respiratory system- discussion, viva

Respiratory system:

1. Name the parts of respiratory system.
• Upper respiratory tract
• Nasal cavity
• Pharynx
• Larynx
• Lower respiratory tract
• Trachea
• Extrapulmonary bronchi or primary bronchi
• Intrapulmonary bronchi 
• Secondary bronchi or lobar bronchi
• Tertiary bronchi or segmental bronchi
• Bronchioles
• Terminal bronchioles
• Respiratory bronchioles
• Alveolar duct
• Alveolar sac
• Alveoli
2. Classify respiratory system on functional basis.
• Conducting portion- From trachea to terminal bronchiole
• Transition zone- respiratory bronchiole 
• Respiratory portion-  from alveolar duct to alveoli 
3. Name the functions of conducting, transition and respiratory portions.
• Conducting portion- conducts air to and from lungs, cleans and humidifies air
• Transition zone- conducts air and also exchange of gases
• Respiratory portion-  exchange of gases 
4. Name the cells in the respiratory passage.
• Tall columnar ciliated cells
• Basal cells
• Goblet cells
• Clara cells
• Brush cells (non-ciliated columnar cells)
• Small granule cells (Kulchitsky cells)
• Type 1 alveolar cells (type 1 pneumocytes)
• Type 2 alveolar cells (type 2 pneumocytes)
• Dust cells (alveolar macrophage cells)

Trachea:

1. Name the layers of trachea?
• From luminal surface to outwards
• Mucosa- 1. epithelial lining, 2. lamina propria
• Submucosa
• Fibromusculocartilagenous layer
• Adventitia
2. What is the epithelium lining the trachea?
• Pseudostratified ciliated columnar epithelium which has tall columnar ciliated cells and basal cells
3. Name the contents of lamina propria.
• Loose connective tissue
• Lymphocytes
• Blood vessels
• Seromucous glands, mainly mucous
4. Name the components of submucosa.
• Dense connective tissue
• Seromucous glands
5. Why the third layer is called fibromusculocartilagenous layer?
• The layer is made of 
• C-shaped hyaline cartilage which is deficient posteriorly.
• Smooth muscle bundle called trachealis muscle binds to two ends of hyaline cartilage
• Fibroelastic tissue mixed with smooth muscle
• Since this layer has all the three parts- cartilage, smooth muscle and fibroelastic tissue, it is called as fibromusculocartilagenous layer
6. Give the structure of hyaline cartilage.
• See the post on cartilage
7. What is adventitia made of?
• Connective tissue
• Blood vessels
• Nerves

Lung:

1. What are the components of lung?
• Intrapulmonary bronchi- secondary and tertiary bronchi
• Bronchioles- terminal and respiratory bronchioles
• Alveolar duct
• Alveolar sac
• Alveoli
2. What are the differences between trachea, extra pulmonary bronchus and intra pulmonary bronchus
• Refer the table below
3. What are the differences between bronchus and bronchiole?
• Refer the table below
4. Name the cells present in the walls of the alveoli.
• Type 1 alveolar cells (type 1 pneumocytes)
• Type 2 alveolar cells (type 2 pneumocytes)
• Dust cells (alveolar macrophage cells)
5. What are the functions of the cells in alveoli?
• Type 1 alveolar cells - squamous cells for exchange of gases
• Type 2 alveolar cells - cuboidal cells for secretion of surfactant
• Dust cells - macrophages for phagocytosis
6. What is blood-air barrier?
• Blood-air barrier are the layers present between blood in the capillary network and the air in the alveoli for the exchange of oxygen and carbon-dioxide.
7. Name the layers of blood-air barrier.
• Endothelial cells in the capillary
• Basal lamina of capillary
• Basal lamina of type 1 alveolar cells
• Type 1 alveolar cells

Differences between trachea and different parts of bronchial tree

Parts	Epithelium	Features of wall
Trachea	Pseudostratified ciliated columnar epithelium, goblet cells, basal cells	Lamina propria, submucosa with seromucous glands, fibromusculocartilagenous layer, adventitia
Bronchi	Pseudostratified ciliated columnar epithelium with goblet cells	Narrow thin lamina propria, layer of smooth muscle cells, submucosa with bronchial glands, irregular hyaline cartilage plates, adventitia
Bronchiole	Pseudostratified ciliated columnar to simple cuboidal epithelium from proximal to distal with occasional goblet cells, brush cells (nonciliated columnar), Kulchitsky cells (small granule cells), Clara cells	Mucosal folds, smooth muscle layer, adventitia. No cartilage and glands
Terminal bronchiole	Simple cuboidal epithelium, clara cells	Thin, incomplete layer of smooth muscle. No cartilage and glands
Respiratory bronchiole	Simple cuboidal epithelium, clara cells with scattered alveoli	Few smooth muscle fibers mostly around alveolar openings
Alveolar ducts, sacs	Simple cuboidal between many alveoli	Bands of smooth muscle around alveolar openings
Alveoli	Type 1 and type 2 alveolar cells (pneumocytes)	Only network of elastic and reticular fibers

placenta, umbilical cord- discussion, viva

Placenta:

