anatomy and physiology II chapter 20

Blood vessels form a _______ transport system

closed

Blood moves in a cycle: Heart → ______ → _______ → Capillaries → ______ → Veins → _____

arteries; arterioles; venules; heart

Vessels differ in _________, but all serve the same goal: ______ & ______ blood efficiently

structure; deliver; return

carry blood away from the heart

arteries

return blood to the heart

veins

thin vessels where exchange of gases, nutrients, and wastes occurs

capillaries

what circuit goes from the right side of the heart → Lungs → Back to left side?

pulmonary circuit

function of the pulmonary circuit

exchange CO2 for O2

what circuit goes from the left side of the heart → Body tissues → Back to right side?

systemic circuit

function of systemic circuit

deliver O₂ and nutrients; remove wastes

arteries ________ transport oxygen-____ blood

usually; rich

in arteries, ____ pressure, _______ lumen (opening)

high; smaller

veins _________ carry oxygen-____ blood

usually; poor

in veins, ______ lumen and contain valves to prevent _______

larger; backflow

3 tunics of BV walls

intima, media, externa

tunica intima contain ___________ (smooth lining) + ____ connective tissue

endothelium; thin

tunica ______ reduces friction for blood flow

intima

tunica ______ lines the lumen (inside space of the vessel).

intima

tunica media contain _______ muscle + ______ fibers

smooth; elastic

tunica _______ allows vasoconstriction (narrowing) & vasodilation (widening)

media

tunica _____ are thicker in arteries

media

tunica externa contains connective tissue with _______ & ______ fibers

collagen; elastic

tunica ______ protects and anchors vessel to surrounding tissue

externa

Endothelium regulates exchange between _____ and _______

blood; tissues

exchange for food and oxygen: into _______

tissues

exchange for wastes and CO2: into _____

blood

vascular endothelium produces compounds that control: vasodilation/_____________, Inflammation, ____ formation (injury response), _______ muscle activity

vasoconstriction; clot; smooth

Small arteries; regulate flow to capillaries

arterioles

Small veins; return CO₂-rich blood

venules

Veins have low ________ → need help _________ blood to heart

pressure; returning

in veins, blood flows ________ gravity, aided by: _______ and _______ muscle contractions

against; valves; skeletal

______ lumen allows more blood flow at _____ pressure

large; lower

factors aiding venous return: ________ pump, _______ pump, and ____________

respiratory; muscular; vasoconstriction

respiratory pump: Breathing changes _____ pressure → pulls blood _______ the heart

chest; toward

Muscular Pump: ________ muscles contract → ______ (milking) veins and push blood forward.

skeletal; squeeze

vasoconstriction – Veins narrow under ___________ control → blood moves ______ toward the heart.

sympathetic; faster

blood flows because of pressure _________

gradients

venous return depends on: ___ and _______ _____ pressure

CVP; right atrial

pressure in the large veins near the heart.

central venous pressure

if atrial pressure rises too much (like in heart failure), venous return decreases.

right atrial pressure

_______ venous return → stretches atrial walls → supports ______ output (Frank–Starling law).

increased; cardiac

venous return is also influenced by blood _______

volume

_____ blood volume (hemorrhage, dehydration) = ____ venous return

low; low

____ blood volume (fluid overload, pregnancy) = ____ venous return

high; high

When skeletal muscles contract, they _______ veins running between them

squeeze

Vein valves prevent _________, so blood only moves ___ way.

backflow; one

Long periods of inactivity (sitting, standing) → reduced muscle _________ → blood pools in ____

pumping; veins

chest expands, thoracic pressure drops, blood pulled toward the heart

inhalation

pressure in abdomen increases, pushing blood up into thoracic veins

exhalation

Acts as a “vacuum effect” aiding venous return

respiratory pump

Smallest blood vessels, one cell thick (endothelium only)

capillaries

Site of exchange for capillaries: ________, _________, _______

oxygen; nutrients; wastes

capillaries have the ________ blood flow for _________ exchange

slowest; maximum

continuous capillaries are found in ____, _______ and most ________

skin; muscles; tissues

structure of continuous capillaries: _________ cells joined by ______ junctions

endothelial; tight

in brain capillaries, _____ junctions are complete, forming the _____-_____ ______ (BBB)

tight; blood-brain barrier

brain capillaries protects brain tissue by preventing leaks of _____, ______, and _______

water; toxins; solutes

fenestrated capillaries are _________ cells that contain _____ (fenestrations)

endothelial; pores

fenestrated capillaries are ____ permeable than continuous capillaries

more

fenestrated capillaries are found in _____ intestine, ________ glands, _______

small; endocrine; kidneys

sinusoidal capillaries have large _________ clefts, large ______, ______ tight junctions

intercellular; lumens; fewer

sinusoidal capillaries allow passage of large _________ and _____ cells

molecules; blood

sinusoidal capillaries are found in _____, ____ marrow, ______

liver; bone; spleens

sinusoidal capillaries have very ____ permeability

high

Capillaries form capillary ____ (networks for ________).

beds; exchange

capillaries are fed by a __________ (bridge between ________ and capillary)

metarteriole; arteriole

____ capillaries branch off → site of gas & _______ exchange.

true; nutrient

___________ sphincters regulate entry into true capillaries.

precapillary

blood takes one of two routes: ____ capillaries, or a _________ shunt

true; vascular

volume of blood per time (ml/min).

blood flow

blood flow is equal to _______ output for the whole system

cardiac

blood flow is ________ overall, but varies by _____

constant; organ

opposition to flow (friction).

resistance

major factors of blood flow

viscosity, length and diameter

force of the blood flow when blood is pumped out of the heart.(heart contracts)

systolic pressure

measured between heartbeats when the heart is filling with blood (heart relaxes)

diastolic pressure

Persistent elevated arterial pressure (“Silent Killer”).

hypertension

primary hypertension has no known _____

cause

secondary hypertension is due to another _________

condition

Chronic low resting BP

hypotension

causes of hypotension: _____ loss, dehydration, _______, _________, _____ problems.

blood; anemia; pregnancy; heart

Rhythmic expansion & recoil of arteries as blood is ejected from the left ventricle.

pulse

pulse reflects the pressure wave created by _______

systole

pulse is strongest in _____ arteries closest to the _____ (e.g., carotid, radial).

large; heart

pulse ________ with distance from the heart

weakens

______ and _______ arteries have the highest systemic blood pressure

aorta; large

aorta and large arteries maintains __________ flow

continuous

what do we feel as the pulse?

aorta and large arteries

“Resistance vessels” — control blood flow into capillaries

arterioles

Steepest pressure drop occurs in ________ due to narrowing diameter

arterioles

blood pressure in capillaries is much ______, _____

lower; smooth

blood pressure in capillaries is important for ________ and ___ exchange.

nutrient; gas

venules and veins have very ___ pressure

low

venous blood return relies on ________ muscle pump, ________ pump, and _______.

skeletal; respiratory; valves

largest artery in the body

aorta

the aorta originates from the ____ ventricle

left

the aorta distributes ________ blood to all _______ arteries

oxygenated; systemic

__________ Aorta → coronary arteries (heart)

ascending

________ ____ → brachiocephalic trunk, left common carotid, left subclavian

aortic arch

__________ ________ Aorta → chest wall & organs

descending thoracic