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of Vernadsky CFU
 

 

 
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Main page | Structure | Departments | Department of Histology and Embryology | Materials for students | Modul 2 | HEART. MICROCIRCULATORY BED.

HEART. MICROCIRCULATORY BED.
 
Heart.
  1. Heart wall is composed 3 tunics:
    1. Endocardium  (inner tunica) ;
    2. Myocardium (middle, muscular tunica);
    3. Epicardium (outer tunica).
  2. Endocardium is composed 4 layers:
  1. endothelium (simple squamous epithelium);
  2. subendothelial layer (loose irregular connective tissue);
  3. layer of smooth muscle cells and elastic fibres;
  4. outer layer of connective tissue.
  1. Myocardium is composed striated cardiac muscle tissue. It presented by  cardiac muscle  fibres. One muscle fibre is chain of cardiac muscle cells, which attached “end-to-end” by intercalated disks.
 
  1. Myocardium of ventricles contains contractile cardiac muscle cells. These cells are columnar-shaped, have 1-2 nuclei and abundance of myofibrills. Its function- is contraction.
  2. Myocardium of atria contains secretory  cardiac muscle cells. These cells are star-shaped. Cytoplasm contains secretory granules. Its function is secretion into blood hormone “Na-uretic factor”.
  3. After death,  zone of necrosis of cardiac muccle cells is replaced by connective tissue scar.
  4. Epicardium, like pericardium, is composed of layer of connective tissue, which covered by mesothelium (.simple squamous epithelium).
 
Microcirculatory bed
(capillaries, arterioles, venules).
 
  1. Muscles, lungs, skin contain capillaries with continuous endothelium. Its wall is composed of 2 cell types: endothelial cells and pericytes.
  2. Small intestine, endocrine glands containe capillaries with fenestrated endothelium. Cytoplasm of endothelial cells has narrow pores, named fenestrae.
  3. Liver, red bone marrow, spleen contain sinusoidal capillaries. Cytoplasm of endothelial cells has wide clefts.      Pericytes are absent
  4. Main function of all capillary types is gases and nutrients exchange.
  5. Wall of  arterioles is composed of 3 tunics:
  1. tunica intima (or interna)
            B.  tunica media
                                C. tunica adventitia (or externa) – loose irregular connective tissue
  1. Tunica intima is composed of 3 layers:
          - endothelium
                         - subendothelial layer (loose irregular connective tissue)
                                      -internal elastic membrane
  1. Tunica media contains strictly and only1-2 layers of smooth muscle cells.
  2. Function - arterioles regulate level of blood pressure.
Куратор темы – доцент В.В. Бондаренко.
 
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