1. Give histological structures of the placenta
• Maternal surface irregular because of cotyledons separated by placental septa. It is formed by basal plate which includes decidua basalis
• Fetal surface is smooth, covered by amnion and gives attachment to umbilical cord. It is formed by amnion, chorionic plate, chorionic villi from outside inwards
2. What is decidua basalis?
• Decidua basalis is the part of endometrium present between the implanted embryo and myometrium
3. What are chorionic villi? What are the types? 
• Chorionic villi are the finger like projections from the chorionic plate formed by cytotrophoblast and syncytiotrophoblast. 
• 3 types of chorionic villi- primary, secondary, tertiary villi
4. Give the structure of the three villi
• Primary villi- simple cord with a solid core of cytotrophoblast surrounded by syncytiotrophoblast
• Secondary villi- projection with central core of mesoderm surrounded successively by cytotrophoblast and syncytiotrophoblast
• Tertiary villi- projection with fetal blood vessels in the core of mesoderm surrounded successively by cytotrophoblast and syncytiotrophoblast. along with fetal capillaries there are fibroblasts and phagocytic cells called Hofbauer cells
5. What are anchoring villi and floating or free villi
• Anchoring villi- villi attached to chorionic plate
• Floating or free villi- the branches from anchoring villi which float in intervillous spaces
6. Name the site of exchange occurring in placenta
• Exchange occurs between the embryonic blood in chorionic villi outside the embryo and maternal blood in lacunae called intervillous spaces of decidua basalis
7. Name the layers of placental barrier
• Upto 20 weeks
• Syncytiotrophoblast
• Cytotrophoblast
• Connective tissue of villi
• Endothelium of fetal capillaries
• After 20 weeks
• Syncytiotrophoblast
• Connective tissue of villi
• Endothelium of fetal capillaries
8. What are the functions of placenta?
• Exchange of nutrients, oxygen, carbon-dioxide, wastes between mother and fetus
• Passive immunity to fetus by transfer of maternal IgG antibodies
• Secretes human chorionic gonadotrophin (hCG), estrogen, progesterone and placental lactogen

Umbilical Cord:

1. Give the structure of umbilical cord
• It is surrounded by amnion
• It consists of two umbilical arteries and one umbilical vein
• The vessels are surrounded by primary mesoderm called Wharton's jelly which protects the vessels
2. What is Wharton's jelly?
• Wharton’s jelly is a mass of loose connective tissue with fibroblasts separated by fine collagen fibers and ground substance containing hydrated glycosaminoglycans rich in hyaluronic acid. It gives cushioning effect to vessels.
3. What are the functions of umbilical arteries and vein?
• Umbilical arteries- carry deoxygenated blood from fetus to placenta
• Umbilical vein- carry oxygenated blood from placenta to fetus

epithelial / salivary glands, serous gland, mucous gland, mixed gland- discussion, viva

Epithelial / Salivary glands

1. How many salivary glands are present and where are they located?
• Serous or parotid salivary gland- largest glands located anterior and inferior to external ear
• Mucous or sublingual salivary gland- smallest glands located inferior to tongue
• Mixed or submandibular gland- small glands located inferior to mandible in the floor of mouth
2. What type of glands are salivary glands functionally?
• They are exocrine glands
3. What type of glands are salivary glands structurally?
• They are compound tubuloacinar glands
4. Where and how do they pour their secretion?
• Secretions are poured into the mouth through their large excretory ducts
5. What are the components of salivary glands?
• Cellular secretory units- acini
• Excretory ducts
6. What are acini?
• Acini are small, sac like dilations at the terminal end of intercalated ducts.
7. What are intercalated ducts?
• Intercalated ducts are the first segments of the excretory duct system attached to acini
8. What are different types of acini?
• Serous acini- made up of serous cells which are pyramidal in shape. Spherical or round nuclei are present at basal half and secretory granules in the apical region of the cells
• Mucous acini- made up of mucous cells which are columnar or pyramidal in shape. Flat nucleus present near the basement membrane and cytoplasm completely filled with mucus
• Serous demilune- Serous cells form a crescent or moon shaped cap over the mucous cells which is called serous demilune. They discharge their secretion into lumen through canaliculi present between the mucous cells
9. What are myoepithelial cells?
• Myoepithelial cells are flattened cells that surround both serous and mucous acini.
• They are highly branched and contractile in nature
• They are also called basket cells
• They are located between the basement membrane and the secretory cells
10. Details about excretory ducts
• Intercalated ducts- they are lined by low cuboidal epithelium. Initially all acini empty their secretions into intercalated ducts and part related to acini is surrounded by myoepithelial cells
• Striated ducts- intercalated join to form striated and are lined by columnar epithelium with basal infoldings of the cell membrane with numerous mitochondria which gives striated appearance
• Intralobular ducts- striated join to form intralobular ducts and are lined by columnar epithelium
• Interlobular ducts- intralobular join to form interlobular ducts and are lined by columnar epithelium
• Interlobar ducts- interlobular join to form interlobar ducts and are lined by stratified cuboidal or columnar epithelium
11. What is the arrangement of connective tissue in the glands?
• The whole gland is surrounded by connective tissue capsule.
• The gland is divided into lobes and lobules by the connective tissue fibers.
12. What are the differences between the mucous, serous and mixed salivary glands?

