chapter 22 - vessels and circulation

Arteries

Blood vessels that carry blood away from the heart.

Veins

Blood vessels that carry blood toward the heart

Pulmonary Circuit

Supplies the lungs; carries deoxygenated blood to the lungs and back to the heart

Systemic Circuit

Supplies the rest of the body; carries oxygenated blood to body tissues and back.

Anastomotic Connections

Connections between vessels that reduce the impact of blockage of a single vessel

Tunica Intima (interna)

Inner layer; consists of endothelium and connective tissue. Selectively permeable

Tunica Media

Middle layer; consists of smooth muscle and connective tissue. Controls luminal diameter (vasomotion)

Tunica Adventitia (Externa)

Outer layer; mostly connective tissue sheath. Thicker than the media in veins

Artery vs. Vein Wall

Artery walls are thicker due to the thickness of the tunica media. Veins have thinner walls but larger luminal diameters

Artery Lumen (Shape)

Arteries contract, giving the lumen a smaller diameter and a pleated appearance in cross-section

Vein Structures

Veins typically contain valves (internal structures that prevent backflow)

Elastic Arteries (Conducting)

Largest arteries (e.g., aorta, common carotid). Deliver blood at high speed; expand during systole and recoil during diastole

Muscular Arteries (Distribution)

Transport blood to skeletal muscles and organs. Tunica media is thick

Arterioles

Considerably smaller arteries. Major point of resistance to blood flow. Regulate flow to capillaries

Capillaries

Smallest and most delicate vessels. Walls permit exchange between blood and interstitial fluid

Continuous Capillaries

Endothelium forms a complete lining; found in all tissues except epithelia and cartilage

Fenestrated Capillaries

Contain "windows" or pores; more permeable; permit rapid diffusion (e.g., in areas where rapid diffusion is needed)

Venules

The smallest veins; collect blood from capillaries

Large Veins

Include the superior and inferior venae cavae. Movement relies on pressure changes, not valves

Aorta

The first artery of the systemic circuit; exits the left ventricle

Aortic Arch Branches

Brachiocephalic trunk, Left common carotid artery, and Left subclavian artery

Common Carotid Arteries

Supply the head and neck. Split into External (feeds face) and Internal (travels to brain)

Vertebral Arteries

Receive blood from subclavian arteries; travel through cervical vertebrae to supply the brain

Cerebral Arterial Circle (Circle of Willis)

A union of arteries at the base of the brain that provides collateral circulation (alternate routes for blood flow).

Thoracic Aorta

Segment of the descending aorta above the diaphragm; branches include intercostal arteries

Abdominal Aorta

Segment of the descending aorta below the diaphragm; gives rise to celiac trunk, renal, and mesenteric arteries

Internal Jugular Vein

Primary vein that drains blood from the brain and returns it to the heart

Hepatic Portal System

Specialized venous system that drains digestive organs before blood returns to the heart

How are the right and left sides typically represented visually regarding oxygenation?

Right side is blue (carrying deoxygenated blood to the lungs), and Left side is red (carrying oxygenated blood to the body)

What are the major "great veins" and their destination?

The Superior Vena Cava (draining above the diaphragm) and Inferior Vena Cava (draining below the diaphragm). They deliver systemic blood to the right atrium

What third vessel delivers blood specifically from the heart wall itself to the right atrium?

The Coronary Sinus. It receives deoxygenated blood from the coronary circuits

Where is the majority of the body's blood volume located at any given time?

The majority of blood is contained within the venous system (veins, venules, and venous reservoirs)

Which vessels specifically enter the atria and which exit the ventricles?

Only veins (vessels carrying blood toward the heart) enter the atria. Only arteries (vessels carrying blood away from the heart) exit the ventricles

What is the primary vessel that drains blood from the heart muscle tissue itself (the coronary circuit) back into the right atrium?

The Coronary Sinus. The right atrium receives oxygen-poor blood from the systemic circuit and the coronary circuit via the superior vena cava, inferior vena cava, and the coronary sinus. The systemic circuit includes the coronary circuit, which supplies the myocardium

What are the Vertebral Arteries and where do they receive blood?

They are major suppliers of blood to the brain, along with the internal carotid arteries. They receive blood from the subclavian arteries and travel through the transverse foramina of the cervical vertebrae into the foramen magnum of the skull

What mechanism exists to ensure blood flow continues to a tissue, such as the brain, if a vessel becomes blocked?

Collateral circulation (alternate routes for blood flow). Arteries and veins often make anastomotic connections (alternate connections) that reduce the impact if a single vessel is blocked. The Cerebral Arterial Circle (circle of Willis) provides collateral circulation in the brain

What types of strokes are defined by a blocked vessel versus a burst vessel?

A blockage of blood flow (congestion) leading to tissue damage is called an ischemic stroke. If a vessel bursts and causes bleeding in the brain, it is called a hemorrhagic stroke.

Where is blood traveling when it enters a vein?

All veins are defined as vessels that carry blood toward the heart. The heart is the muscular pump that provides the force for circulating blood throughout the body