circulatory system shiping ding ( 丁世萍 ), ph. d school of medicine, zhejiang university
TRANSCRIPT
Circulatory system
Shiping Ding (丁世萍 ), Ph. D
School of Medicine, Zhejiang University
Learning Objectives
• To be familiar with the type of capillary.• To be familiar with the type of artery and
vein.• To distinguish with all the types of blood
vessels.
Concepts of organs and systems
Organ: composed of four kinds of the tissues in a particular way
TypesHollow organs: studied from inside to outside
Substantial organs:
System: composed of many organs which have relationship with each other in structure and function.
parenchyma
interstitium
General outline
•Blood vascular system (cardiovascular system)
•Lymphatic vascular system
---Closed tubular system
According to the circulating
fluid in the tubes, blood or lymph:
Cardiovascular System
The histological study of the cardiovascular system includes two major components
• Heart – mainly functions as a pump to move blood (and all the things blood carries) through the body.
• Blood vessels – are the tubes that distribute the blood to the cells and then back to the heart.
The blood vessels include three major divisions:
Arteries – deliver blood from heart to capillariesCapillaries – the smallest blood vessels and closest to body cells, the interchanges between blood and tissues occur thereVeins – carry blood from body to the heart
Histological Structure of Blood Vessels
Structural feature of Arteries and Veins:
Tunica intimae 1. Endothelium 2. Subendothelial layer 3. Internal elastic membrane Tunica media Mainly smooth muscle
Tunica adventitia external elastic membrane Mainly connective tissue
medium-sized A
Artery Artery
transport blood from heart to capillaries
according to their size, structure and function
Large artery
Medium-sized artery D>1mm
Small artery D>0.3~1mm
Arteriole D<0.3mm
are classified
• The wall of Arteries consist of three layers or “coats” often referred to as tunics.– Tunica intimae – is the inner coat
– Tunica media – is the middle layer
– Tunica adventitia or tunica externa is the outer layer of the wall of the blood vessel
• Layers of arteries wall differ in different size blood vessels. The structure and function of arteries change as their diameter decreases.
Structure features of artery
Tunica intimaeTunica intimae
• is the inner coat and it consists of
1)inner endothelial layer
2)subendothelial layer: a layer of loose connective tissue
3)internal elastic membrane (often very distinct)
• This layer is relatively constant within different size arteries.
Tunica mediaTunica media• This layer makes up the greatest part of the wall of the
artery. • It is comprised primarily of smooth muscle.• In small arteries or arterioles it may be only 1-3 cells thick
but in larger arteries may comprise hundreds of layers of muscle cells.
• In large arteries, there in increased amounts of elastin fibers.
Tunica adventitiaTunica adventitia• This is the outer layer of the wall of the artery. • It consists primarily of connective tissue and serves to
attach the blood vessel into the surrounding connective tissue.
• Often contains adipose tissue and often contains blood vessels (vasa vasorum) that supply the walls of the blood vessels.
Medium-sized artery (Muscular artery):Medium-sized artery (Muscular artery):
muscular artery: diameter larger than 1mmdiameter larger than 1mm
Tunica intimaTunica intima
EndotheliumEndothelium
Subendothelial layer: LCTSubendothelial layer: LCT
Internal elastic laminaInternal elastic lamina: clear: clear
Tunica media: contain Tunica media: contain 10~40 layers10~40 layers of circular of circular
smooth musclesmooth muscle
Tunica adventitiaTunica adventitiaExternal elastic laminaExternal elastic lamina
LCT: contain vasa vasorumLCT: contain vasa vasorum
TunicaTunicaAdventitiaAdventitia
TunicaTunicaMediaMedia
Tunica Tunica intimaintima
Medium-sized artery
Classic muscular artery- elastic stain
Large (elastic) artery: contains aorta, the pulmonary trunk and their main branches
With a large lumen relative to wall thickness
subendothelial layer is thicker with a few smooth muscles
tunica media is thick, contains a 40-70 concentrically-arranged elastic lamina
internal and external elastic lamina are not distinguished
tunica adventitia are thinner, abundant vasa vasorum
PTPT stain stain
Elastic arteryElastic artery Muscular arteryMuscular artery
Small artery:Small artery:
muscular artery and peripheral resistance vessel
internal elastic lamina is clear, while external elastic lamina is not distinguished
the tunica media contains 3~9 layers of smooth muscles
Arterioles:Arterioles:
Less than 0.3mm in Less than 0.3mm in diameter. Have similar and diameter. Have similar and simpler structure as that of simpler structure as that of muscular arterymuscular artery..SeveralSeveral layers of smooth layers of smooth muscle in tunica media.muscle in tunica media.Responsible for the Responsible for the presence of blood pressure.presence of blood pressure.
Vein Vein large lumen, thin wall, irregular
internal and external elastic lamina are not clear
tunica media is thin, with a few elastic fibers and smooth muscles
tunica adventitia is thick (best-developed)
some veins have valves
Large veins D>10mmLarge veins D>10mm
Medium-sized vein D=2~9mmMedium-sized vein D=2~9mm
Vein valves: Bag-like protrusion of tunica intima, which prevents the blood flow from running to opposite direction. Exists only in the vein that has low position or far away from heart.