Types	Serous	Mucous	Mixed
Connective tissue	Well developed connective tissue capsule. Interlobular connective tissue with vessels and adipose tissue.	Well developed connective tissue capsule. Well developed connective tissue septa.	Well developed connective tissue capsule and stroma.
Acini (alveoli)	Serous.	Mucous.	Seromucous.
Cells	Pyramidal in shape with round nuclei at the base. Darkly stained apical cytoplasm because of the zymogen granules.	Globular in shape. Flat and condensed nuclei, at the basement membrane. Cells appear empty in H and E staining, because during the   processing mucinogen granules are washed off.	Both serous and mucous alveoli present. Demilunes or crescents of Gianuzzi, are the appearance of the sectioned serous alveoli seen as half moon or crescent shape over the mucous alveoli.
Duct system	Numerous inter lobular, intra lobular and  intercalated ducts. Lined by stratified to simple columnar to low cuboidal   epithelium.	Intercalated ducts are very rare or absent, more nonstriated intralobular ducts. Lined by stratified to simple columnar to low cuboidal   epithelium.	Few intercalated, more striated ducts. Lined by stratified to simple columnar to low cuboidal   epithelium. Serous demilunes discharge the secretion through the intercellular canaliculi located between the mucous cells.
Secretion	Watery secretion rich in enzymes and antibodies.	Viscid secretion.	Both watery as well as the viscid secretions.
E.g. Salivary gland	Parotid.	Sublingual.	Submandibular.

Thick skin, thin skin- discussion, viva

Skin:

1. What are the two regions/layers of skin?
• Superficial nonvascular epidermis
• Deep vascular dermis
2. What are the derivatives/ appendages of the skin?
• Nail
• Hair
• Sweat gland
• Sebaceous gland
• Arrector pili muscle
3. What are the two types of skin?
• Thick skin
• Thin skin
4. Where do you find Thick skin?
• Palm, sole
5. Where do you find thin skin?
• Whole body except palms and soles is covered by thin skin
6. What are the functions of the skin?
• Protection from mechanical abrasion, forms physical barrier to pathogens or foreign microorganisms
• Prevents the loss of body fluids
• Temperature regulation
• Acts as sensory organ responding to external stimuli like temperature, touch, pain and pressure
• Acts as excretory organ by producing sweat through which water, sodium salts, urea and nitrogenous wastes are excreted
• Vitamin D necessary for calcium absorption is synthesized in the skin

Thick skin:

1. Give examples of thick skin?
• Palm and sole
2.  Is there any difference in the structure between thick and thin skin?
• There is no difference in the structure, except in the thickness of the epidermis and the appendages. In thick skin only sweat glands are present
3. What are sweat glands?
• Sweat glands are exocrine glands which are simple tubular highly coiled glands.
• coiled secretory portion is lined by simple columnar epithelium
• Ductal excretory portion is lined by stratified cuboidal epithelium
4. Why is epidermis in palm and sole very thick?
• These regions are constantly exposed to wear, tear and abrasion
5. What are the types of cells present in epidermis?
• Keratinocytes
• Melanocytes
• Langerhan's cells
• Merkel's cells
6. What are dermal papillae?
• The numerous raised projections in the superficial layer of dermis which interdigitate with evaginations of epidermis is called dermal papillae
7. What are epidermal ridges?
• The evaginations of epidermis which interdigitate with the dermal papillae are called epidermal ridges
8. What are the two layers of dermis?
• Superficial papillary layer
• Deep reticular layer
9. What is papillary layer made up of?
• It is made up of loose irregular connective tissue with cells and fibers, capillaries, blood vessels, fibroblasts, macrophages, nerves, Meissner's corpuscles
10. What is reticular layer made up of?
• It is made up of dense irregular connective tissue with less number of cells, Pacinian corpuscles
11. What are the layers of epidermis?
• From deep to superficial- Stratum basale (germinativum), stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
12. Why is stratum basale also called as germinativum?
• The single layer of cuboidal or columnar cells are capable of cell division which increases the number of cells and differentiate into other layers. They act as stem cells and also produce intermediate keratin filaments
13. Explain stratum spinosum?
• It consists of 4 to 6 rows of cells. During routine histologic preparations the cell membranes shrink except near the desmosomes which appear as spines. The keratin filaments are arranged in the form bundles called tonofilaments.
14. Why is third layer given the name stratum granulosum?
• The cells in the third layer are filled with dense basophilic keratohyalin granules which lack membrane and are associated with bundles of keratin filaments, together form keratin. Because of the keratohyalin granules the third layer is called stratum granulosum
15. What is stratum lucidum?
• It is a translucent layer present superficial to stratum granulosum. The cells lack nuclei or orgenelles
16. What is stratum corneum?
• It is the superficial layer of cells without nuclei and organelles, filled with keratin filaments. They are continuously shed or desquamated
17. Where are melanocytes derived from?
• Melanocytes are derived from Neural crest cells
18. Where are melanocytes located?
• They are located between stratum basale and stratum spinosum. The function is to synthesize melanin pigment which protects the skin from damaging effects of ultraviolet radiation

