Organization of peripheral nerve Vs organization of skeletal muscle: easy understanding

Peripheral nerve : it is a collection of nerve bundles surrounded by a connective tissue coat, epineurium . 

Nerve bundle : it is a collection of nerve fibres surrounded by a connective tissue coat, perineurium 

Nerve fibre: it is a process of a neuron (usually axon) surrounded by myeline sheath (schwann cells) and  a connective tissue coat, endoneurium. 

Skeletal muscle: it is a collection of muscle bundles surrounded by a connective tissue coat, epimysium.

Muscle bundle: it is a collection of muscle fibres (muscle cells) surrounded by a connective tissue coat, perimysium.

Muscles fibre: when an individual muscle cells are surrounded by a connective tissue coat, endomysium.

Cornea : easy and brief description

Cornea:

Cornea is a miracle structure of our body. It is a living avascular, wet, transparent structure.

Development: 

The tissue of eyeball are derived from neuroectoderm, surface ectoderm & mesoderm. 

1. The corneal epithelium ( non-keratinized stratified squamous epithelium ) is developed from surface ectoderm 
2. Stroma of cornea (rest of the layers of cornea)  is developed from mesoderm 

Features of cornea:

1. avascular 
2. rich in nerve supply by long ciliary nerve - branches of ophthalmic division of trigeminal nerve 
3. transparent 

How it get nutrition: 

1. aqueous humor
2. tear

Histological features of cornea : 

The cornea consists of five layers (outward to inward ) 

1. Corneal epithelium: non-keratinized stratified squamous epithelium 
2. Bowman's membrane (anterior basement membrane) 
3. Corneal stroma: substantia propria 
4. Descemet's membrane 
5. Corneal endothelium 

Features of corneal epithelium :

1. Non-keratinized stratified squamous with five layers of cells, basal cells are low columnar and surface cells are squamous with microvilli with helps to spread tear on corneal surface 
2. it is continuous with conjunctiva 
3. it has remarkable capacity to regenerate, it correct superficial injury with 24 hrs and its turnover time: 7 days 
4. stem cells of cornea are situated at sclero-corneal junctions, these cells prevent conjunctivalization of corneal epithelium 
5. it is innervated by numerous free nerve ending, pain receptors of cornea is 300-600 times greater than the skin and 20-40 times greater than the dental pulp, so pain sensation is the only sensation in cornea 
6. it contain no melanin pigmentation, but corneal cancer is very rarely seen. how corneal DNA protected from UV light ?
7. corneal epithelial cells nuclei contain ferritin an iron storage protein which protect DNA of corneal epithelium from UV light 

What do you mean by conjunctivalization of corneal epithelium: 

1. the corneal epithelium become vascular 
2. appearance of goblet cells 
3. irregular and unstable cells 

Bowman's membrane : 

1. Homogeneous 
2. collagen fibrils (no collagen fibre)  of it randomly oriented 
3. it has no capacity to regenerate 
4. it support cornea 
5. damage of this structure causes opacity 

Corneal stroma: substantia propria 

1. it is the thickest layer of cornea (about 90%)
2. it is formed by 60 lamellae 
3. each lamella contain parallelly arranged  collagen fibrils, this contribute transparency of cornea, this regular arrangement is lost in any injury of cornea causes opacity  
4. the collagen fibrils in each lamella are arranged at right angles to adjacent lamella 
5. fibroblasts are situated in between lamellae 
6. 
   

Descemet's membrane : 

1. it is consider as basal lamina of corneal endothelium 
2. it has the capacity to regenerate 
3. it maintain curvature of cornea 

Corneal endothelium

1. it is formed by simple squamous epithelium 
2. it maintain water contain of cornea 
3. it has limited capacity to regenerate 
4. damage of it causes swelling of cornea, collagen fibrils arrangement  in lost, cornea become opaque 
5. severely damage corneal endothelium is repaired by corneal transplantation 

Terminology related to the name of the muscle

Terminology related to the name of the muscles.

1. Name of muscles according to location : Pectoralis major (muscle of pectoral region/ chest muscle) , brachialis (muscle of brachium/ arm)
   
2. Name of muscles according to size : pectoralis major (large size muscle) pectoralis minor(smaller size muscle) Flexor carpi radialis longus (longer muscle), flexor carpi radialis brevis(brevis=shorter muscle) 
3. name of muscles according to shape : deltoid (from delta triangular shape) , teres minor (teres mean round = a round shape muscle ) , pronator quadratus (square shape muscle) 
   
4. Name of muscles according to functions: Flexion carpi ulnaris (it flexed  wrist joint) pronetor teres ( it pronated forearm) 
5. Name of the muscle according to attachment sites (origin & insertion) : Flexion carpi radialis (origin radial bone of forearm and insertion carpal of hand ) 
6. Name of the muscles according to attachment ( origin ): bi(two) ceps (head) brachii , triceps brachii (origin from three difference bone surfaces ) Quadriceps femoris ( four different origin= four heads) 

Short question on general histology

1Qwhat is tissue?

