Rough and smooth endoplasmic reticulum

 Rough and smooth endoplasmic reticulum 

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The endoplasmic reticulum (ER) is a network of membranous tubules within the cytoplasm of a eukaryotic cell, continuous with the nuclear membrane that serves many roles in the cell including calcium storage, protein synthesis and lipid metabolism. The diverse functions of the ER are performed by distinct domains; consisting of tubules, sheets and the nuclear envelope.

The rough endoplasmic reticulum (rough ER) is a part of the endomembrane system of the cell and a subset of the endoplasmic reticulum (ER).

Smooth endoplasmic reticulum (sER) is (a part of) endoplasmic reticulum that is tubular in form and lacks ribosomes.

Bell palsy and facial palsy due to stroke

 Bell palsy vs facial palsy due to stroke  

The two most common causes of acute facial paralysis are Bell’s palsy and ischemic stroke

Facial weakness can be caused by strokes in many different locations in the brain and brainstem. Strokes involving the brain typically cause central facial weakness that involves the mouth and spares the eye and forehead. Strokes involving the brainstem can sometimes cause weakness of the mouth, eye and forehead–mimicking a peripheral lesion. In these cases however, there will be other focal neurologic deficits. A review of systems and neurologic examination can help to identify signs and symptoms of stroke.

Bell's palsy is a condition that causes sudden weakness in the muscles on one side of the face. In most cases, the weakness is temporary and significantly improves over weeks. The weakness makes half of the face appear to droop. Smiles are one-sided, and the eye on the affected side resists closing.

Bell palsy vs facial palsy due to stroke  

Topic	Upper motor type/ stroke		Lower motor type/ bell’s palsy
Age	>60 years		20 -50
Time course	Second to minutes		Few hours to few days
Upper face	Usually not affected		Affected
Lower face	Affected		Affected
Associate symptoms	•      Rapid onset of mild weakness to total paralysis on one side of your face — occurring within hours to days •      Facial droop and difficulty making facial expressions, such as closing your eye or smiling •      Drooling •      Pain around the jaw or in or behind your ear on the affected side •      Increased sensitivity to sound on the affected side •      Headache •      A loss of taste •      Changes in the amount of tears and saliva you produce	stroke causing isolated left lower facial weakness. There’s a flattened nasolabial fold & inability to smile on the affected side with sparing of the forehead &  eye closure muscles. Weakness or numbness in the arm or leg: Weakness or numbness can occur either on the same side as the facial palsy, or on the opposite side, Difficulty swallowing (dysphagia): Dysphagia secondary to brainstem ischemi

Connective tissue mast cell and mucosal mast cell: difference and similarity

 

Connective tissue mast cell and  mucosal mast cell: difference and similarity

Topics	connective tissue mast cell	mucosal mast cell
Another name	Also known as MCTC mast cell	Also known as MCT mast cell
Location	Skin , intestinal submucosa, breast and axillary lymph nodes	Lungs, intestinal mucosa
Granules and its internal structure	Granules with Lattice like internal structure	Granule with a scroll like internal structure
Granules contain	Tryptase and chymase	Only tryptase

Pericardium : viva voice questions

 

Pericardium: viva voice questions 

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     Q. 1. Define pericardium.  

Ans: it is a conical fibro-serous sac which contains the heart and the roots of great vessels.

Q. 2. Mention the parts of pericardium.

Ans: a) fibrous pericardium

         b) serous pericardium : i) parietal pericardium ii) visceral pericardium

Q. 3.  mention the attachment of fibrous pericardium

Ans: The fibrous pericardium is a conical-shaped sac.

Its apex is fused with the roots of the great vessels and

base is fused with central tendon & a small left muscular part of the diaphragm.

     Q. 4. What is the other name of visceral pericardium?

      Ans: Epicardium

Q.5. Mention the arterial supply of pericardium.

 FFibrous and parietal pericardium are supplied by

·        Pericardio-phrenic artery branch of internal thoracic a ,

·        bronchial & esophageal branch of descending thoracic aorta and

·        branches from inferior phrenic artery

Visceral pericardium is supplied by coronary arteries 

Q. 6. Mention the venous drainage of pericardium.

·        Fibrous and parietal pericardium are drained by azygous veins and internal thoracic veins.  

·        Visceral pericardium is drain by coronary sinus.

