Chapter 19 (Lecture) Flashcards
hardening of the arteries
arteriosclerosis
deposition of material in the walls of arteries to form plaques
atherosclerosis
causes of atherosclerosis
wearing out over time, pathological due to smoking, high cholesterol, fat consumption, autoimmune disease, genetics
- made up of endothelia and a basement membrane of CT
- blood flows smoothly along this layer
tunica intima
- the middle layer, contains smooth muscle arranged circularly for regulating blood flow
- can be regulated to constrict or dilate the lumen
- supplied with sympathetic nerve endings (exception being clitoris and penis)
tunica media
decreases blood supply
vasoconstriction
increases blood supply
vasodilation
- have thicker walls than veins due to more smooth muscle
- carry blood away from the heart
- have more elasticity
arteries
classes of arteries
- elastic
- muscular
- arterioles
blood containing space of the blood vessel
lumen
a system of tiny blood vessels that nourish the more external tissues of the blood vessel wall
vasa vasorum
the volume of blood flowing through a vessel or organ
blood flow
the force per unit area that blood exerts on a vessel
blood pressure
- opposition to flow in a blood vessel
- most important effector of both blood pressure and flow
resistance
change in blood pressure / resistance
blood flow equation
factors that impact flow and pressure
- blood viscosity
- blood vessel length
- blood vessel diameter
how to calculate blood vessel diameter
R = 1/(r)^4
what anastamose to form brachocephalics
subclavians and internal jugulars
supplies the ascending the transverse colons, and most of the small intestine
superior mesenteric artery
supplies the descending and sigmoid colons and rectum
inferior mesenteric artery
paired branches of the abdominal aorta
- renal
- suprarenal
- gonadal
- iliacs
unpaired branches of the abnominal aorta
- celiac trunk
- mesenteric
composed of blood from two different sources: internal carotids and vertebrals
circle of willis
all systemic arteries can be traced back to
the left ventricle
true or false: arteries run superficial and deep
false
arteries only run deep
which pathways are more interconnected and variable
venous pathways
which systems have distinct drainage systems
brain and digestive system
causes vasoconstriction
excess oxygen and nutrients
contains the endothelium (made up of simple squamous epithelium)
tunica intima
inhibits fibrinolysis by competing w/ plasminogen and may contribute to the formatin of atherosclerotic plaques
lipoprotein
a vessel that is an intermediate between the arteriole and the capillary bed
metarteriole
reduction in the lumen diameter of a blood vessel as the smooth muscle contracts
vasoconstriction
thick-walled, large vessels near the heart that conduct blood continuously away from the heart
elastic arteries
smallest of the vessels that lead into capillary beds
arterioles
smaller vessels that distribute blood to specific body organs
muscular arteries
vessel layer that has a direct role in vasoconstriction
tunica media
what is the correct sequence of layers in the vessel wall from outside to inside
tunica externa –> tunica media –> tunica intima
which vessels have a tunica media with relatively more smooth muscle than elastic tissue, and an elastic membrane on each face of the tunica media
muscular arteries
which blood vessels have the proportionally thickest tunica media of all vessels
distributing arteries
which layer of the artery wall is regulated by the sympathetic nervous system and many hormones
middle layer
blood flows directly from …. into capillary beds
arterioles
the endothelium is composed of
simple squamous epithelium
prefix meaning blood vessels
vaso-
prefix meaning osmosis or osmotic
osmo-
prefix meaning layer of tissue
tunic-
prefix pertaining to hair
capill-
prefix meaning artery
arterio-
innermost layer of blood vessels made of endothelial tissue
tunica intima
blood flow into a capillary bed is regulated by
the precapillary sphincter
reduction in the diameter of a blood vessel is called … and typically results in …
vasoconstriction; an increase in blood pressure
the pressure of nondiffusable molecules pulling water to them
colloid osmotic pressure
small arteries that are dilated or constricted to control peripheral resistance, and thus blood pressure
arterioles
only found in arteries to help absorb the shock of the heartbeat and return the vessel to its natural size
elastic membranes
supply the lungs
pulmonary blood vessels
- supply all of the body except the lungs
- are distensible
- contain a large proportion of the blood volume
systemic veins
why are veins called capitance vesses or blood reservoirs
because they contain can hold more blood than corresponding arteries
pathway of capillaries
- terminal arteriole
- metaarteriole
- postcapillary venule
types of capillaries
- continuous capillary
- fenestrated capillary
- sinusoid capillary
- least permeable in most common
- abundant in skin, muscles, and CNS
- intercellular clefts between endothelial cells (exception in the brain)
- pinocytotic vesicles
continous capillary
- have large fenestrations (pores) that increase permeability
- occur in areas of active filtration or absorption, and areas of endocrine hormone secretion
fenestrated capillary
- the most permeable capillaries that occur in limited locations (liver, bone marrow, spleen, and adrenal medulla)
