HUMAN EXCRETORY SYSTEM|| STRUCTURE OF KIDNEY AND NEPHRON This video deal with lecture class on human excretory system and structure of …
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The Chapter for today is helpful for school students and aspirants for competitive exams
The chapter is Human Excretory system
What is Human Excretory system? What are the organs involved? Their structure etc. are dealt with in this chapter
Many metabolic reactions take place in our body
Metabolic wastes are generated as a result of these reactions. These are toxic
The accumulation of these toxic wastes inside the body will lead to many diseases
Hence these metabolic wastes are removed from the body
Human excretory system does the removal of the wastes
List out the different metabolic wastes you know in the comments below.
Let's see the major metabolic wastes
Main metabolic wastes are: Carbon dioxide, water, salt, and finally urea- the nitrogenous waste in the human body
Among these, Carbon dioxide is removed by exhaling.
But in the case of urea, it has to be filtered out from the blood and removed.
The kidney is the organ that plays the role of filtering and removing the urea.
Urea is the nitrogenous waste of mammals including human beings
Other nitrogenous waste forms are ammonia and uric acid.
Aquatic animals including fishes have their nitrogenous waste as ammonia
Mammals have their nitrogenous waste as urea
Birds, insects etc have their nitrogenous waste as uric acid
The loss in water content is different for these nitrogenous wastes
The water loss is more in the case of ammonia, because for fishes there is abundancy in water around.
However, it would be difficult for birds to lose so much of water
Hence their nitrogenous waste is removed as uric acid and hence the loss of water from body would be lesser.
The case of humans falls in between these two categories
Coming back to human excretory system,
The organs of excretion are: Skin, liver, large intestine, lungs and Kidney
Skin has sweat glands. The fluid waste removed through skin is called sweat.
In the case of liver, hemoglobin catabolic waste namely bilirubin is excreted by liver
Braking down of substances in blood including toxins is done in liver
Large intestine helps in removing the indigested food after absorbing some amount of water.
Lungs help to exhale the waste product carbon dioxide
Among these organs, Kidney would be dealt in-detail in this chaper.
Remaining organs would be presented in other sessions
Kidney with its fine structure, position etc would be discussed in this video.
The kidney is located at the backside of the body at either side of the spinal cord.
The kidney is a bean-shaped structure
To be clear, the position of the kidney is at the lower abdomen, back of the body and sides of the spinal cord.
The ureter is connected to the kidney and bladder.
Detailed structure would be discussed now
As shown, kidney is connected to ureter, which is connected to urinary bladder.
Urethra is located at the tip of urinary bladder
This is the pathway of the excretory system.
Repeating once again for better understanding
the kidney is a bean-shaped structure, which is connected to wire-like ureter,
which is connected to urinary bladder.
The urine from the kidney is collected in urinary bladder.
Urine is eliminated from the body through the urethra, which is located at the tip of the urinary bladder
Now let’s look at the structure of the Kidney
This is a diagrammatic representation of cross-sectioned kidney
As seen in the image, Outer layer (blue) is called capsule, which is the outer covering of kidney
Inside that is cortex (brown)
Inside of cortex is medulla (light-purple)
Pelvis (yellow) is connected to the pyramid (violet) like structures
From kidney the waste passes thought the ureter (green), as we have discussed earlier
Renal vein and renal artery are also seen there
Blood to the kidney flows through the renal artery (red). This is the impure blood with nitrogenous wastes.
The purified blood from the kidney flows through the renal vein after filtration.
This is the overall structure of the kidney
The detailed structure can be discussed now.
The outer layer cortex, inner portion medulla
The structure that lies in both cortex and medulla is called nephron
Nephrons are the structural and functional units of Kidney
Head portion of nephron lies in cortex and remaining in medulla
This is the filtering unit of Kidney
Nephrons are very small structures. There are millions of nephrons in both the kidneys.
Let’s look at the magnified image of the structure of a nephron.
As shown in the image, the cup-like structure is called Bowman’s capsule
A network of capillaries found in Bowman’s capsule is called the glomerulus
Bowman’s capsule is extended as a renal tubule and is connected to the collecting duct at the end.
Renal tubule has 3 parts 1) Proximal convoluted tubule, 2) Loop of Henle and 3) Distal convoluted tubule
Detailed structure is shown here:
The cup-like structure is called Bowman’s capsule, which is extended as a renal tubule (yellow or green)
Space inside Bowman’s capsule is called Bowman’s space (blue)
A network of capillaries found in Bowman’s capsule is called glomerulus
2 parts of the glomerulus are: afferent arteriole and efferent arteriole
Blood to the nephron is carried by afferent vessels or arteriole
and blood from the nephron is carried by efferent vessels or arteriole
The unit that includes Bowman’s capsule and glomerulus is called renal corpuscles,
which is the encircled portion in the figure.
Bowman’s capsule is extended as proximal convoluted tubule, the first part of renal tubule
Next portion is called loop of Henle, which is loop-like structure
The remaining portion after loop of Henle is distal convoluted tubule,
which is connected to collecting duct (green)
Repeating once again for better understanding,
The cup-like structure is called Bowman’s capsule,
A network of capillaries found in Bowman’s capsule is called glomerulus
with afferent arteriole and efferent arteriole
Bowman’s capsule is extended as proximal convoluted tubule, the first part of renal tubule
Next portion is called loop of Henle, which is loop-like structure
The remaining portion after loop of Henle is distal convoluted tubule,
which is connected to collecting duct
This is the structure of a nephron
What we have seen is the filtration pathway inside the kidney
Blood from the afferent arteriole is filtered and finally reaches the collecting duct
The remains of the blood that reaches the collecting duct is urine
Urine is the product filtered from the blood.
So this is the filtration pathway or urine formation pathway.
Substances absorbed and released in Bowman’s capsule, loop of Henle and
distal convoluted tubule would be different.
Urine formation depends on these absorption
It is a detailed chemical reaction of absorption and release, which could be discussed in another chapter
What we have discussed today is the basic structure of kidney and nephron and parts associated with them.
Class for the chemical reaction of absorption and release inside kidney would be uploaded later.
That is also an important part
Hope you understand basic structure of kidney and nephron
Classes are explained for better and easy understanding
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