The document discusses the structure and function of lymphatic vessels and the heart. Lymphatic vessels drain excess fluid from tissues and have thin endothelial walls lacking basement membrane and pericytes. The heart has three layers - endocardium, myocardium, and epicardium. The myocardium is the thickest layer and contains specialized conduction system nodes that coordinate heart contractions.

9. MUSCULAR ARTERY HAS THICK MEDIA

17.  Drains excess fuid
 Found in all tissues except CNS, cartilage, the bone,
bone marrow, thymus, placenta, cornea and teeth.
 They can be distinguished from the venous vessels by
the absence of erythrocytes and the presence of small
number of lumphocytes.
 Lymphatic capillaries differ from blood capillaries that
they have great permeability.
 Endothelial cells are extremely thin.

18.  Basement membrane is absent
 There are no pericytes.
 Fine collagenous filaments known as anchoring
filaments link the endothelium to the surrounding
supportive tissue preventing collapse.

21.  Wall consists of three
tunics:
◦ Endocardium: homologous
with the intima of blood
vessels; subendothelial
layer
◦ Myococradium: thickest;
arranged in layers that
surround the heart chamber
in a complex spiral and
insert themselves onto the
fibrous skeletal.

22.  Epicardium: a subepicardial layer of loose
connective tissue contains veins, nerves and
nerve ganglia and edipose tissue; it corresponds
to the visceral layer of pericardium.
 Fibrous skeletal is composed of dense connective
tissue. Its components are trigona fibrosa and
annuli fibrosi. These structures are composed of
dense connective tissue with thick collagen fibers.
They also contain nodules of fibrous cartilage.

23.  Two nodes located in
the atrium are SA node,
AV node and the AV
bundle.
 The cells of the impulse
conducting system are
functionally integrated
by gap junctions.

24. The SA node is a mass of modified cardiac muscle
cells that is fusiform smaller than the atrial muscle
cells and has fewer myofibrils.
 The cells of AV node are similar to that of the SA
node but their cytoplasmic projections branch in
various directions to form a network.
 The AV bundle is formed by similar cells of the AV
node but they are larger than ordinary cardiac
muscle cells and acquire a special apperance so
called purkinje cells.

25.  They have one or two central nucleis.
 Mitochondria and glycogen rich cytolplasm.
 Few myofibrils which are restricted to the
periphery of the cytoplasm.
 After travelling the subendocardial layer, they
penetrate the ventricle and become
intramyocardiac. This arrangement allows the
stimulus to get into the inner most layer of the
ventricular muscles.