Thin skin:

1. What are the layers present in thin skin?
• Four layers from deep to superficial- stratum basale, stratum spinosum, stratum granulosum, stratum corneum. Stratum lucidum is absent.
• Except the thickness and the absence of stratum lucidum the rest of the features are same as in thick skin
2. Name the appendages of thin skin
• Hair, sebaceous glands, arrector pili muscle, sweat glands
3. What is dermal papillae?
• The papillary layer indents the base of the epidermis to form the dermal papillae
4. What are sebaceous glands?
• Sebaceous glands are exocrine and holocrine glands with aggregates of clear cells connected to duct opening into hair follicle
• It secretes oily or wax material to lubricate and water proof the skin
5. What is holocrine secretion?
• The whole is cell is destroyed during the secretion which is poured into the lumen
6. What are arrector pili muscles?
• Arrector pili muscles are smooth muscles aligned at oblique angle from papillary layer of dermis to the hair follicle
• Contraction of the muscle moves hair shaft into vertical position

Lymph node, spleen, thymus, tonsil- discussion, viva

Lymphatic system:

1. What is the function of lymphatic system?
• The function of lymphatic system is immunity / to protect the organism from invading pathogens or antigens
2. What are the components of lymphatic system?
• Cells- distributed throughout the body as single cells or aggregations of cells or non-encapsulated lymphatic nodules
• Lymphatic organs- lymph node, spleen, thymus, tonsil
3. Name the lymphatic organs surrounded by connective tissue capsule
• Lymph node, spleen, thymus
4. Name the lymphatic organ covered by epithelium
• Tonsil

Lymph node:

1. What are the parts of lymph node?
• Outer cortex- network of reticular fibers, non-encapsulated aggregations of lymphocytes called lymphatic nodules with pale germinal center
• Inner medulla- medullary cords (irregularly arranged lymphocytes, macrophages, plasma cells in network of reticular fibers) and medullary sinuses
2. What is direction of flow of lymph?
• Afferent lymphatic vessel--subcapsular sinus--trabecular sinus--medullary sinus--efferent lymphatic vessel
3. What is the function of lymph node?
• The function of lymph node is to filter the lymph as it enters the lymph node
4. What are lymph sinuses?
• Lymph sinuses are the spaces with fine network of reticular fibers filled with lymph
• Subcapsular sinus- sinus present beneath the connective tissue capsule
• Trabecular sinus- sinus present around the connective tissue septa (trabeculae) entering the lymph node
• Medullary sinus- sinus present in the medulla
5. What are germinal centers?
• The germinal centers are the pale regions in the center of lymphatic nodule which represent the active sites of lymphocyte proliferation

Spleen:

1. What are the parts of spleen and their components?
• Red pulp- splenic cords of Billroth (network of reticular fibers with macrophages, lymphocytes, plasma cells, blood cells) and splenic/blood sinuses
• White pulp- dark staining lymphoid aggregations/nodules surrounding a central artery. Along with lymphocytes, antigen-presenting cells and macrophages are also seen
2. What is the function of red pulp?
• The function of red pulp is to filter the blood. It removes the antigens, microorganisms, platelets and aged or abnormal erythrocytes from the blood.
3. Is there a germinal center in the lymphatic nodule present in spleen?
• Yes
4. What are the types of lymphatic cells seen in white pulp?
• T cells- surround the central arteries
• B cells- present in rest of lymphatic nodule
5. What are the functions of spleen?
• Fetal life- produces granulocytes and erythrocytes
• Important reservoir for blood
• Filters blood
• Takes part in immunity
6. Is spleen essential for life?
• No, it is not

Thymus:

