The Urinary System

1. The Urinary System By: Jasmine Henderson Joyce Chery Nathalie Jean

2. Urinary system • The urinary system or renal system is the organ system that produces, stores, and eliminates urine. • In humans it includes two kidneys, two ureters, the bladder and the urethra. • The female and male urinary system are very similar, differing only in the length of the urethra.

3. Functions • Excretion of metabolic wastes • Preservation of water-salt balance • Maintenance of blood pressure • Secretion of hormones

4. Organs in the Urinary System • -kidneys: regulation of blood volume, regulation of blood pressure, regulation of the ph. of the blood, regulation of the ionic composition of the blood, production of red blood cells, synthesis of vitamin D, and excretion of waste products and foreign substances. • -ureters: there are two ureters, one leading from each kidney to the urinary bladder. Each of these transports urine to the renal pelvis of the kidney to which it is attached to the bladder. • -urethra: The urethra is the passageway through which urine is discharged from the body. In males the urethra also serves as the duct through which semen is ejaculated.

5. Urination • Urination: Urination, also known as micturition, voiding, peeing, weeing, pissing, and more rarely, emiction, is the ejection of urine from the urinary bladder through the urethra to the outside of the body. • In healthy humans (and many other animals) the process of urination is under voluntary control. • In infants, some elderly individuals, and those with neurological injury, urination may occur as an involuntary reflex. • In male placental mammals, urine is ejected through the penis. • In female placental mammals, urine is ejected through the vulva.

6. Anatomy of the Kidney & Excretion • a sagittal section of a kidney shows that many branches of the renal artery and renal vein reach inside a kidney. • Removing the blood vessels shows that a kidney has three regions. The renal cortex is an outer, granulated layer that dips down in between a radially striated inner layer called the renal medulla. • The renal medulla consists of cone-shaped tissue masses called renal pyramids. • The renal pelvis is a central space, or cavity, that is continuous with the ureter

7. Anatomy of a Nephron • Each kidney is composed of over one million nephrons, sometimes called renal or kidney tubules, which are micro-scopic structures. • Each nephron has its own blood supply, including two distinct capillary regions. • The nephron receives oxygenated arterial blood from an afferent arteriole, which originates from a smaller branch of the renal artery.

8. Fluid and Electrolyte Balance • Average male body 60% water by weight. • Average female body is 50% water by weight. • For the body to be normal, it is necessary for the body fluids to be balanced • water intake should equal water loss

9. Re-absorption of Water • Osmosis- the re-absorption of salt • Most of the salt and water present in the filtrate are reabsorbed across the plasmas of the cells lining the proximal convoluted tubule. • Amount of salt and water reabsorbed is not sufficient to result in hypertonic urine. • Hypertonic urine- More concentrated urine i.e. less water. This is caused by Increased ADH (anti-diuretic hormone) levels which cause more re-absorption in the kidney.

10. Hormones • These 3 hormones help maintain blood and volume pressure • Antidiuretic Hormone (ADH): Produced by the hypothalamus and is released by the posterior lobe of the pituary. • Aldosterone:hormone secreted from the adrenal cortex, promotes the excretion of potassium ions and the re-absorption of sodium ions. • Atrialnatriuretic(ANH): hormone secreted by the atria of the heart when cardiac cells are stretched due to increased blood volume.

11. Anti-diuretic Hormone

12. The Kidneys • Made up of 99% of sodium filtered at the glomerulus is returned to the blood. • Most sodium is reabsorbed at the proximal convoluted tubule and a sizable amount is actively transported from the tubule by the ascending limb of the loop of the Henle. • The rest is reabsorbed from the distal convoluted tubule and collecting duct.

14. Composition of Urine • Urine is composed mostly of water containing organic wastes as well as some salts. • The composition of urine can vary according to diet, time of day, and diseases. • In one measure, the make-up of urine is 95% water and 5 percent solids • Urine contains the positive ions sodium, potassium, magnesium, and calcium, as well as the negative ions chlorides, sulfates, phosphates.

15. Urinalysis • The examination of the physical, chemical, and microscopic properties of the urine. • These tests are ran to determine the state of the body.

17. Effects of Aging • Kidneys decrease in size and have significantly fewer nephrons • Renal function decreases by 50% of that of a young adult • Kidney stones become more frequent • Infections among the urethra, bladder, ureters and kidneys • Incontinence occurs among the elderly • -a loss of urine • -an elderly person has the capacity of less than half that of a young adult

18. Homeostasis • The urinary system works with the other systems to help the body maintain homeostasis • Homeostasis- is the process used by the body to maintain a stable internal environment. • Excretion- to rid the body of a metabolic waste • The sweat glands in the skin excrete perspiration • The liver breaks down hemoglobin and excretes bile pigments • The lungs excrete carbon dioxide • They excrete mostly nitrogenous wastes, namely urea, creatinine. And uric acid.

19. Homeostasis Contd. • The kidneys are the primary organs of excretion • -They excrete mostly nitrogenous wastes, namely urea, creatinine. And uric acid. • The Kidneys are also the primary organs of homeostasis because they maintain the water-salt and the acid-base balances; blood volume and blood pressure are affected. • The kidneys produce erythropoietin which aids the endocrine and cardiovascular • -Erythropoietin stimulates red bone marrow to produce red blood cells • The Kidneys also assist the skeletal, nervous and muscular systems by helping regulate the amount of calcium ions in the