When the kidneys fail People with kidney failure (腎衰竭) must be treated immediately.

When the kidneys fail Otherwise, they may die quickly.

undergo a kidney transplant (移植).
When the kidneys fail They can either undergo a kidney transplant (移植). transplanted kidney

When the kidneys fail They can either use a kidney machine (洗腎機).

When the kidneys fail They can either undergo peritoneal dialysis (腹膜透析). dialysis fluid in 4 hours later dialysis fluid out

They also have to make some changes in their diet.
When the kidneys fail They also have to make some changes in their diet.

e.g. avoid taking too much fluid and high-protein food.
When the kidneys fail e.g. avoid taking too much fluid and high-protein food.

1 Why may a person die quickly if the kidneys fail to function

2 How does a kidney machine treat kidney failure

3 Why can’t people with kidney failure
take in too much fluid and high-protein food

1.1 Importance of regulating water content
water intake water loss balanced

Water Balance in the Body
Figure 20-2 13

Land animals manage water budgets by drinking and eating moist foods and using metabolic water
balance in a kangaroo rat (2 mL/day) balance in a human (2,500 mL/day) gain loss Derived from metabolism (1.8 mL) Ingested in food (0.2 mL) metabolism (250 mL) in food (750 mL) in liquid (1,500 mL) Evaporation (900 mL) Feces (100 mL) Urine Evaporation (1.46 mL) Feces (0.09 mL) (0.45 mL)

if water intake  water loss  affects water content in blood  affects water potential of tissue fluid  water enters or leaves cells by osmosis  cells do not function properly or even die

control of the water content in the body osmoregulation (滲透調節) done by kidneys of urinary system (泌尿系統)

1.1 Importance of regulating water content keeps the water potential of the tissue fluid and hence the water potential of the cells stable, so that cells can function properly to sustain life. Osmoregulation

2 The of the system are the major organs for osmoregulation.
1.1 Importance of regulating water content 2 The of the system are the major organs for osmoregulation. kidneys urinary

1.2 The human urinary system
(dorsal aorta) (posterior vena cava) (renal artery) (renal vein) female

kidneys ureters urinary bladder female

control urination 1.2 The human urinary system sphincter muscles
female

male female urethra

ureters urinary bladder (vas deferens) urethra (penis) male

Examination of the mammalian urinary system
1.2 The human urinary system Video 1.1 Examination of the mammalian urinary system 1 Examine the urinary system of a dissected rat. 2 Identify the structures.

Structure of the kidney
1.2 The human urinary system Structure of the kidney 3D model cortex (皮質) medulla (髓) renal vein pelvis (腎盂) renal artery ureter

1.2 The human urinary system Structure of the kidney

1.2 The human urinary system Structure of the kidney cortex medulla

1.2 The human urinary system Structure of the kidney branch from renal artery branch from renal vein

1.2 The human urinary system Structure of the kidney nephron (腎元)

Key functions of most excretory systems:
Filtration: pressure-filtering of body fluids Reabsorption: reclaiming valuable solutes Secretion: adding toxins and other solutes from the body fluids to the filtrate Capillary Excretory tubule Filtration Filtrate Reabsorption Secretion Urine Excretion

1.2 The human urinary system Structure of the kidney proximal convoluted tubule distal convoluted tubule Bowman’s capsule kidney tubule loope of Henle collecting duct

1.2 The human urinary system Structure of the kidney proximal convoluted tubule distal convoluted tubule flow of urine Bowman’s capsule from another nephron loop of Henle collecting duct

1.2 The human urinary system Structure of the kidney glomerulus Bowman’s capsule kidney tubule

Capillary Beds of the Nephron
Every nephron has two capillary beds Glomerulus Peritubular capillaries Each glomerulus is: Fed by an afferent arteriole Drained by an efferent arteriole

Blood supply of a nephron
1.2 The human urinary system Blood supply of a nephron efferent arteriole glomerulus afferent arteriole Peritubular capillary branch from renal artery branch from renal vein

Examination of the mammalian kidney
1.2 The human urinary system 1.2 Examination of the mammalian kidney 1 Put a fresh pig’s kidney on a dissection tray. 2 Examine whether there are tubes coming from the kidney. Remove any fatty tissues and identify the tubes.

3 Cut the kidney longitudinally.
1.2 The human urinary system 1.2 3 Cut the kidney longitudinally.

4 Identify various structures of the kidney.
1.2 The human urinary system 1.2 4 Identify various structures of the kidney. 5 Draw a labelled diagram of the longitudinal section of the kidney.