Vein with valve
A Comparison of a Typical Artery and a Typical Vein
elastic tissue is colored dark purple, cytoplasm (in smooth muscle and nerve) is lighter purple, and collagen is pale pink.
Artery, vein, nerve, elastin stain
Artery, vein, nerve, elastin stain
elastic tissue is colored dark brown, collagen is pale pink and cytoplasm
(in smooth muscle and nerve) is purple.
Artery, vein, nerve, trichrome stain
collagen is colored blue and smooth muscle is red. Red blood cells
in the venous lumen are brighter red.
CapillariesCapillaries• Capillaries are the site where materials carried in the
blood are unloaded and other materials are loaded into the blood.
• In many organs the capillaries form a network. • Consist of a single layer of simple squamous epithelium.
the average diameter about 8um.
CapillariesCapillaries
1) L/M: • A single layer of endothelial
cells• Pericyte• A basement membrane
Pericyte:
long cytoplasmic processes
have a contractile function, participating in the repair process
Capillary - pericyte
The types of Capillaries
Continuous C.Continuous C.
Fenestrated C.Fenestrated C.
SinusoidSinusoid
E/ME/M
Continuous capillary
Fenestrated capillary Sinusoid
Structure endothelial cell: large number of pinocytotic vesicles
cell junctions between the endothelia (tight junction)
no pores, no gaps
basement membrane: integrity
endothelial cells: present abundant perforated pores (60-80nm in D, with 4-6 nm diaphragm)
have or haven’t diaphragm on them
basement membrane: continuous
a greatly enlarged diameter (30~40um)
endothelial cell: intercellular clefts are large between cells, many pores without diaphragm
absence of a continuous basement membrane
macrophages are located either among or outside the cells of the endothelium
Location distributed in muscle tissue, brain, lung and connective tissue, etc.
distributed in tissues where rapid interchange of substances occurs between the tissue and the blood, as in the kidney glomerulus, mucosa of gastrointestine, some endocrine glands
distributed in tissues where interchange of substance in big size occurs, as in the liver, spleen, and some endocrine glands
The types of Capillaries
Continuous capillary Fenestrated capillary Sinusoid
Heart Heart
a hollow muscular organ that contracts rhythmically
pump blood through the circulatory system
The wall of heartThe wall of heart
endocardiumendocardium
myocardiummyocardium
epicardiumepicardium
The wall of heartThe wall of heart
ESE
subendocardial layer
endocardium
myocardium
epicardium
Purkinje fibers
endocardium
EndotheliumEndothelium
Subendothelial layer: fined CTSubendothelial layer: fined CT
SubendocardialSubendocardial layer: LCT, blood vessels, nerves and layer: LCT, blood vessels, nerves and the impulse-conducting system of the heartthe impulse-conducting system of the heart
闰盘 线粒体
myocardium thickest layer, consists of cardiac muscle, is richly supplied with capillaries
three layers are divided roughly, cardiac muscle arrange spirally.
Cardiac muscle:HE×100
构成心包脏层
心包受损 影响心脏功能
epicardiumLCT: contain adipose cells, blood vessels and
nerves
MethotheliumMethothelium
Conducting SystemConducting Systemcomponents: components:
sinoatrial node (SA node): sinoatrial node (SA node): the primary pacemaker of the heartthe primary pacemaker of the heart
located in epicardium of right atriumlocated in epicardium of right atrium
atrioventricular node( AV node)atrioventricular node( AV node)
bundles( AV bundles) located in bundles( AV bundles) located in subendocardial layer. subendocardial layer.
network of Purkinje fibernetwork of Purkinje fiber
Impulse generating and conducting Impulse generating and conducting system of the heart:system of the heart:
Pacemarker cell
Transitional cell Purkinje cell
Location SA / AV SA / AV /AV bundle
AV bundle / branches
Structure small, fusiform or polygonal in shaped
less myofibril
thinner and shorter than caridac muscle
more myofibril than P cell
shorter, boarder than caridac muscle, with 1-2 centrally located nuclei
rich in mitochondria, glycogen, less myofibril
well-developed intercalated disks
Function heartbeat heartbeat generatinggenerating
transmit impulsetransmit impulse Transmit impulse into the Transmit impulse into the ventricle quicklyventricle quickly
transitional cell Purkinje cell
Purkinje cellPurkinje cell Cardiac cellCardiac cell
Purkinje cells Purkinje cells both broader and shorter than both broader and shorter than ordinary cardiac muscle fibers, rich in ordinary cardiac muscle fibers, rich in sarcoplasm, two nuclei can be found,sarcoplasm, two nuclei can be found, well-well-developeddeveloped intercalatedintercalated disks.disks.
Purkinje fiber
Purkinje fibers
cardic valveThe core of dense connective tissueThe core of dense connective tissue
endotheliumendothelium prevent the back flow of bloodprevent the back flow of blood
Question1. To describe the difference between large artery and medium-sized artery.2. To describe the types of capillary.
Good-bye!
Thank you for your attention!