1. Where is thymus located?
• Thymus is located in the root of neck and upper anterior mediastinum
2. What are the stages of thymus?
• Childhood- most active upto puberty
• After puberty- undergoes involution
• Adults- replaced with adipose tissue
3. What are the parts of thymus?
• Connective tissue capsule divides the thymus into incomplete thymic lobules. Each thymic lobule has peripheral cortex and inner medulla which is continuous with adjacent lobules
• Cortex- densely packed lymphocytes
• Medulla- few lymphocytes, more epithelial reticular cells, thymic/Hassall's corpuscles
4. What are Hassall's corpuscles?
• They are oval structures consisting of round or spherical aggregations of flattened epithelial cells around the calcified or degenerating mass of epithelial cells
5. What are the functions of epithelial reticular cells?
• The epithelial reticular cells forms the blood-thymus barrier and secretes hormones necessary for proliferation, differentiation and maturation of T-cells
6. What happens to the child if thymus is removed?
• The child may not be able to fight pathogens and death may occur as a result of infection and lack of functional immune system
7. What are the hormones secreted by epithelial reticular cells?
• Thymulin, thymopoietin, thymosin, thymic humoral factor, interleukins, interferon
8. Name the layers forming blood-thymic barrier?
• Endothelial cells
• Epithelial reticular cell
• Macrophages

Tonsil:

1. Where is tonsil located?
• Tonsil is located at the oro-pharyngeal isthmus on either side of oral cavity
2. What are the parts of tonsil?
• Attached surface- covered by connective tissue capsule
• Free surface- covered by stratified squamous non-keratinized epithelium which invaginates into the tonsil as tonsillar crypts
• Tonsillar crypts are surrounded by numerous lymphatic nodules

Blood vessels- discussion, viva

Circulatory system/ Vascular system/ Blood vessels:

1. Name two parts of circulatory system
• Blood vascular system and lymph vascular system
2. Name the 3 layers of blood vessels
• From inside out- tunica intima, tunica media, tunica adventitia
3. What are the components of tunica intima?
• endothelium- simple squamous epithelium 
• subendothelial connective tissue
• internal elastic lamina
4. What are the components of tunica media?
• smooth muscle fibers
• elastic fibers
• reticular fibers
5. What are the components of tunica adventitia?
• connective tissue (collagen, elastic fibers)
• blood vessels/ vasa vasorum
• nerves
• lymphatics
6. Name the smallest blood vessels
• Capillaries, venules
7. Name the different types of capillaries
• Continuous capillaries- endothelial cells join and form uninterrrupted solid endothelial lining. Seen in muscle, skin, connective tissue, nervous tissue, respiratory organs
• Fenestrated capillaries- pores/ fenestrations present in the cytoplasm of endothelial cells for rapid exchange of molecules. Seen in endocrine tissues and glands, small intestine, kidney
• Sinusoidal capillaries- wide gaps present inbetween endothelial cells. Seen in liver, spleen and bone marrow
8. Name the three types of arteries in the body
• Elastic/ large arteries
• Muscular/ medium sized/ distributing arteries
• Arterioles
9. What are the general differences between arteries and veins?
• lumen is intact in artery and collapsed in vein
• the wall of the artery is thicker than the wall of the vein
• tunica media is thick in the artery, tunica adventitia is thick in the vein
• well developed internal and external elastic laminae present in the artery, absent in the vein

Medium sized artery:

1. What is the composition of tunica intima?
• Endothelium- simple squamous epithelium
• Subendothelium- loose connective tissue
• Internal elastic lamina- prominent
2. What is the composition of tunica media?
• Equally thick as tunica adventitia with various amounts of reticular  and elastic fibers, abundant  smooth muscle fibers 
3. What is the composition of tunica adventitia?
• Thickness equal compared to tunica media composed of collagen and elastic connective tissue fibers, blood vessels, nerves and lymphatics
4. What is vasa vasorum?
• These are the small blood vessels supplying the walls of large blood vessels to provide nutrition to tunica media and adventitia
5. Give examples for medium sized artery
• Brachial artery, radial artery, ulnar artery, femoral artery, popliteal artery, etc

Large artery/ Elastic artery:

1. Give examples for large artery
• Aorta, brachiocephalic artery, common carotid artery, subclavian artery, vertebral artery, common iliac artery, pulmonary trunk
2. Why elastic artery has more of elastic fibers?
• The elastic fibers provide great resilience and flexibility during blood flow
3. Name the layers of the blood vessel
• From inside out- tunica intima, tunica media, tunica adventitia
4. What is the composition of tunica intima?
• Endothelium- simple squamous epithelium
• Subendothelium- loose connective tissue
5. What is the composition of tunica media?
• Very thick with various amounts of reticular  and smooth muscle fibers, abundant elastic fibers present in the form of laminae
6. What is the composition of tunica adventitia?
• Thin compared to tunica media composed of collagen and elastic connective tissue fibers, blood vessels, nerves and lymphatics
7. What is vasa vasorum?
• These are the small blood vessels supplying the walls of large blood vessels to provide nutrition to tunica media and adventitia

