Blood Vessels Flashcards
General Organization: Pulmonary Circulation
- between right ventricle and the left atrium
* responsible for elimination of CO2 and acquisition of O2
General Organization: Systemic Circulation
- supply to the majority of the body’s tissues
- could be considered as 2 parts: divides to supply 1) head, neck, and upper extremities and 2) the lower (remainder) portion of the body
- between left ventricle and right atrium
- two parts return via the superior and inferior vena cava, respectively
General Organization: Portal Circulation
- further subdivision of the lower systemic circulation.
- represents venous return from the G.I. tract in the abdomen.
- flows thru portal vein eventually into the liver and then back into the general circulation via the hepatic veins to the inferior vena cava.
General Organization: Circulatory System
composed of a series of blood vessels which move blood to and from the heart and bring about the transport of nutrients and waste products back and forth between the lungs and the body’s tissues.
- The arterial end is considered to be taking blood away from the heart, and with the exception of the pulmonary circulation, is considered to be transporting oxygenated blood.
- The venous end is considered to be taking blood back toward the heart, and with the exception of the pulmonary circulation is transporting deoxygenated blood.
Arteries (Layers)
A. Composed of 3 circular layers - tunics
- Tunica intima (tunica interna) - inner coat
- a lining of endothelium (simple squamous ep.) that is in contact with blood of lumen
- layer of connective tissue immediately surrounding this - in larger arteries the outer portion of this will be called the internal elastic membrane (lamina) - Tunica media - middle coat - in arteries - usually thickest tunic
- contains mostly smooth muscle arranged circumferentially with some elastic C.T. (more in larger arteries) - Tunica Externa (Tunica Adventitia)
- composed mostly of loose C.T.
- will have some elastic and collagenous fibers
- may contain some smooth muscle fibers (few)
- in some arteries is separated from the tunica media by external elastic membrane (lamina)
Arteries (Details)
B. The largest arteries are called elastic arteries and these have the greatest amount of elastic tissue in their walls. An example is the aorta - when blood is forced in, it causes the walls to be stretched, and the force from their recoil aids in propelling the blood forward.
C. When the smooth muscle in the walls contracts, it will narrow the width of the lumen. This is called vasoconstriction - when it relaxes one has an increase in diameter of the lumen and vasodilation.
D. Collateral circulation - when there exists more than one route of blood supply to an area. In cases where one of the routes may become blocked, the area will still receive adequate blood supply.
Arterioles (2 details)
A. Small arteries which will eventually flow into the capillaries.
B. Important in regulation of blood flow to capillaries by contraction and relaxation of smooth muscle in walls.
Capillaries (7 details)
A. Microscopic blood vessels between arterioles and venules.
B. Not much more than endothelium with a lumen the diameter of a single RBC.
C. Ubiquitous throughout the body.
D. Relative distribution varies with nutrient demand.
E. Permits exchange of gases and nutrients between blood and interstitial fluid (therefore between blood and cells).
F. Precapillary Sphincter - a ring of smooth muscle at the opening of a capillary - determines the amount of blood that enters.
G. Lining may be continuous, discontinuous.
Venules (2 details)
A. Blood vessels between capillaries and veins.
B. Very small or non-existant tunica media
Veins (6 details)
A. Contain same basic 3 tunics as arteries but have a very poorly developed tunica media.
B. Considerably less smooth muscle and elastic tissue.
C. Walls are much thinner - do not need as much strength because blood pressure is so much lower in the veins.
D. Veins unlike arteries, have valves to stop backflow of blood.
E. Varicose Vein - when walls of vein lose their elasticity and become stretched - often the result of a damaged valve.
F. Hemorrhoids - varicosities in the veins in the walls of the anal canal.
Ascending Aorta
- Blood Supply to the Heart
A. Right and Left Coronary Arteries - branch from just above semilunar valves
B. Venous Drainage: Coronary Sinus - with its major tributaries the Great Cardiac Vein ( anterior aspect) and the Middle Cardiac Vein (posterior aspect)
Arch of the Aorta (asymmetric)
A. Brachiocephalic Artery - branches into:
1. Right Subclavian Artery - supplies the right upper extremity (also gives off vertebral artery)
2. Right Common Carotid Artery - along with vertebral arteries and left common carotid, supplies the head and neck.
B. Left Common Carotid Artery - directly from arch
C. Left Subclavian Artery - directly off - to upper left extremity - also gives off left vertebral.
Blood Supply to the Upper Extremity (Same for both) *8 Details
A. Subclavian Artery
B. Axillary Artery - continuation of subclavian in the axilla (armpit)
C. Brachial Artery - continuation of Axillary in the upper arm
D. Ulnar Artery -continuation of Brachial Artery on the ulnar side of the forearm.
E. Radial Artery - continuation of the Brachial Artery on the radial side of the forearm.
F. Deep Palmer Arch and the Superficial Palmer Arch - anastomosis of the Radial and Ulnar Arteries in the hand.
G. Digital Arteries - arise from Palmer Arches and supply the digits
*Venous Drainage of the Upper Extremity
H. Deep Veins: Correspond to the arteries of the same name
1. Brachial
2. Axillary
3. Subclavian
I. Superficial Veins
1. Cephalic Vein - begins in veins of the hand (posterior radial side) and courses superiorly on the radial side of the forearm - sometimes unites with an Accessory Cephalic Vein just below the elbow, and then continues superiorly on the lateral side of the arm.
2. Basilic Vein - begins on ulnar side of the hand. Extends along the posterior surface of ulna and joins medial cubital vein in cubital fossa (this is vein that is punctured for injection or sampling). The Basilic Vein unites with the Brachial Vein to form the Axillary Vein which flows into the Subclavian Vein.
Blood Supply to the Head and Neck (Same on both sides) *14 details
A. Common Carotid Artery - from Brachiocephalic on right - directly from aortic arch on left. Branches into Internal and External branches at the carotid sinus
B. Internal Carotid Artery - supplies the brain
C. External Carotid Artery - supplies external aspects of the head and neck. Gives rise to (among others): Facial Artery, Maxillary Artery, Superficial Temporal Artery(ies) and the Occipital Artery
D. Vertebral Artery - arises from Subclavian, passes through transverse foramina of the cervical vertebrae and the foramen magnum (or vertebral foramen) to the brain.
E. Basilar Artery - formed by union of left and right vertebral arteries.
F. Circle of Willis - circular anastomosis of four arteries that supply the brain (2 internal carotids and 2 vertebrals)
- surrounds hypothalamus
*Venous Drainage
G. Superior Saggital Sinus
H. Inferior Saggital Sinus
I. Straight Sinus - connects above
J. Transverse Sinus
K. Sigmoid Sinus
L. Internal Jugular Vein
M. External Jugular Vein - drains external aspects of the head and neck.
*Jugular veins unite with Subclavian vein to form the Brachiocephalic Vein (on each side). These in turn unite to form the:
N. Superior Vena Cava
*note: possible route for spread of infection to the inside of the cranium is via Diploic Veins and Opthalmic Veins.
Thoracic Aorta *3 details
- Sends numerous branches that supply structures of the mediastinum and also the esophagus.
A. Intercostal Arteries - surround the thorax in the intercostal groove - accompanied here by vein and nerve.
B. Internal Thoracic Arteries - inside anterior chest wall
C. Venous Drainage
1. Azygous Vein - empties into superior vena cava - some connections to inferior. - anterior and to right of vertebral column
2. Hemiazygous Vein - smaller - to left of vertebral column
3. Accessory Hemiazygous Vein
