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Digestive System

 Digestive System Human digestive system is a pipe-like structure which starts from the mouth and ends in anus. In between there are some organs like stomach, small intestine and large intestine where digestion of foods occurs. There are some glands which help in digestion e.g. salivary gland, liver and pancreas.  Digestion means breaking down the food into those molecules that can be absorbed by the body.so if we divide food into the macro categories they will be 1)carbohydrate,  2)protein and 3)fat. In carbohydrates, there can be these types of bonds – Starch and glycogen : starch and glycogen are storage polymers of glucose in plants and animals respectively. In starch and glycogen the glucose molecules are bonded by glycosidic bonds ( alpha 1-4 glycosidic bond and alpha 1-6 glycosidic bond). Our body cannot absorb the big molecules as starch, so it has to be broken to free glucose molecules for absorption. Amylase enzyme is released by the salivary gland and pancreas can break thes
Recent posts

Poliomyelitis | polio | polio virus

  Symptoms : Most infected individuals have no symptoms . Paralytic disease 1%   high fever Intense muscle pain from spasm and weakness  loss of muscle reflexes  paralysis asymptomatic Affect larger proximal muscles specially legs  infants develop acute flaccid paralysis floppy baby syndrome  Diaphragm motor nerves are affected difficulty in  breathing Diagnosis: Besed on Polio virus recovery from stool sample throat swab  lumbar puncture cerebral fluid removed from Lamba Sach might have high white blood cells or poliovirus RNA Treatment: Pain medicines for muscle spasm bladder decompression  respiratory support for trouble breathing by Iron lung machine. Polio vaccine and post polio syndrome will be discussed in next video.

Fasciola Hepatica | Liver Fluke |

  Mode of infection :  Infection of freshwater plants with metacercariae or by drinking water with floating metacercariae example lettuce green salad. Definite host : human Intermediate host : freshwater snails  Reservoir host : sheep  Infective form : metacercariae  Pathogenicity :   While passing through the liver the large form causes hepatitis damage.   may cause abscesses of lungs , body wall on fibrotic lesions.  produces severe parenchymal disease of liver for which the parasite is called liver fluke and disease is known as liver rot. necrosis of liver  anaemia common inflammation and damage of bile duct. respiratory blockage of lungs Hyperplasia   Symptoms :  abdominal pain Anemia prolonged high fever  Nausea Jaundice Lethargy  Tenderness Hepatomegaly  fatty food intolerance   Treatment :   B ithional :  Highly Effective  large dose high cost  long period     Triclabendazole :  easier to use  one to two oral doses in 24 hours Surgery  Control :  people residing in areas f

Sliding Filament Theory

Sliding Filament Theory:  The sliding filament theory explains the mechanism of muscle contraction based on muscle proteins that slide past each other to generate movement. According to the sliding filament theory the myosin filaments of muscle fibres slide past the actin thin filaments during muscle contraction while the two groups of filaments remained at relatively constant at length.  1. I bands are composed of actin filaments and the A Bands principally of myosin filaments. 2. during muscle contraction the actin filaments move into the A bands between the myosin filaments. 3. The backbone of a muscle fibre is actin filaments which extend from z line up to one end of H zone, where they are attached to an elastic component which is named as S filament. 4. Myosin filaments extend from one end of the A band through the H zone up to the other end of the A band. 5. Myosin filaments remain in relatively constant length during muscle stretch or contraction. 6. During stretching only I ban

Molecular basis of Sliding filament theory

Molecular basis of sliding filament theory :  The contraction of skeletal muscle generates the force necessary to move the Skeleton. A contraction is triggered by a series of molecular events known as cross Bridge cycle. I n a skeletal muscle fibre the function of unit contraction is called sarcomere.  A sarcomere shortens when myosin head in thick myofilament forms cross bridges with actin molecules. 1. initiation  :  the formation of a cross Bridge is initiated when calcium ions, released from the sarcoplasmic reticulum binds to troponin. This binding causes troponin to change shape. Tropomyosin moves away from the myosin binding site on actin allowing myosin head to bind and form a cross Bridge. 2. activation   of myosin head :  Activation of myosin head occurs when ATP binds to myosin head and is hydrolysed to ADP and inorganic phosphate. The energy liberated activate the myosin head forcing it into the curved position. 3. Cross Bridge formation :  The activated myosin head binds

Oogenesis that is formation of ovum of female gamete :

Oogenesis that is formation of ovum of female gamete : Oogenesis starts in the ovary of the female foetus when it is in the womb of her mother. if we zoom into the female reproductive system of the foetus we can see in the ovaries of the female foetus the oogenesis has already started.  the germinal epithelial cells inside the ovary wall of the foetus starts dividing by mitotic cell division and forms  oogonium. This oogonium cells goes through growth phase and forms the primary oocyte inside the ovary of the female foetus.  now the primary oocyte goes through meiosis 1 it gets arrested in prophase 1 of meiosis cell division 1 and stops here until the female foetus borns and becomes a mature woman and comes to the puberty. When it reaches the puberty inside the ovary of the matured female, the cell which got arrested in prophase 1, the primary oocyte, starts dividing again and complete the meiosis 1 and forms secondary oocyte and one polar body that is the first

Entamoeba histolytica (parasitic protozoan) life cycle | Amoebic dysentry

Entamoeba histolytica  is a parasitic protozoan responsible for the disease amoebic dysentry. Entamoeba   histolytica life cycle  : There are two forms - 1. cyst  : non-mobile form  2. trophozoit :  Mobile form   A.Cyst entry :  Injection of food or water contaminated with Entamoeba histolytica cyst will move through the mouth down the oesophagus into the stomach. Cysts are resistant to gastric environment and passes through the stomach. B.Excystation : Each cyst can divide and produce 8 trophozoits the mobile form of Entamoeba histolytica in the small intestine.   C.Multiplication : The trophozoites will then move to colon of large intestine then multiply and colonizes. Entamoeba can cause 2 types of infection :  1.  non-invasive:  90% 2.  invasive  : 10%  1. Non-invasive : Trophozoits remain on the surface of mucus layer of colonic epithelium and multiplies by binary fission. This non-virulent form feeds on bacteria and detritus in lumen. D. Encystation  : The trophozoites wil