Blood Vessels Flashcards
what are the main types of vessels?
arteries, veins, capillaries and lymphatics
what are the patterns of the vessels in the body?
basic distribution pattern
what are the great vessels?
the aorta and pulmonary trunk
T/F. There can be much anatomic variance of vessels from one person to another?
T
T/F, There are many ways to clinically evaluate the vascular system (stethoscope)?
T
how does portal circulation occur?
occurs when blood travels through two capillary beds before returning to the heart
how does blood circulate through the body, what two ways?
Blood circulates through the body in two serial circulations: pulmonary and systemic.
what is the importance of the lymphatic system?
an important part of the circulatory system for returning fluid to the venous system.
what are anastomoses?
connections between vessels that can be present at birth or develop over time due to demand or disease
how do varicose veins occur?
Occur when veins loose elasticity, weaken and dilate. Valves become incompetent. Musculovenous pump may fail. This results in torturous superficial veins in the lower extremities
what is the pressure of the systemic arteries?
higher pressure, carry oxygenated blood to tissues.
what is the pressure of the pulmonary arteries?
are under low pressure, carry deoxygenated blood to lungs.
what are the characteristics of arteries?
- thicker tunica media
- no valves
- some variation
- may have anastomoses or be terminal arteries.
how can large arteries be identified?
by the presence of vasa vasorum as their thick walls require their own blood supply.
what are capillaries?
endothelial tubes that function as exchange vessels
what is the purpose of the systemic veins?
return deoxygenated blood to heart.
what type of blood do pulmonary veins carry?
carry oxygenated blood to heart.
T/F, Veins are capacitance vessels? if so, what percent of the blood is in the venous system?
Veins are capacitance vessels, most blood is in venous system (70-80%).
what are the characteristics of veins?
-thin tunica media but thicker -tunica adventitia (overall thin walled)
-larger lumen than arteries
-highly variable patterns
often multiple (venae comitantes)
-many anastomoses with other veins and with lymphatics, for thermoregulation.
T/F, veins contain valves? if so, where?
T, extremities
T/F, veins are also valveless?if so, where?
T, hepatic portal system, face
how many pumps does the venous system have? what?
The venous system has two “pumps” that enhance venous return:
the arteriovenous pump from the accompanying vein (venae comitante), an arrangement that increases venous return with arterial pulsations
and
the musculovenous pump that increase venous return with muscular contraction
what is the vasa vasroum?
supplies blood to the aorta
what is the lymphatic system?
start as blind-ended thin wall capillaries that pass through chains of lymph nodes and ultimately drain in to the thoracic duct or right lymphatic duct which return the lymph to the venous system.
what are anastomoses?
connections between vessels
why do veins and lymphatics have many?
Return of blood to the heart
T/F, Some anastomoses are present at birth?
Example: anastomoses between anterior and posterior intercostal arteries
Why is this important?
T; To supply blood to all of the thoracic wall
why do anastomoses develop over time?
Example: coronary arteries. If blockage in the anterior interventricular artery develops slowly than anastomoses can enlarge from the posterior descending and help supply the narrowed vessel
Why is this important?
due to demand or disease; to maintain blood supply
what are the different types of anastomoses?
- Arterial
- Venous
- Lymphatic
- Venous-lymphatic
- Portacaval, lack of blood flow in the liver due to cirrhosis
- Arteriovenous (shunts), due to dialysis
- Surgical anastomosis, coronary bypass by rerouting using the internal thoracic artery, Great saphenous vein used for heart bypass and sutured on aorta to the coronary vessel affected to maintain perfusion
what is the watershed area?
occurs when an area has dual supply by distal branches of two large arteries; found in the brain and marginal artery of drummond
What is the importance of this? It puts them at risk for ischemia due to lack of pressure
why do anatomic variations in the blood vessels matter? highest variability?
Understanding potential for variation and what common variations can be is important for interpreting imaging studies, surgery and the variations themselves could be clinically significant.
Variability: Lymphatics>veins>arteries
Common variations include:
Duplication of vessels
A common trunk
A split trunk
why are the pulmonary trunk and arteries thinner walled than the systemic arteries?
as they are in a lower pressure system (the pulmonary circulation).
what is the origin and termination of the pulmonary trunk? Anastomoses? Branch?
the right ventricle and it bifurcates in to the left and right pulmonary arteries which travel in the root of the lung and enter the lungs at the hilum; Anastomoses in the alveoli of the lungs; After entering the lungs they branch to supply the lung parenchyma.
what is a pulmonary embolism?
Clot from lower extremities and pelvis (Deep venous thrombosis) can break off and travel through the venous system and become lodged in the pulmonary arterial branches (Pulmonary embolism)
what are the regions of the aorta? do they have anastomoses?
the ascending aorta
arch of the aorta
descending thoracic aorta abdominal aorta; no
what are the branches of the aorta?
ascending aorta
aortic arch
descending thoracic
abdominal aorta
Aorta
origin:
terminate:
Branches:
left ventricle; bifurcates into right and left common iliac arteries; Branches into three planes: The three vascular planes shown in inset above represent unpaired visceral braches (stomach, esophagus, intestines) (A) which arise anteriorly, paired visceral branches (kidneys) (B) which arise laterally and paired parietal branches (C) which arise posteriorly (thoracic walls).
what do the bronchial arteries supply?
the bronchi themselves
what are the dominant blood supply to the lungs?
the pulmonary arteries
in terms of origins and terminations for veins, how should we think about them?
origins are distal and terminations as proximal
what are the arteries of the thoracic wall derived from?
