Chapter 9 Circulatory system

---Closed tubular system

---Blood circulatory or cardiovascular S

---Lymph vascular S

The cardiovascular S

heart

artery

vein

capillary

Organs:---cavity organ:

inner → outerlayers

---parenchymal organ: capsule parenchyma: -cortex

-medulla interstitia

1.    Capillaries1) LM:

endothelium:

basement membrane:

pericyte:

/flattened with processes

/function:

i.  support

ii. undifferentiated cell

endothelial cell: processes –microvilli-like, finger-likedplasmalemmal 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)Weibel-Palade body: rod-liked, 3um long, 0.1-0.3um in D, secrete factor VIII related antigenmicrotubule and microfilament

EM: classification①Continuous 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(60-80nm 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

3) Function:

a.  Selected permeability and exchange of material

b. Synthesis(F VIII Rag, endothelin, ET and PGI2) and metabolism(angiotensin I→angiotensin II) activity

c.   Anti-blood coagulate

2.     Artery---large A: aorta, pulmonary trunk

---medium-sized A: all named A, the diameter > 1mm(radial A,ulnar A)

---small A: 300um<D<1mm

1) Medium-sized A – muscular A---Tunica intima

endotheliumsubendothelial layer: CT

-collagenous F -elastic F -smooth muscle

internal elastic membrane: wave-liked, pink-colored band- elastin

---Tunica media: thickest layersmooth muscle: 10-40 layers of, circularlyelastic F: produced by SMcollagenous F: produced by SM

---Tunica adventitia: LCT –with small BV-vasa vasorum, NF and LVexternal 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

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- collapsedb.  no internal and external elastic membrane, s

o 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)

1) The wall of heart

---endocardium:

endothelium

subendothelial layer: more dense CT- contain fibroblast, CF, EF, SM

subendocardial layer: LCT, with BV, N and conducting S- Purkinje fiber

---myocardium: cardiac M:

a.    atrial muscle: /thin, short, unbranch, 6-8um in D, 20-30u

m long /atrial granules: 0.3-0.4um in D, contain atr

ial natriuretic factor, ANF or cardionatrin b.   ventricular M: thick, long, branches

LCT: rich in capillaries*atrioventricular fibrous annulus: DCT

---epicardium: visceral layerof pericardium- serous membrane:mesothelium LCT: more fat cell- subepicardial layer

---cardiac valve: formed by infolding of endocardium: endothelium + DCTprevent 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 branchesshorter, boarder than CM, with 1-2 centrally located nucleirich in mitochondria, glycogen, less myofibrilwell-developed intercalated disks