, digestive tract

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Principal systemic veins.  Zooming InHow many brachiocephalic veins are there?

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Checkpoint 15-9: Veins are described as superficial or deep. What does superficial mean?

Checkpoint 15-10: What two large veins drain the systemic blood vessels and empty into the right atrium?

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Venous Sinuses

• Coronary sinus• Cranial venous sinuses

• Cavernous sinuses• Petrosal sinuses

• Superior sagittal sinus• Confluence of sinuses

• Transverse sinuses (lateral sinuses)

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Cranial venous sinuses. The inset shows the paired transverse sinuses, which carry blood from the brain to the jugular veins.

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Checkpoint 15-11: What is a venous sinus?

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The Hepatic Portal System

Carries blood from abdominal organs to liver• Superior mesenteric vein• Splenic vein• Gastric, pancreatic, inferior mesenteric veins• Sinusoids

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Hepatic portal system. Veins from the abdominal organs carry blood to the hepatic portal vein leading to the liver. Arrows show the direction of blood flow.  Zooming InWhat vessel do the hepatic veins drain into?

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Checkpoint 15-12: The hepatic portal system takes blood from the abdominal organs to what organ?

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The Physiology of CirculationThe Physiology of Circulation

• Blood exchanges oxygen, carbon dioxide, other substances generated by cells

• Tissue fluid (interstitial fluid) is exchange medium

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Connection between small blood vessels through capillaries. The blood delivers oxygen (O2) to the tissues and picks up carbon dioxide (CO2) for transport to the lungs. Note the lymphatic capillaries, which aid in tissue drainage.

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Capillary Exchange

How substances move between cells and capillary blood• Diffusion

• Main process • Blood pressure

• Moves material into tissue fluid• Osmotic pressure

• Moves material into capillaries

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Checkpoint 15-13: As materials diffuse back and forth between the blood and tissue fluid across the capillary wall, what force helps to push materials out of the capillary? What force helps to draw materials into the capillary?

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The Dynamics of Blood Flow

Vasomotor center in medulla regulates vasomotor activities• Vasodilation• Vasoconstriction• Precapillary sphincter

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Checkpoint 15-14: Name the two types of vasomotor changes.

Checkpoint 15-15: Where are vasomotor activities regulated?

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Return of Blood to the Heart

Mechanisms that promote blood’s return to heart• Contraction of skeletal muscles• Valves• Breathing

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Role of skeletal muscles and valves in blood return. (A) Contracting skeletal muscle compresses the vein and drives blood forward, opening the proximal valve, while the distal valve closes to prevent backflow of blood. (B) When the muscle relaxes again, the distal valve opens, and the proximal valve closes until blood moving in the vein forces it open again.  Zooming InWhich of the two valves shown is closer to the heart?

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The Pulse

• Ventricular contraction• Wave of increased pressure• Begins at heart and travels to arteries• Influenced by various factors

• Body size• Gender• Age• Muscular activity• Emotion• Body temperature• Thyroid secretion

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Checkpoint 15-16: What is the definition of pulse?

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Blood Pressure

• Force exerted by blood against vessel walls• Determined by heart’s output and resistance to

blood flow

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Cardiac Output

Volume of blood pumped out of each ventricle inone minute• Heart rate

• Beats per minute• Stroke volume

• Controlled by force of contractions

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Resistance to Blood Flow

Peripheral resistance is affected by• Vasomotor changes• Elasticity of blood vessels• Viscosity• Total blood volume

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Measurement of Blood Pressure

Pressure is measured in the brachial arm artery using asphygmomanometer• Systolic pressure

• Occurs during heart contraction• Diastolic pressure

• Occurs during heart relaxation

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Checkpoint 15-17: What is the definition of blood pressure?

Checkpoint 15-18: What two components of blood pressure are measured?

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Abnormal Blood Pressure

• Hypotension• Lower than normal blood pressure

• Hypertension• High blood pressure

• Essential hypertension• No apparent medical cause

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Treatment of Hypertension

• Stage 1• 140/90 mm Hg• Diet, exercise, weight loss

• Stage 2• 160/100 mm Hg• Drugs added to treatment

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Checkpoint 15-19: What is meant by hypertension and hypotension?

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Arterial Degeneration andArterial Degeneration andOther Blood Vessel DisordersOther Blood Vessel Disorders

• Arteriosclerosis• Atherosclerosis

• Clot formation• Leg cramps, pain, lameness• Cerebral artery sclerosis• Hypertension• Coronary artery arteriosclerosis• Renal artery damage• Ischemia

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Treatment for Arterial Degeneration

• Balloon catheterization• Bypass grafts• Stents• Endarterectomy

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Aneurysm

• Bulging sac in blood vessel wall• Swelling deranges other structures• Can burst, causing death• Surgery can replace damaged segment

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Hemorrhage

• Profuse escape of blood from vessels• Internal or external• Can be life-threatening

• Apply pressure to wound• Elevate extremity above heart• Apply pressure to pressure point

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Shock

Inadequate blood flow to tissues• Classified by type

• Cardiogenic• Septic • Hypovolemic• Anaphylactic

• Classified by severity (cause unknown)• Mild• Severe

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Checkpoint 15-20: With regard to the circulation, what is meant by shock?

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Thrombosis

Formation of blood clot in a vessel• Deep venous thrombosis (DVT)• Embolus• Pulmonary embolism• Phlebitis• Thrombophlebitis

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Varicose Veins

Superficial veins that are swollen, distorted, and ineffective• Saphenous veins of lower extremities• Rectal veins (hemorrhoids)