Cadriovascular system Flashcards
Cardiac fibrous skeleton
4 fibrous rings surrounding Valve orifices
2 fibrous trogones connecting the rings and the membranous part of the interventricular septum
Valves
Atrioventricular (tricuspid, bicupsid)
Semilunar (Aorta, pulmonary)
layers: dense CT (Valve leaflet) subendothelial CT Endothelium
Three layers of heart wall
Endocardium
Myocardium
Epicardium
Endocardium
thicker in atrium than in ventricle
Layers:
1. Endothelium - simple suqamous
2- Subendothelial loose CT
3. Myoelastic layer - CT and smooth muscle cells
4. Subendocardial layer: loose CT and Purkinje cells
Myocardium
thicker in ventricles than in atria
Epicardium
2 layers:
- Mesothelium (simple squamous) (außen)
- Underling loose CT and adipose tissue (innen)
Cardiac conducting system
Sinoatrial node (SA): specialized cells near Junction of sup. vena Cava and right atrium --> initiates Impulse along internidal tracts
Atrioventricular node (AV): carried across ventricles by bundle of His
Bundle of his: divides into left and right and then into purkinje fibers
Purkinje cells
- in subendocardial layer
- elongates cells with large nuclei
- glycogen and mitochondria
- propagate impuls and stimulate cardiac muscle
Classification of blood vessels
ARTERIES - elastic - musclular ARTERIOLES CAPILLARIES AND AV SHUNTS VENULES VEINS - small - middle sized - large
Organization of blood vessel wall
von innen nach außen
- tunica intima
- tunica media
- tunica adventitia
Tunica intima
Endothelium
Subendothelial loose CT
Internal elastic membrane (in arteries)
Structures have longitudinal orientation
Endothelial cells
- connected by tight junctions
- vesicles for Transport across Endothelium
- actin and Myosin fibers in cytoplasm
- Variety of Surface adhesion molecules and receptors
Functions of Endothelium (6)
- selective permeability barrier
- nonthrombogenic barrier
- Regeneration and growth
- Modulation of blood flow
- immune Responses
- hormonal Synthesis
Tunica media
- smooth muscle and CT
- External elascic membrane (in arteries)
- structues have circular orientation
Tunica adventitia
loose CT
structures have longitudinal orientation
- thickest layer of veins
Vasa vasorum
- tunica Adventitia and media of arteries
- all layers of veins
System of vessels that supply wall of vessels themselves
Nervi vasculares
- autonomic nerves that Control contraction and Dilation of smooth muscle in vascular walls
Elastic arteries
Aorta, brachiocephalic, subclavian, common carotid…
t. intima:
- Endothelium
- subendothelial loose CT with myocytes
- internal elastic membrane (non conspicuous)
t. media:
- 40-70 concentric lamellae
- external elastic membrane (non conspicuous)
t. Adventitia
- loose CT with fibroblasts, Collagen and elastic fibers
Muscular arteries
t. intima:
- Endothelium
- subendothelial loose CT
- internal elastic membrane (sheet of Elastin)
t. media:
- smooth muscle
- external elastic membrane
t. adventitia
- loose CT with Collagen and elastic fibers
Sectors of microvascular bed
Arterioles
Capillaries or Arteriovenous shunts
Venules
Arteriole
t. intima:
Endothelium
t. media:
- 1-3 smooth mscule cells arranged radially
t. adventitia:
- loose CT (thin)!
Capillary wall
Endothelial cells
Basement membrane
+ occasional pericytes
Types of capillaries
Continuous
Fenestrated
Sinusoidal (discontinuous)
Continuous capillary
- continuous Endothelium
- continuous b.m.
- in tissues where gases and small molecules are exchanged
- CNS, msucles, nerves, lungs
Fenestrated capillary
- Endothelium with fenestrations
- contiuous b.m.
Most fenestrations have membranous diaphragms
- for large volumes of fluid, electrolytes, AA
Sinusoidal (discontinuous) capillary
- discontinuous Endothelium: >pores and holes >Fenestrations without diaphragms >Gaps between cells - dicontinuous b.m.
in liver, Spleen, bone marrow
Pericytes
capillaries, postcapillary venules
contract
structural support
stem cells to repair damage
Classification of Arteriovenous shunts
- preferential thoroughfare channels
- arteriovenous anastomoses (AVA)
»> simple AVA
»> specialized AVA
Preferential thoroughfare channle
- allows blood to pass from arteriole to venule
- proximal Segment –> metarteriole
- metarteriole has precapillary sphinters
- common in mesentery
Simple AVA
- between arteriole and venule
- straight or coiled
- thick smooth muscle layer
- Skin, noes, lips, erectile tissues
Specialized AVA
- simple AVA with additional structures
- branches of afferent arteriole that roll into a ball (glomera AVA )
- additional longitudinal and circular muscular cells (epithelioid AVA)
Postcapillary venule
t. intima:
- Endothelium on b.m.
t. media:
- pericytes (not smooth muscle!)
t. Adventitia
- loose CT
Vein
t. intima:
- Endothelium
- subendothelial CT
- smooth muscle cells in large veins
- valves in middle-sized veins
t. media:
- thin/absent: muscle cells, Collagen fibers, elastic fibers
t. Adventitia:
- loose CT (thick) with longitudinally oriented smooth mscules bundles in large veins
Lymph vascular system
- vessels drain excess fluid from the tissue
- begin as blind lymphatic capillaries that take up excess fluid
- lymph flows from peripheral tissue through collectinc lymphatic vessels
- lymph is filtered in lmyph nodes
Lymphatic capillaries
- Continusou Endothelium (without tight junctions!!), cell borders are overlapping
- Discontinuous b.m.
