ELAINE N. MARIEB EIGHTH EDITION 15 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin...

ELAINE N. MARIEB

EIGHTH EDITION

15

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

PowerPoint® Lecture Slide Presentation by Jerry L. Cook, Sam Houston University

ESSENTIALSOF HUMANANATOMY

& PHYSIOLOGY

PART A

The Urinary System


I. Introduction

1) The kidneys maintain the purity and constancy of our internal fluids.

2) Each day, they filter gallons of fluid, process the filtrate and remove wastes and excess ions in urine.

3) They also regulate blood’s volume and chemical makeup maintaining a balance between water and salts


4) They producea) Renin & Erythropoietin:b) Converts Vit.D to its active form

5) The urinary system also includes the ureters, bladder and urethra


Organs of the Urinary system Kidneys

Ureters

Urinary bladder

Urethra

Figure 15.1a


II. Kidneys

1) Locationa) Bean like, dark red organs against the dorsal wallb) They are behind the T12 –L 3 vertebrac) The right kidney is slightly lower because of the liver

2) Description:a) About 12 CM long X 6 cm wide X 3 cm thick


b) Renal hilus:c) Adrenal glands sit on top of each kidneyd) Renal capsule:

3) Parts:a) Cortex: lighter, outer part b) Medulla: darker, inner part


c) Medullary pyramids: triangular regions within the medulla, separated by renal columnsd) Renal pelvis: funnel shaped end of the uretere) Calyces: encloses the tip of the pyramids to collect urine


Regions of the Kidney

Figure 15.2b


III. Nephrons

1) Nephron: the microscopic structural and functional unit of the kidney

2) Parts: Glomerulus, Bowman’s capsule & Tubules

3) Path of urine: glomerulus Bowman’s capsule proximal CT loop of Henle distal CT collecting tubule Collecting ducts renal pelvis ureter urinary bladder urethra


4) Urine formation: a) Filtration:

b) Tubular reabsorption: passive and active process returning material to the blood from the filtrate

c) Tubular secretion: Removing material from the blood into the filtrate

5) Urine characteristics:a) Freshly voided: clear and pale to deep yellow, slightly acidicb) Urochrome: pigment resulting from hemoglobin breakdown


Formation of Urine

Figure 15.5


c) Bacteria cause urine to cloud and release ammonia

d) Normal constituents: Na, K, Ca, urea, uric acid, creatine, ammonia, bicarbonate, sulfuric acid, phosphoric acide) Abnormal materials can indicate a disorder (Table 15.1)


IV. Other structures

1) Ureter:2) Urinary bladder has rugae3) Bladder can hold up to 1000 ml


3) Urethra:a) Internal urethral sphincter: Involuntary muscle closing the urethrab) External urethral sphincter: voluntary muscle controlling urination

4) Micturition:a) also called voiding: release of urine

b) Bladder collects urine until it holds about 200 ml, it then passes through the internal sphincter and the urge to void occurs


c) This urge will stop until the volume reaches 400-500 mld) Loss of control usually occurs at 700 ml


V. Fluid and electrolyte balance

1) Water makes up a varying % of body weighta) 50% young adult femalesb) 60% young adult malesc) 75% babiesd) 45% in old age

2) Water is located in the intracellular space, interstitial fluid, plasma (small amounts in other areas)


Distribution of Body Fluid

Figure 15.8


3) Water and electrolyte levels are closely associated

4) Slight changes in electrolyte balance causes water to move from one area to another

5) To maintain balance we must take in enough water to equal what is removed

6) Kidneys help regulate water loss by producing dilute or concentrated urine


7) Kidneys also regulate electrolyte balance during urine production

8) Hormones:a) Osmoreceptors in the hypothalamus become more active when water levels fallb) ADH: hormone released to prevent excess water loss by causing duct cells to reabsorb more water


c) Aldosterone: Regulates sodium ions, effecting water balance

9) Blood pHa) Blood maintains a pH between 7.35 & 7.45b) Metabolism releases H ions causing pH to change in blood


c) Buffers help maintain pH by reacting with these ionsd) Major buffers: bicarbonate, phosphate and protein buffer

e) The kidneys remove excess acidic compounds from the body


Maintaining Water and Electrolyte Balance

Figure 15.10

ELAINE N. MARIEB EIGHTH EDITION 15 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin...

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