File Name: human excretory system parts and functions .zip
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The human excretory system functions to remove waste from the human body. This system consists of specialized structures and capillary networks that assist in the excretory process. The human excretory system includes the kidneys and their functional unit, the nephron. The excretory activity of the kidneys is modulated by specialized hormones that regulate the amount of absorption within the nephron. The human kidneys are the major organs of bodily excretion see Figure
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All material given in this website is a property of physicscatalyst. The Kidneys are located in the abdominal cavity, situated below the level of last thoracic and third lumbar vertebra close to the dorsal inner wall of abdominal cavity.
Each kidney is been shaped reddish brown. The right kidney is lower and smaller than left kidney because the liver takes up much space on the right side. From each kidney, one ureter arises, and the two Ureters open obliquely into the Urinary bladder, which is a hollow, muscular sac-like structure that stores urine.
Urethra is the membranous tube that arises from the neck of the bladder and conduct the urine to the exterior. Structure of kidney: The outer surface of each kidney is convex, and the inner surface is concave, where it has notch called hilum. Each kidney has three protective covering that is renal fascia outermost layer , the adipose layer and then renal capsule innermost layer. Inside the kidney, outer cortex and inner medulla region are present. The medulla is divided into few conical masses call Medullary Pyramids.
The cortex extend in between the pyramids as renal column is called Column of Bertini. Each kidney has nearly 1 million Complex structures called nephrons which are the functional unit. Structure of Nephron: Each nephron consists of two parts that is Glomerulus and Renal tubule. Glomerulus along with Bowman's capsule is called Malpighian body or Renal corpuscles.
Glomerulus is a tuf of capillaries bunch formed by afferent arterioles branch of renal artery. Bowman's capsule is a double walled cup like structure that surrounds the glomerulus.
Henle's loop: It is a quite narrow and U-shaped hair pin like loop with a descending limb that ends into the medulla and an ascending limb that coarse back to the cortex. Distal convoluted tubule: The ascending limb on entering the cortex become highly coiled distal convoluted tubule. It then continues as short straight collecting tubule that joins the collecting duct.
Each collecting duct receives the collecting tubules of number of nephrons. Types of Nephron: There are two types of Nephron, based on their position in the Kidney. Cortical nephron - In majority of nephrons, the loop of henle is too short and extends only very little into the medulla, such nephrons are called cortical nephron. These nephrons are called juxtamedullary nephron. The glomerular capillary blood pressure causes filtration of blood through three layer that is endothelium of glomerular blood vessels, epithelium of bowman's capsule and the basement membrane between these two layers.
The epithelial cells of bowman's capsule are called podocytes and arranged in such a manner so as to leave some minute space called filtration slits. Therefore, this process is considered as of ultrafiltration. Tubular reabsorption: A comparison of the volume of filtrate formed by per day that is litre with that of urine released that is 1.
This process is called selective reabsorption. Water and urea reabsorbed by passive transport, glucose and amino acids are reabsorbed by active transport. Tubular secretion Certain chemicals in the blood that are not removed by filtration from the glomerular capillary are removed by the process of tubular secretion. It is about ml per minute or litre per day in a healthy human individual. Juxtaglomerular apparatus JGA is a specialised cellular apparatus located where the DCT passes close to the bowman's capsule between the afferent and efferent arterioles.
They constitute a mechanism called counter-current mechanism. The two factors responsible for increasing the osmolarity towards the medullary interstitium are- i The proximity between loop of henle and Vasa recta ii The counter-current system in them. The osmolarity in the cortex is about m. This gradient is maintained by NaCl and urea. The interstitial gradient of NaCl is maintained by the loop of Henle.
Urea is added to the interstitial fluid of medulla by its diffusion from the collecting duct, if it re-enter the ascending limb by diffusion. The counter-current mechanism thus, help to maintain a concentration gradient between the medullary interstitium and urinary tubule. As the filtrate moves in the collecting duct pass the interstitial fluid, water moves out of tubule by osmosis and urine become concentrated.
ADH signal the DCT, collecting tubule and collecting duct to reabsorb water from filtrate to prevent diuresis. It also causes constriction of blood vessels and increases blood pressure which increases GFR. Angiotensin II is a powerful vasoconstrictor and increases glomerular blood pressure and maintain GFR. By atrial wall of heart: An increase in the blood flow and pressure to the atria of the heart causes the release of atrial natriuretic factor ANF which causes vasodilation and increases the blood pressure.
