Blood Vessels (For Exam 3) Flashcards
(47 cards)
Blood vessels consist of…
arteries, veins, and capillaries
Arteries carry blood…
from the heart (regardless of whether it is oxygenated or deoxygenated)
Veins carry blood…
toward the heart
The exchange of gases (oxygen and carbon dioxide), nutrients, and waste products take place at the…
capillaries
How many layers are there in the arteries and veins?
3
Tunica Intima
- innermost layer of a blood vessel
- composed of endothelium (simple squamous epithelium and a thin layer of connective tissue)
Tunica Media
- middle layer of a blood vessel
- consists of circular layers of smooth muscle
Tunica Externa (Adventitia)
- outermost layer of a blood vessel
- composed of connective tissue for anchoring blood vessels to other structures
- has vaso vasorum, which gives blood to large blood vessels
Elastic (Conducting) Arteries
- largest of the arteries
- have large amount of elastic fibers throughout all 3 tunics (especially the media)
- elastic fibers allow the arteries to stretch when blood is pumped through and recoil
- branch into muscular arteries
Muscular Arteries
- medium-sized arteries that distribute blood to organs and tissues
- elastic fibers are distributed in two layers (internal and external laminae)
- less elastic tissue makes them less extensible, but allows for vasoconstriction and vasodilation
- muscular arteries branch into arterioles
Arterioles
- smallest of arteries
- larger arterioles have all 3 tunics but the smallest arterioles have endothelium surrounded by a single layer of smooth muscle
Vasoconstriction ________ blood flow into arterioles
reduces
Vasodilation ________ blood flow into arterioles
increases
Capillaries
- smallest blood vessel
- located between arterioles and venules
- composed of tunica intima (endothelium and a basement membrane), some smooth muscle cells surrounding
- allow for diffusion of gases and nutrients
- capillary bed is fed by a metarteriole and drained by a thoroughfare channel (which connects to a post-capillary venule)
True Capillaries
receive O2, release CO2
Venules
- smallest of the veins
- run with arterioles
- have thin layer of smooth muscle
- little ability to vasoconstrict
- merge to form large venules which merge to form veins
Veins
- small to medium veins run with muscular arteries
- large veins run with elastic arteries
- low pressure in vein necessitates valves to maintain one-way flow of blood
Skeletal Muscle Pump
- skeletal muscle contraction and relaxation helps move venous blood
- muscles squeeze the veins, pushing venous blood toward the heart
- inactivity results in reduced muscle pump and greater risk of clot formation
Respiratory Pump
- blood flow is assisted by contraction and relaxation of diaphragm
- during inhalation, the diaphragm is depressed - this results in increased abdominal pressure and decreases thoracic pressure (blood is moved from abdominal part of inferior vena cava into thoracic part)
- during exhalation, the diaphragm is elevated - this results in decreased abdominal pressure and increased thoracic pressure (blood is moved from thoracic part of inferior vena cava into heart)
The skeletal muscle pump does not benefit which blood vessel?
the inferior vena cava, which ascends in the abdomen and thorax
Which arteries in the systemic system branch off of the aortic arch?
brachiocephalic artery
left common carotid artery
left subclavian artery
The brachiocephalic artery divides into the…
right common carotid and right subclavian artery
The common carotid arteries supply blood to the…
head and neck
The brachiocephalic arteries supply blood to the…
upper extremities
