3 Basic structures of blood vessel
tunica intima
tunica media
tunica adventitia
Tunica intima parts
endothelium, subendothelial layer, elastic lamina
Tunica media
external elastic lamina
Tunica externa
external wall, not much to it reallly
What do arteries do?
convert output of heart to steady flow through the capillaries
What does elastic artery do?
conducts
they’re thick walled arteries near heart, like the aorta and its major branches
most elastic
diameter ranges from 2.5 cm to 1 cm
What does muscular artery do?
distribute
What do arterioles do?
they function as high resistance vessels which regulate distribution of flow to capillary beds
Arteries do what?
carry blood AWAY from heart
Veins do what?
carry blood TO heart
Pulmonary arteries?
carry deoxygenated blood from Right Ventricle
Arteries branch into?
smaller branches called arterioles
Arterioles branch into?
capillaries
Capillaries are what?
site of nutrient exchange, fluid exchange, gas exchange, etc. Every cell is near a capillary for pick me ups.
They flow into larger vessels that head back to heart later, called venules
Venules
collection of capillaries that are headed back to the heart
in the vein category
and venules flow into bigger vessels called veins, which drain into the heart
Artery structure
big, thick, round. They can stand up on their own.
Surrounded by smooth muscle, which is regulated by Autonomic NS, so it can change diameter as necessary.
Finally, it has a Fibrous CT that surrounds whole artery, so it provides structure cuz of toughness.
very flexible. It has to be because heart pump force.
All vessels contain what layer?
endothelium, made of special endothelial tissue that lines vessels
Capillaries are only made of what?
endothelium, thin layer of squamous endothelial tissue because it exchanges nutrients, so it’s easier for things to get through
Arterioles structure
NO fibrous tissue
lots of smooth muscle,
NO elastic tissue
Arterioles, because of lots of smooth muscle, function in changing diameter of the vessel which changes the amount of blood that can be in that part of the body
Capillary
just endothelium
entire function is nutrient and gas exchange
Venule
surrounded by fibrous tissue
not too stretchy
The first vessels to branch off ascending aorta are
R and L Coronary Arteries
Venous blood is collected in what? before it empties into R Atrium?
coronary sinus
Elastic arteries are
conducting arteries,
large arteries close to heart,
expand during contraction acting as pressure reservoirs, and then recoil during diastole to keep blood moving.
Muscular arteries are what?
distributing arteries that carry blood to specific organs
they’re less stretchy and more active in vasoconstriction
Arteriosclerosis
degenerative vascular disease that decreases elasticity of arteries
due to formation of fatty subendothelial lesions
The most permeable capillaries are
sinusoids, which are wide channels.
2nd most permeable capillaries are
fenestrated capillaries with pores
Least permeable capillaries are
continuous capillaries, due to lack of pores
Vascular shunts do what?
connect terminal arteriole and postcapillary venule at opposite ends of capillary bed
Most true capillaries arise from and rejoin the
shunt channels
Amount of blood flowing into true capillaries is regulated by
precapillary sphincters
Veins have larger what? than arteries
lumens
Why are most veins only partially filled?
so they can be blood banks or reservoirs
Joining together of arteries to provide alternate channels for blood to reach same organ is called
anastomosis.
Vascular anastomosis also forms between veins, between arterioles, and between venules
What is blood flow?
amount of blood flowing through a vessel, an organ, or entire circulation in a given period of time.
What is blood pressure?
Blood pressure is the force per unit area exerted on a vessel wall by the contained blood.
Blood resistance?
opposition to blood flow
blood viscocity aka thickness and vessel length and diameter contribute to reesistance
Blood viscocity?
thickness or gooeyness
Blood pressure is directly proportional to _________ and inversely proportional to _______.
directly proportional to blood pressure
inversely proportional to resistance
Systematic BP is highest and lowest in what area?
highest in aorta
lowest in venae cavae
Steepest drop in BP occurs in ________, where resistance is greatest.
arterioles
Arterial BP depends on what?
compliance fo elastic arteries and on how much blood is forced into them.
Systolic pressure
Arterial blood pressure is pulsatile and peaks during contraction
Diastolic pressure
during diastole, the phase of the heartbeat when the heart muscle relaxes and allows the chambers to fill with blood,
as blood is forced distally into circulation by rebound of elastic arteries, Arterial BP drops to its lowest value.
Pulse pressure is
systolic pressure minus diastolic pressure
Mean arterial pressure is
diastolic pressure plus one third of pulse pressure and is the pressure that keeps blood moving throughout the cardiac cycle
Why is Capillary pressure low?
so the delicate walls don’t rupture, and it allows enough nutrient exchange through the walls
BP varies directly with
CO, peripheral resistance, and blood volume.
Vessel diameter is major factor determining resistance, and small changes in the diameter of vessels, especially arterioles, affect BP
BP regulated by
Autonomic neural reflexes involving baroreceptors or chemoreceptors,
the vasomeotor center, which is a medullary center that regulates blood vessel diamter,
and Sympathetic vasomotor fibers, which act on vascular smooth muscle
when BP falls, what happens to get it back up?
the fall stimulates vasomotor center to increase vasoconstriction and the cardioacceleratory center to increase heart rate and contractility.
when BP is too high, what happens to get it down?
rising BP inhibits the vasomotor center
and
activates cardioinhibitory center
True or False?
