KIDNEY

KIDNEY

The kidneys are a pair of bean-shaped organs that are situated on either side of the spine below the rib cage. The kidneys support healthy electrolyte balance, blood pressure regulation, and waste removal from the body.

LOCATION

The positioning

While the right kidney is lower as a result of the liver's minor displacement, the left kidney is situated about between the T12 and L3 vertebrae. The eleventh and twelfth ribs provide some protection for the upper regions of the kidneys.

The kidneys measure around 3 centimetres (cm) in thickness, 6 cm in width, and 12 cm in length. The typical weight of the kidneys in men is around 129 grammes (g) for the right kidney and 137 g for the left. The average weight of these organs in females is 116 g for the left kidney and 108 g for the right kidney.

INTERNAL ANATOMY

The renal cortex, which is located outside of the kidney, and the medulla, which is located inside, are visible in a frontal slice of the kidney. The renal columns are connective tissue extensions that stretch downward from the cortex into the medulla to divide the two most recognisable elements of the medulla, the renal pyramids and renal papillae. The kidney's calyces are where urine is excreted, and the papillae are collections of collecting ducts that carry urine from nephrons to those locations. Besides from dividing the kidney into six to eight lobes, the renal columns also act as a structural support for blood arteries that enter and leave the cortex. The kidney lobes are made up of the pyramids and renal columns combined.

Renal Hilum

The renal hilum serves as the entry and exit point for the arteries, nerves, lymphatics, and ureters that supply the kidneys. The arching convex contour of the cortex tucks the medial-facing hila into its folds. The kidney's major and minor calyxes combine to produce the renal pelvis, which emerges from the hilum. Urine is directed into the ureter via peristalsis by the smooth muscle in the renal pelvis. While the inferior vena cava receives cleansed blood from the renal veins, the renal arteries develop directly from the descending aorta. Anterior to posterior is the order of the renal pelvis, artery, and vein.

Nephrons and Vessels

The renal artery first separates into segmental arteries, then it continues to branch to create interlobar arteries, which then go through the renal columns to the cortex. The interlobar arteries then divide into afferent arterioles, arcuate arteries, and cortical radiate arteries. In each kidney, there are 1.3 million nephrons that are served by the afferent arterioles.

NEPHRONS

The "functional units" of the kidney, or nephrons, are responsible for balancing the components of circulation and purifying blood. The glomerulus, formed by the afferent arterioles, is a tuft of 200-m-diameter high-pressure capillaries. The Bowman's capsule is a continuous, complex tubule that surrounds the glomerulus in an affectionate embrace at its proximal end.

The Bowman's capsule and glomerulus combine to form the renal corpuscle. These glomerular capillaries filter the blood according to particle size, as was already described. The capillaries create the efferent arteriole after passing through the renal corpuscle. The peritubular capillaries and vasa recta will then create a capillary network around the more distant parts of the nephron tubule before returning to the venous system. The majority of the solutes and water are recovered by these capillary networks and returned to the circulation when the glomerular filtrate moves through the nephron.

The criteria of a portal system is met because the glomerulus, a capillary bed, drains into a vessel, which then creates another capillary bed. The first and second capillary beds of this portal system are separated by an arteriole solely in this system. The liver and the blood arteries of the digestive viscera are connected by portal systems, which also connect the hypothalamus to the anterior pituitary.

CORTEX

The cortex of the kidney can be easily distinguished in a dissected kidney because it has a lighter hue than the remainder of the kidney. Here are located the proximal convoluted tubules (PCTs) and the distal convoluted tubules, as well as all the renal corpuscles. Some nephrons have a brief Henle loop that does not dip past the cortex. Cortical nephrons are the name given to these nephrons. Juxtamedullary nephrons, which make up around 15% of nephrons, are long Henle loops that reach deep within the medulla.

STRUCTURE

Two bean-shaped organs around the size of a fist make up the kidneys. Each kidney has a strong, fibrous renal capsule that protects the soft tissue inside and supports the kidneys. Two additional layers of fat offer additional defence on top of that. On top of the kidneys are the adrenal glands.

