Lecture 8/9 - Cardio Flashcards
circulation overview - low pressure, high pressure, capillary beds, lymphatic circulation, heart as a pump
high pressure
* arterial side
* well oxygenated blood
* rich in nutrients
low pressure
* venous side
* poorly oxygenated blood
* poor in nutrients
* waste products
- heart acts as a pump arteries away from heart veins back to heart
- capillary beds act as site of exchange between tissues & blood
lymphatic circulation tends to parallel blood vasculature
blood vessels overview - hollow tubes of what, what is the cavity lined with, what does the wall contain, what size vessels have more elaborate wall contents
- blood vessels are hollow tubes of tissue, with blood flowing in the interior (lumen)
- cavity lined with simple squamous epithelium: endothelium
- wall contains varying amounts of smooth muscle, dense and loose connective tissue, including elastin sheets, organized into 3 layers
- larger vessels have more elaborate wall contents than
smaller vessels
components of blood vessel walls - names of three layers, there its predominant, major components, function, variability if thickness of each component
-Tunica Intima or Intima; predominates in microcirculation
- major components = endothelium, basal lamina, loose CT
- function = non thrombogenic
surface; interface with underlying tissue; signaling
-Tunica Media or Media; predominates in arteries
- major components = circumferential vascular smooth
muscle, CT with collagen & elastin
- function = smooths & regulates flow
-Tunica Adventitia or Adventitia;
predominates in veins
- major components = CT with collagen & elastin; sometimes
longitudinal smooth muscle; vasa vasorum
- function = resistance to maintain blood pressure; anchors
vessel in place
thickness of each component varies in characteristic fashion with blood vessel type
components of blood vessel walls - more details of each layer
Tunica Intima (Intima)
* inner layer of endothelium in contact with flowing blood
* supported by basement membrane and variable amount of loose CT
Tunica Media (Media)
* middle layer of primarily smooth muscle
* variable amount of collagen &
elastin
Tunica Adventitia (Adventitia)
* outer layer of dense irregular CT
* merges with surrounding CT to
anchor vessel in place
specializations - what is the name for vessels of the vessels, where is it found, what does it ensure
where are valves found and its function
vasa vasorum:
* ‘vessels of the vessels”
* found in media/adventitia of large arteries & veins
* ensures tissue of vessel wall
receives nutrients, etc.
valves:
* found in small-medium veins
* protrusions of intima that
prevent blood backflow
artery vs vein - more what in each, pressure
- high pressure with pulsations
- more muscle & elastin
- valves, sometimes cardiac muscle, thoracic pressure
- more fibrous CT
features of blood vessel walls - what happens when you go from larger to smaller vessels (arteries and veins), general differences
larger to smaller vessels (both
arteries and veins):
* lumen diameter decreases
* wall thickness decreases
* fewer layers of smooth muscle
* less elastic tissue & less connective tissue
in general:
* arteries have thicker walls for their diameter than veins
* smallest vessels lack complete coat of smooth muscle
elastic artery - specifics of the three layers, example of where its found
- Intima: variable CT; endothelium; rare smooth muscle cells
- Media: extensive smooth muscle, multiple elastin laminae; “internal elastic membrane” not obvious
- Adventitia: mostly dense irregular CT; collagen rich
e.g. thoracic aorta and major initial branches
large muscular veins - specifics
- Intima: endothelium; some smooth muscle
- Media: some smooth muscle; cardiac muscle near heart; collagen & elastin
- Adventitia: dense irregular CT, some elastin; longitudinal smooth muscle
muscular artery specifics and example
- Intima: endothelium; prominent internal elastic membrane
- Media: extensive smooth muscle, sparse elastin fibres; internal elastic membrane very obvious; external elastic membrane not obvious
- Adventitia: dense irregular CT; collagen rich but more elastin
e.g. femoral artery
medium vein specifics and example
- Intima: endothelium; some smooth muscle
- Media: some smooth muscle; collagen
- Adventitia: dense irregular CT; some elastin; some longitudinal
smooth muscle
e.g. saphenous vein
small artery and vein
- muscular arteries maintain
similar appearance as they get
smaller and smaller - small veins get thinner walled
as they get smaller
microcirculation - 4 kinds we talk about and what they look like
arterioles:
* 100 - 10 μm in diameter
* 1-3 layers of smooth muscle
* sparse adventitia
capillaries:
* 4 - 10 μm in diameter
* no smooth muscle; occasional pericytes
* no real media or adventitia
postcapillary venules:
* 10 - 50 μm in diameter
* no smooth muscle (some pericytes)
* no real media or adventitia
muscular (large) venules:
* 50 - 100 μm in diameter
* 2+ layers smooth muscle
* some obvious adventitia
pericytes - what do they subsitute, function
- substitute for smooth muscle
in capillaries/ small venules - wrap around vessel tube;
share basal lamina with endothelial cell - vessel stability, signaling
capillary wall structure - what layers are present, direction and function, what determines amount and exchange, three routes of exchange
- basically only intima: endothelium & varying amounts of basal lamina; may be pericytes
- sites of exchange between blood and tissue; bidirectional!
- amount and type of exchange depends on type of vessel
Routes of exchange:
-‘between’ cells (cell-cell junctions)
-‘across’ cells (pinocytosis/transcytosis)
-‘through’ cells (fenestrations and gaps)
