L20. Circulatory System Flashcards
What does the cardiovascular system consist of?
- heart
2. two circuits of the blood vessels: systemic and pulmonary
What are the 2 circuits of the blood vessel
- systemic
2. pulmonary
What are arteries?
- Vessels and tubes that send blood away from the heart
- high pressure
- have thicker tunia than veins
- Branches into capillaries that supply all regions of the body
What are capillaries?
thin walls of vessels that allow the exchange of gases, hormones, nutrients and waste between the blood and tissues
- endothelial cells and pericytes surrounded by the basement membrane = T.Intima
- consist almost entirely of the tunica intima only
What are veins?
A series of vessels that drain the capillary bed forms larger diameter that return blood to the heart
What are the 3 layers covering the blood vessel?
Start from innermost to outermost
- tunica intima
- tunica media
- tunica adventrilia
How does the composition of the 3 layers surrounding the blood vessel vary?
vary depending on blood vessel type and location
Identify the 3 layers in the blood vessel on L20. page 3a.
L20, pg 3a
Describe the characteristics of blood vessel organization
- mesodermally-derived tubes
- central lumen contains blood
- outer wall contains 3 layers (tunica intima, tunica media,tunica adventrilia)
- tunica vary in tissue composition and structure depending on the vessel type
Describe the tunica intima
- Simple squamous and cubodial epitelium forms the simple epithelial ( endothelium)
- has pericytes
- basement membrane
- contains elastic fibers
Describe the tunica media
- concentric layers of smooth muscles
- concentric layers of elastic fibers
- C.T varies in amount and type
Describe the tunica adventitia
- contains vas vasora (blood vessels that supply walls of large vessels)
- outermost connective tissue, varies in thickness and type
- largest veins may have longitudinal smooth muscles
What are the different types of arteries?
- elastic arteries
- muscular arteries
- arterioles
Describe the elastic artery
- TI: has prominent lamina propria
- TM: has elastic fibers that aid in the contraction and recoil
- TA: has a prominent vas vasorum
What is the cause of an aneurysm?
lost of elasticity in the tunica media
Describe the muscular artery
- TI: has many accordion folds, has elastic fibers
- TM: contains up to 40 layers concentric smooth muscle
- TA:contains dense amount of collagen
Describe the arteriole
- TI: endothelium and basement membrane , little lamina propria
- TM:1-3 layers of muscle
- TA: loose connective tissue
What controls teh contraction of the arteriole
- paracrine factors
- autonomic nerves (contraction=epinephrine; relaxation=acteylcholine and NO)
- regulate blood pressure and blood flow into capillary beds at the metarterioles
What are metarterioles
they are the smallest pre-capillaries branched from the arterioles
What are the different types of capillaries
- continuous capillaries
- fenestration capillaries
- sinusoidal capillaries
Describe the continuous capillaries
- exchange between blood and surrounding tissue is highly regulated
- endothelium has tight junctions;
- macromolecular transport is highly regulated by pinocyotosis or vesicular transcytosis
Where can continuous capillaries be found?
- brain
- lungs
Describe the fenestration capillaries
- exhcange between blood and surrounding tissue is selective
- endothelium has small gaps that has a proteoglycan (diapgram) that is selective for marcromolecular passage
Where can fenestration capillaries be found
kidney, intestine endocrine gland
What is the function of proteoglycan diaphragm?
prevents free passage of large macromolecules (eg. plasma protein)
What is the function of sinusoidal capillaries?
- allow free exchange between the blood vessel and surrounding tissues
- large gaps in the endothelial walls so cells can move through
- large diameter (40um)
- aka venous sinosoids
Where ccan sinusoidal capillaries be found?
bone marrow, liver, spleen
What are the 3 types of veins
- venules
- small and medium veins
- large veins
What are venules?
- immediate post capillary - large diameter lumen vs arteriole
- prominent tunica intima - major site of diapedesis
What are small and medium veins?
- folds of tunica intima push into the lumen
- forms valves - TM: less prominent than arteries
- prominent tunica adventitia
- lots of collagen 1
What are the large veins
- TI: prominant; lamina propria is fibroelastic
- TM: not well develop
- prominent tunica adventitia
- collagen 1 , elastin , some longitudinal smooth muscles
Name factors that drive blood flow in veins
- presence of valves in tunica intima
2. skeletal muscles constrict veins
What are the differences between venules and arterioles
- veins have a larger lumen diameter than arterioles
- the TI is prominent in veins than in arterioles
- the TM in veins have a sparse CT while arterioles have smooth concentric muscles