Higher brain centers like cerebrum or hypothalamus may modify neural controls of BP via medullary centers
True
list Hormones that increase BP by promoting vasoconstriction
Epinephrine
NE,
ADH,
angiotensin II
list Hormones that reduce BP by promoting vasodilation include
atrial natriuretic peptide, which also causes a decline in blood volume
How do Kidneys regulate blood Volume?
rising BP enhances filtrate formation and fluid losses in urine
falling BP causes kidneys to retain more water, increasing blood volume
How do you assess cardiovascular efficiency?
measure pulse and BP
What is Pulse anyway?
alternating expansion and recoil of arterial walls with each heartbeat.
are Pulse and Pressure points the same thing?
Yes sir
Normal BP in adults is?
120, 80.
the first number is systolic, and the second is diastolic
BP numbers for people with Hypertension
140 over 90
High BP
indicates increased peripheral resistance, which strains the heart and promote vascular complications of other organs, particularly the eyes and kidneys. It is a major cause of myocardial infarct, stroke, and renal disease. Risk factors are high fat, high salt diet, obesity, diabetes, mellitus, advanced age, smoking, stress, being black?
Blood flow is involved in
delivering nutrients and wastes to and from cells,
gas exchange,
absorbing nutrients,
and
forming urine
Blood flows fastest when __________
and slowest when ______________.
fastest where the cross sectional area of the vascular bed is least, like in the aorta
slowest where the total cross sectional area is greatest, like in the capillaries. Slow flow in capillaries allows for nutrient-waste exchange time.
Auto-regulation is?
local adjustment of blood flow ti individual organs based on their immediate requirements.
so it involves myogenic or muscular control that maintain flow despite change sin BP and local chem factors
Vasodilators are and include?
medicines that help to widen vessels to lower BP
they include increased CO2, hydrogen, and nitric oxide.
Decreased Oxygen concentrations also cause vasodilation.
other factors like endothelins, decrease blood flow
In most instances, autoregulation is controlled by
oxygen deicits and accumulation of local metabolites
Autoregulation in the brain is controlled by
primarily by a drop in pH and by myogenic mechanisms
vasodilation of pulmonary circuit vessels occurs in response to high levels of O2
What passes through capillary walls by diffusion?
nutrients, gases, and other solutes
What moves through clefts or fenestrations?
water soluble substances
What moves through lipid portion of endothelial cell membrane of capillary?
fat soluble substances
Larger molecules that can’t pass through capillary walls or apparatus are transported by?
pinocytotic vesicles aka the infoldings in the membrane like a pouch,
or caveolae
In general, fluid flows out of the capillary bed at the ______ end and reenters at the ________ end.
enters at arterial end
reenters at venule end
The small net loss of fluid and protein in interstitial space is collected by _________ and returned to the cardio system.
lymphatic vessels
Circulatory shock occurs when ______ is inadequate
perfusion, the process of a body delivering blood to a capillary bed in its tissue.
Pulmonary circulation transports
O2 poor, CO2 laden blood to lungs for oxygenation.
Systematic circulation transports
O2 rich blood from Left Ventricle to all body via Aorta and its branches
Venous blood returning is delivered to Right Atrium via Vena Cavae
All arteries are ________, while veins are both _______ and _______.
all Arteries are Deep
Veins are both deep/superficial, and superificial veins have tons of interconnections
what are some unique venous drainage patterns?
Dural venous sinuses,
and
Hepatic portal circulation
Conducting arteries are
elastic arteries with large lumens, low resistance pathways that conduct blood from heart to medium sized arteries
3 types of capillaries?
CONTINOUS capillaries, abundant in skin and muscles, most common. Have unjoined membrane gaps called intercellular clefts, which are big enough to allow limited passage of fluids + small solutes
FENESTRATED capillaries, similar to continuous, except have pores, which are more permeable to fluids + solutes
SINUSOIDAL capillaries. highly modified, leaky capillaries only in Liver, Boen marrow, Spleen, and Adrenal Medulla. Big, weird shaped lumens. They have pores or fenestrations.
Why different types of capillaries?
allow large molecules and even blood cells to pass between blood and surrounding tissues.
Hepatic macrophages, do what where?
remove and destroy contained bacteria,
in lining of sinusoid capillaries in Liver
Microcirculation is?
flow of blood from an arteriole to a venule, through a capillary bed.
Capillary bed consists of 2 types of vessels
1. Vascular Shunt, a short vessel that directly connects arteriole and venule at opposite ends of bed
2. True Capillaries, actual exchange vessels.
Flow through capillary bed
The terminal arteriole that feeds bed leads into a
metarteriole, which is continuous with the
thoroughfare channel, which is an intermediate between arteriole and capillary bed,
joins the post-capillary venule that drains the bed
Pre-Capillary Sphincter is?
cuff of smooth muscle fibers that surrounds root of each true capillary at metarteriole and acts as a valve to
regulate blood flow into capillary
