Monday, July 28, 2014

The role of liver in material metabolism

Material metabolism in liver

liver metabolism
  • carbohydrate metabolism
  • lipid metabolism
  • protein metabolism
  • vitamin metabolism
  • hormone metabolism 

Carbohydrate metabolism

Functions

Maintaining the constancy of the concentration of sugar in blood; supplying energy to peripheral tissues, especially to brain and erythrocytes.

Main pathways for carbohydrate metabolism

  • gluconeogenesis
  • glycogenesis and glycogenolysis
  • glycolysis 

Carbohydrate metabolism in varied nutrient conditions in liver

    --  glycogenesis↑
          --  excess carbohydrate is converted to fatty acids and exported in VLDL form
  • postabsorption state
     --  glycogenolysis↑→release glucose to replenish blood sugar
  • starvation state
     --  gluconeogenesis
     --  lipid mobilization↑→acetone body↑→saving glucose

Lipid metabolism


Functions: 

Play important role in digestion, absorption, synthesis, catabolism and transportation of lipids.  

 Main pathways lipid metabolism

  • oxidation of fatty acids
  • synthesis of fatty acids and esterification
  • formation of ketone bodies
  • synthesis of lipoproteins and apolipoproteins (VLDLHDLapoC II)
  • degradation of lipoproteins

Role of liver in varied processes of lipid metabolism

  • digestion and absorption
    --  biliation.  Bile acid is essential for lipid digestion and  absorption
     --  liver dysfunction→fatty diarrhea
  • synthesis
     --  fatty acid, triacylglycerol, ketone body, cholesterol,phospholipid
     --  liver dysfunction→fatty liver, Ch/ChE↑
  • catabolism
     --  β-oxidation of fatty acids, degradation and excretion of cholesterol, degradation of LDL
  • tranportation
     --  synthesis and secretion of VLDL, HDL, apoC II and LCAT

Protein metabolism


Functions: synthesis (γglobulin is excepted), secretion and elimination (albumin is excepted) of plasma proteins.

Liver dysfunction:

  • albumin↓→edema, A/G↓
  • plasma thromboplastin component ↓ →disturbance of blood coagulation
  • blood ammonia
  • amine↑→hepatic encephalopathy 

Vitamin metabolism

Functions

  • absorption of fat-soluble vitamins
  • storadge of vitamins (VA, VK,VE,VB12)
  • transpotation of vitamins synthesis of retinol-binding protein and VitD-binding protein
  • transformation of vitamins
  • β-carotene→VitA Vit D3 → 25-(OH)-Vit D3 water-soluble vitamins →cofactors

Liver dysfunction

  • biliary obstruction→VitK↓→hemorrhagic tendency
  • hepatic rickets

Hormone metabolism

Functions: inactivation of hormones
Manner: biotransformation

Liver dysfunction:

  • Spider angioma of skin
  • liver pulms
  • cutaneous pigmentation
  • hypoglycemia


Saturday, March 15, 2014

Magnesium functions – the role of magnesium in human body

Magnesium function
Magnesium is the fourth most common cation in the human body and second most abundant intracellular cation in the human body. Human body contains approximately 24g (1000mmole) of magnesium and it is involved in many intracellular processes and is very essential for life. The metabolic irregularity or disturbance is associated with various abnormalities. The main sources of magnesium are vegetables, soybeans, nuts, whole grain cereals, eggs and seafood. The minimum daily dietary magnesium intake to maintain magnesium balance in normal person is about 240mg per day.

Magnesium functions – Co-factor and agitator of many enzymes

Magnesium plays an important in role in functions of more than 300 enzymes, Na+. K+ ATPase, hexokines, choline esterase. It actively participates in many metabolic activities in the body. Magnesium helps to metabolize proteins, lipids, carbohydrates and nucleic acid. Magnesium is also vital in regulating the cellular distribution of sodium and potassium through involvement in Na+, K+ ATPase.

