Table of contents | |
Human Excretory System? | |
What are kidneys? | |
Location of Kidneys | |
Structure of Kidney | |
Internal Structure of Kidney | |
(a) Structure and Parts of Nephron | |
(b) Types of Nephrons |
Different organisms have different excretory mechanisms. In humans, the excretory system primarily consists of the kidneys . Excretion is an important process in living organisms that involves the removal of waste products and harmful substances from the body. It is a vital function for maintaining the internal balance and overall health of an organism. If excretion did not occur, these waste products would build up in our bodies and disrupt normal bodily functions.
The Human excretory system is responsible for removing waste products from the body. It consists of several organs, including the kidneys, ureters, urinary bladder, and urethra. Excretion plays a crucial role in maintaining homeostasis (Hemostasis is the body's process of maintaining a stable and balanced internal environment).
Pair of Kidneys
The kidneys are bean-shaped organs in our bodies having reddish brown color. and they are located between the last thoracic and third lumbar vertebrae, near the back wall of the abdomen.
Location Of Kidneys
External Structure Of Kidney
Structure Of Nephron
The Nephron is the functional unit of the kidney responsible for filtering and processing blood to form urine. It consists of Two main parts:
The Glomerulus, composed of a cluster of tiny capillaries, acts as a filter to remove waste products and excess water from the blood.
The glomerulus consists of three main parts
Afferent Arteriole: This small artery carries blood into the glomerulus under high pressure. It brings blood from the main renal artery into the glomerulus for the process of filtration.
Glomerular Capillaries: These small blood vessels form a network of loops within the glomerulus. They are highly specialized for the purpose of filtration. As blood flows through these capillaries, waste products and excess fluids are filtered out and collected for further processing.
Efferent Arteriole: This small artery carries the filtered blood away from the glomerulus. It transports the purified blood to the next stage of the renal circulation
The Renal tubule is a long and twisted tube, plays a crucial role in the kidney's filtration process. It reabsorbs important substances like water, glucose, and salts back into the bloodstream while allowing waste products to continue their journey for elimination as urine.
(a) Bowman's Capsule: This cup-like structure surrounds the glomerulus and collects the filtrate produced during glomerular filtration.
(b) Proximal Convoluted Tubule (PCT): This highly coiled region reabsorbs valuable substances from the filtrate, such as glucose, water, and electrolytes, back into the bloodstream. It also secretes waste products for elimination.
(c) Loop of Henle: The U-shaped portion of the renal tubule consists of a descending limb and an ascending limb. It helps maintain urine concentration by allowing water reabsorption in the descending limb and electrolyte reabsorption in the ascending limb.
(d) Distal Convoluted Tubule (DCT): Located after the Loop of Henle, this coiled section further reabsorbs water and electrolytes and regulates acid-base balance and the excretion of certain substances.
(e) Collecting Duct: This larger tube receives filtrate from multiple nephrons and carries it towards the renal pelvis, where it becomes urine.
NOTE: The glomerulus, together with Bowman's capsule, is referred to as the Malpighian body or renal corpuscle.
Malpighian Body
The efferent arteriole that comes out of the glomerulus creates a small network of capillaries surrounding the renal tubule known as the peritubular capillaries. Within this network, there is a tiny vessel that runs alongside the Henle's loop, taking the shape of a 'U', which is called the vasa recta.
(i) Cortical Nephrons
(ii)Juxtamedullary Nephrons:
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1. What is the function of the kidneys in the human excretory system? |
2. Where are the kidneys located in the human body? |
3. What is the basic structure of a kidney? |
4. What are the main parts of a nephron within the kidney? |
5. What are the two types of nephrons present in the kidney and how do they differ? |
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