Kidneys are bean-shaped structures located on either side of the backbone and are protected by the ribs and muscles of the back. Each human adult kidney has a length of 10-12 cm, a width of 5-7 cm and weighs around 120-170g.
The kidneys have an inner concave structure. The blood vessels, ureter and nerves enter the kidneys through the hilum, which is a notch at the inner concave surface of the kidney. The renal pelvis, a large funnel-shaped space.
is present inner to the hilum, is has many projections known as calyces.
Structure of Kidney
Capsule
The outer layer is called the capsule. Inside the kidney, there are two zonesthe outer zone is the cortex and the inner zone is the medulla. The cortex extends in between the medullary pyramids as renal columns called columns of Bertin.
“Nephrons Nephrons are the functional units of the kidney. Each nephron has two partsglomerulus and renal tubule.
Glomerulus consists of a bunch of capillaries formed by afferent arterioles. Blood from glomerulus is carried away by efferent arterioles.
The renal tubule starts with a cup-like structure called Bowman's capsule and this encloses the glomerulus. The malpighian body consists of glomerulus and Bowman's capsule. The highly coiled structure in the tubule next to the Bowman's capsule is the proximal convoluted tubule.
Explore more: Nephrons
Henle's loop
The next part of the tubule is Henle’s loop which has an ascending and a descending limb. The ascending loop continues as a distal convoluted tubule. The distal convoluted tubules of many nephrons open into the collecting duct.
The cortical region of the kidney comprises of malpighian corpuscle, proximal convoluted tubule and distal convoluted tubule and the medullary region contains a loop of Henle.
ascending loop continues as a distal convoluted tubule. The distal convoluted tubules of many nephrons open into the collecting duct.
The cortical region of the kidney comprises of malpighian corpuscle, proximal convoluted tubule and distal convoluted tubule and the medullary region contains a loop of Henle.
There are two types of nephrons — cortical and juxtamediullary. In the case of cortical, the loop of Henle is very short and extends only a little into the medulla. In juxtamedullary, the loop of Henle is very long and runs deep into the medulla.
Ureter
A pair of thin muscular tubes called the ureter comes out of each kidney extending from the renal pelvis. It carries urine from the kidney to the urinary bladder.
Urinary Bladder
It is a muscular sac-like structure, which stores urine. The urinary bladder is emptied by the process of micturition, i.e. the act of urination.
Urethra
This tube arises from the urinary bladder and helps to expel urine out of the body. In males, it acts as the common route for sperms and urine. Its opening is guarded by sphincter muscles.
_ ay
Brain
It is the most complicated organ in our body. The human brain is located in our head and is surrounded by a strong bony structure, called the skull and is suspended in a layer of fluid called the cerebrospinal fluid, which functions by protecting the brain from minor mechanical shocks and jolts.
The brain, along with the spinal cord, composes the central nervous system. It is responsible for thougNts, interpretation, regulation and control of body movements.
On average, an adult brain weighs between 1.0 kg — 1.5 kg. It is mainly composed of neurons — the fundamental unit of the brain and nervous system. Recent estimates have suggested that the brain contains anywhere between 86 billion to 100 billion neurons.
The brain, along with the spinal cord, constitutes the central nervous system. It is responsible for
thoughts, interpretation and origin of control for
body movements.
Where is the Brain located?
The brain is enclosed within the skull, which provides frontal, lateral and dorsal protection. The skull consists of 22 bones, 14 of which form the facial bones and the remaining 8 form the cranial bones. Anatomically, the brain is contained within the cranium and is surrounded by the cerebrospinal fluid.
The Cerebrospinal Fluid (CSF) is a fluid that circulates within the skull and spinal cord, filling up hollow spaces on the surface of the brain. Every day, the specialised ependymal cells produce around 500mL of cerebrospinal fluid.
The primary function of the CSF is to act as a buffer for the brain, cushioning mechanical shocks and dampening minor jolts. It also provides basic immunological protection to the brain.
Furthermore, CSF provides buoyancy for the brain. i.e., the brain is suspended in a layer of CSF, wherein, the weight of the brain is nearly negated.