ANF functions antagonistically to the renin angiotensin mechanism by inhibiting the release of renin. This is accomplished by simultaneous contraction of smooth muscles of urinary bladder wall and relaxation of the skeletal muscle of sphincter of the bladder into the urethra. Urine: An adult human excretes about 1- 1. The urine has straw yellow colour and slightly acidic pH 6 with the characteristic odour. It contains urea, creatinine and very little amount of ammonia and uric acid.
Glucose glycosuria and Ketone bodies ketonuria are found in the urine of the patient of diabetes mellitus. Accessory Organs of Excretion Disorders of Excretory System: Malfunctioning of Kidneys can lead to accumulation of Urea in blood, a condition called Uremia which is highly harmful and may lead to kidney failure.
In such patients urea can be removed by a process called hemodialysis. Kidney transplantation is the ultimate method in the correction of acute renal failure that is kidney failures. A functioning kidney is used in transplantation from a Donor, preferably a close relative to minimise its chances of rejection by the immune system of the host.
Renal calculi: Stone or insoluble mass of crystallized salts oxalate etc formed within the kidney. Glomerulonephritis: Inflammation of glomeruli of kidney.
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Click Image to Enlarge. The body takes nutrients from food and changes them to energy. After the body has taken the food components that it needs, waste products are left behind in the bowel and in the blood. The kidney and urinary systems help the body to get rid of liquid waste called urea. Urea is produced when foods containing protein such as meat, poultry, and certain vegetables are broken down in the body. Urea is carried in the blood to the kidneys. This is where it is removed, along with water and other wastes in the form of urine.
The excretory system is the system of an organism's body that performs the function of excretion, the bodily process of discharging wastes. There are several parts of the body that are involved in this process, such as sweat glands, the liver, the lungs and the kidney system. Each kidney is made up of three sections: the renal cortex, the renal medulla and the renal pelvis. The blood arrives at the kidney via the renal artery, which splits into many afferent arterioles. These arterioles go to the Bowman's Capsules of nephrons, where the wastes are taken out of the blood by pressure filtration. Peritubular capillaries also surround the nephron so substances can be taken in and out of the blood.
The excretory system is a passive biological system that removes excess, unnecessary materials from the body fluids of an organism , so as to help maintain internal chemical homeostasis and prevent damage to the body. The dual function of excretory systems is the elimination of the waste products of metabolism and to drain the body of used up and broken down components in a liquid and gaseous state. In humans and other amniotes mammals , birds and reptiles most of these substances leave the body as urine and to some degree exhalation, mammals also expel them through sweating. Only the organs specifically used for the excretion are considered a part of the excretory system. In the narrow sense, the term refer to the urinary system. However, as excretion involves several functions that are only superficially related, it is not usually used in more formal classifications of anatomy or function. As most healthy functioning organs produce metabolic and other wastes, the entire organism depends on the function of the system.
Organs of the Excretory System Humans produce waste products that must be removed from their body. Overview of Nephron Structure and Function.
The kidney is the central organ of body fluid and electrolyte homoeostasis and metabolic waste excretion, the conditions of which were settled early in the evolution of multicellular organisms. Life in different environments such as sea water, fresh water, or arid land implies complex challenges for kidneys to maintain body fluid and electrolyte homoeostasis, which is achieved by distinct hormonal pathways regulating water and salt handling via transporter channels across cell membranes. For this to occur there is a tight link between the anatomy and physiology of the nephrons, the independent functional units of the kidney.
Excretion is the process of removal of toxic wastes from the body of an organism. The major wastes produced by us are: Carbon dioxide and Urea. Carbon dioxide is produced by the process of respiration and urea is produced by the decomposition of unused proteins in the liver. It is necessary to remove these wastes from our body as their accumulation is poisonous and harm us.
The kidney is the central organ of body fluid and electrolyte homoeostasis and metabolic waste excretion, the conditions of which were settled early in the evolution of multicellular organisms. Life in different environments such as sea water, fresh water, or arid land implies complex challenges for kidneys to maintain body fluid and electrolyte homoeostasis, which is achieved by distinct hormonal pathways regulating water and salt handling via transporter channels across cell membranes.
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Телефонный звонок окончательно прогнал сон.