Large vein:

1. What is the composition of tunica intima?
• Endothelium- simple squamous epithelium
• Subendothelium- loose connective tissue
2. What is the composition of tunica media?
• Thin layer with various amounts of reticular  and elastic fibers, smooth muscle fibers 
3. What is the composition of tunica adventitia?
• Very thick compared to tunica media composed of collagen and elastic connective tissue fibers, blood vessels, nerves, lymphatics and longitudinally arranged smooth muscle fibers. 
4. What is vasa vasorum?
• These are the small blood vessels supplying the walls of large blood vessels to provide nutrition to tunica media and adventitia
5. Give examples for large sized vein
• Portal vein, inferior venacava, superior venacava
6. Give the differences between arteries and veins

• Types	Medium sized artery	Large artery	Large vein
  Tunica intima: Endothelium Subendothelial CT Internal elastic membrane (fenestrated membrane of Henle)	Endothelial cells with basal lamina. Sparse. Well defined wavy structure.	Thick lining endothelium with basal lamina. Well defined with collagen and elastic fibers and smooth muscle cells. Fibroblasts absent. Present, Not distinct.	Endothelial layer with basal lamina. Thin, but also with smooth muscle cells. Not distinct.
  Tunica media External elastic lamina	Mainly of smooth muscle cells with intervening collagen, reticular and elastic fibers. Few or no fibroblasts Prominent	Thickest of the 3 layers. Abundant elastic fibers with intervening smooth muscle cells, collagen fibers and ground substance. Elastic fibers in the form of membranes. Not distinct	Thin consisting of smooth muscle cells, collagen fibers and fibroblasts. Not distinct
  Tunica adventitia	As thick as tunica media. Mainly collagen fibers. Adjacent to tunica media form prominent external elastic lamina.	Less than half the thickness of tunica media. Mainly of collagen fibers with loose network of elastic fibers. Fibroblasts and macrophages present. Vasa vasorum seen.	Thickest of the 3 layers  consisting of longitudinally running smooth muscle cells.  Fibroblasts, collagen and elastic fibers seen. Vasa vasorum extends up to the tunica media.
  Lumen	Round and intact.	Round and intact.	Collapsed and irregular. Larger lumen than the artery.
  E.g.	Radial, ulnar, tibial.	Aorta, pulmonary trunk.	Superior vena cava, inferior vena cava, portal vein.

Please refer the above table for the questions given below:

What are muscular arteries and elastic arteries? What is the functional significance of each layer in the wall of the vessel

What are the differences in the structure between the aorta (large artery) and any medium sized artery

What are the features in the structure of the inferior venacava (large vein)

Give the differences in the structure between large artery and vein

Give the differences between the medium sized artery and vein

Give examples for muscular artery and elastic artery

Peripheral nerve, sympathetic ganglia, spinal ganglia- discussion, viva

Peripheral nerve:

1. What are the components of nervous tissue?
• The components of nerve tissue are neurons, nerve fibers and neuroglia
2. What are the parts of nervous tissue?
• Peripheral nervous tissue and central nervous tissue
3. What are the components of peripheral nerve tissue?
• Cranial nerves, peripheral nerves, sympathetic ganglia, spinal ganglia
4. Name the cells involved in myelination of peripheral nerve? 
• Schwann cells
5. What is node of Ranvier? What is its function
• Node of Ranvier is the gap present between two adjacent Schwann cells
• It helps the impulses to jump from one internode to another and helps in faster conduction of impulses
6. What are ganglia?
• Ganglia are the aggregations of cell bodies outside the central nervous system
7. What are the different types of neuroglia in peripheral nervous system?
• Schwann cells and satellite cells
8. What are the connective tissue layers covering the peripheral nerve?
• Epineurium: It is the strong dense irregular connective tissue sheath binding all the fascicles 
• Perineurium: It is a thin connective tissue surrounding the individual fascicle
• Endoneurium: It is the loose vascular connective tissue with reticular fibers surrounding the myelinated axon or cluster of unmyelinated axons
9. What is the constitution of the neurolemma sheath, Myelin sheath and Axis cylinder. What are the nerve fibrils
• Neurolemma sheath- the cytoplasm and nucleus of Schwann cell lying outside the myelin sheath
• Myelin sheath- the modified cell membrane of Schwann cell wrapped around the axon
• Axis cylinder- axon
• Nerve fibril- a delicate fibril found in the cell body and processes of a neuron
10. In what situation is the neurolemma sheath absent?
• Neurolemma sheath is absent in central nervous system
11. What is neuroglia? What are the cell types in it
• Neuroglia are the supporting cells present in the nervous system
• Cell types:
• CNS- ependyma, astrocytes, oligodendrocytes
• PNS- Schwann cells, satellite cells
12. What is axon hillock?
• Axon hillock is a special part present between the cell body and axon. It is devoid of nissl granules
13. Difference between thick and thin fiber in PNS
• Thick fiber- it is myelinated and helps in faster conduction of the impulses
• Thin fiber- it is unmyelinated and helps in slow and uniform conduction of impulses

