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 → outer layers ---parenchymal organ: capsule parenchyma: -cortex -medulla interstitia

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) Weibel-Palade body: rod-liked, 3um long, um in D, secrete factor VIII related antigen microtubule and microfilament

EM: classification ① Continuous 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

③ Sinusoid 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 PGI 2 ) 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 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: 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 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- 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)

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, um long /atrial granules: um in D, contain atrial 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 + 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