- have large intercellular clefts, fenestrations, few gap junctions, incomplete basement membranes
- irregularly shaped, have larger lumens than other capillaries
- allow large molecules to pass through
sinusoid capillary
what happens when the precapillary sphincters open
blood flows through true capillaries
what happens when the precapillary sphincters are closed
blood flows through the metarteriole–throroughfare channel and bypasses true capillaries
factors that impact blood flow and blood pressure
- blood viscosity
- blood vessel length
- blood vessel diameter
resistance is caused by
vasoconstriction and vasodilation mainly of arteries
what units are blood pressure measured in
mmHg
what unit is blood flow measured in
mL/min
how do we calculate total resistance in the body
Cardiac Output = BP / R
true or false: systemic blood pressure drops over distance from the heart
true
pulse pressure (PP) =
systolic BP - diastolic BP
mean arterial pressure =
diastolic pressure (DP) + (pulse pressure / 3)
why is mean arterial pressure highly skewed
to reflect that the heart spends more time in diastole than in systole
why does mean arterial pressure vary
depends on whether you are sitting, standing, or reclining
most systemic capillaries have an arterial pressure between
35-45 mmHg
- is due to fluid pressing against a wall
- “pushes” fluid out of capillary into interstitial fluid and vice versa
hydrostatic pressure (HP)
by the time blood is returned to veins it has a blood pressure between
5-15 mmHg
how is it possible for venous return to equal cardiac output?
- structural modifications
- respiratory pump
- muscular pump
- gravity
change in blood pressure =
cardiac output x resistance
when the ventricles contract (~120 mmHg)
systolic bp
when the heart relaxes (~80 mmHg)
diastolic bp
systemic blood pressure is normally
120/80 mmHg
why is the difference in presures necessary
to keep moving from areas of higher to lower pressure
aortic pressure =
100 mmHg
arterial capillary pressure =
30 mmHg
as blood travels farther from the heart,
its flow is greater and its pressure drops
if resistance goes down,
blood flow increases
if resistance goes up,
blood flow decreases
- very superficial on the medial side of the leg and empties into the femoral vein
- often used as a graft in coronary artery bypass grafts (CABG)
greater saphenous vn
superficial vein on the lateral side of the leg
small saphenous vn.
superficial veins of the lower limb
- greater saphenous vn
- smaller saphenous vn
deeper veins of the lower limb
- digital veins
- venous arches
- fibular, anterior and posterior tibial vein
- femoral vein
- external iliac vein
venous pathway of the deeper lower limb veins
- digital veins
- venous arches
- fibular, anterior and posterior tibial vein
- femoral vein
- external iliac vein
hepatic veins empty into
the inferior vena cava
a specialized vascular system that begins and ends with a capillary bed
portal system
which veins join to form the hepatic portal vein
mesenteric veins, gastric veins, and splenic veins
drains blood from the small and large intestines, pancreas, spleen, and stomach
hepatic portal vein
what happens to blood when it is in the liver sinusoids
it detoxifies and removes nutrients before releasing the blood via the hepatic veins
what does the ascending lumbar veins empty into
the hemiazygos vein
what are the paired veins of the abdomen and where do they empty into
- renals, gonadals, adrenals
- empty into ivc
what is the pelvis drained by
internal iliac (joins common iliac and forms IVC)
which two veins join on the posterior of the chest wall and empty into the SVC
azygos and hemiazygos veins
the site of blood draws
median cubital vein
venous pathway of the superficial veins of the upper limb
- cephalic
- median cubital vein
- basilic vein
- axillary vein
- subclavian vein
venous pathway of the deep veins of the upper limb
- radial and ulnar veins
- brachial veins
- axillary vein
- subclavian vein
venous pathway of the hand
- digital veins
- palmar arches
- basilic vein
- axillary vein
- subclavian vein
drains posterior head and neck superficially and empties into subclavian veins
external jugular veins
left and right drain into the SVC
brachiocephalic veins
join the subclavians to form the brachiocephalic veins
internal jugular veins
drain into internal jugulars
venous sinuses
drain blood from the heart wall
cornonary sinus
drain the abdomen, pelvis, and lower limbs
inferior vena cava
drain the head, neck, thorax, upper limbs
superior vena cava
when is pressure created
when flow is opposed by resistance
peak pressure generated by ventricular contraction
systolic bp
resting pressure of blood in the arteries when the ventricles relax
diastolic bp
what is the MAP in large arteries
~90-93 mmHg
by the time blood reaches the terminal arterioles the pressure has dropped to
35-45 mmHg due to resistance
what would too high of a pressure do to thin capillary membranes
damage
blood pressure pushing filtrate out
hydrostatic pressure
arteries are primarily named for
the regions they serve
when the external iliac crosses the inguinal line, it becomes
the femoral artery
arterial pathway of the lower limb
- femoral artery
- popliteal artery
- ant. and post. tibial artery
- fibular artery
