Mediastinal part of right and left lung

Mediastinal part of lung:

the impression and relation of mediastinal surface differ in two lungs

Mediastinal surface of right lung:

Cardiac area is related with   Anterior surface of Right auricle, Anterior and right surface of right atrium,  Part of anterior surface of right ventricle  

In front of hilum upper part : Groove for SVC

In front of hilum lower part groove for  IVC are present

Above the hilum : groove for azygous vein

Behind the hilum : osophagus except upper and  lower part

From apex to groove for azygous vein:Anterioposteirly

Right brachiocephalic vein,Trachea,Osophagus

Three neural structures:right phrenic nerve, Right vagus nerve, Right sympathetic chain

Mediastinal surface of left lung

Cardiac area is related withAnterior and left surface of left ventricle and left auricle, Anterior surface of a part of the right ventricle

In front of hilum : upper part impression for ascending aorta

Just below and little in front  the ascending aorta , the impression for pulmonary trunk is present

Above the hilum : arch of aorta

Behind the hilum: descending thoracic aorta and osophagus present just above  and below the descending aorta

So osophagus is related twice with the left lung  

From apex to groove for arch of aorta  

Anterioposteirly

Left common carotid arter,Left subclavian artery,Trachea,Osophagus,Thoracic duct

Four neural structures

Left  phrenic nerve

Left  vagus nerve

Left recurrent laryngeal nerve

Right sympathetic chain

Summary of pleura

pleura

Pleura, plural

Pleurae , singular

Origin of word : Greek   [Gr.]

The serous membrane investing the lungs (visceral p.) and lining the walls of the thoracic cavity (parietal p.); the two layers enclose a potential space, the pleural cavity. The two pleurae, right and left, are entirely distinct from each other.pleu´ral cavity .

The glistening surface of the pleura is made up of a sheet of flat cells, the mesothelium, which covers an underlying layer of loose elastic tissue. The pleura exudes a thin fluid that keeps it moist and lubricated.

Major disorders of the pleura include pleurisy, the inflammation of the pleura; pleural effusion, the accumulation of excess fluid between the visceral and parietal pleurae; empyema, the collection of pus in the pleural space; mesothelioma and other tumours of the pleura; chylothorax, the rupture of the thoratic duct; hemothorax, the accumulation of blood in the pleural space; and fibrothorax, the encasement of the lung in fibrin following a severe pleural inflammatory process such as empyema.

Normally, there is no air in the pleural space and, if air should enter, perhaps as the result of a stab wound or a diseased lung, the increase in pressure causes the lung to collapse. Air in the pleural space is known as pneumothorax. If the pleural space becomes continuous with the air outside, after a piercing injury for example, this is called an open pneumothorax.

Pleura: /pleu·ra/ (ploor´ah) pl. pleu´rae   [Gr.] the serous membrane investing the lungs (visceral p.) and lining the walls of the thoracic cavity (parietal p.); the two layers enclose a potential space, the pleural cavity. The two pleurae, right and left, are entirely distinct from each other.pleu´ral cavity .

 

Parietal pleura : it is the outer part of serous sac which lines the thoracic wall and mediastinum.

It develops from somatopleuric layter of lateral plate mesoderm .Innervated by somatic nerves

It is sensitive to pain

Blood supply and lymphatic draianage is same as that of thoracic wall 

Visceral pleura

Lines the surfeces of lung except hilum.  It develops from splanchnopleuric layter 

of lateral plate mesoderm. Innervated by autonomic nerves

It is insensitive to pain. It  is only sensitive to stretch.

Blood supply and lymphatic drainage is same as that of the lung 

 

Summary of umbilical veins

Umbilical veins

Definition :

One of three embryonic vessels of fetus .

Veins of fetus

•      Vitelline system : develops portal system

•      Umbilical system : which disappear after birth

•      Cardinal system : forms caval system

Fetal circulation :

it enters the embryo body at the umbilicus and

 then passes into the liver, where it is joined by the portal vein; its blood then flows by way of the ductus venosus and the inferior vena cava to the right atrium

Fate of umbilical veins :

the right umbilical vein disappears during the seventh week.

it is degenate at least a week after birth  

Fucntions:

It functions to return the blood from the placenta and fuses to form a single vein in the umbilical cord.

Applied anatomy :

Recanalization :

 Under extreme pressure, the round ligament may reopen to allow the passage of blood. Such recanalization may be evident in patients with cirrhosis and portal hypertension.

Catheterization :

A newborn baby has a patent umbilical vein for at least a week after birth. This umbilical vein may be catheterised for ready intravenous access.

Summary of osteoblast : bone forming cell of skeletal system

Osteoblast :

It is single nucleated,  large cell  responsible for the synthesis and mineralization of bone during both initial bone formation and later bone remodeling. 

it is differentiated from osteoprogenitor cell. 

Skeletal system contain four types of bone cells.

1.       Osteoprogenitor cells

2.       Osteoblast

3.       Osteocyte

4.       Osteoclast

Functions of osteoblast:

It  is generating new bone matrix .

It synthesis, secrete  and mineralize bone matrix 

It secretes

1.      Type I collagen

2.      Small amount of type V  collagen fibre

3.      Bone matrix protein osteocalcin , osteonectin

4.      Multiadhesive glycoprotein : bone siloproteins 1 and 11, osteoponin and thrombospondin

5.      Various proteoglycans and

6.      Alkaline phosphate 

Features of osteoblast :

·         Size  : 15-30 µm

·         Cuboidal, low columnar or polygonal ,

·         arranged in single layer,

·         eccentrically placed oval single nuclei

·         cytoplasm is basophilic leaving a clear area due to golgi complex,

·         Ultra structurally they have features typical of protein secreting cells

·         Cytoplasm contain abundant rER and free ribosomes 

 

·         Cell membrane of osteoblast has processes which communicate with the adjucent osteoblasts and with osteocytes by gap junctions

·         The osteoblast is differentiate from osteoprogenitor cell

·         As osteoblasts move along the bone matrix, they get stuck in the tissue and turn into osteocyctes.

·         It has ability to divide

·         Osteoblast processes communicate with other osteoblasts and with osteocytes by gap junctions