Module 2 Introductory Anatomy and Physiology of Blood Vessels Flashcards
Compare and contrast the three tunics that make up the walls of most blood vessels
a
Distinguish between elastic arteries, muscular arteries, and arterioles on the basis of structure, location, and function
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Explain the structure and function of venous valves in the large veins of the extremities
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Identify the major structures and subdivisions of the renal corpuscles, renal tubules, and renal capillaries
a
What is the tunica intima
- Innermost layer of a blood vessel
- > direct contact with blood as it flows through lumen
- Includes
- > Endothelial lining
- > -> Active participant in regulating vessel tone, coagulation, inflammation…
- > Basement membrane
- > In many vessels, an internal elastic lamina
What is the tunica media
- Middle layer containing concentric sheets of smooth muscle tissue in a framework of loose CT
- Collagen fibers bind all layers together
- Greatest variation among different vessel types
What is the tunica externa
- Outermost layer forming a CT sheath around the vessel
- Very thick and composed mostly of collagen fibers and some elastic fibers
- Contain numerous nerves and tiny blood vessels (vasa vasorum)
What is the sub-layers in the 3 layers in a blood vessel from internal to external
- Tunica intima (endothelium -> basement membrane -> internal elastic lamina)
- Tunica media (smooth muscle -> external elastic lamina)
- Tunica externa (loose fibrous CT -> epithelial cells)
In traveling from the heart to peripheral capillaries, blood passes through:
- Elastic/conducting
- > Large vessels, diameter up to 2.5 cm
- > Pressure reservoir - Muscular/distributing
- > Medium vessels, diameter around 0.4 cm - Arterioles
- > Smaller vessels, diameter around 30 µm
Fill in the blanks about elastic arteries:
Help ____ blood onward while the ventricles are _______
As blood is ejected from the heart into the elastic _____, their walls ______, easily accommodating the surge of blood.
As they stretch, the elastic fibers momentarily _______ mechanical energy functioning as a ______ reservoir.
Then, the elastic fibers ______ and convert stored (potential energy) in the vessel into _____ energy of the blood. Thus, blood continues to move through the arteries even when the ventricles are ______.
Help PROPEL blood onward while the ventricles are RELAXING
As blood is ejected from the heart into the elastic ARTERIES, their walls STRETCH, easily accommodating the surge of blood.
As they stretch, the elastic fibers momentarily STORE mechanical energy functioning as a PRESSURE reservoir.
Then, the elastic fibers recoil and convert stored (potential energy) in the vessel into kinetic energy of the blood. Thus, blood continues to move through the arteries even when the ventricles are RELAXED.
In Muscular Arteries, the
- > Tunica intima very thin and consists of:
1. _______
2. _________
3. ___________ - > Tunica media is major identifying characteristic:
1. ______________
2. _____________ - > (Thin/thick?) external elastic lamina
- > Tunica adventitia is (not/well?) developed
In Muscular Arteries, the:
- > Tunica intima very thin and consists of:
1. Endothelium
2. Flattened subendothelial layer of COLLAGEN and ELASTIC fibres
3. Internal ELASTIC LAMINA - > Tunica media is major identifying characteristic:
1. THICK SMOOTH MUSCULAR layer
2. very FEW ELASTIC fibres - > THIN external elastic lamina
- > Tunica adventitia is WELL developed
Where is the major site of systemic vascular resistance?
Arterioles
Terminal end (metarteriole) tapers towards capillary junction and forms _____
precapillary sphincter
Describe the 3 layers in arterioles:
- Tunica intima
- > Endothelium, no sub-endothelial layer - Tunica media
- > Composed of 1-3 layers of smooth muscle - Tunica adventitia
-> Fairly prominent
Lots of nerves
Describe venules:
- (Thinner/thicker?) walls than arterial counterparts
- ______ venule
- > Smallest venule - Form part of microcirculatory exchange unit with _____
- Muscular venules have thicker walls with _____ layers of smooth muscle
- THINNER walls than arterial counterparts
- POSTCAPILLARY venule
- > Smallest venule - Form part of microcirculatory exchange unit with CAPILLARIES
- Muscular venules have thicker walls with 1 OR 2 layers of smooth muscle
Fxn of veins
Collect blood from all tissues and organs and return it to the heart
How are veins classified?
- Classified on the basis of their size (3):
- Venules
- > Average diameter 20 µm - Medium sized
- > Diameter of 2 to 9 mm
- > Tunica media thin, thick tunica externa with longitudinal bundles of elastic and collagen fibers - Large
- > Diameter of 10 mm to 3 cm
- > Slender tunica media surrounded by thick tunic externa
Pressure in venules and medium sized veins is too ___ to oppose the force of ____
- LOW
2. GRAVITY
Veins contain ____ to prevent backflow of blood
one way valves
Venous valves fxn to
Compartmentalize the blood within the veins
Describe how pressure changes throughout Systemic system:
- From aorta (____ mmHg) to right atrium (_____mmHg)
- Pressure _____ as does velocity of flow
- Friction on walls (converted to _____, and decreasing pressure) is represented by _____
- Resistance and pressure drop is increased with ____ flow
- From aorta (95 mmHg) to right atrium (0-3 mmHg)
- Pressure DECREASES as does velocity of flow
- Friction on walls (converted to HEAT, and decreasing pressure) is represented by RESISTANCE
- Resistance and pressure drop is increased with TURBULENT flow
Describe how pressure changes throughout CAPILLARY BEDS:
- High as ___ at arteriole end, low as ___ at venous end
- Functional average is __mmHg
- High as 35 at arteriole end, low as 10 at venous end
- Functional average is 17mmHg
In the Theory of Circulatory Function, what are the 3 basic principles that underlie all functions of the system
- Blood flow to each tissue of body is almost always precisely controlled in relation to tissue needs
- CO is controlled mainly by the SUM of all the local tissue flows
- Arterial pressure is controlled independently of either local blood flow control or CO
Discuss the principle “The rate of blood flow to each tissue of the body is almost always precisely controlled in relation to the tissue need.”
- Active tissues can need as much as _____x the amount of blood flow compared to at rest BUT heart can only increase output ______x the resting levels
- Therefore, (it is/it is not?) possible simply to increase blood flow everywhere in the body when a particular tissue demands increased flow
- Instead, the microvessels of each tissue continuously monitor tissue needs, (e.g. availability of ______ and ______ and the accumulation of ____ and other waste products)
- These in turn act directly on the ________, dilating or constricting them, to control local blood flow precisely to that level required for the tissue _____.
- Active tissues can need as much as 20-30x the amount of blood flow compared to at rest BUT heart can only increase output 4-7x the resting levels
- Therefore, IT IS NOT possible simply to increase blood flow everywhere in the body when a particular tissue demands increased flow
- Instead, the microvessels of each tissue continuously monitor tissue needs, (e.g. availability of OXYGEN and NUTRIENTS and the accumulation of CO2 and other waste products)
- These in turn act directly on the LOCAL BLOOD VESSELS, dilating or constricting them, to control local blood flow precisely to that level required for the tissue ACTIVITY.