the anterior tibial artery becomes what on the dorsum of the foot
dorsal pedis artery
the common iliacs become
the internal and external iliacs
become the arteries of the lower limb
external iliac artery
supplies the pelvic organs, bladder, and rectum
internal iliac artery
the abdominal aorta terminates as
the right and left common iliac arteries
unpaired branches of the abdominal aorta
celiac trunk (hepatic a., gastric a., and splenic a.), and mesenterics
supply blood to the intestines
superior and inferior mesenteric arteries
branches of the thoracic aorta
- bronchial arteries
- posterior intercostals
blood pressure ranges from what to what in the venous end of the capillary
0-20 mmHg
what occurs in the venous end of the capillaries
- fluid is returned vial blood colloid osmotic pressure (i.e. oncotic pressure)
- very little hydrostatic prssure at this end
- about 90% of the plasma that leaves at the arterial end is returned at the venous end
what is the net filtration pressure out of the arterial end
10 mmHg
what is the net filtration pressure into the venous end
-8 mmHg
what are structural modifications to venous blood pressure
large lumens and valves to prevent backflow
what is meant by a respiratory pump in relation to venous blood pressure
abdominal pressure increases during breathing and squeezes veins, forcing blood upward through valves toward the heart
above the heart, what plays an important role in venous return?
gravity
what is meant by the muscular pump in relation to venous blood pressure
as skeletal muscles contract and expand, they squeeze surrounding veins and “milk” the blood up through the valves
hormonal regulators of blood pressure
- adrenal medulla hormones (NE, Epi)
- angiotensin II
- ADH
- ANH
- NO
what affect do adrenal hormones (NE, Epi) have on blood pressure
increase blood pressure
what is the effect of angiotensin II on blood pressure
increases blood pressure
what is the effect of ADH
increases water retention and increases blood pressure
what is the effect of ANH
increases water loss and decreases blood pressure
a major vasodilator, mainly in vessels leading to genitalia; localized hormone-like substance, acts as a major vasodilator to decrease BP
nitrous oxide
nervous system regulators of blood pressure
- vasomotor centers
- sympathetic innervation of blood vessels
- baroreceptors
responsible for smooth motor tone in many blood vessels
vasomotor centers in brainstem
where does blood spend the majority of its time
systemic veins and venules
what will increase tone in most blood vessels
increasing sympathetic output
vasomotor center steps
- brain (vasomotor center)
- sympathetic nervous system
- vasomotor tone
- NE controls tone in most blood vessels
located in arteries near the heart
baroreceptors
what does increased BP cause
parasympathetic stimulation to decrease HR
decreased blood pressure does what
activates sympathetic nerves and increases HR and SV
arterial pathway of the upper limb
- subclavian a.
- axillary a.
- brachial a.
- radial and ulnar a.
- superficial and deep palmar arches
- terminal digital a.
where does the brachial artery bifurcate
above the antecubital fossa
the division of something into two branches or parts
bifurcation
- essentially a backup system composed of internal carotids and vertebrals
circle of willis
right and left vertebrals fuse into the
basilar artery
the basilar artery splits to become the
posterior cerebral arteries
the internal carotids give off what that anastomose with the basilar artery
posterior communicating arteries
the internal carotids also give off the …, which join the anterior communicating to finish the circle
anterior communicating arteries
splits into the right subclavian, and right common carotid
brachiocephalic trunk
splits into the external and internal carotids
common carotid arteries
supplies superficial face and head
external carotid artery
supplies deeper structures of the head and brain
internal carotid artery
supplies the shoulder and upper arm
subclavian artery
what is the order in which the arteries come off of the aortic arch
- brachiocephalic
- left common carotid
- left subclavian
what is the first branch at the base of the aorta (ascending)
coronary arteries
arteries that extend from the aortic arch
brachiocephalic trunk, left common carotid, left subclavian
abdominal aorta terminates as the
common iliac arteries
branches of the descending aorta
thoracic and abdominal
what causes the kidneys to reabsorb more water and raise volume and pressure
decreased blood pressure and/or blood volume
activates the Renin-angiotensin-aldosterone mechanism
decreased blood pressure and/or blood volume
what is the goal of the renin-angiotensin mechanism
increase blood pressure
an enzyme secreted by the kidneys when blood pressure drops
renin
myogenic regulators of blood flow
- increased stretch (pressure) in blood vessel walls will cause vessels to constrict and reduce flow into a tissue or organ
- reduced stretch (pressure) in blood vessel walls will cause vessels to dilate and increase blood flow to an organ
cause a relaxation of precapillary sphincters and increase blood flow to the tissue
increases in vasodilator substances such as CO2, lactic acid, prostaglandins, histamine, nitrous oxide
an extremely powerful vasodilator that is released by many endothelial cells
nitric oxide