Parts of urinary system
1.2 The human urinary system 1 Parts of urinary system Function Purify blood and form urine Carry urine from kidneys to urinary bladder Kidneys Ureters

Parts of urinary system
1.2 The human urinary system 1 Parts of urinary system Function Stores urine temporarily Carries urine from urinary bladder to the outside Urinary bladder Urethra

proximal convoluted tubule distal convoluted tubule
1.2 The human urinary system 2 Structure of a nephron: a A nephron consists of the Bowman’s capsule , the proximal convoluted tubule , the distal convoluted tubule and the collecting duct

2 Structure of a nephron:
1.2 The human urinary system 2 Structure of a nephron: b The Bowman’s capsule encloses a network of capillaries called the glomerulus . The kidney tubule is surrounded by another network of capillaries which is continuous with the glomerulus.

ultrafiltration reabsorption
1.3 Functioning of a nephron urine is formed by mainly two processes: ultrafiltration (超濾) reabsorption (重吸收)

ultrafiltration reabsorption Active secretion
1.3 Functioning of a nephron and: ultrafiltration reabsorption Active secretion

Mechanism of Urine Formation
Urine formation and adjustment of blood composition involve three major processes Glomerular filtration Tubular reabsorption Active Secretion Figure 24.9

1 Ultrafiltration blood is under high hydrostatic pressure
1.3 Functioning of a nephron 1 Ultrafiltration Bowman’s capsule blood is under high hydrostatic pressure capillary wall is differentially permeable forces small molecules through the thin walls glomerulus

1 Ultrafiltration urea salts glucose water amino acids 1.3
Functioning of a nephron 1 Ultrafiltration urea salts glucose water amino acids

1.3 Functioning of a nephron 1 Ultrafiltration fluid filtered into the Bowman’s capsule: glomerular filtrate to proximal convoluted tubule

 1 Ultrafiltration composition similar to plasma water
1.3 Functioning of a nephron 1 Ultrafiltration composition similar to plasma water plasma proteins  glucose amino acids salts urea to proximal convoluted tubule

Net Filtration Pressure (NFP)
The pressure responsible for filtrate formation NFP equals the glomerular hydrostatic pressure (HPg) minus the osmotic pressure of glomerular blood (OPg) combined with the capsular hydrostatic pressure (HPc) NFP = HPg – (OPg + HPc)

Glomerular Filtration Rate (GFR)
Figure 24.10

1.3 Functioning of a nephron 2 Reabsorption absorption of useful substances and most of the water from the filtrate to the blood Your kidneys filter approximately 180L of plasma/day 99% of the filtrate gets reabsorbed, leaving L of urine per day

2 Reabsorption to renal vein flow of urine from renal artery 1.3
Functioning of a nephron 2 Reabsorption to renal vein flow of urine from renal artery

Sodium Reabsorption: Primary Active Transport
Tubule lumen with renal fluid

Glucose Reabsorption: Secondary Active Transport

Reabsorption: Both Primary and secondary Active Transport
Sodium reabsorption is almost always by active transport Na+ enters the tubule cells from the lumen / filtrate Na+ is actively transported out of the tubules by a Na+-K+ ATPase pump From there it moves to peritubular capillaries Na+ reabsorption provides the energy and the means for reabsorbing most other solutes

Reabsorption by PCT Cells
Figure 24.12

Active pumping of Na+ drives reabsorption of: Water by osmosis Anions by diffusion Organic nutrients and selected ions by secondary active transport

Figure 24.12

2 Reabsorption proximal convoluted tubule blood glucose amino acids
1.3 Functioning of a nephron 2 Reabsorption proximal convoluted tubule blood glucose amino acids water salts amino acids

Region where reabsorption occurs
1.3 Functioning of a nephron 2 Reabsorption Substance reabsorbed Process Region where reabsorption occurs Glucose (100%) Diffusion, active transport At proximal convoluted tubule only Amino acids (100%) Diffusion, active transport At proximal convoluted tubule, loop of Henle, distal convoluted tubule & collecting duct Water (99%) Osmosis Diffusion, active transport Salts (80%) Urea (50%) Diffusion

Filtration Fraction Figure 19-5 62

1.3 Functioning of a nephron 2 Reabsorption kidney tubule is highly coiled to increase the surface area and the time for reabsorption

mostly water with salts, urea and other metabolic waste
1.3 Functioning of a nephron 2 Reabsorption remaining glomerular filtrate in collecting duct is called urine mostly water with salts, urea and other metabolic waste

