Overview of the Excretory System Pages 306 310 Chapter 9 Excretion and the interactions of systems Structures of the Excretory System Structure Function 1 renal artery carries blood into the kidney from the aorta ID: 593994
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Slide1
Chapter 9.1 – Overview of the Excretory System
Pages 306 - 310
Chapter 9 – Excretion and the interactions of systemsSlide2
Structures of the Excretory SystemSlide3
Structure
Function
1. renal artery
carries blood into the kidney from the aorta
2. renal vein
carries blood away from the kidney into the inferior vena cava
3. aorta
carries blood away from the heart toward the lower torso and legs
4. inferior vena cava
carries blood from the lower torso and legs to the heart
5. kidney
removes wastes from the blood, thus producing urine
6. ureter
carries urine from a kidney to the urinary bladder
7.
bladder
temporarily stores urine
8. urethra
carries urine from the urinary bladder to the exterior of the bodySlide4
The Problem of Waste in a Human BodyA functioning system that produces waste uses different methods to release waste from the system, waste in the human body include excess water, chloride and sodium ions, carbon dioxide, etc. The excretory system is used to eliminate these waste from the fluids already in use, or are yet to be used, by cells to function.
The main organ of the excretory for separating useful fluids and waste in the body is the kidney.Slide5
The Function of a Nephron in the Kidney
The function of Nephrons in the kidney can be compared to the function of the pulmonary valve in the human heart Nephrons are millions of microscopic structures that filter away waste from the blood and transforming it into urine
The Nephrons are organized into 3 main regions, a filter, a tube and a duct which can be viewed in the image below Slide6Slide7
Chapter 9.2 – Urine Formation and the Nephron
Pages 311 - 315Slide8
Urine Formation
Four processes used for urine to be created:Glomerular filtration - moves filtrate (water and solutes) from blood into nephron.Tubular reabsorption –
removes useful solutes from filtrate back into blood for reuse by body systems.
Tubular secretion –
moves additional wastes and substances from blood into filtrate.
Water reabsorption –
returns water from the filtrate back to blood for reuse.Slide9Slide10
Glomerular Filtration
Start of urine formation, glomerular filtration:Water and dissolved substances are forced from the blood in the glomerulus into the Bowman’s capsule
Capillaries of the glomerulus are very porous and allow water and dissolved solutes to easily pass through
Pores are small enough that blood cells and proteins cannot cross
High pressure in the glomerulus (4x higher than elsewhere), aides filtrationSlide11
Tubular Reabsorption
Tubular reabsorption – the recovery processOccurs in the loop of Henle65% of filtrate is reabsorbed to the body
Reabsorption occurs via active and passive transport
Nutrients like sodium, glucose and other solutes are actively transported back into blood from filtrate.
Negatively charged ions are passively absorbed by electrical attraction
Water is absorbed by osmosisSlide12Slide13
Tubular SecretionOccurs in distal tubule and collecting duct
Excess hydrogen ions (H+) are secreted into the distal tubule to maintain the pH of the bloodOther substances not normally in the blood, such as medication, are secreted into the distal tubule filtrateReabsorption and secretion in the distal tubule are under the control of hormonesSlide14Slide15
Water ReabsorptionWater reabsorption occurs in the collecting duct
Filtrate still contains a lot of waterThe reabsorption of water in the collecting duct causes the filtrate to become 4x as concentrated by the time it exits the duct.The end product is approx. 1% of the volume of the original filtrate and is now called urineSlide16
Summary
Part of the NephronFunction
Glomerulus and bowman’s capsule
Filtration
- b
lood pressure forces water
and dissolved substances from the blood plasma through the pores of the
glomerular
wall. Bowman’s capsule receives filtrate.
Loop of
Henle
Reabsorption
– passive and active reabsorption of water and ions from the filtrate back to blood
Distal tubule
Secretion – foreign components of blood are secreted from blood into the filtrate
Collecting duct
Reabsorption – water is reabsorbed back into blood. Final product
is called urine.Slide17
Chapter 9.3 – Maintaining the Excretory System
Pages 316 - 325Slide18
Water Balance
The solute concentration of blood remains constant despite variations in the amount of water we consume:If water intake is too high the kidneys allow more water to pass into the urineIf water is scare, the kidneys conserve water by producing concentrated urineSlide19
Osmotic Pressure
Osmotic pressure is the force generated by water as it moves via osmosisThe greater the concentration gradient the higher the osmotic pressureOsmotic pressure affects many cellular activities, especially the exchange of matter between cells and blood.Blood volume influences blood pressure, affecting the health of your cardiovascular systemSlide20
Regulating the Reabsorption of Water
The hypothalamus regulates mechanisms maintain homeostasis:Osmoreceptors in the hypothalamus measure osmotic pressureWhen you are dehydrated, blood concentration increases and osmotic pressure increases
Hunger
Thirst
Blood pressure
Body temperature
Fluid balance
Salt balanceSlide21
Osmotic receptors send a signal to the pituitary gland to release ADH (antidiuretic hormone)Slide22
ADH travels through the blood to the kidneys and increases the permeability of the distal tubule and collecting duct, allowing more water to be reabsorbedSlide23
If blood plasma is too dilute, osmotic pressure is lowOsmoreceptors stop or prevent the release of ADHThe distal tubules and collecting duct become less permeable to water; more water is excreted in the urine.Slide24Slide25
Reabsorption of Salts
A drop in blood Na+ concentration triggers a release of the hormone aldosteroneAldosterone
stimulates the distal tubules and collecting ducts to reabsorb Na
+Slide26
Urine Analysis
Analyzing the physical and chemical composition of urine enables physicians to make inferences about an individual’s healthSlide27
Disorders of the Excretory System
Common excretory system disorders:Urinary tract infection (UTI) – due to bacterial or viral infectionCan affect the bladder or urethraCharacterized by urge to urinate, even when no urine is formed
Painful urination
Brown or bloody urineSlide28
Kidney Stones – due to crystalline formations in the kidneyMaybe caused by: recurrent UTIs, insufficient water consumption, low activity levelsTreatment may include ultrasound shock waves to break down stones to be passed via urethra; large stones may require surgerySlide29
Problems with Kidney Function
Nephrons can regenerate and restore kidney function after short-term injuries.A person can survive on as little as 1/3 of one kidney.If 75% or more of the nephrons
are destroyed, urine output is inadequate to maintain homeostasis
Kidney function may be replaced by kidney transplant or through dialysisSlide30
Dialysis
Two types of dialysis:Hemodialysis – artificial membrane in an external device acts as an artificial kidneyPeritoneal dialysis – utilizes the peritoneum (intestinal membrane) as the dialysis membrane.Slide31
HemodialysisSlide32
Peritoneal DialysisSlide33
Kidney Transplant
Dialysis is not intended to be a long-term treatment for kidney failureKidney transplant organs can come from cadaveric donors or from living donorsIndividuals can function normally with one kidneyThe success rate of kidney transplant is 90-95% with the aide of anti-rejection drugs