Magnesium functions -Maintains irritability of the cells

Magnesium acts as an inhibitor to central nervous system, neuromuscular and cardiac muscles. For neuromuscular irritability magnesium and calcium are synergic and for cardiac muscles they are antagonist.

Magnesium functions – Maintains homeostasis of cells

Magnesium is an essential cofactor in correlative enzymes of DNA, cell cycle and apoptosis. In plasma, magnesium is important for maintaining DNA structure and veracity of DNA replication, and activating DNA repairing including nucleotide excision repair, base excision repair, miss match repair and microtubilin assembly. 


Tuesday, March 11, 2014

Necrosis – the exact causes and types of necrosis

necosisCell death is the one of the most crucial event in pathology, affecting every cell type and being a major consequences of ischemia, infection, toxin,and immune reaction. There are two types of pattern of cell injury and deaths, necrosis and apoptosis. Necrosis refers to a spectrum
of morphologic changes that follow cell death in living organisms. Necrosis is characterized denaturation of cytoplasmic proteins, failure of membrane integrity , break down of cell organelles and swelling of lethally injured cells.

 

Types of necrosis 

Necrotic cells have different morphological types. It can be classified into total of five types

Coagulative Necrosis

Coagulative necrosis is the most common type of necrosis in which cells death happen after exogenous or endogenous stimuli, occurring after such stresses as ischemia, virus toxin, physical and chemical injury. It is manifested by severe cell rupture, denaturation and coagulation of cytoplasmic proteins.
In coagulative necrosis, the texture of the tissue will be normal or firm, but later it may become soft as a result of digestion by macrophages. The myocardial infarction is the typical example of coagulative necrosis. 




Caseous necrosis

Caseous necrosis is a distinctive form of coagulative necrosis in tuberculosis infection. The term caseous is derived from the gross appearance of area of the necrosis. On microscopic examination, the necrotic focus appear as amorphous coarsely granular eosinophillic debris, without any original out line of cells and tissues. This distinctive types of necrosis is generally attributed to the toxic affect of unusual cell wall of mycobacterium, which contain complete waxes. 



Liquefactive necrosis


Liquefective necrosis is a characteristics of focal bacterial or occasionally fungal infections, because these agents constitute powerful stimuli to the accumulation of inflammatory cells. The polymorphonuclear leukocytes in the acute inflammatory reactions are endowed with potent hydrolases, capable of completely digesting dead cells. For the reasons of the presence of more abundant lysosomal enzymes or different hydorlases and the lack of any substantial supporting stroma specific to the nervous cells, hypoxic death of cells within the central nervous system often evokes  liquefactive necrosis. 



Fibroid necrosis

Fibroid necrosis refers to an alteration of injured tissues which are homogenous, deeply eosinophilic in necrosis. For example, malignant hypertension, the wall of the arterioles is under such necrosis, because of the insudation and accumulation of immunoglobulins, plasma proteinsard especially the consequences deposition of fibrin.  

Gangrenous necrosis

Gangrenous necrosis is a necrosis putrefaction of the tissues as a results of the action of the saprophytic bacteria, mainly clostridium. There are three types of gangrenous necrosis:
1.       Dry gangrenous
2.       Wet gangrenous
3.       Gas gangrenous 

Tuesday, January 14, 2014

The Primary Functions of Thyroid Hormone

The primary functions of the thyroid hormone basically include:
Functions of Thyroid Hormone
Heat Production
Increases oxygen consumption and BMK of targeted tissues, especially in liver, cardiac muscles and kidney

Protein Metabolism
Promote the synthesis of proteins and enzymes

Carbohydrate Metabolism
Elevates the glucose level in the blood

Fat Metabolism
Promotes oxidization of fatty acids and strengthen the effects of catecholamine and glycogen of lypolysis.

