Download Chapter 9 Circulatory system

Chapter 9
Circulatory
system
---Closed tubular system
---Blood circulatory or cardiovascular S
---Lymph vascular S
The cardiovascular S
• heart
• artery
• vein
• capillary
1.
Capillaries
1) LM:
• endothelium:
• basement membrane:
• pericyte:
/flattened with processes
/function:
i. support
ii. undifferentiated cell
endothelial cell:
• processes –microvilli-like, finger-liked
• plasmalemmal vesicle
/60-70nm, constitute about 25-35% of total
volume
/transendothelial channel
function: transport large molecules and
storage of membrane (for enlarge,
enlongated, pore-formed and microvilli)
EM: classification
①Continuous capillary:
---Structural feature:
• endothelial cell:
-more plasmalemmal
vesicles
-tight junction
• basal lamina: complete
---Distribution: CT, MT,
lung and CNS
② Fenestrated capillary
---Structural feature:
• endothelial cell: -have
fenestrae or pore (6080nm in D, with 4-6 nm
diaphragm)
• basal lamina: complete
---Distribution:
gastrointestinal tract,
endocrine gland and
renal glomerulus
③Sinusoid capillaries (enlarge capillary)
---Structural feature:
• endothelium: gap, pore
• basal lamina: incomplete or no (absent)
---Distribution: liver, spleen and bone
marrow
2.
Artery
---large A: aorta, pulmonary trunk
---medium-sized A: all named A,
diameter > 1mm (radial A, ulnar A)
---small A: 300um<D<1mm
the
1) Medium-sized A
– muscular A
---Tunica intima
• endothelium
• subendothelial layer: CT
-collagenous F
-elastic F
-smooth muscle
• internal elastic membrane:
wave-liked,
pink-colored
band- elastin
---Tunica media: thickest
layer
• smooth muscle: 10-40
layers of, circularly
• elastic F: produced by SM
• collagenous F: produced
by SM
---Tunica adventitia:
• LCT –with small BV-vasa
vasorum, NF and LV
• external elastic M
2) Large A: elastic A
---Structural features:
a. Tunica intima is thick, and internal
elastic M is not prominant
b. Tunica media: consists of 40-70 layers
of elastic membrane, CF and SM
Large A
SM
elastic M
3) Small A:
---large SA:
• internal EM
• 3-4 layers SM
• no external M
---small SA:
• no internal M
• 1-2 layers SM
2.
Veins
---three type
---correspond with A except for LV
---three layers
---structural features:
a. larger diameter, thinner walls- collapsed
b. no internal and external elastic membrane,
so the boundaries between three tunica are
not very clear
c. contains more CT, less smooth M, SM are
arranged in bundles
d. vein valve:
/infolding of tunica intima
/semilunar-liked
/prevent back flow of blood
4.
Heart
---atrium(right and left)
---ventricle (right and left)
The wall of heart
E
SE
endocardium
subendocardial layer
myocardium
epicardium
1) The wall of heart
---endocardium:
• endothelium
• subendothelial layer: more dense CTcontain fibroblast, CF, EF, SM
• subendocardial layer: LCT, with BV, N
and conducting S- Purkinje fiber
---myocardium:
• cardiac M:
a. atrial muscle:
/atrial granules: 0.3-0.4um in D, contain
atrial natriuretic polypeptide or cardionatrin
b. ventricular M: thick, long, branches
• LCT: rich in capillaries
*atrioventricular fibrous annulus: DCT
---epicardium:
visceral
layer of pericardiumserous membrane:
• mesothelium
• LCT: more fat cellsubepicardial layer
---cardiac valve:
• formed by infolding of
endocardium:
endothelium + DCT
• prevent the back flow
of blood
2) Conducting S
① components:
---sinoatriol node (SA node):
located in epicardium of
right atrium
---atrioventricular node (AV
node) and bundles (AV
bundles):
located
in
subendocardial layer
---network of Purkinje fiber:
② three types of cells
a. pacemaker cell ( P cell):
• mainly distributed in SA and AV node
• small, fusiform or polygonal in shaped
• enclosed by DCT
• less organelle: myofibril,
plasmalemmal vesicles and more
glycogen
b. transitional cell:
• mainly distributed in periphery of SAN
or AVN and AV bundle
• The structure is between pacemaker
cell and cardiac M
• thinner and shorter than CM
• more myofibril than P cell
c. Purkinje cell:
• mainly constitute AV bundle and
branches
• shorter, boarder than CM, with 1-2
centrally located nuclei
• rich in mitochondria, glycogen, less
myofibril
• well-developed intercalated disks