Q.   7. Mention the nerve supply of pericardium.

The fibrous pericardium and the parietal part of the pericardium are pain sensitive and supplied by the phrenic nerve (root value: Cervical 3-5).

The visceral pericardium is insensitive; and is supplied by vagus and sympathetic nerves via coronary plexus.

Therefore, the pain from the pericardium originates in the parietal layer only and is transmitted by the phrenic nerve.

Q. 8. What is the function of pericardium?

It protects the heart, prevents over distension and friction during heart contractions

Q. 9. Show the transverse sinus. Tell its boundaries.

Ans. Boundaries:

In front- ascending aorta and pulmonary trunk enclosed in a single layer of serous pericardium.

Behind - Intra pericardial part of superior vena cava and upper portion of atrium and their auricles.

Q.10. Importance of transverse sinus.

           Ans. During cardiac surgery, the transverse pericardial sinus allows a surgeon to isolate the pulmonary trunk and ascending aorta and apply a temporary ligature or clamp.

Q.11. Show oblique sinus. Mention its boundaries.

Ans. It is a cul-de-sac behind the left atrium.

Boundaries

In front - Left atrium.

Behind -Parietal layer of serous peri cardium.

Right side - Right pair of pulmonary vein and inferior vena cava.

Left side - Lest pair of pulmonaryveins.

Q. 12. Tell the importance of oblique sinus.

Ans.   1. It gives space to expose the heart during atrial diastole.

2. It permits pulsation of the left atrium and hence known as cardiac bursa.

 Q.13. Tell the contents of pericardium.

Ans.   a) Heart with caridc vessels & nerves

b) Ascending aorta

c) pulmonary trunk

d) Terminal part of IVC

e) Terminal part of pulmonary veins

Q.14. What is pericardial effusion?

Ans. Collection of fluid in the pericardial cavity is called pericardial effusion.

Q.112. Development of pericardium.

Ans.   a) Fibrous pericardium - From septum transversum.

b) Parietal layer · From somato pleuric layer of lateral plate mesoderm.

c) Visceral layer - From splanchno pleuric layer of lateral plate mesoderm.

 

Q.6. Why the pericardium is closely attached to central tendon of diaphragm?

Ans.   The pericardium and central tendon of diaphragm both are developed from septum transversum.So they are closely attached.

Q.11. Transverse sinus - what it indicates developmentally?

Transverse sinus is developed by the degeneration of the central cells of the dorsal mesocardium.

Q.12. Why the pericardium is connected with sternum?

Ans. Due to both structure are developed from septum transeversum.

Q.13. Name the sites where visceral layer is separated from the heart .

Ans. At the root of great vessel of theheart where they are continuouswith each other. 

Facial nerve : intracranial and extracranial branches

 Facial nerve 

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Intracranial segment intracranial and extracranial branches 

Within the facial canal	Innervation
1.       Greater petrosal nerve	arises at the superior salivatory nucleus of the pons and provides parasympathetic innervation to several glands, including the nasal glands, the palatine glands, the lacrimal gland, and the pharyngeal gland. It also provides parasympathetic innervation to the sphenoid sinus, frontal sinus, maxillary sinus, ethmoid sinus, and nasal cavity. This nerve also includes taste fibers for the palate via the lesser palatine nerve and greater palatine nerve.
2.       The nerve to the stapedius	provides motor innervation for the stapedius muscle in middle ear
3.       The chorda tympani	provides parasympathetic innervation to the sublingual and submandibular glands, as well as special sensory taste fibers for the anterior two thirds of the tongue

 

Extracranial segment

At it’s exit from stylomastoid foramen	Innervation
4.       Posterior auricular	nerve which controls movements of some of the scalp muscles around the ear
5.       Nerve to Digastric	Digastric muscle
6.       Nerve to stylohyloid	Stylohyloid muscle

 

 

Terminal branches within the parotid gland

1.       temporal

2.       zygomatic

3.       buccal

4.       mandibular

5.       cervical

Communicating branches with trigeminal and glossopharyngeal nerves

Internal thoracic artery with clinical anatomy and radiology

 

Internal thoracic artery

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Origin : from subclavian artery

Another name : internal mammary artery

Supply areas: thoracic wall and breast  

Branches :

Two terminal branches: superior epigastric and musculophrenic artery

Anterior intercostal arteries : two for each intercostal space. Upper six pairs arises from internal thoracic artery and 7-9^th pairs arises from musculophrenic nerves  

SN: in each intercostal space two intercostal arteries anastomoses with  collateral branches of one posterior intercostal artery .