Spinal / sensory ganglion:

1. Where is spinal ganglion situated?
• Spinal ganglion is situated on the dorsal root of spinal nerve, sensory ganglion of 5, 7, 9 and 10 cranial nerves
2. What are the other names for spinal ganglion?
• Dorsal root ganglion, sensory ganglion
3. What are the identifying features of spinal ganglion?
• Large, round pseudounipolar neurons of different sizes arranged peripherally in groups 
• Single nucleus placed in center of neuron
• Bundles of nerve fibers running between the groups of neurons
• More number of satellite cells surround the neurons
4. Give the examples for spinal ganglion
• Dorsal root ganglia of spinal nerves, sensory ganglia of cranial nerves 5, 7, 9, 10.
5. What are the functions of satellite cells?
• The satellite cells provide the structural and metabolic support to the neurons and insulate the neurons
6. What are pseudo ganglia?
• Localized thickening of the nerve trunk without cell bodies and having only nerve fibers
7. What are the differences between spinal and sympathetic ganglia?
• Refer the table below

 Sympathetic / autonomic ganglion:

1. Where is sympathetic ganglion situated?
• Sympathetic ganglion is situated along the sympathetic trunk and parasympathetic ganglia (ciliary, otic, pterygopalatine, submandibular)
2. What is the other name for sympathetic ganglion?
• Autonomic ganglion
3. What are the identifying features of sympathetic ganglion?
• Small, irregular shaped, uniform size, scattered multipolar neurons
• Nucleus placed eccentrically in the neuron
• Nerve fibers are irregularly arranged separating the neurons
• Few satellite cells arranged around the multipolar neurons
4. Give examples for sympathetic ganglion
• Sympathetic ganglia along sympathetic chain, otic ganglion, ciliary ganglion, submandibular ganglion and pterygopalatine ganglion
5. What are the functions of satellite cells?
• The satellite cells provide the structural and metabolic support to the neurons and insulate the neurons
6. What are the differences between the sympathetic and spinal ganglion?
• Refer the table below

Type	Spinal ganglia	Autonomic ganglia
Capsule	Thick.	Thin.
Neurons	Peripherally arranged, large and round pseudo-unipolar neurons.	Irreguarly arranged multipolar neurons appear star shaped and are of varying sizes in sections.
Nerve fibers	Bundles of nerve fibers separate the neurons. Regularly arranged fibers enter and leave the ganglion.	Axons and dendrites pass through the widely spaced neurons, without being involved in synapses. Irregularly scattered nerve fibers.
Satellite cells	A layer of small cuboidal cells envelopes the neurons.	Few satellite cells incompletely surround the cell body.
E.g.	Dorsal root ganglia of the spinal nerves, sensory ganglia of cranial nerves (V, VII, IX, X).	Sympathetic ganglia along sympathetic chain, Otic/ ciliary/ Submandibular/ pteryogopalatine ganglia.

Muscle tissue- discussion, viva

Muscle tissue:

1. What are the types of muscle tissue based on histology?
• Skeletal muscle, cardiac muscle, smooth muscle
2. What is sarcolemma, sarcoplasm?
• The cell membrane or the plasma membrane of the muscle fiber is called as sarcolemma and the cytoplasm of the muscle fiber is called as sarcoplasm
3. What are myofibrils?
• Myofibrils are composed of myofilaments (contractile proteins) actin and myosin and are present in the sarcoplasm of the muscle fiber
4. Myofilamentsàmyofibrilsà muscle fibersàmuscle fascicles/ bundlesàmuscle

Skeletal muscle:

