كلية الصيدلة والعلوم الطبية احترام التنوع والتعددية والرأي الآخر قسم التغذية « من قيمنا » احترام التنوع والتعددية والرأي الآخر

العلم خير من المال، لأن المال تحرسه ، والعلم يحرسك. العلم حاكم والمال محكوم عليه. مات خزان المال وهم أحياء، والعلماء باقون ما بقي الدهر، أعيانهم مفقودة وآثارهم موجودة.

Body Fluid Regulation and Excretory Systems (Chap. 36 Body Fluid Regulation and Excretory Systems (Chap. 36. Pages: 678, 681-690 +Fig.36.1 page 678) 36.1 Animal Excretory Systems 678 36.2 The Human Urinary System 681

An important part of maintaining homeostasis in animals involves osmoregulation, or balancing the levels of water and salts in the body. Often the osmoregulatory system of an animal also removes metabolic wastes from the body, a process called excretion. Nitrogenous Waste Products (Fig.36.1 page 678) The breakdown of N2-containing molecules, such as amino acids and nucleic acids, result in excess N2 that must be excreted.

Excretory Functions

Depending on the species, this excess N2 may be excreted in the form of : 1.Ammonia 2.Urea 3.Uric Acid

Nitrogenous Wastes

Nitrogenous Wastes

Human Urinary system (Fig.36.6 page 682) Composed of: A. 2 kidneys are the ultimate regulators of blood composition because they can remove various unwanted products from the body. They are bean-shaped, reddish-brown organs, each about the size of the fist. Located on either side of the vertebral column just below the diaphragm, in the lower back, where they are partially protected by the lower rib cage.

B. 2 ureters C. Urinary bladder D. Urethra In males, the urethra passes through the penis, and carries sperm during ejaculation. In females, the urethra opens ventral to the opening of the vagina, i.e. there is no connection between the reproductive and urinary systems.

The Human Urinary System

Kidneys (Fig.36.7 page 682) In a longitudinal section, the kidney has 3 parts: 1. The renal cortex 2. The renal medulla 3. The renal pelvis A kidney stone or renal calculus is a hard granule of phosphate, calcium, protein, or uric acid that forms in the renal pelvis.

Macroscopic & Microscopic Anatomy of the Kidney

Nephrons (Fig.36.8 page 683) Each kidney is composed of over one million tiny tubules called nephrons. The nephrons produce urine. Are the functional and structural unit of the kidney. Some lie in the renal cortex and others in the medulla. Each nephron is made of: 1.Glomerular capsule (Bowman's capsule) 2.Proximal convoluted tubule 3.Loop of the nephron (Loop of Henle) 4.Distal convoluted tubule 5.Collecting duct The loop of the nephron and the collecting duct give the pyramids of the renal medulla their striped appearance.

Each nephron has its own blood supply as follows: a. Afferent arteriole b. Glomerulus c. Efferent arteriole d. Peritubular capillaries The nephron functions in urine formation.

Nephron Anatomy

Urine formation (Fig. 36.9 page 684) An average human produces 1-2L of urine daily. Urine production requires 3 distinct processes: 1.Glomerular filtration 2.Tubular reabsorption 3.Tubular secretion

Processes in Urine Formation

لا توجد شجرة لم يهزها ريح! ولا يوجد إنسان لم يهزه فشل ، لكن توجد أشجار صلبة، ويوجد أشخاص أقوياء. فكن منهم!!!!!!!!!

The Kidneys and Homeostasis The kidneys are organs of homeostasis for 4 main reasons: 1. Excrete metabolic wastes such as urea, which is the primary nitrogenous waste of humans. 2. Maintain the water-salt balance, which in turn affects blood volume and blood pressure. 3. Maintaining the acid-base balance, and therefore, the pH balance. 4. Secrete hormones (one of the hormones is erythropoietin, stimulates the stem cells in the bone marrow to produce more R.B.Cs). Another substance produced by the kidneys, called renin.

Maintaining the salt-water Balance Most of water and salt (NaCl) present in the filtrate is reabsorbed across the wall of the proximal convoluted tubule. The excretion of hypertonic urine (one that is more concentrated than blood) is dependent on the reabsorption of water from the loop of the nephron and the collecting duct. During the process of reabsorption, water passes through water channels called aquaporins. Three hormones are involved in maintaining the water content of the blood and controlling the reabsorption of salt: 1.Antidiuretic hormone (ADH) 2.Aldosterone 3.Atrial natriuretic hormone (ANH)

The Renin-Angiotensin-Aldosterone System

Maintaining the Acid-Base Balance The bicarbonate (HCO3-) buffer system and breathing work together to maintain the pH of the blood. H+ + HCO3‾ <----------> H2CO3 <----------> CO2 + H2O The kidneys reabsorb bicarbonate ions and excrete hydrogen ions as needed to maintain the normal pH of the blood. The fact that urine is usually acidic (pH about 6) shows that usually an excess of hydrogen ions are excreted. Ammonia provides a means for buffering these hydrogen ions in the urine: NH3 + H+ → NH4+. Phosphate provides another means of buffering hydrogen ions in urine.

Maintaining Acid-Base Balance

Connecting the Concepts

A lie is any communication with intent to deceive.

واحد أهبل راح عند الصيدلي قله: عندك حليب أطفال ؟ قالو الصيدلي : شو اسمه؟ قلو الأهبل:عبد الرزاق