Clinical anatomy: during pericardiocentesis, to avoid puncturing the internal thoracic vessels, insert the needle just at the lateral margin of the sternum and no more than 1 cm laterally.

mast cell : lecture note

 mast cell 

•       Mast cells contribute to homeostasis in the immune system.

•       They serve as a first line of defense against antigens entering the body due to their location in the skin and mucosa

•       Mast cells are especially important in the homeostasis of the commensal bacteria of the gut

 

•      Mast cell granules are metachromatic because of the high content of acidic radicals in the heparin glycosaminoglycan. Metachromasia is a property of certain molecules that changes the color of some basic aniline dyes (eg, toluidine blue). The structure containing the metachromatic molecules takes on a color (purple-red) different from that of the applied dye (blue).

•      Although they have similar morphology, there are at least two populations of mast cells in connective tissues. One type, called the connective tissue mast cell, is found in the skin and peritoneal cavity; these cells measure 10–12 µm in diameter and their granules contain the anticoagulant heparin. The second type, the so-called mucosal mast cell, is present in the connective tissue of the intestinal mucosa and in the lungs. These cells are smaller (only 5–10 µm) than the connective tissue mast cells and their granules contain chondroitin sulfate instead of heparin.

•       Difference between connective tissue mast cell and mucosal mast cell

Topics	connective tissue mast cell	mucosal mast cell
Another name	Also known as MCTC mast cell	Also known as MCT mast cell
Location	Skin , intestinal submucosa, breast and axillary lymph nodes	Lungs, intestinal mucosa
Granules and its internal structure	Granules with Lattice like internal structure	Granule with a scroll like internal structure
Granules contain	Tryptase and chymase	Only tryptase

However, mature mast cells are generally not thought to undergo cell division and are considered terminally differentiated. Occasionally cell division is occurred

The surface of mast cells contains Fc receptors for immunoglobulin E (IgE),

 a type of immunoglobulin produced by plasma cells. Most IgE molecules are bound

 to the surface of mast cells and blood basophils; very few remain in the plasma.

 

Mast cells originate from progenitor cells in the bone marrow. These progenitor cells circulate in the blood, cross the wall of venules and capillaries, and penetrate the tissues, 

The most important aspect of cohesin

 The most important aspect of cohesin

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It is a protein complex that forms a ring-like structure, and sister chromatids are thought to be held together by trapping within the cohesin ring.

Cohesin is formed by  multi-subunit protein complex

1.      SMC1, SMC3,

2.       RAD21 and

3.      SCC3 (SA1 or SA2

·         SMC proteins have two main structural characteristics

·         a head domain : an ATP-binding cassette with ATPase activity (formed by the interaction of the N- and C- terminals of RAD21)

·         a hinge domain that allows dimerization of SMCs.

·         The head and the hinge domains are connected to each other via long anti-parallel coiled coils. 

·         RAD21 is a protein that in humans is encoded by the RAD21 gene

·         Rad21 binds to the ATPase heads of Smc3 and Smc1 via its N- and C- terminus, 

Once RAD21 binds the SMC proteins, SCC3 can also associate with RAD21. 

Function of cohesion

1. It is used to keep the sister chromatids connected with each other during metaphase ensuring that during mitosis (and meiosis), each sister chromatid segregates to opposite poles.

•      2. It facilitates  attachment of microtubules of spindle  onto chromosomes.

3. It facilitates DNA repair by recombination.

4. Cohesin has been shown to be responsible for transcription regulation, DNA double strand break repair

Mechanism of Sister Chromatid Cohesion

•      it is not clear how the cohesin ring links sister chromatids together. There are two possible scenarios:

•      Cohesin subunits bind to each sister chromatid and form a bridge between the two.

•      cohesin has a ring structure, it is able to encircle both sister chromatids.

•      Localization of cohesin rings

•       

•      A few cohesin rings are found in chromosome arms that have AT-rich DNA sequences

•      Cohesin rings, are also located in the region surrounding the centromere,  especially in budding yeast,