3. Secretion Essentially reabsorption in reverse, where substances move from peritubular capillaries or tubule cells into filtrate Tubular secretion is important for: Eliminating undesirable substances such as urea and uric acid Controlling blood pH

1.3 Functioning of a nephron Proteins pass through the walls of the glomerulus and the Bowman’s capsule. 

1.3 Functioning of a nephron It is the amino acids that are filtered into the Bowman’s capsule and reabsorbed later.

1 In ultrafiltration, the high
1.3 Functioning of a nephron 1 In ultrafiltration, the high hydrostatic pressure inside the glomerulus forces small molecules out of the blood into the Bowman’s capsule.

differentially permeable
1.3 Functioning of a nephron 1 The capillary wall of the glomerulus is differentially permeable and only allows small molecules to pass through.

1.3 Functioning of a nephron 2 The composition of the glomerular filtrate is similar to that of plasma but it contains no plasma proteins

3 Reabsorption along the kidney tubule:
1.3 Functioning of a nephron 3 Reabsorption along the kidney tubule: a All and glucose amino acids in the glomerular filtrate are reabsorbed into the blood by diffusion and active transport.

1.3 Functioning of a nephron 3 Reabsorption along the kidney tubule: b Most is reabsorbed by osmosis. water

1.3 Functioning of a nephron 3 Reabsorption along the kidney tubule: c Some are reabsorbed by diffusion and active transport. salts

1.3 Functioning of a nephron 3 Reabsorption along the kidney tubule: d Some is reabsorbed by diffusion and the rest is removed in the urine. urea

1.4 The role of the kidneys Osmoregulation kidneys carry out osmoregulation by controlling the amount of water reabsorbed from the glomerular filtrate

secretion of ADH is controlled by the hypothalamus (下丘腦)
1.4 The role of the kidneys the amount of water reabsorbed is controlled by antidiuretic hormone (ADH) (抗利尿激素) secretion of ADH is controlled by the hypothalamus (下丘腦)

Diuresis Diuretics are a group of drugs given to help the body eliminate excess fluid through the kidneys. e.g. to treat hypertension, glaucoma, et Natural diuretic foods and drinks Melon Watercress Coffee Tea Coke (caffeinated soda)

has receptors to detect water content in blood
1.4 The role of the kidneys hypothalamus has receptors to detect water content in blood controls secretion of ADH

ADH is transported by blood
1.4 The role of the kidneys pituitary gland secretes ADH ADH is transported by blood

 permeability of the wall of the collecting duct to water increases
1.4 The role of the kidneys under the action of ADH  permeability of the wall of the collecting duct to water increases  a greater proportion of water is reabsorbed from the filtrate urine in different volumes and concentrations can be formed

Urine Concentration Osmolarity changes as filtrate flows through the nephron Figure 20-4 81

Formation of Dilute Urine / hypotonic urine
Filtrate is hypotonic after passing through the loop of Henle Dilute urine is created by allowing this filtrate to continue into the renal pelvis This will happen as long as antidiuretic hormone (ADH) is not being secreted Collecting ducts remain impermeable to water; no further water reabsorption occurs Diuresis – hypotonic urine (large volume of)

Water Reabsorption Figure 20-5b 83

Water Reabsorption Water movement in the collecting duct in the presence of vasopressin (ADH) Figure 20-5a 84

Formation of Concentrated / hypertonic Urine
Antidiuretic hormone (ADH) inhibits diuresis In the presence of ADH, 99% of the water in filtrate is reabsorbed ADH is the signal to produce concentrated urine The kidneys’ ability to respond depends upon the high medullary osmotic gradient

Click the diagram to see an animation
The kidneys’ ability to make hypertonic urine depends upon the high medullary osmotic gradient Click the diagram to see an animation

receptors in hypothalamus pituitary gland less ADH detected by
1.4 The role of the kidneys receptors in hypothalamus pituitary gland less ADH detected by wall of collecting duct water content increases less permeable smaller proportion of water reabsorbed normal water content in blood larger volume of dilute urine

smaller volume of concentrated urine normal water content in blood
1.4 The role of the kidneys smaller volume of concentrated urine normal water content in blood greater proportion of water reabsorbed water content decreases more permeable wall of collecting duct detected by receptors in hypothalamus more ADH pituitary gland

Proximal tubule Distal tubule NaCl Nutrients H2O HCO3– H2O K+ NaCl HCO3– H+ NH3 K+ H+ CORTEX Filtrate Descending limb of loop of Henle Thick segment of ascending limb H2O Salts (NaCl and others) HCO3– ; H+ (control pH) Urea Glucose; amino acids Some drugs NaCl H2O OUTER MEDULLA NaCl Thin segment of ascending limb Collecting duct Key Urea Active transport Passive transport NaCl H2O INNER MEDULLA

