Lecture 14 Vessels and Circulation Flashcards
Classes of Vessels
- Arteries: take blood away from heart
- Capillaries: tiny blood vessels where gas exchange occurs and distribution of nutrients
- Veins: return blood back to heart
Pathway of Vessels
arteries move blood from heart to capillaries move blood to veins, veins return blood back to heart
Anastomoses
Anastomoses : converging arteries and/or veins for the purpose of having alternative routes
End Arteries
End arteries: one pathway for blood to travel
Functional end arteries
Functional end arteries : are small anastomoses but act like end arteries still use only one path over again
Companion Vessels
Companion Vessels: corresponding vessel for an artery , an artery has a companion vessel of a vein .
What are Tunics
Layers of arteries and veins
what are the three tunics
Tunica Externa: simple squamous and areolar CT
Tunica Media: smooth muscles middle meaty part
Tunica Intima: simple squamous and areolar CT, internal layer
what is the function of arteries
Transport blood away from the heart
what are the characteristics of arteries
Thick tunica media
Contains more collagen for strength and elastic for stretching and recoil
High pressure because the blood is leaving the heart
small lumen
What are the three types of arteries
- Elastic arteries: biggest and most flexible
- Muscular arteries: are going to be majority /most common
- Arterioles: small arteries
Elastic Arteries
Size: largest
the artieres near heart
- Increased elastic fibers, Will have elastic because they are the largest and very close to the heart
Increase of elastic fibers make it possible for artery to keep up with the high pressure and strength for pumping blood
Examples of elastic arteries
pulmonary artery, aorta, brachiocephalic, common carotid , subclavian
Muscular arteries
- Medium size
- Distributing arteries because they distribute blood throughout the body (organs and tissues)
- Thicker tunica media, less elastic fibers, more muscle, muscle artery
- *Better vasoconstricting and vasodilation
- *Vasoconstriction: constricting lumen lessen blood to go through
- *Vasodilation: relax to allow blood to flow through
What are examples of muscular arteries
brachial, anterior tibial, coronary
Aterioles
Smallest
Control blood flow to capillaries
Important because they are the last part before capillaries , last part before capillaries
Capillaries do not have smooth muscle. So it can not control blood
Last point of blood control is arterioles
Vasodilate and Vasoconstriction to help regulate blood pressure
Function of Capillaries
- Function:
- Rapid gas and nutrient exchange
- “Functional units”
Functional units: capillaries work together in capillary bed, capillary gives nourishment to tissues
Only place where gas is exchanged
Characteristics of Capillaries
Considered the smallest vessel, size of one rbc fits into a capillary
Only a tunica intima
Clefts: spaces in between the capillary which allow certain things to travel through
No smooth muscle only endothelium (thin layer)
Capillary bed is fed by metarteriole
Distal end is called thoroughfare channel and it has no smooth muscle
Thoroughfare channel lead to venual known as postcapillary venule
Proximal: smooth muscle
What are the types of capillaries
- Continuous capillaries
- Fenestrated capillaries
- Sinusoids
Continuous Capillaries
- Most common
- Tight junctions
Tight junctions : connect cells together adhesions
Location of Continuous Capillaries
- Locations: muscles, skin, lungs, thymus, CNS
Fenestrated Capillaires
Small holes - Allow fluid exchange Small holes looked punctured Holes allow for fluid exchange Small holes looked punctured Holes allow for fluid exchange Think kidneys filters fluid
Locations of Fenestrated Capillaries
Location: Kidneys and intestines
Think kidneys filters fluid
Sinusoids
Large gaps/openings
- Allows exchange of larger materials and cells
Think process of recycling blood for this type of capillary
Location of Sinusoids
Location: spleen, liver
Function of Veins
Function:
- Transport blood to the heart (Brings blood back to the heart
- Blood reservoirs
Characteristics of Veins
Lumen of veins is very big/large
Blood reservoirs, they can hold a lot of blood
Veins contain valves to help prevent back flow
Thicker Tunica Externa (outer layer )
Low pressure
what are the two types of veins
- Venules
2. Veins
Venules
Size: small
- CompSize large anion: arterioles
What are the featres of venules
Postcapillary venules: what drains the capillaries,
Diapedesis: ability for WBC to migrate into the interstitial fluid,
Veins
Size large
Companion vessels: muscular and elastic arteries
Features of veins
Skeletal muscle pump: very efficient, both sides of the vein will have skeletal muscle, the skeletal muscle can contract, once it contracts they squeeze on vein pushing blood either upward toward heart or keeps it from going back , when relaxed it sucks blood up
Valves: promotes blood flowing upward , but can not go back
Structures of Newborn Circulation
- Ductus arteriosus
- Ductus venosus
- Foramen ovale
Ductus Arteriosus
Ductus arteriosus is a vessel between pulmonary trunk and aorta, your not using your lungs, no need for pulmonary circulation because you get O2 blood from mother, so it is bypassed
Adult: ligamentum arteriosum, the ductus arteiosus collapses and turns into the ligamentum arteriosum
Ductus Venosus
Vessel meant to bypass liver,
Fetus has no functional GI tract
Adult: ligamentum venosum
Foramen Ovale
Oval shaped hole between right atrium and left atrium
why: to bypass pulmonary circulation
Adult: foramen ovale flap falls over hole and becomes an indentation on right atrium wall known as fossa ovalis
Circulation pathway
Blood comes from Systemic Circulation (SVC, CS, IVC),then enters the right atrum, goes through the tricuspid valve,enters the right ventricle, right ventricle pumps it through the pulmonary semilunar valve into the pulmonary trunk and arteries, goes to lungs and comes back to heart oxygenated through [aired pulmonary veins,. Then enters the left atrium and goes through the bscuspid valve, next entering the left ventricle which will eject blood through the aortic semilunar valve, goes up ascending aorta into the aortic arch and t the descending thoracic aortaback to the systemic circualtion.
