the excretory system. functions of the urinary system filtration of the blood –occurs in the...
TRANSCRIPT
The Excretory System
Functions of the Urinary System
Filtration of the blood– Occurs in the glomerulus of the kidney
nephron– Contributes to homeostasis by removing
toxins or waste
Unit 1 - Objective 1
Urinary System
Renal arteryKidney
Ureter
Urinary Bladder
Renal Vein
For sphincters, see next slide
Functions of the Urinary System
Reabsorption of vital nutrients, ions and water– Occurs in most parts of the kidney
nephron– Contributes to homeostasis by
conserving important materials
Unit 1 - Objective 1
Urinary System
Internal urethral sphincterExternal Urethral Sphincter
Male Sphincters Female Sphincters
Functions of the Urinary System
Secretion of excess materials– Assists filtration in removing material
from the blood– Contributes to homeostasis by
preventing a build-up of certain materials in the body such as drugs, waste,etc.
Unit 1 - Objective 1
Functions of the Urinary System
Activation of Vitamin D– Vitamin D made in the skin is converted to
Vitamin D3 by the kidney– Active Vitamin D (D3) assists homeostasis
by increasing calcium absorption from the digestive tract
Functions of Kidney Structures
The Renal Artery– Transports oxygenated blood from the
heart and aorta to the kidney for filtration
Functions of Kidney Structures
Renal Vein– Transports filtered and deoxygenated
blood from the kidney to the posterior vena cava and then the heart
Unit 1 - Objective 1
Functions of Kidney Structures
Nephron– The physiological unit of the kidney used
for filtration of blood and reabsorption and secretion of materials
Functions of Kidney Structures
Capsule– The outer membrane that encloses,
supports and protects the kidney
Functions of Kidney Structures
Cortex– The outer layer of the kidney that contains
most of the nephron; main site for filtration, reabsorption and secretion
Unit 1 - Objective 1
Functions of Kidney Structures
Medulla– inner core of the kidney that contains the
pyramids, columns, papillae, calyces, pelvis and parts of the nephron not located in the cortex; used for salt, water and urea absorption
Unit 1 - Objective 1
Functions of Kidney Structures
Ureter– Transports urine from the renal pelvis to
the bladder
Functions of Kidney Structures
Renal Pyramids– Triangular shaped units in the medulla that
house the loops of Henle and collecting ducts of the nephron; site for the counter-current system that concentrates salt and conserves water and urea
Diagram of Kidney Nephron
Efferent arteriole
Afferent arteriole
Bowman’s capsule
Collecting duct
Proximal convoluted tubuleGlomerulus
Peritubular capillaries
Vasa recta
Decending limb of loop of Henle
Ascending limb of loop of Henle
Distal convoluted tubule
Functions of Nephron Structures
Glomerulus– The site for blood filtration– operates as a nonspecific filter; in that, it will
remove both useful and non-useful material
– the product of the glomerulus is called filtrate
Functions of Nephron Structures
Bowman’s Capsule– A sac that encloses Bowman’s Capsule and
transfers filtrate from the glomerulus to the Proximal Convoluted Tubule (PCT)
Unit 1 - Objective 1
Functions of Nephron Structures
– The primary site for secretion (elimination) of drugs, waste and hydrogen ions
– Saves water for the body
Site of Filtration
Glomerulus– the Glomerulus is the site of filtration– the filtration mechanism is sieve-like and
consists of fenestrated glomerular capillaries, podocytes and a basement membrane that allows free passage of water and solutes smaller than plasma proteins
The Juxtaglomerular Apparatus
Used in maintaining blood pressure
Disorders of the Urinary System
Renal Calculi (kidney stones)– caused by the crystallization of calcium,
magnesium or uric acid salts that precipitate in the renal pelvis.
– If the calculi become large and travel down the ureter, they can cause excruciating pain
Disorders of the Urinary System
Cystitis– typically caused by bacteria from the anal
region, but, can also be caused by sexually transmitted diseases and various chemical agents
– can lead to inflammation, fever, increased urgency and frequency of urination and pain
Disorders of the Urinary System
Glomerulonephritis ( Bright’s Disease)– caused by inflammation of the glomeruli due
to an abnormal immune response (autoimmune, streptococcal antibody complexes).
– Inflammation of the glomeruli leads to faulty filtration (passage of blood cells and proteins) and possible kidney failure.
Unit 1 - Objective 1
Disorders of the Urinary System
Incontinence– caused by loss of the ability to control
voluntary micturition (releasing urine from the bladder) due to age, emotional disorders pregnancy, damage to the nervous system, stress, excessive laughing and coughing
– leads to wetting of clothing, discomfort and embarrassment
Dialysis Therapy
Dialysis is a process that artificially removes metabolic wastes from the blood in order to compensate for kidney (renal) failure. Kidney failure results in the rapid accumulation of nitrogen waste (urea, etc.) which leads to azotemia. Uremia and ion disturbances can also occur. This condition can cause acidosis, labored breathing, convulsions, coma and death.
Dialysis Therapy
The most common form of dialysis is hemodialysis which uses a machine to transfer patient’s blood through a semipermeable tube that is permeable only to selected
substances.
Dialysis Therapy
Some key aspects of hemodialysis are:
- blood is typically transferred from an arm artery
- after dialysis, blood is typically returned to an arm vein
- to prevent clotting, blood is typically heparinized
- dialysis sessions occur about three times a week
- each dialysis session can last four to eight hours!
- long term dialysis can lead to thrombosis (fixed blood clots),
infection and death of tissue around a shunt (the blood access
site in the arm)
Source:
Modified from Robert F. Allen