1. What are the identifying features of skeletal muscle?
• Voluntary, Long, cylindrical, unbranched muscle fiber
• Multinuclei present deep to sarcolemma at the periphery of the muscle fiber
• Distinct cross-striations are seen
2. Why is it called as striated muscle?
• It is called as striated muscle because of the cross-striations which are seen as light I-band and dark A-band under light microscope
3. What are cross-striations?
• Cross-striations are formed due to the regular arrangement of the actin and myosin. under light microscope they are seen as light I-bands and dark A-bands
4. What is sarcomere?
• Sarcomere is the smallest contractile unit present between two adjacent Z-lines. They are repeated throughout the entire length of each myofibril
5. What are the coverings of skeletal muscle? or Give the connective tissue arrangements in C.S of skeletal muscle
• Epimysium: outer dense irregular connective tissue covering of the muscle
• Perimysium: less dense irregular connective tissue covering the bundles of muscle fibers
• Endomysium: thin layer of reticular connective tissue covering each muscle fiber
6. What is syncytium?
• Syncytium is a multinucleated cell that results from multiple cell fusions of uninuclear cells
7. What are the structures present along with connective tissue sheaths?
• Blood vessels, nerves and lymphatics
8. What are the features of the muscle fiber in cross-section?
• All the fibers are all most same in size
• One or two nuclei seen in each muscle fiber deep to sarcolemma
• Cross-sections of myofibrils observed
• Surrounding each fiber is the connective tissue sheath endomysium, blood vessels, nerves and lymphatics
9. What are the features of skeletal muscle in longitudinal section?
• Section of each long, cylindrical unbranched muscle fibers
• Multinuclei present deep to sarcolemma
• Cross-striations seen as light I-band and dark A-band
10. What are cross-striations?
• Cross-striations are the light (I band) and dark (A) bands observed under light microscope due to regular arrangement of protein filaments actin and myosin
11. What are motor end plates?
• Motor end plates or neuromuscular junctions are the sites where impulse from axon is transmitted to the skeletal muscle fiber
12. What is present between the individual muscle fibers?
• Connective tissue sheath endomysium with blood vessels, nerves and lymphatics
13. Give examples for skeletal muscle?
• All muscles attached to bones. Flexor pollicis longus, deltoid etc.
14. What are the differences between skeletal muscle and cardiac muscle?
• Refer the table below
15. What are the differences between skeletal muscle and smooth muscle?
• Refer the table below

Cardiac muscle:

1. What are the characteristic features of cardiac muscle?
• Cardiac muscle is involuntary, short, cylindrical, branched fibers
• One or two nuclei present in the center of the fiber
• Cross-striations and intercalated discs seen
2. What are cross-striations?
• Cross-striations are the light I-band and dark A-band observed under light microscope due to regular arrangement of protein filaments actin and myosin
3. What are intercalated discs?
• Intercalated discs are characteristic features of cardiac muscle
• They are the junctional complexes present between the adjacent muscle fibers
• The gap junction in the intercalated disc enable ionic communication and continuity between adjacent cardiac muscle fibers
4. Give examples of cardiac muscle
• Walls and septa of heart, walls of large vessels (aorta, pulmonary trunk) attached to heart
5. What are the differences between cardiac muscle and skeletal muscle?
• Refer the table below
6. What are the differences between cardiac muscle and smooth muscle?
• Refer the table below

Smooth muscle:

1. What are the characteristic features of smooth muscle?
• Involuntary, non-striated, spindle shaped fibers
• Single nucleus present in the center of the muscle fiber
2. Do the smooth muscle fibers contain actin and myosin?
• Yes, the fibers contain actin and myosin
3. Why is it called as non-striated or smooth muscle fibers?
• The myofilaments actin and myosin are not arranged regularly as in skeletal and cardiac muscle. So they appear smooth
4. What are the features observed in cross-section?
• They are present in small fascicles
• The size and shape of each fiber varies depending on the plane of section passing through the fiber
• If the plane passes through the center of the fiber, the section is larger with large central nucleus
• If the plane passes at the tapered end of the fiber, the section is very small without nucleus
• If the plane passes between the two, the fiber appears small with smaller nucleus
5. Give examples for smooth muscle fibers
• Walls of visceral hollow organs like respiratory, GIT, urinary tract, reproductive tracts and blood vessels
6. What are the differences between smooth muscle and skeletal muscle?
• Refer the table below
7. What are the differences between smooth muscle and cardiac muscle?
• Refer the table below

	Skeletal muscle	Cardiac muscle	Smooth muscle
Muscle cells (fibers)	Long cylindrical un-branched muscle fibers.	Tubular fibers branch and anastomoses.	Spindle shaped.
Striations	Cross striations of alternating light (Isotropic or I bands) and dark bands (Anisotropic or A bands). Light band bisected by a dark transverse line, the Z line. Dark band shows the lighter zone in center, the H band.	Faint cross-striated banding patterns.	Lack visible cross striations.
Nuclei	Multinucleated, flat or oval, peripherally arranged.	Uni-nucleate, central in position.	Uni-nucleate, central in position.
Distinguishing feature	Sarcomere, the smallest repetitive subunit of the contractile apparatus lies between two Z lines. Sarcomere consists of thick and thin filaments. Thick filament mainly composed of myosin and thin filament actin  tropomyosin and troponin.	Intercalated disk, faintly seen, under the light microscope, represent the junctional complexes.	-
Functions	Movements.	Autonomic, rhythmic, involuntary movements.	Involuntary movement - i.e. churning of food, movement of urine from the kidney to the bladder, parturition of the fetus.
E.g.	Muscles attached to the bone.	Heart.	Walls of hollow organs (stomach, intestine, uterus, ureter).