cause precapillary sphincters to contract and reroute the blood to other more needy tissues
increases in vasodilators (O2 and endothelins)
tissue perfusion is essential for
- delivery of oxygen to tissues
- gas exchange in the lungs
- absorption of nutrients in the digestive tract
- proper urine formation
during physical activity, blood flow is directed away from which region and goes where
- away from digestive and urinary functions
- into skeletal muscles and heart
metabolic factors in blood flow
- increase in vasodilators
- increase in vasoconstrictors
renin converts angiotensinogen in the plasma into
angiotensin I
what converts angiotensin I to angiotensin II
ACE (angiotensin converting enzyme) in the lungs
- a powerful vasoconstrictor that raises blood pressure
- stimulates aldosterone release by the adrenal glands so that more sodium and water will be reabsorbed in the kidneys, thus increasing BP
angiotensin II
when aldosterone is released,
bp increases
characteristic of veins but not arteries
large internal diameter
true or false:
arteries always carry oxygen-rich blood away from the heart
false
Varicose veins seen in the superficial veins of the legs are unsightly and are often treated by surgical removal. However, even without these veins being present, the return of all blood toward the heart from the legs is not diminished. This is primarily because
blood can still return via the deep veins
As the kidneys filter blood, it is necessary for both fluid and dissolved chemicals in the plasma to be rapidly removed without the removal of larger proteins or cells. Which capillary would be best suited for this filtration
fenestrated capillaries
most common capillaries in the body
continuous capillaries
factors that aid venous return
- venous valves
- pressure changes in the thorax
- activity of skeletal muscles
what would decrease total peripheral resistance to blood flow
decreasing hematocrit
Blood flow is __…______ proportional to the difference in blood pressure. Blood flow is ____…____ proportional to the total peripheral resistance
directly; inversely
which vessels sustain a drop in pressure from approx 35 mmHg to around 17 mmHg
capillaries
systolic bp - diastolic bp =
pulse pressure
possible consequences of low blood pressure on capillary function
- MAP would not be high enough for adequate capillary exchange to occur
- tissues become ischemic because of lack of adequate perfusion
effect of atrial natiuretic peptide (ANP)
decreases bp (decreases blood volume) by reducing sympathetic vasomotor response
true or false:
decreased output from the vasomator center allows arterioles and veins to constrict
false
Decreased output from the vasomotor center allows arterioles and veins to dilate (not constrict). The vasomotor center uses the sympathetic nervous system to stimulate contraction of vascular smooth muscle, which results in constriction of arteries (vasoconstriction) and veins (venoconstriction). While increased output from the vasomotor center results in constriction of these vessels, decreased output results in dilation
A muscle that is being regularly contracted during exercise will attract blood flow by dilating arterioles. Which factor would contribute to this effect?
increased levels of CO2
true or false:
osmotic pressure is fairly constant along the entire length of a capillary bed
true
For a special (mesenteric) capillary, each true capillary, where it branches from the metarteriole, is surrounded by a precapillary sphincter. These sphincters are controlled only by
local chemical conditions
expected responses to a drop in MAP
- increased thirst
- secretion of aldosterone
- release of renin from the kidneys
how would baroreceptor reflexes respond to a fall in blood pressure
vasomotor center would increase sympathetic output to arterial smooth muscle to increase TPR (total peripheral resistance)
which organs experience a decrease in blood flow during exercise
kidneys and GI tract
directed toward muscles, heart, and skin
reduction in the concentration of albumin in blood plasma would alter capillary exchange by
decreasing colloid osmotic pressure and edema will occur
which vessels will return oxygenated blood to the left atrium of the heart to complete the pulmonary circuit
pulmonary vein
a blood clot in the first branch of the aorta would affect the blood flow to the
right side of the head and neck and right upper arm
true or false
an obstruction in the SVC would decrease the flow of the blood from the head and neck to the heart
true
true or false:
Arterial pressure in the pulmonary circulation is much higher than in the systemic circulation because of its proximity to the heart.
false
the abdominal aorta splits into which vessels
R and L common iliac arteries
- consists of a vein connecting two capillary beds together
- its major vesssels are the S. mesenteric, I. mesenteric, and splenic veins
- carries nutrients, toxins, and microorganisms to the liver for processing
hepatic portal system
from what artery does the right common carotid arise
brachiocephalic trunk
found only on the right side of the body, and it splits to form the right common carotid artery and the right subclavian artery. These two arteries arise independently from the aorta on the left side of the body.
originates on the medial foot and empties into the femoral vein
great saphenous vn