Water Reabsorption (reference)
The mechanism of vasopressin action Collecting duct lumen Filtrate 300 mOsm H2O Exocytosis of vesicles Cross-section of kidney tubule Collecting duct cell Second messenger signal cAMP Storage vesicles Aquaporin-2 water pores 600 mOsM Medullary interstitial fluid Vasopressin receptor Vasa recta 700 mOsM binds to membrane receptor. Receptor activates cAMP second messenger system. Cell inserts AQP2 water pores into apical membrane. Water is absorbed by osmosis into the blood. 1 2 3 4 Figure 20-6 90

Collecting duct lumen Filtrate 300 mOsm Cross-section of kidney tubule Collecting duct cell Medullary interstitial fluid Vasopressin receptor Vasa recta binds to membrane receptor. 1 600 mOsM 700 mOsM Figure 20-6, step 1 91

Collecting duct lumen Filtrate 300 mOsm Cross-section of kidney tubule Collecting duct cell Second messenger signal cAMP Medullary interstitial fluid Vasopressin receptor Vasa recta binds to membrane receptor. Receptor activates cAMP second messenger system. 1 2 600 mOsM 700 mOsM Figure 20-6, steps 1–2 92

Collecting duct lumen Filtrate 300 mOsm Exocytosis of vesicles Cross-section of kidney tubule Collecting duct cell Second messenger signal cAMP Storage vesicles Aquaporin-2 water pores Medullary interstitial fluid Vasopressin receptor Vasa recta binds to membrane receptor. Receptor activates cAMP second messenger system. Cell inserts AQP2 water pores into apical membrane. 1 2 3 600 mOsM 700 mOsM Figure 20-6, steps 1–3 93

Collecting duct lumen Filtrate 300 mOsm H2O Exocytosis of vesicles Cross-section of kidney tubule Collecting duct cell Second messenger signal cAMP Storage vesicles Aquaporin-2 water pores 600 mOsM Medullary interstitial fluid Vasopressin receptor Vasa recta 700 mOsM binds to membrane receptor. Receptor activates cAMP second messenger system. Cell inserts AQP2 water pores into apical membrane. Water is absorbed by osmosis into the blood. 1 2 3 4 Figure 20-6, steps 1–4 94

Factors Affecting Vasopressin Release
Figure 20-7 95

Water Balance The effect of plasma osmolarity on vasopressin secretion by the posterior pituitary Figure 20-8 96

higher concentration of salts in blood
1.4 The role of the kidneys taking in excess salts higher concentration of salts in blood smaller amount of salts and greater proportion of water reabsorbed smaller volume of urine with a high salt concentration formed (hypertonic urine)

Regulation of Kidney Function
The osmolarity of the urine is regulated by nervous and hormonal control of water and salt reabsorption in the kidneys Antidiuretic hormone (ADH) increases water reabsorption in the distal tubules and collecting ducts of the kidney

hypothalamus detect an increase in the osmolarity of the blood
Osmoreceptors in hypothalamus Thirst Hypothalamus Drinking reduces blood osmolarity to set point ADH Increased permeability Pituitary gland Distal tubule Collecting duct H2O reabsorption helps prevent further osmolarity increase STIMULUS The release of ADH is triggered when osmo- receptor cells in the hypothalamus detect an increase in the osmolarity of the blood Homeostasis: Blood osmolarity

What’s the effect of the following on urine output :
1. a lot of water 2. a lot of salty foods 3. a large volume of salty solution. E.g seawater Assignment: 1.Explain why we cannot survive on seawater as drinking water. 2. Write an essay on how one can survive without drinking water while drifting on a raft in the open ocean (>300 words)

Excretion by forming urine  to remove metabolic waste (e.g. urea) 1.4
The role of the kidneys Excretion by forming urine  to remove metabolic waste (e.g. urea)

Excretion by forming urine  to remove metabolic waste (e.g. urea)
1.4 The role of the kidneys Excretion by forming urine  to remove metabolic waste (e.g. urea) constantly produced high concentration is toxic

Diuretics (reference)
Chemicals that enhance the urinary output include: Any substance not reabsorbed Substances that exceed the ability of the renal tubules to reabsorb it Osmotic diuretics include: High glucose levels – carries water out with the glucose Alcohol – inhibits the release of ADH Caffeine and most diuretic drugs – inhibit sodium ion reabsorption Lasix – inhibits Na+-K+-2Cl symporters