Thoracic aorta – posterior intercostal and subcostal arteries
Subclavian artery – internal thoracic and supreme intercostal arteries
Axillary artery – superior and lateral thoracic arteries
how is the digestive system divided?
foregut, midgut, and hindgut
what is the supply to the foregut, midgut, and hindgut?
Foregut – celiac trunk
Midgut – superior mesenteric artery (small intestine and part of large intestine)
Hindgut – inferior mesenteric artery (last 1/3 of the large intestine and rectum)
what are the three venous systems?
systemic veins
pulmonary veins
hepatic portal vein
what are the systemic veins?
“Caval system”
Superficial and deep veins
Drains all but some of the GI tract, spleen and lungs
Includes the Azygous system
what are the pulmonary veins?
“Pulmonary system”
Drain lungs
what is the hepatic portal vein?
“Portal system”
Drains abdominal GI organs and spleen
how is the superior vena cava formed?
by the joining of the brachiochepalic veins.
what is the major tributary of the superior vena cava?
the azygous vein
what is the termination of the SVC?
the right atrium
where does the SVC pass?
passes anteriorly to the right pulmonary artery.
what does the SVC drain?
drains the head and neck, upper extremities , anterior chest wall as well as the lateral and posterior chest wall via the azygous system.
what is SVC syndrome?
If the SVC becomes obstructed (for example by a tumor), there is insufficient drainage of the head, neck and upper extremities and swelling and discoloration can be seen on physical exam
where does the inferior vena cava originate?
by the joining of the common iliac veins
What does the IVC drain?
the lower extremities, pelvis and posterior abdominal wall via multiple tributaries.
what is the termination of the IVC?
enters the right atrium
what is the course of the of the IVC?
traverses the diaphragm and enters the right atrium
where can we find the azygous system?
on either side of the vertebral bodies
where does the azygous system drain?
This system drains the posterior thoracic and abdominal walls, and the thoracic esophagus.
what conduit does the azygos system form?
a conduit between the IVC and the SVC
where does the azygos system originate?
in the abdomen from the ascending lumbar veins from the common iliac veins.
what does the azygos system communicate with?
the lumbar veins and IVC.
how is the azygous vein formed?
lumbar veins and the hemiazygous veins
where does the accessory hemiazygous vein originate from?
the lumbar veins and IVC.
what is the route of the azygous vein?
travels along the vertebral bodies, passes posterior to the root of the right lung and makes an arch over the root of the right lung
where does the azygous vein terminate?
the SVC
where do both the hemiazygous and accessory hemiazygous drain?
drain in to the azygous vein by crossing anterior to the vertebral bodies.
what is IVC obstruction?
If the IVC becomes slowly occluded, there is anastomosis with the azygous system. The azygous system can serve as one alternate conduit for venous return of IVC territory.
what is the portal system?
occurs when blood flows through two capillary beds before returning to the heart.
what is the major benefit of the portal system?
The major benefit of a portal system is it allows for substances (such as hormones or nutrients) drained from the organs of the first capillary bed to be exposed to the organ of the second capillary bed WITHOUT having to travel through the entire circulation. It can be both
what are the examples of the portal systems
Hepatic portal
Hypothalamic-pituitary
Kidneys
what does the hepatic portal circulation drain?
Drains the abdominal viscera associated with the GI tract as well as the spleen. After traveling through the liver capillaries it drains into the IVC and this allows liver to “see” anything presented to the GI tract and spleen before returning to the heart.
what is portal hypertension?
If pressure in the portal system gets elevated (e.g. cirrhosis), flow in the portal vessels reverses (no valves) leading to splenomegaly and varices. Varices occur because of anastomoses between the portal and caval systems.
what are the three functions of the lymphatics?
it has circulatory, immune and digestive functions.
what is the basic lymphatic drainage pattern?
Blind capillary plexuses drain to regional lymph nodes then progressive “chains” of nodes until thoracic duct or right lymphatic duct and to the venous angle in the neck
Afferent vessels to lymph nodes, efferent vessels away from lymph nodes
what is the relationship of the lymphatics to the blood vessels?
superficial vessels travel with superficial veins, deep vessels travel with arteries
what helps the lymphatics with flow?
Lymphatic vessels have valves as well as use arterial pulsation and muscular contraction to assist with flow.
what are the anastomoses like for lymphatics and veins?
Multiple anastomoses among lymphatics and with veins. This means that obstruction or injury to small vessels does not result in impaired drainage. Sometimes even large vessels can be obstructed with minimal consequences.
are their lympathics in the teeth?
none, neither do bone
in terms of cancer, what is contiguous spread? metastatic spread?
Multiple anastomoses among lymphatics and with veins. This means that obstruction or injury to small vessels does not result in impaired drainage. Sometimes even large vessels can be obstructed with minimal consequences.
the seeding of serous membranes, consists of two types: the lymphagenous and hematogenous spread. Hematogenous spread is most carcinomas and hematogenous spread is most sarcomas and renal carcinoma
left supraclavicular lymphadenopathy?
The thoracic duct which drains the lower body and left upper body empties into the venous system at the jugulovenous angle (joining of internal jugular and subclavian). The left supraclavicular nodes is near the termination of the thoracic duct. If a cancer from the abdominal viscera spreads via the lymphatic system, reflux of tumor cells can occur in the left supraclavicular node (Virchow’s node). Thus a patient presenting with left supraclavicular adenopathy, spread from abdominal visceral must be included in the differential diagnosis. In lab we will see the thoracic duct in the posterior mediastinum and its termination at the jugulovenous angle.
