Card Set Information
What three structures/layers do all blood vessels have?
What is the tunica media composed of?
smooth muscle and elastic fiber layer
What layer is the endothelium that lines the lumen of all vessels?
What is the lumen of blood vessels?
central blood containing space
What is the tunica media regulated by?
sympathetic nervous system
What layer of blood vessels does vasoconstriction occur?
What 3 things happen in vasoconstriction?
smooth muscle contractions
reduction in lumen diameter
What 3 things happen in vasodialation?
smooth muscle relaxes
increase in lumen diameter
What layer of blood vessels is made of collagen fibers which protect and reinforce vessels?
What do larger blood vessels contain that nourishes the blood vessel wall?
Where do arteries, veins, and capillaries transport blood?
arteries - from the heart
veins - to the heart
capillaries - tissue cells
What are the largest of arteries?
What are the conducting vessels?
What type of arteries are the thick walled and near the heart?
What can elastic arteries withstand by smoothing out?
large blood pressure fluctuations
What are the next largest arteries next to elastic arteries?
What type of arteries are the distributing vessels?
What type of artery delivers blood to the body and organs?
How does the tunica media differ in the muscular arteries?
more smooth muscle and less elastic tissue
What type of artery is active in vasoconstriction?
How do arterioles control flow into capillary beds?
vasconstriction and vasodialation
What is the name for resistance vessels?
What type of arteries lead into capillary beds?
What are the smallest of blood vessels?
What are three types of capillaries?
What blood vessels are composed of endothelium with sparse basal lamina?
How many RBCs pass through capillaries at a time?
1 RBC a time
Which type of capillaries have an uninterrupted lining?
What type of capillaries are abudant in skin and muscle?
What structure allows the passage of fluid in the structure of capillaries?
What type of capillaries have an endothelium layer with fenestrations?
What do the pores of fenestrated capillaries allow?
greater permeability to solutes and fluid
Where are fenestrated capillaries found?
small intestines, endocrine glands, kidneys
What type of capillaries are leaky and fenestrated with large lumens?
Which type of capillaries form the blood brain barrier?
Why are sinusoidal capillaries so much more fenestrated?
so large molecules such as protein and blood cells can pass through
What type of capillaries are found in the liver, bone marrow, lymphoid tissue, and some endocrine organs?
What open to allow blood to flow through true capillaries?
When a person is at rest/ parasympathetic system is active, where is most of their blood volume and why?
digestion and kidney function
When a person's sympathetic nervous system is activated (when they're exercising), where is most of the blood flow?
Does blood from the brain fluxuate?
No, stays at ~750mL
What is formed when venules converge?
Is pressure in veins low or high?
What are the body's blood reservoirs?
Which has thinner walls, arteries or veins?
What forms when capillary beds unite?
What does it mean that veins are reservoirs, or capacitance, for blood?
There is greater than 55% of blood found in the veins, although still moving
Why is more blood found in the veins?
Lumen is wider, more blood can flow without increasing pressure
What is actual volume of
through a vessel/organ/ or the entire circulation in a given period, and how is it measured?
measured in ml per min
What is the
, per unit area, exerted on blood vessel walls by the contained blood, and how is it measured?
What does the difference in pressure provide?
the driving force which keeps blood moving
from high to low pressure
What is the
opposition to flow
of blood, measured in the amount of friction blood encounters in vessels?
What is resistance referred to as?
peripheral resistance (PR)
What 3 factors cause peripheral resistance?
blood vessel length
blood vessel diameter
What is the thickness of blood called, and what happens when there is an increased thickness?
increased viscosity=increased BP (polycythemia)
What happens when blood vessel length is longer?
increased resistance, increased BP
Do babies or adults have higher BP and why?
adults have higher BP because they have greater blood vessel length
Which 2 of the three factors of resistance are relatively constant?
blood viscosity and blood vessel length
What factor frequently changes and alters peripheral resistance?
blood vessel diameter
vasoconstriction and vasodiameter
What contributes more to peripheral resistance, larger arteries or small diameter arterioles?
large arteries contribute little to PR
small diameter arterioles are the major determinate of peripheral resistance
Resistance is the _______ factor in influencing local bloodpressure
When resistance increases, what happens to blood pressure?
blood pressure increases
What is blood flowing through vessels along a pressure gradient?
systemic blood pressure
Where is systemic pressure highest?
in the aorta
Where does systemic pressure decline?
as it travels trhough the length of the pathway
Where is systemic pressure 0 mmHg?
right atrium after receiving blood from vena cava
What is arterial BP like?
pulsatile, rising and falling
What is pressure that exerted on arterial walls during ventricular contraction?
