Download Preparation of circulatory system

Chapter 8
Circulatory system
Teacher ：Huang Ju-en
(黄巨恩)
Dept.of Histology and
Embryology
1.Concepts of organs and systems
 Organ: composed of four kinds of the tissues
in a particular way
Types
Hollow organs: studied from inside to outside
parenchyma
Substantial organs:
interstitium
 System: composed of many organs which
have relationship with each other in
structure and function.
2.Composition of circulatory system
 Cardiovascular system
 lymph vascular system
lymphatic duct
lymphatic vessel
lymphatic capillary
heart
vein
artery
capillary
tissue fluid
artery
vein
heart
capillary
一、Composition of blood vessel and their general structures
Endothelium
Tunica
intima
Subendothelium
Internal elastic M.
Tunica media
Tunica adventitia
1.Intima
(1)Endothelium
Distribution、morphology
Face the lumen and belong to squamous
Model of endothelium of blood vessel
WeibelPalade body
Fig. Of EM
(2)Subendothelial
layer
Located beneath the endothelium
Composed of thinner layer of C.T containing small amount of
collagenous fibers,elastic fibers or some smooth muscle
(3)Internal elastic membrane
Internal elastic membrane is composed of elastic protein
and there exist many fenestrations on it. It is wave-like and
serve as a border between intima and media of artery.
2. Media
Located between Intima and adventitia
Thickness depend on different kinds
of blood vessels
Composition
Large A. ——elastic M.
medium A. —— Smooth M.
Function Dilate and retract blood vessels,
Maintain tension of blood vessels
3.Adventitia
Distribution outermost、
Thickness
thicker
Composition
L.C.T containing fibroblast,
collagenous F. , elastic F. and
external elastic membrane
adventitia
Heart
The wall is thickest and
consist of largely cardiac
muscle
nucleus
Intercalated
disc
Cardiac
muscular fiber
 heart
1. The structure
of heart wall
endocardium：endothelium,
subendothelial layer,
subendocardial layer.
myocardium：three layers are divided
roughly, cardiac muscle arrange spirally.
epicardium：plasma membrane,
mesothelium on the surface
Intercalated
disc
Mesothelium
Adipose
tissue
Tunica adventitia
2．Heart conducting system
Definition：This system is composed of specific cardiac
muscle fibers that can generate and conduct impulses to all parts of
the heart, making heart contraction in rhythm.
Types of cell：pacemaker cell,
transitional cell,
Purkinje fiber.
※cardiac skeleton── A supporting structure, locating between atrial muscle
and ventricular muscle and consisting of DCT. It is a frame of heart and provide
a attachment for cardiac muscle and cardiac valve.
※cardiac valve──The thin-scalloped structure, formed by endocardium
protruding into cavity of heart.
The core of dense connective tissue
Endothelium
Endocardium
Valve
Arteries（Artery，A）
1. Grade：
large A：Φ>10 mm
medium-sized A：Φ1─10mm
small A：Φ0.3─1mm
arteriole：Φ<0.3 mm.
2. Characteristics of various arteries :
 large A（elastic A）：
Conducting A.
Medium-sized A
（muscular A）：
Distributing A.
Features of large A
(1) Subendothelial layer: is thicker. There not only
are many layers of internal elastic membrane outsides, but
also confused together with elastic membrane of middle
membrane. As a result, layering of large A are not as clear
as medium-size A.
(2) Middle tunic: consist mainly of elastic membrane
of 40～70 layers, with occasional smooth muscle cells,
elastic fibers and collagen fibers among elastic membranes.
Major components of ground substance are chondroitin
sulfate.
(3) External tunic：This is a thin layer of connective
tissue and there is not obvious border with enveloping
connective tissue. External elastic membrane is not obvious.
Intima
Elastic M.
Smooth Muscle
Media
Adventitia
Large Artery
external tunic
Middle tunic
Features of medium-side A
（1）Layering clearly. internal elastic membrane is
integrate
（2）Middle tunic consist of smooth muscle of 10～40
layers, intermixing with elastic fibers, collagenous fibers
and ground substance.
（3）Thickness of external tunic equal middle and often
there is obvious external elastic membrane between two
tunic.
3．Small A：
They are also muscular A but layering is not clear. Smooth
muscle is small. There is no external elastic membrane.
4．Arteriole：
layering is not more clear. There is only one or two layers
of smooth muscle
Arteriole
Small
A.
Small V
 Capillary (Cap.)
1.Distributions：broadly and have a relation with
metabolism.
Size：Cap. generally is 6～8 μm, but some sinusoid can
reach 40 μm in diameter.
2.General structures：
①endothelia
②basal membrane
③pericytes：The flat-thin cells with processes between
endothelium and basal membrane.
④small amounts of connective tissues
3.Classifications and their EM structures：
 continuous cap.：
fenestrated cap.：
sinusoid（sinusoidal cap., discontinuous cap.）：
4.The structural bases of substance interchange of cap.：
（1）Larger square, thin vascular wall, short distance with surrounding cells.
（2）O2 、CO2 and lipid-soluble substances can penetrate the walls of cap.
directly.
（3）liquid and macromolecule can pass through endothelial pores.
（4）pinocytotic vesicles can transport liquid.
（5）intercellular space facilitate more easily elements to pass through.
（6）basal membrane make small molecular substances filtrate readily , so
disintegrate basal membrane or no is easier to material exchanges.
5. Capillary permeability:
The ability of substances passing
through capillary.
Classifications and
ultrastrutural feature
of Cap.
continuous cap.
fenestrated cap.
sinusoid
Pore
Pinocytotic
vesicle
pinocytotic (plasmalemmal)
vesicles
Endothelium
Intercellular
space
RBC
Basal membrane
pore
sinusoid
 Vein, V
1.structural characteristics：
①internal and external elastic membrane both are unclear
②The thickness of external tunic> middle tunic
③large and irregular lumens, thin walls.
2.Vein valves：
Internal tunic of veins (their diameter usually are over 2 mm) protrude into
lumens and form pleats , in the center of which connective tissue containing
elastic fibers exist, but endothelia overlap on the surfaces.
3.Microcirculation
1．Definition：The blood circulation of micro-small blood vessels between
arterioles and venules
2．Compositions：arterioles, precapillary arterioles, metaarterioles, true
capillaries, short cuts, arteriovenous anastomosis and venules.
Questions
1. By comparison, what are the same and different items among
larger, medium-side and small arteries in the structures of
vessel walls? Try to describe the relationships between the
structures and functions of blood vessels
2.
How to distinguish arteries and veins under LM?
3. How to distinguish the surface of endocardium from that of
epicardium under LM?
4. Try to describe the general characteristics of structures of
capillaries. What are structural and functional features for each
kind of capillaries respectively?
Good-bye!