Bone metabolism Bone consists of both organic and organic components. The major inorganic compound is calcium phosphate which accounts for 2/3rd of the bone weight. This calcium phosphate interacts with calcium hydroxide to from hydroxyapatite. Other inorganic compounds include calcium carbonate, sodium, magnesium and fluoride. The remaining organic portion of the bone is made up of

Synovial fluid in joints Joints Joint is a junction between two bones. It is also called as articulation. Joints are classified into three types- Fibrous Joints These are immovable and the bones are firmly united by fibrous tissue. Eg.: Joints found between the skull bones. Cartilaginous Joints These joints are slightly movable. Eg.: Intervertebral disks between the bodies of

Cerebrospinal fluid or CSF Cerebrospinal fluid or CSF is formed by the choroid plexus of the lateral, third and fourth ventricles of the brain. CSF is periodically absorbed by the arachnoid villi of the subarachnoid space. This structure is quite large in man and horse, but generally small or microscopic in other domestic animals. The

Lymph contains few or no RBCs, numerous leukocytes, inorganic salts, glucose, NPN substances and some proteins. Lymph derived from the intestine during absorption contains lipids which gives milky white appearance known as chyle.

Concentration and urine characteristics of birds Concentration of avian urine Renal response to ADH in birds is similar to that of the mammals. In addition to the action of ADH on the tubular cells it also controls the functioning of reptilian  and mammalian type of nephrons. Urine characteristics and flow Birds urine when  mixed with faeces

Uric acid formation and excretion in birds The metabolic end product of protein and amino acids in reptiles and birds is the uric acid (instead of urea in mammals). Uric acid is formed in liver and also in kidneys from ammonia. Uric acid is freely filterable at the glomerulus, and it is also secreted by

Renal portal system (RPS) in birds An unique feature of avian kidney is its Renal Portal System (RPS) which provides an extra branch of blood flow to the renal tubules along with peritubular capillaries. Venous blood from portal vein gives one branch to the kidney and this branch provides the microcapillaries which perfuse the tubules along

Excretion in birds In the birds, the ureters transport the urine to the cloaca, which is the common collection site for digestive, reproductive and urinary organs. There is no urinary bladder in birds.  Urine formation in birds is almost similar to the mammals but still then there are some notable differences: Presence of two major