Urinalysis Unit 5 Chapter 25 Anatomy and Physiology of the Urinary System Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.
Urinary System Metabolic reactions in body create chemical by-products Some are useful for body and recycled Others are harmful and removed Urinary system Primary means of waste removal Consists of: 2 kidneys, 2 ureters, urinary bladder, and urethra Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 2
3
Kidneys Located in the dorsal part of the abdominal cavity Just ventral to first lumbar vertebrae Most animals have smooth, bean-shaped kidneys Horses Right kidney is heart-shaped Bovine Lobulated appearance Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 4
Physiology Hilus Area where blood, lymph vessels, nerves, and the ureter enter and leave the kidney Outer cortex Inner medulla Nephrons Work of the kidneys done here Depending on size of animal – 100s to 1000s Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 5
Physiology (cont.) Nephrons Renal corpuscle Proximal convoluted tubule Loop of Henle Distal convoluted tubule Collecting tubule Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 6
Physiology (cont.) Renal corpuscle Glomerulus surrounded by a Bowman’s capsule Tuft of capillaries between arterioles entering and leaving the renal corpuscle Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 7
Formation of Urine Blood enters renal corpuscle Plasma and wastes are filtered through the glomerulus in the next portion of the proximal convoluted tubule Large proteins and cells do not enter unless damaged Filtered fluid passes through the rest of the nephrons Water and glucose are resorbed back into body Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 8
Formation of Urine (cont.) Renal threshold Nephrons have specific limits for resorption When the limit is met, the excess is excreted as urine When fluid reaches the collecting tubules it is urine Collecting tubules drain in the renal pelvis to the opening of the ureter Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 9
10
Ureters Transport urine from renal pelvis to urinary bladder Muscular tubes Move urine by smooth muscle contractions Enter bladder at oblique angles Forming valvelike openings No backflow Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 11
Urinary Bladder Stores urine until release Urination Muscular sac lined with epithelial cells Kidneys constantly produce urine As bladder enlarges, stretch receptors in the wall are activated at a certain point Spinal reflex initiates contraction of the muscle wall A voluntary sphincter muscle around neck of bladder controls urination Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 12
Urethra Tube that carries urine from bladder to outside of body Female Short and fairly straight, wide and strictly functions in urination Males Relatively long, curved, and narrow and serves in both urinary and reproductive functions Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 13
Urine Volume Regulation Volume of urine produced is controlled by two hormones Antidiuretic hormone (ADH) Released from the pituitary gland Acts on the collecting ducts to promote resorption of water Aldosterone Secreted by the adrenal cortex Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 14
Terms Oliguria Decreased urine production Polyuria Increased urine production Anuria No urine production Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 15
Summary Anatomy of the urinary system Nephron – functional unit of the kidney Parts of the nephron Renal threshold Hormones ADH Aldosterone Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 16