Chapter 22: Blood Vessels and Circulation Flashcards
what are blood vessels?
closed circuits of tubes
What are the three types of blood vessels and what do they d?
Arteries: carry blood away from the heart
Capillaries: exchange vessels
Veins: return blood to the heart
True or False: Oxygen in the blood distinguishes arteries from veins
false
summarize the flow of circulation (very brief; one word per step_
Heart --> Arteries--> Arterioles--> Capillaries--> Venules--> Veins--> Heart
What makes up the blood vessel tissues? describe
Endothelium -smooth surface for blood flow -simple squamous epithelium CT -provides elasticity to withstand BP changes Smooth muscle -vasoconstriction -vasodilation
What are the three layers for the blood vessel histology?
Tunica intima Tunica media Tunica externa (Adventitia)
describe the tunica intima (3)
- innermost
- endothelium on top of CT membrane
- internal elastic membrane
what are the three functions of the tunica intima?
separates blood flow from vessel wall
prevents blood clotting
helps regulate BP
describe the tunica media (3)
middle
bulk of wall
smooth muscles and elastic CT
describe the tunica externa (adventitia) (5)
outer thin made of CT, elastic & collagenous fibers attaches artery to surrounding tissues contains vasa vasorum -BV of BV because they are so thick
what are the characteristics of arteries?
strong and elastic
subdivided into arterioles
how are arteries different from veins?
artery wall is thicker
artery lumen appears smaller
endothelium of artery can not contract
what are the two types of arteries?
elastic and muscular
describe elastic arteries
large diameter in areas of high pressure Media -high % elastic tissue -less smooth muscle
what are some examples of elastic arteries?
pulmonary trunk, aorta, carotid, subclavian, common iliacs
describe muscular arteries
large to small diameter carry blood to skeletal muscles and organs Media -much smooth muscle -less elastic tissue
What are some examples of muscular arteries?
Femoral, brachials, mesenterics
what are arterioles? describe them
Microscopic continuations of arteries
- small diameter
- adventitia is thin
- no external elastic membrane
- no vasa vasorum
What do capillaries consist of?
only intima -basement membrane -simple squamous epithelium very thin variable permeability
what materials are exchanged in capillaries?
nutrients
dissolved gases
wastes
Capillary permeability is maximized by… (3 things)
thin wall
low BP
Slow blood flow
what are the four mechanisms of permeability for capillaries?
- ) Diffusion across endothelial cells
- lipids, gases - ) Diffusion through gaps between endothelium
- water, small solutes - ) Diffusion through pores
- water, larger solutes - ) Vesicular transport with pinocytes
- large, bound solutes
Continuous Capillaries allow movement by…
passive diffusion and active transport
where are continuous capillaries located?
CNS
Skeletal muscle
lungs
Slide 14
it says many with bullets…. idk wtf D’Amore is talking about
Fenestrated capillaries have the appearance of ________ because they have ________
swiss cheese; pores
fenestrated capillaries allow movement of what 2 things?
peptides and small proteins
where are fenestrated capillaries located?
Kidneys, intestines, endocrine glands, choroid plexus
Sinusoid capillaries are specialized for max exchange by: (3)
- large intercellular gaps
- pores
- discontinuous basement membrane (allows cells to enter and exit)
Sinusoid capillaries are located where?
spleen, bone marrow, liver, adrenal glands
A network of interconnected capillaries are known as what? describe
Capillary Beds
- derived from arterioles
- Precapillary sphincters (manages blood flow to bed)
- Metarterioles (direct connection through the bed and leads to a thoroughfare channel)
in capillary beds, describe Collateral arteries anastomosis
- 2 arteries fuse
- twice as much blood supplies the arteries
- found in areas with high O2 demands
In capillary beds, describe Artiovenous anastomosis
direct connection between arteriole and venule
where blood flow may be hindered by posture
What are venules? describe them
smallest veins that collect blood from capillaries
- can lack a media
- scatter, minimal amount of smooth muscles occasionally
describe medium sized veins (6)
2-9 mm in diameter thin media few smooth muscle fibers thick adventitia low BP valves
describe large sized veins(4)
thin media
thick adventitia
low BP
valves
what are some examples of Large Sized veins
Great Veins
Superior/Inferior Vena Cava
(and their tributaries)
What are venous valves?
flap-like structures projecting inward
- folds of media
- found in exteremities
Why are venous valves important?
Veins have low BP (valves prevent back flow of blood)
Movement of blood through veins
-movement of limbs and contraction of muscles (skeletal muscle pump)
-expansion of the thoracic cavity
-thoracoabdominal pump
describe blood distribution
- ) Its Uneven
- oxygenated blood in the heart, arteries, capillaries–> 1/3 of blood
- deoxygenated, venous blood–> 2/3 of blood - ) Known as the blood reservoir
- ) Veins contract during blood loss
What are the two circuits?
Pulmonary and Systemic
describe the Pulmonary circuit (5)
- Deoxygenated blood goes to lungs from right ventricle
- Oxygenated in alveolar capillaries of lungs
- Brought to left atrium, then left ventricle
- Veins=oxygenated
- Arteries=deoxygenated
describe Systemic circuit (5)
- Oxygenated blood goes from left ventricle to body
- Deoxygenation occurs in systemic capillaries
- Brought to right atrium, then to right ventricle\
- Veins=deoxygenated
- Arteries-oxygenated