What is the lowest levels of arterial pressure during a ventricular cycle?
What is athe range of blood pressure for capillaries?
What is the capillary blood pressure good enough for?
filtrate blood into interstitial space
distribute materials between blood and tissues
What is venous BP when returning to the heart?
Why does blood in the veins need help pumping blood to the heart?
BP is too low
What 2 variables act on diffusion of blood between capilarries and interstitial space?
What 2 things does maintaining blood pressure require?
cooperation of the heart, blood vessels, and kidneys
supervision of the brain (medulla, hypothalymus/pituitary)
What kind of control counteracts moment to moment fluctuations in BP by altering peripheral resistance?
What is changing in short term control of BP?
blood vessel diameter
What acts as a short term control of BP?
baroreceptors and vasomotor center (medulla)
Where are basoreceptors found?
aortic arch and cartoids
What do baroreceptors do when they are stimulated?
when stimulated(BP is high), basoreceptors inhibit the vasomotor center and decrease heartrate/contractility/cardiac output
When are basoreceptors inhibited?
When BP is low
What do basoreceptors do when they are inhibited?
when basoreceptors are inhibited (BP is low), the
vasomotor system is stimulated
/contractility/ cardiac output
What 3 chemicals increase BP?
What 2 chemicals decrease BP?
What is the relation between histamine and epinephrine when associated with allergies?
basophils release histamine when stimulated by allergy
histamine acts on the whole body dialting vessels
BP decreases drastically
epinephrine shots are used to constrict vessels to counteract histamine reaction
What 3 things helps increase venous BP to return blood to the heart?
What do long term controls for regulating Bp involve?
regulating blood volume
What do the kidneys
do if the body has increased BP?
kidneys are stimulated to let go of water
blood viscosiity decreased
What do the kidneys
do if the body has decreased BP?
kidneys are stimulated to conserve water
blood thickness is increased
What does the kidney release if BP declines?
What is the potent vasoconstrictor the kidney controls the release of?
What two chemicals does angiotensin stimulate the release of to increase BP?
ADH and Aldosterone
What 2 ways does the kidney act to maintain long term blood pressure?
direct and indirect
What process does the indirect renal mechanism for increasing BP involve?
What 5 steps happens in the renin angiotensin mechanism for increasing BP?
kidneys release renin
renin binds to inactive angiotensinogen in the blood stream
renin converts angiotensinogen to angiotensin I
angiotensin I travels to capillaries in the lungs
enzyme in lungs converts angiotensin I to angiotensin II
What enzyme converts angiotensin I to angiotensin II?
angiotensin converting enzyme (ACE)
What 3 things does angiotensin II do to increase BP?
stimulates adrenal cortex to release
What is the average BP?
When is BP most often highest in a person's daily routine?
in the morning
What is the term for a person's BP being below 100 mm Hg?
What is hypertension?
When a person's BP is above 140/90 + mmHg
What is the major cause of heart failure, vascular disease, renal failure and stroke?
What 3 affects happen on the heart and blood vessels in a person with hypertension?
heart is forced to pump against greater resistance
heart is weakened
blood vessels are damaged
How is hypertension treated?
What are the risk factors for hypertension?
What is the cause of circulatory shock?
blood vessels inadequetly filled
blood cant circulate normally
tissues cant receive blood flow
What are 3 kinds of circulatory shock?
Which type of circulatory shock results from a large scale blood loss?
Which type of circulatory shock results from extreme vasodialation and decreased peripheral resistance?
What type of circulatory shock happens when an inefficient heart cannot sustain adequate circulation?
What type of circulatory shock is associated with severe allergic reactions?
What happens to arteries during atherosclerosis?
walls of arteries thicken
Why do the walls of arteries thicken in a case of atheroclerosis?
irritation to the endothelium
What issues occur during atheroclerosis?
arteries become hardened and narrow
What is arteriosclerosis?
end stage of atherosclerosis