There are several pyramid-shaped lobes inside the kidneys. Each kidney has an inner renal medulla and an outer renal cortex. These portions are connected by nephrons. A filter called the glomerulus and a tubule are both parts of a nephron. Blood is filtered in the glomerulus after it passes through the kidneys' renal arteries and veins. Although being relatively small organs, the kidneys receive 20–25% of the heart's output.

The tubule eliminates waste, which is then converted to urine, and returns vital components to the circulation. Through the ureter, a tube that connects to the bladder, the kidneys expel urine.

FUNCTION

The maintenance of equilibrium is the kidneys' primary function. They control fluid levels, electrolyte balance, and other elements that maintain the body's stable and comfortable interior environment.

There are numerous biological activities that these organs do.

 EXCRETION OF WASTE

Many waste items are removed by the kidneys and eliminated in the urine. Among the main substances the kidneys filter are:

urea, which is produced when proteins break down, and uric acid, which is produced when nucleic acids break down, are both products of drug metabolism.

REABSORPTION OF NUTRIENTS

Tubules are used by the kidneys to reabsorb nutrients from the blood and move them to the areas of the body where they will support health the most. To support equilibrium, they reabsorb more substances. among the items that are reabsorbed

sodium, magnesium, potassium, and bicarbonate ions are present in glucose along with water and amino acids.

PH MAINTENANCE

The appropriate pH range for humans is 7.35 to 7.45. The body assumes an acidemic or alkalemic state at concentrations that are either below or above this range. Proteins and enzymes degrade and stop working under these conditions. This may be lethal in extreme circumstances.

The pH of the body is maintained in part by the kidneys and lungs. By controlling the blood's carbon dioxide concentration, the lungs are able to achieve this. The kidneys control pH by generating and reabsorbing the acid-neutralizing bicarbonate from urine.

If the pH is manageable, the kidneys can store and release Trusted Source bicarbonate, respectively. By excreting acid, they can create fresh bicarbonate.

REGULATION OF OSMOLALITY

Osmolality is a gauge of the body's electrolyte-water balance, or the proportion of fluids to minerals. Electrolyte imbalance is primarily brought on by dehydration.

The brain's hypothalamus reacts by sending a signal to the pituitary gland if the blood plasma's osmolality increases. This organ produces antidiuretic hormone (ADH). The kidney undergoes a number of modifications in response to ADH, including:

increasing urine content

boosting water uptake

opening up areas of the collecting duct where water ordinarily cannot enter, allowing water to return to the body, keeping urea in the kidney's medulla rather than excreting it, as this chemical sucks in water.

CONTROL OF BLOOD PRESSURE

When blood pressure needs to be adjusted, the kidneys are in charge of slower changes.

By altering the fluid around cells, they influence the long-term pressure in the arteries. Extracellular fluid is the formal name for this fluid in medicine. With the production of a vasoconstrictor called angiotensin II, these fluid shifts take place. Hormones called vasoconstrictors force blood vessels to tighten.

These hormones contribute to an increase in salt, or sodium chloride, absorption by the kidneys. Blood pressure rises as a result of this absorption, which also expands the extracellular fluid compartment. The kidneys can be harmed by excessive alcohol use, smoking, and obesity, among other things that change blood pressure. Over time, a reliable source.

SECRETION OF ACTIVE COMPOUNDS 

Several significant substances are released by the kidneys, including;

1)Red blood cell production, or ERYTHROPOIESIS, is regulated by the hormone erythropoietin. Erythropoietin is also produced by the liver, but in adulthood, the kidneys are its primary source.

2).RENIN: This enzyme aids in controlling artery growth as well as blood plasma, lymph, and interstitial fluid levels. White blood cells, which promote immune function, are found in the fluid known as lymph, and interstitial fluid makes up the majority of extracellular fluid.

3).CALCITRIOL: is the hormone-active vitamin D metabolite. It boosts the kidney's ability to reabsorb phosphate while also increasing the amount of calcium that the intestines can absorb.

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