2. T- TUBULES & SARCOPLASMIC RETICULUM Less regular arrangement T- Tubules are more numerous At level of Z- line DIAD CONDUCTING SYSTEM Mitochondria more numerous Lipofuscin pigment granules

3. CARDIAC FIBROUS SKELETON Septum membranaceum Trigona fibrosa Annuli fibrosa Composed of dense connective tissue CONDUCTING SYSTEM

5. CIRCULATORY SYSTEM BLOOD VASCULAR SYSTEM LYMPH VASCULAR SYSTEM COMPONENTS HEART ARTERIES CAPILLARIES LYMPHATIC CAPILLARIES LYMPH VESSELS LYMPHOID ORGANS

6. DIVISIONS MACROVASCULATURE: > 0.1µm, large arterioles, muscular & elastic arteries, muscular veins MICROVASCULATURE: < 0.1µm, arterioles, capillaries, post capillary venules Exchange vessels

7. TISSUE COMPONENTS Endothelium Muscular tissue Connective tissue (Elastic elements)

8. STRUCTURAL PLAN OF BLOOD VESSELS TUNICA INTIMA Endothelium Basal lamina Sub endothelial connective tissue Internal elastic lamina TUNICA MEDIA Smooth muscles Elastic lamellae, reticular fibers Ground substance elements External elastic lamina

9. TUNICA ADVENTITIA Collagen & elastic fibers VASA VASORUM Vessels of vessels Arterioles, capillaries, venules in adventitia INNERVATION Sympathetic fibers (norepinephrine) Vasoconstriction Arteries in Skeletal Muscles- cholinergic vasodilator fibers

10. ENDOTHELIUM: Semi permeable barrier Monitor bidirectional exchange Nonthrombogenic surface; heparin, tissue plaminogen activator & Von Willibrand factor Regulate Vascular tone & Blood flow; Contraction: endothelin 1 & ACE Relaxation: NO & Prostacyclin Inflammation & Local Immune response; Adhesion of WBCs, expression of P-Selectin, Weibel Palade Bodies Growth Factors; VEGF in Vasculogenesis, Angiogenesis, role of Angiopoeitins Lipolysis Produce Vasoactive substances Thrombosis, emboli (Role of TPA)

11. VASCULAR SMOOTH MUSCLES Present in all vessels EXCEPT capillaries and post capillary venules Enclosed in basal lamina & connective tissue Arranged helically Connected by gap junctions VASCULAR CONNECTIVE TISSUE Variable proportion Collagen, IV, III, I Elastic fibers Ground substance; heterogenous gel

12. Medical Application Arteriosclerosis Thickening of walls of small arteries Monkeberg’s calcific sclerosis Atherosclerosis

13. LARGE ELASTIC ARTERIES T. INTIMA Intima is thicker; smooth muscles in sub endothelial connective tissue Internal elastic lamina, though present not prominent T. MEDIA Concentric lamellae of elastic fibers (40-70) Reticular fibers, smooth muscles T. ADVENTITIA Less developed

15. Arterial Sensory Receptors Carotid & Aortic Sinus: Baroreceptors Tunica Media is thin--- allows distension Afferent impulses via 9 th cranial nerve Vasomotor center in brain Efferent adjust lumen to control BP Carotid & Aortic Bodies: Chemoreceptors Para ganglia with rich capillary network Glomus type I cells; dense core granules containing Dopamine, Ach Supported by Satellite Type II cells Ion channels in Glomus cells respond to Low Oxygen, High CO2 or Acidosis Afferents to brain efferents to cvs or respiratory system

17. MEDIUM SIZED, MUSCULAR ARTERIES T. INTIMA Subendothelial layer thin Prominent internal elastic lamina T. MEDIA Smooth muscles- 40 layers Elastic fibers T. ADVENTITIA Connective tissue, vasa vasorum, lymphatics

20. SMALL ARTERIES & ARTERIOLES <0.5mm lumen Thin subendothelial connective tissue Int. elastic lamina absent in small arterioles T. Media: smooth muscle layer Adventitia is thin Hypertension

21. CAPILLARIES Diameter : 5-7 µm Single layer of endothelium; permit metabolic exchange Function in groups- Capillary Beds Richness conforms to metabolic activity of tissue Structure and pulsatile flow of blood through capillaries and thoroughfare channel.

23. TYPES Continuous Fenestrated Sinusoidal

24. CONTINUOUS CAPILLARIES No fenestrations, complete basal lamina Pinocytic vesicles Location: Muscles, nervous tissue, exocrine glands

25. FENESTRATED CAPILLARIES Transcellular openings (80nm) Limited by cell membrane Covered by diaphragm ( thinner than cell membrane, proteoglycans) In endocrine glands Kidneys etc

26. SINUSOIDAL CAPILLARIES Diameter 30-40µm Endothelial cells discontinuous layer Fenestrations without diaphragm Incomplete basal lamina Macrophages Found in liver, hematopoietic organs

27. PERICYTES Cells at periphery of continuous capillaries enclosed in own basal lamina Mesenchymal origin Actin, myosin– contractile properties Role in repair process Diabetic Microangiopathy