73 terms

Chapter 19: Blood Vessels

How does amount of elastic tissue and smooth muscle differ between arteries and veins?
veins have less than arteries
How does the amount of fibrous tissue differ between arteries and veins?
veins contain more than arteries
Where do most veins have valves?
in the extremities
What is the shape of smooth muscle in the blood vessel wall?
mostly circularly arranged
How is peripheral resistance related to the diameter are the arterioles?
They are inversely related
What can lead to decreased venous return of blood to the heart?
damage to the venous valves
What causes arterial blood pressure to increase?
increasing stroke volume, heart rate, arteriosclerosis, and blood volume
What results in the dilation of the feeder arterioles and opening of the precapillary sphincters in systemic capillary beds?
a decrease in local tissue oxygen content, an increase in local tissue CO2, and a local increase in histamine
What is the difference between the capillary wall of a vein and artery?
veins have one single tunic, the tunic intima
What are the baroreceptors in the carotid sinus and aortic arch sensitive to?
changes in arterial pressure
Where does the myocardium receive its blood supply directly from?
coronary arteries
Blood flow in the capillaries is steady despite the rhythmic pumping of the heart because of what?
elasticity of the large arteries
What are the three branches off the aortic arch called?
brachiocephalic artery, left common coratid artery, and left subclavian vein
What drains directly into the inferior vena cava?
inferior phrenic veins, hepatic veins, and renal veins
In atherosclerosis, which layer of the vessel wall thickens most?
tunica intima
What is the second branch of the aortic arch?
let common carotid artery
Which branch of the ANS innervates blood vessels?
sympathetic nervous system
Which layer of the blood vessel wall do these nerves innervates?
tunica media
What are effectors (cells that carry out the response) in the tunica media?
smooth muscle cells
When vascular smooth muscle contracts, what happens to the diameter of the blood vessel? What is this called?
the diameter of the blood vessel decreases; vasoconstriction
Which artery plays a major role in dampening the pulsatile pressure of heart contractions?
elastic arteries
What artery allows vasodilation or constriction to determine blood flow to individual capillary beds?
What artery has the thickest tunica media relative to their lumen size?
muscular arteries
What is the function of valves in veins?
they prevent blood from flowing backwards in veins
What forms valves?
they are formed from folds of the tunica intima
In the systemic circuit, which contains more blood-arteries or veins- or is it the same?
veins contain more blood than arteries
What are 3 factors that determine resistance?
blood viscosity, vessel length, and vessel diameter
The kidneys play an important role in maintaining MAP by influencing which variable?
blood volume
Explain how renal artery obstruction could cause secondary hypertension
The blood pressure in the kidneys is lower than the rest of the body. This triggers direct and indirect renal mechanisms to increase blood pressure by increasing blood volume.
Suppose you are in a bicycle race. What happens to the smooth muscle in the arterioles supplying your leg muscles? What is the key mechanism in this case?
The smooth muscle relaxes, dilating the vessels and supplying more oxygen and nutrients to the exercising muscles; autoregulation by intrinsic metabolic controls
If many arterioles in your body dilated at once, you would expect MAP to plummet. What prevents MAP from decreasing during your bicycle race?
extrinsic mechanisms, primarily the SNS, and cardiac output increases
Which paired artery supplies most of the tissues of the head except for the brain and orbits?
the external carotid arteries
What is the name of the arterial anastomosis at the base of the brain?
the cerebral arterial circle, aka the circle of willis
What is the name of the 4 unpaired arteries that emerge from the abdominal aorta?
celiac trunk, superior and inferior mesenteric arteries, and the median sacral artery
Which veins drain the dural sinuses and where do these veins terminate?
the internal jugular veins; each internal jugular vein joins a subclavian vein to form a brachiocephalic vein
What is a portal system?
a system where 2 capillary beds occur in series
What is the function of the hepatic portal system?
to transport venous blood from the digestive organs to the liver for processing before it enters the rest of the systemic circulation
What are three differences between systemic arteries and veins with respect to their general pathways and courses?
arteries run deep, veins run deep and superficial, venous pathways are more interconnected than arterial pathways, the brain and digestive systems have unique venous drainage systems, and the arterial drainage system is not different
What are three common age-related vascular problems?
varicose veins, atherosclerosis, and hypertension
How do you calculate blood flow?
blood flow (F) = difference in blood pressure / peripheral resistance
How do you calculate mean arterial pressure (MAP)?
diastolic pressure + pulse pressure / 3
How do you calculate net filtration pressure?
hydrostatic pressure - osmotic pressure
What would be the approximate blood pressure in a blood vessel leaving the stomach for a person lying on her back (not standing) be?
below 20 mmHg
When does the velocity of blood flow decrease?
when viscosity increases
What is the most important force driving filtration at the arterial end of a capillary?
blood hydrostatic pressure
What increases capillary filtration?
obstructed venous return, blockage of lymphatic capillaries, dietary protein deficiency, and increased capillary permeability
What can a MAP below 60 mmHg cause?
What can a MAP above 160 mmHg cause?
cerebral edema
What type of shock occurs when bacterial toxins trigger vasodilation and increases capillary permeability?
septic shock
Myocardial infarction can lead to what type of shock?
cardiogenic shock
How many pulmonary arteries empty into the right atrium of the heart?
How do you calculate pulse pressure?
systolic blood pressure - diastolic blood pressure
What has the most important effect on blood velocity?
vessel radius
What are two powerful vasoconstrictors?
epinephrine and angiotensin II
What can lead to edema?
hypertension, liver disease, vasoconstriction of arterioles leading to the capillary bed, obstruction of lymphatic vessels, and famine
What contributes to venous return?
the expansion and contraction of the thoracic cavity, contraction of skeletal muscles, activation of angiotensin II, the difference of pressure between venules and the vanae cavae, and the suction created by the atria slightly expanding during ventricular systole
What is the innermost layer of the pericardial sac called?
epicardium, or visceral layer of the serous pericardium
What is the different between a parallel artery and vein?
the artery wall is thicker
When will precapillary sphincters in systemic capillary beds dilate?
when exposed to high carbon dioxide, in areas of low oxygen, or when pH drops
What structure is a fetal remnant associated with in a healthy adult heart?
ligamentum arteriosum
Aspirin functions as an anticoagulant by interfering with what?
thromboxane A2
The fight or flight response results in the constriction of what?
renal arteries, celiac trunk, and the internal iliac arteries
What are the regulatory chemicals that target the kidneys?
angiotensin II, ANP, and aldosterone
What is an example of an elastic artery?
Where is most vascular smooth muscle found?
tunica media
What is an exception to the normal effects of decreased oxygen on vasoconstriction?
pulmonary arterioles
If rising angiotensin II levels increased ADH, what would occur?
blood pressure would rise because of more water reabsorption
If the diameter of a vessel decreases, what would happen to the peripheral resistance? This change in diameter is most relevant in what?
it would increase; arterioles
What are the "holes" that capillaries have which allow for cell and protein passage?
The net filtration pressure of a blood capillary is the different between which two pressures?
net hydrostatic pressure and osmotic pressure
What is the outer wall of an artery or vein called? What does it contain in the large arteries and veins?
tunica externa; vasa vasorum
In a blood pressure ratio (x,y) what units is x measured in and what does it refer to?
millimeters of mercury; peak arterial pressure during systole
A release of histamine can cause what?
vasodilation of blood vessels and a decrease in arterial blood pressure