Circulation Flashcards
What do arteries do?
Carry blood away from the heart and branch into smaller arteries
What do veins do?
Carry blood to the heart and merge into larger veins
What joins arteries to veins
Capillaries
What are the layers of walls and arteries called?
Tunics
What are the layers of walls and arteries
Tunica Intima: Most inner layer; simple squamous epithelium and areolar CT
Tunica Media: Circularly arranged smooth muscle that can cause vasoconstriction
Tunica Externa: CT that aids in anchoring blood vessel
What are the small arteries found in the tunica externa?
Vasa Vasorum (to accomodate a blood supply to large blood vessels)
Elastic Arteries
Largest; contains elastic fibers in all three tunics and branch into the muscular arteries
Muscular Arteries
Medium size; two concentric rings of elastic fibers; inner ring is the internal elastic lamina which separates the tunica intima from the tunica media; outer ring is the external elastic lamina which separates the tunica media from tunica externa
Arteioles
Smallest; contain smooth muscle in their tunica media when contracted leads to an increase in BP and when relaxed it would lead to a drop
Blood flow is unidirectional except
Venous system of brain
Capillaries
-smallest of blood vessels
-only tunica intima (diameter the size of a erythrocyte)
-only blood vessel where metabolic exchange can occur between blood and tissues
-form capillary beds
Continuous Capillary
Most common, complete lining
Fenestrated Capillary
Contains pores that allow for fluid exchange.
Sinusoid Capillary
Has large gaps and incomplete basement membrane. Transports large molecules and cells to and from the blood.
Veins
Drain capillaries and return blood to the heart
-same layers as artereies but thinner esp tunica media
-60% of blood volume at rest known as blood resevoir
What is a metarteriole?
Feeds each bed; supplies true capillaries, each contains a ring of smooth muscle, that branch off the metarteriole to supply the tissue
What is the throughfare channel?
Connects last true capillary to a postcapillary venule which becomes the venous system.
What are the two major groups that veins are divided into?
Venules-smallest of veins (postcapillary are the smallest and is where diapedesis occurs)
Small/medium/large veins- Small and medium travel with muscular arteries while large travels with elastic arteries
What is the skeletal muscle pump?
squeezes veins when the muscle contracts and forces the blood in the vein to travel toward the heart
What is the respiratory pump?
The respiratory pump
functions in the abdominopelvic
cavity where the veins are
compressed when the
diaphragm contracts decreasing
the volume in the cavity and
increasing the pressure
■ When the diaphragm relaxes,
the volume in the thoracic cavity
decreases and the pressure
increases squeezing the veins.
■ Since the veins have one-way
valves, the blood is forced towards the heart
How does a pulse exist?
When the systolic and diastolic are not equal
-only in arteries, there is no more pulse in the capillaries
-BP is greatest in the aorta and almost zero in superior and inferior vena cava
What is systemic circulation?
All the vessels that extend to the body regions
What are two branches of the ascending aorta?
Right and left coronary arteries
What are the branches of the aortic arch?
1) Brachiocephalic trunk which bifurcates into the
right common carotid and the right subclavian
arteries
2) The middle branch is the left common carotid
artery
3) Final branch is left subclavian artery
What does the aortic arch become?
descending thoracic aorta until it crosses through the diaphragm when it then
becomes the descending abdominal aorta
What are the arteries that branch off of the descending thoracic aorta?
Bronchial arteries
What does the descending abdominal aorta branch into at the 4th lumbar vertebrae?
Left and right common iliac arteries
What do the common iliac arteries branch into?
Right and left internal/external iliac arteries
What forms the superior vena cava?
Fusion over the right and left brachiocephalic veins.
What does the superior/inferior vena cava drain into?
The right atrium
What forms the inferior vena cava?
The fusion of the left and right common iliac veins
What supplies most of the blood to the head and neck?
Right and left common carotid arteries
What do the right and left common carotid arteries branch into?
Left and right internal and external carotid arteries