Effects on growth and development
Essential for mental and physical development in human, especially for the development of brain and bone tissues

Effects on CNS
Increases the effectiveness of permissive antigen and increase the excitability of CNS

Effects of Cardiovascular System

Increases heart rate, cardiac contractility, cardiac output and vasodilatation  

Friday, January 10, 2014

The structure and functions of BCR Complex

structure of BCR complex
It’s a membrane Ig (IgM), associated glycoporotein, Ig α and Igβ , which has a moderately large cytoplasmic domain. These domains each include a short region important for transmitting a signal indicating antigen has bound. This region is called immune tyrosin based activation motif ( ITAM ).

Functions of BCR complex

On activation by antigen, B cells differentiate into plasma cells producing antibody molecules of the same antigen specificity as the receptors.

Saturday, January 4, 2014

Physiological Dead Space

Wednesday, November 27, 2013

Amazing Video Showing a Pipe in a live Man's Neck


Wednesday, October 30, 2013

Anatomy of Abdominopelvic Cavity

The abdominopelvic cavity extends from the diaphragm to the pelvis. It is subdivided into a superior abdominal cavity and aninferior pelvic cavity (Figures 1–9 and 1–10a). The abdominopelvic cavity contains the peritoneal cavity, a potential space lined by a serous membrane known as the peritoneum. The parietal peritoneum lines the inner surface of the body wall. A narrow space containing a small amount of fluid separates the parietal peritoneum from the visceral peritoneum, which covers the enclosed organs. You are probably already aware of the movements of the organs in this cavity. Who has not had at least one embarrassing moment when the contraction of a digestive organ produced a movement of liquid or gas and a gurgling or rumbling sound? The peritoneum allows the organs of the digestive system to slide across one another without damage to themselves or the walls of the cavity.

The abdominal cavity extends from the inferior surface of the diaphragm to the level of the superior margins of the pelvis. This cavity contains the liver, stomach, spleen, small intestine, and most of the large intestine.  The organs are partially or completely enclosed by the peritoneal cavity, much as the heart and lungs are enclosed by the pericardial and pleural cavities, respectively. A few organs, such as the kidneys and pancreas, lie between the peritoneal lining and the muscular wall of the abdominal cavity. Those organs are said to be retroperitoneal (retro, behind). per-i-to_ -NE_ -um per-i-to_ -NE_ -al


The pelvic cavity is the portion of the ventral body cavity inferior to the abdominal cavity. The bones of the pelvis form the walls of the pelvic cavity, and a layer of muscle forms its floor. The pelvic cavity contains the urinary bladder, various reproductive organs, and the distal portion of the large intestine. The pelvic cavity of females, for example, contains the ovaries, uterine tubes, and uterus; in males, it contains the prostate gland and seminal glands. The pelvic cavity also contains the inferior portion of the peritoneal cavity. The peritoneum covers the ovaries and the uterus in females, as well as the superior portion of the urinary bladder in both sexes. Visceral structures such as the urinary bladder and the distal portions of the ureters and large intestine, which extend inferior to the peritoneal cavity, are said to be infraperitoneal.

Monday, October 21, 2013

Beneficial Effects of the Normal Flora

Priming of Immune system

Normal floraOrganisms of normal flora play an important role in the development of immunologic competence. Animals delivered and raised under completely aseptic conditions have a poorly developed reticuloendothelial system, low serum level of immunoglobulin and none of the antibodies to normal floral antigen that often cross-react with those of pathogenic organisms and confer a degree of protection against them.


Exclusionary Effects

The normal flora produces conditions that tend to block the establishment of e4xtraneous pathogens and their ability to infect the host. The bifidobacteria in the colon of the breastfed infant produce an environment inimical to colonization by enteric pathogens, this protective effect is aided by ingested maternal IgA. Breastfeeding has clearly shown to help to protect infant from enteric bacterial infections.

Production of Essential Nutrients by Normal flora

In humans, member of the vitamin B group and vitamin K are produced by normal flora. Bacterial vitamin production is reduced during broad spectrum antibiotic therapy, and supplementation with vitamin B complex is indicated in malnourished individuals.