Excretory System - Handout rae.pdf

Excretory System What is Human Excretory System? The excretory system is regarded as one of the main parts of the human internal system that helps to remove all the waste materials from the body. In humans, this includes the removal of urea from the bloodst...

Excretory System What is Human Excretory System? The excretory system is regarded as one of the main parts of the human internal system that helps to remove all the waste materials from the body. In humans, this includes the removal of urea from the bloodstream and other wastes produced by the body. The removal of urea happens in the kidneys, while solid wastes are expelled from the large intestine. Some specific waste products that must be exerted from the body are carbon dioxide, ammonia, urea, and uric acid. Parts of Frog Excretory System What are the functions of Human Excretory System? It is crucial in maintaining internal homeostasis. It regulates the fluid balance of the body, maintaining adequate salt and water levels. Helps in releasing hormones to organize human body blood pressure. What is Frog Excretory System? Amphibians, like all vertebrates, have an excretory system. The body produces waste products as a result of cellular respiration, and these wastes must be expelled. Waste elimination assists the body to maintain an appropriate salt and nutritional How do Kidneys Work? balance. Kidneys Functions of Excretory System Are two bean-shaped organs that filter your blood. It regulates the water in the body. It filter about 200 quarts of fluid every day The wastes products are separated from the — enough to fill a large bathtub. blood During this process, your kidneys remove Parts of Human Excretory System waste, which leaves your body as urine (pee). Functions of Kidneys The nephron includes a filter called the glomerulus and a tubule. They clean toxins and waste out of your blood: The nephrons work through a two-step process: ○ nitrogen waste (urea), ○ The glomerulus filters the blood, ○ muscle waste (creatinine), and ○ acids. ○ The tubule returns needed substances to the blood and Your kidneys filter about half a cup of blood removes wastes. every minute. The structure Control the acid-base balance (pH balance) of your blood. Two major portions: Make sugar (glucose) if your blood doesn’t ○ Renal Tubule have enough sugar. ○ Renal Corpuscle Make a protein called renin that increases blood pressure. Produce the hormones calcitriol (vitamin D that absorbs calcium) and erythropoietin (makes RBC). The Process 1. Blood flows into your kidneys through a large blood vessel called the renal artery. 2. Tiny blood vessels in your kidney filter the blood. Renal Tubule 3. The filtered blood returns to your bloodstream through a large blood vessel a long and convoluted structure that emerges called the renal vein. from the glomerulus. 4. Pee travels through tubes of muscle called Composed of three parts: ureter to your bladder. 1. Proximal convoluted tubule 5. Your bladder stores pee until you release it (PCT), located in the renal cortex through urination (peeing). near the glomerulus. How do kidneys filter blood? 2. Loop of Henle or nephritic loop, Nephrons forms a loop with descending and ascending limbs that extends Is the basic structural and functional unit of through the renal medulla. the kidney. They are the microscopic structure composed of a renal corpuscle 3. Distal convoluted tubule (DCT), and a renal tubule. also situated in the renal cortex.  The structure of the kidney's tubules plays a Ureters crucial role in the reabsorption and secretion processes of urine formation. Starting with A small tube, about 25 cm long. the Bowman's capsule enclosing the It carries urine from the renal pelvis to the glomerular capillaries and extending into the urinary bladder. highly coiled proximal convoluted tubules Location: It descends from the renal pelvis, (PCT), the process continues with the along the posterior abdominal wall, and formation of the loop of Henle and the distal enters the urinary bladder on the posterior convoluted tubule (DCT), which opens into inferior surface. the collecting duct. Muscles in the ureter walls continually tighten and relax forcing urine downward, Renal Corpuscle away from the kidneys. consists of a glomerulus surrounded by a 3 Layers of the Ureter Wall Bowman’s capsule. Outer layer: Fibrous coat Bowman’s capsule consists of three layers: Middle layer: Muscular coat Inner layer: Mucosa 1. Outer Parietal layer is composed of epithelial cells with small pores Urinary Bladder of diameter 12nm. 2. Middle Basement membrane is A temporary storage reservoir for urine. Location: It is located in the pelvic cavity, selectively permeable. posterior to the symphysis pubis, and below 3. Inner Visceral Layer is made up the parietal peritoneum. of large nucleated cells called Structure: The size and shape varies with podocytes, which have finger-like the amount of urine it contains and with the projections called podocel. pressure it receives from surrounding Mechanisms organs. The three mechanisms to convert blood to Micturition (Urination) is an act of urine: expelling urine from the body. When distended with urine, the bladder sends a ○ Filtration - occurs in the signal to the nervous system to initiate the glomerulus, where about one-fifth process of micturition (urination). of the plasma is filtered, with the remaining four- fifths continuing Layers of the Urinary Bladder Wall into the peritubular capillaries. The inner lining of the urinary bladder is a ○ Reabsorption - which is passive or mucous membrane of transitional active, occurs in the renal tubules epithelium. and involves the recovery of water The second layer is the submucosa. and various substances from the The next layer is the muscularis. filtrate. Trigone ○ Secretion - an active process, also takes place in the tubules and collecting duct, involving the transfer of certain substances into the filtrate. Other parts of Excretory System:  Trigone is a triangular area formed by three By expelling carbon dioxide from the blood, openings in the floor of the urinary bladder. the lungs maintain acid-base homeostasis. Two of the openings are from the ureters and form the base of the trigone. The third Comparison of Human & Frog Excretory System opening, at the apex of the trigone, is the Similarities: opening into the urethra. Both frogs and humans have kidneys as the Urethra in Female primary organs for removing waste products Only 3 to cm (about 1.5 inches) long. from the blood. The external urethral orifice opens to the In both, the kidneys filter the blood, outside just anterior to the opening for the producing urine which is then transported to vagina. the urinary bladder for storage before being excreted. Urethra in Male Both systems use a process of filtration, reabsorption, and secretion to maintain The urethra is much longer, about 20 cm (7 water and electrolyte balance. to 8 inches) in length and transports both The basic structural and functional unit of urine and semen. the kidney in both frogs and humans is the In males, urethra is divided into three parts: nephron. prostatic urethra, membranous urethra, and spongy urethra. Differences: Skin Frogs excrete urea as their primary nitrogenous waste, while humans excrete Sweating also eliminates excess water and urea and uric acid. salts, as well as a small amount of urea. Frogs are ectothermic, which means their metabolic rate and, consequently, their Liver excretory needs vary with environmental A very important organ of excretion that temperature. Humans are endothermic and breaks down many substances in the blood, maintain a constant body temperature, including toxins. leading to a more consistent metabolic rate It also excretes in its bile the protein and excretory needs. bilirubin. Bile travels to the small intestine Frogs can also excrete waste through their and is then excreted in feces by the large skin, which is a moist and permeable intestine. surface, whereas humans excrete waste primarily through the kidneys. Large Intestine In frogs nephrons are shorter (they don’t have a loop of Henle) because frogs are As an organ of excretion, its main function semi-aquatic and don’t need to reabsorb is to eliminate solid wastes that remain after water to the same degree that other animals the digestion of food and the extraction of and humans do. water from indigestible matter in food Frogs also consist of a special organ called- waste. Cloaca. It helps in the excretion of urine and feces from the body. In human female Lungs species, it serves the function of the vagina, They are responsible for the excretion of while in human male species- it is the gaseous wastes from the body. The main opening through which sperms are waste gas excreted by the lungs is carbon ejaculated. dioxide.