Ans : each tissue has two features:

1. they are collection of cells and  secretion of cells ( fibres- protein + ground substance : protein carbohydrate composition ) .
2. they do particular function or functions

2. Q: how many types of tissue present in our body ?
Ans: There are four basic types of tissue present in our body
1.  epithelial tissue
2. connective tissue
3. muscular tissue
4. nervous tissue

3. Q. Classify epithelial tissue.

Ans: it is two types:

1. covering epithelium 
2. Glandular epithelium 

4 Q. Classify covering epithelium  

Ans: two features consider in classification of covering epithelium 

1. arrangement of cells : in a single layer (simple) or multiple layer (stratified)
2. shape of cells: squamous(flat) , cuboidal (height and wide same), columnar( height is greater than wide) 

• Simple epithelium:

• simple squamous epithelium 
• simple cuboidal epithelium 
• simple columnar epithelium 
• psuedostratified ciliated columnar epithelium 

           Cilia containing epithelium is always simple epithelium 

• Stratified epithelium

• stratified squamous epithelium: keratinized and non keratinized epithelium 
• stratified cuboidal epithelium
• stratified columnar epithelium 
• transitional epithelium 

5. Q Mention the features of epithelial tissue 

Ans: Features of the epithelial tissue

1. avascular 
2. it has nervous innervation
3. large number of cells with little intercellular substance 
4. each epithelial cells has four surface domain : apical surface, two lateral surface, and basal surface 
5. basal surface rest on basement membrane 

      if basement membrane is destroy epithelium can not grow 

Q 6. Features of simple columnar epithelium

Ans : 1. cells are arranged in single layer 

2. height of cells are more than the wide 

3. basally place oval nuclei

SN: in histological slide it is look like a thinner basally place blue line leaving an apical thicker pink line 

Q 7.What are the features of simple cuboidal epithelium?

Ans: 

1. round shaped nucleus centrally placed 
2. height and wide of cells are equal (cube shaped)
3. 
   

Q 8: What is the features of pseudostratified  ciliated columnar epithelium?

Ans:

1. Basally place nuclei in different layer ( like stratified epithelium) leaving apical pink large areas like simple columnar epithelium 
2. some cells are small in height and some cells are longer in height but all cells are attached with basal lamina so it is simple epithelium 
3. ciliated epithelium is always simple epithelium 
4. irregular margin at apical surfaces of cells due to cilia
5. 
   

Q 9. What are the features of simple squamous epithelium?

Ans:

1. wide of cells are more than the thickness 
2. scale like cells with  round flatten nucleus (like pouched egg) 
3. in cross section nucleus bulging from a pink (cytoplasm) line 

Q . 10: Classify gland on basis of development with example 

Ans : ectodermal : mammary gland 

      Neural crest : adrenal medulla 

Mesodermal : adrenal cortex 

endodermal : Thyroid 

Q 11 Mention the name of glands originate from ectoderm . 

Ans: 

1. mammary gland,
2.  sweat gland, 
3. sebaceous gland , 
4. lacrimal gland , 
5. pituitary ( anterior pituitary from ectoderm and 
6. posterior pituitary from neuroectoderm, pineal gland from neuroectoderm , 
7. from neural crest adrenal medulla ( chromaffin cells) and C cells of thyroid gland

Q 12. Mention the name of glands originate from mesoderm 

Ans: 

1. adrenal cortex 
2. kidney 
3. testes 
4. ovary 
5. spleen 

Q 13. Mention the name of glands originate from endoderm 

Ans: 

1. Liver 
2. Pancreas 
3. Parathyroid 
4. Thyroid (except C cells of thyroid gland )
5. Thymus 

Q 14. Features of myoepithelial cells.

Ans :

1. It is seen in salivary gland, sweat gland , mammary gland 
2. It contain actin so contract and expel secretion of gland 
3. It is true epithelium it contain keratin protein which is the feature of epithelium 
4. it develops from ectoderm or endoderm
5. it is innervated by autonomic nervous system 

Q 15 Classify gland according to the mode of secretion 

Ans :

1. Merocrine : only secretion exit from cell without any lost of cell's part : ex:salivary gland 
2. Apocrine (ap ical region) :secretion + apical portion of cells are lost Ex: mammary gland 
3. Holocrine (w hol e cell) : whole cell with secretion lost : ex : Sebaceous gland 

Covering epithelium: simple epithelium

 There are two logic in classification of covering epithelium
1st : arrangement of cells :
single cellular layer known as simple epithelium

Multiple cellular layer known as stratified epithelium

2nd logic : shape of cells
There are three types of cells
flat cells : squamous
cuboidal cells
columnar cells

so, you can make three types of simple epithelium
1. simple squamous epithelium
2. simple cuboidal epithelium
3. simple columar epithelium
Another simple epithelium is pseudo-stratified ciliated columnar epithelium
Pseudo means false
it looks like multilayered epithelium but it is a simple epithelium
cells are arranged in single layer but size of cell different
some are tall
some are short
 Location of nuclei of cells are in different position so it looks like multilayer epithelium but it is nothing but simple epithelium

finally we find four typres of simple covering epithelium

Histological layers within a vessel: easy discussion

  Vessel (artery, vein) : vessels are tube like structure. 

Histologically there are three district layers within outward.

1. Tunica intima : the inner most layer. it is the combination of three layer

• endothelium : simple squamous epithelium
• subendothelial connective tissue: a very thin connective tissue layer occasionally contain smooth muscle cells 
• internal elastic lamina : a membrane like structure which is formed by elastic fibres

  2.Tunica media :it is formed by

• smooth muscle cells : number of cell layer vary in large, medium and small sized artery and vein 

• elastic and collagen fibres 

3. Tunica adventitia : this layer is formed by connective tissue rich in collagen fibers. The thickness of this layer also vary in artery and vein

some time external elastic lamina separate tunica media from tunica adventitia

Typical synovial joint : easy discussion about features

Synovial joint:

 is the most common joint in the body 

Minimum to Wide range of movement is one of the important features of synovial joint

why synovial joint moves but other joints (like fibrous and cartilaginous) movement are restricted ?

Joint means articulation or junction between two or more bone,
in synovial joint bones are separated by a joint cavity 
This joint cavity are responsible for wide range of movement 
So joint cavity is the unique character of a synovial joint