Kidney

TABLE OF CONTENT 1) General Introduction 2) Anatomy of Urinary System 3) Urine Formation 4) Control System

1) filter blood plasma, separate wastes, return useful materials to the blood, and eliminate the wastes. 2) regulate blood volume and osmolarity.

3) produce hormones 1.renin 2.erythropoietin 3.calcitrol 4) regulate acid-base balance of the body fluids. 5) detoxify superoxides, free radicals, and drugs.

Imagine 5

 Located retroperitoneally  Lateral to T 12 –L 3 vertebrae  Average kidney  12 cm tall, 6 cm wide, 3 cm thick  Hilus  On concave surface  Vessels and nerves enter and exit  Renal capsule surrounds the kidney

- The medial surface of the kidney is concave with a hilum carrying renal nerves and blood vessels. The renal parenchyma is divided into an outer cortex and inner medulla.

Extensions of the cortex (renal columns) project toward the sinus, dividing the medulla into 6-10 renal pyramids. Each pyramid is conical with a blunt point called the papilla facing the sinus.

- Most components of the nephron are within the cortex. The Nephron

- The kidney contains 1.2 million nephrons, which are the functional units of the kidney. - A nephron consists of : i. blood vessels afferent arteriole glomerulus efferent arteriole ii. renal tubules proximal convoluted tubule loop of Henle distal convoluted tubule The Nephron

afferent arteriole glomerulus efferent arteriole proximal convoluted tubule distal convoluted tubule Loop of Henle blood The Nephron

The glomerulus is enclosed in a two-layered glomerular (Bowman's) capsule. Proximal tubule

13 1.Proximal convoluted tubule 2.Descending loop of Henle 3.Ascending loop of Henle 4.Distal convoluted tubule 5.Collecting duct

The kidney produces urine through 4 steps.

1) Glomerular Filtration

The Filtration Membrane From the plasma to the capsular space, fluid passes through three barriers. fenestrated epithelium basement membrane foot processes

The Filtration Membrane Almost any molecule smaller than 3 nm can pass freely through the filtration membrane into the capsular space. These include: Water, electrolytes, glucose, amino acids, lipids, vitamins, and nitrogenous wastes Kidney infections and trauma commonly damage the filtration membrane and allow plasma proteins or blood cells to pass through.

Glomerular Filtration Rate (GFR) - is the amount of filtrate formed per minute by the two kidneys combined. - For the average adult male, GFR is about 125 ml/min. - This amounts to a rate of 180 L/day. - An average of 99% of the filtrate is reabsorbed, so that only 1- 2 L of urine per day is excreted.

Diagram of renal corpuscle structure: A – Renal corpuscle B – Proximal tubule C – Distal convoluted tubule D – Juxtaglomerular apparatus 1. Basement membrane (Basal lamina) 2. Bowman's capsule – parietal layer 3. Bowman's capsule renal corpuscle

 3 processes involved in the formation of urine.  Simple filtration  Selective reabsorbtion  Hormonal control-  Parathyroid hormone, calcitonin  Anti diuretic hormone  Aldosterone  Secretion 20

Maintaining Water/Electrolyte Balance Figure 15.9

Dialysis machine