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the cardiovascular system – CVS ( the function is to carry blood between the heart and the tissues)

the lymphatic system – LS ( the function is to collect lymph and deliver it back to the CVS)

• The circulatory system ( CS) is composed of two components:

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The CVS is composed of :

the heart ( that pumps the blood into two separated circuits: the pulmonary circuit and the systemic circuit)

the blood vascular system ( arteries, capillaries, veins)

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General Structure of Blood Vessels

♥TUNICA INTIMA

♥ Internal elastic lamina

♥TUNICA MEDIA

♥External elastic lamina

♥TUNICA ADVENTITIA

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♥a single layer of endothelial cells

♥a subendothelial layer

TUNICA INTIMA

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TUNICA MEDIA

♥ concentric layers of smooth muscle cells

♥ some elastic fibers

♥ type III collagen

♥ proteoglycans

Capillaries and postcapillary venules do not have a tunica media.

Pericytes replace the media.

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TUNICA ADVENTITIA

♥fibroblasts

♥type I collagen fibers

♥ longitudinally oriented elastic fibers

Vasa vasorum – in large vessels

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Classification of arteries

Elastic ( conducting )

Muscular (distributing)

Arterioles

Arteriole

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Vasa Vasorum

vasa vasorum, which supply blood for the wall of this large vein

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are composed of a single layer of

endothelial cells , rolled into a tube,

resting on a basal lamina

CAPILLARIES

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are mesenchymal origin

each cell contains desmin and vimentin

filaments = provide structural support

are joined together by

zonulae occludentes and gap junctions

ENDOTHELIAL CELLS

IndeksPERICYTES

♥are mesenchymal origin♥are located along the outside of the

capillaries and small venules♥possess a small Golgi complex,

mitochondria, rER, microtubules ♥contain myosin, actin,and tropomyosin

and protein kinase, which are all related to contraction

♥may differentiate into smoooth muscle and endothelial cells- after injury

Continuous capillary

blood-brain barrier

muscle tissue

connective tissue

exocrine glands

Fenestrated capillary

With diaphragme

endocrine glands, intestine

Without diaphragme

renal glomerulus

Discontinuous ( sinusoidal) capillary

liver, spleen, bone marrow

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1. Transport of gases ( O2, CO2), and hydrophylic molecules (e.g.glucose)

2. Metabolic:

a. Production of vasoactive factors:

endothelin I- acts as hypertensive agent

b. Secretion of :

- collagen types II, IV, V,

- fibronectin, laminin ( the ExCM)

c. Antithrombogenic – prevent contact of platelets with the subendothelial CT

d. Lipolysis- breakdown of lipoproteins

e. Inactivation- bradykinin, serotonin, prostaglandins, norepinephrine, thrombin

Functions of capillaries:

CAPILLARY

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♥ a single layer of squamous endothelial cells

♥ a thin subendothelial layer of loose connective tissue

♥ the subendocardial layer ( with veins, nerves and Purkinje cells)

The Endocardium consists of:

IndeksThe Myocardium

♥ is the thickest of the tunics

♥ consists of cardiac muscle arranged in layers and grouped into three populations:

1. contractile cells

2. the impulse-generating and conducting cells

3. specialized cardiac muscle cells – located in the atrial wall-produce peptide:

atrial natriuretic polypeptide ( cardiodilatin, cardionatrin)

it acts on kidneys to cause sodium and water loss ( balance of electrolytes and blood pressure)

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is the serous covering of the heart and forming the visceral layer of the pericardium

is covered externally by mesothelium

The Epicardium

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the sinoatrial node internodal tracts the atrioventricular node the atrioventricular bundle

of His Purkinje cells

The sinoatrial node is the pacemaker of the heart

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Atrioventricular bundle of His

right bundle branches

left bundle branches

fascicles

PURKINJE CELLS

IndeksLymphatic vessels

♥ are found in all organs

♥ are blind-ended

♥ consist of a single layer of endothelium

♥ have no fenestrations in their endothelial cells, no zonula occludens between cells and incomplete basal lamina

♥ they absorb some of electrolytes and proteins that leave the blood capillares