Physical Characteristics of Urine (reference)
Color and transparency Clear, pale to deep yellow (due to urobilin) -from the breakdown of heme Concentrated urine has a deeper yellow color Drugs, vitamin supplements, and diet can change the color of urine Cloudy urine may indicate infection of the urinary tract

Concentrated urine has a deeper yellow color

Physical Characteristics of Urine
Odor / smell Fresh urine is slightly aromatic Standing urine develops an ammonia odor Some drugs and vegetables (asparagus) alter the usual odor

Physical Characteristics of Urine
Slightly acidic (pH 6) with a range of 4.5 to 8.0 Diet can alter pH Specific gravity Ranges from to 1.035 Dependent on solute concentration

Chemical Characteristics of Urine
Urine is 95% water and 5% solutes Nitrogenous wastes include urea, uric acid, and creatinine Other normal solutes include: Sodium, potassium, phosphate, and sulfate ions Calcium, magnesium, and bicarbonate ions Abnormally high concentrations of any urinary constituents may indicate pathology Disease states alter urine composition dramatically

Functions of the Kidneys
Regulation of extracellular fluid volume and blood pressure Regulation of osmotic potential in blood Maintenance of ion balance Homeostatic regulation of pH Excretion of wastes 109

normal water content in blood
1.4 The role of the kidneys 1 Regulation of water content by negative feedback mechanism: pituitary gland secretes less ADH kidneys hypothalamus high water content in blood normal water content in blood

less smaller larger dilute
1.4 The role of the kidneys In the kidneys: a wall of collecting duct becomes less permeable to water b a proportion of water reabsorbed smaller c a volume of urine is formed larger dilute

1.4 The role of the kidneys 1 Regulation of water content by negative feedback mechanism: pituitary gland secretes less ADH kidneys hypothalamus water content in blood falls high water content in blood normal water content in blood

1.4 The role of the kidneys 1 Regulation of water content by negative feedback mechanism: normal water content in blood low water content in blood secretes more ADH kidneys hypothalamus pituitary gland

more greater smaller concentrated
1.4 The role of the kidneys In the kidneys: a wall of collecting duct becomes more permeable to water b a proportion of water reabsorbed greater c a volume of urine is formed smaller concentrated

1.4 The role of the kidneys 1 Regulation of water content by negative feedback mechanism: normal water content in blood water content in blood rises low water content in blood secretes more ADH kidneys hypothalamus pituitary gland

1.4 The role of the kidneys 2 After excess salts are taken into the body, the excess salts have to be excreted. A amount of salts and a proportion of water are reabsorbed. As a result, a smaller greater small volume of urine with a high salt concentration is formed.

1.4 The role of the kidneys 3 Excretion is necessary because metabolic waste is constantly produced and a high concentration of this waste is to the body. The kidneys form to remove metabolic waste (e.g. urea) from the blood. toxic urine

helps remove metabolic waste by haemodialysis (血液透析)
Animation 1.5 The dialysis machine kidney machine helps remove metabolic waste by haemodialysis (血液透析)

1 blood with metabolic waste
1.5 The dialysis machine pump dialysis tubing 1 blood with metabolic waste fresh dialysis fluid

1.5 The dialysis machine dialysis tubing same concentration of solutes as normal plasma but has no metabolic waste fresh dialysis fluid

constant temperature bath
1.5 The dialysis machine dialysis tubing dialysis fluid fresh dialysis fluid constant temperature bath

differentially permeable membrane of dialysis tubing
1.5 The dialysis machine differentially permeable membrane of dialysis tubing

2 urea diffuses through the pores to the dialysis fluid
1.5 The dialysis machine 2 urea diffuses through the pores to the dialysis fluid

1.5 The dialysis machine 3 glucose is retained in blood (no net movement from blood to dialysis fluid

1.5 The dialysis machine 4 plasma proteins and blood cells are too large to pass through the pores

used dialysis fluid (with urea)
1.5 The dialysis machine 5 ‘cleaned’ blood used dialysis fluid (with urea)

each treatment lasts for 4-6 hours three times a week costly
1.5 The dialysis machine each treatment lasts for 4-6 hours three times a week costly

Peritoneal dialysis Peritoneal dialysis (PD) is a treatment for patients with severe chronic kidney disease. The process uses the patient's peritoneum in the abdomen as a membrane across which fluids and dissolved substances are exchanged from the blood.

Kidney transplant

1 A dialysis machine removes
1.5 The dialysis machine 1 A dialysis machine removes metabolic waste from the patient’s blood.

2 The dialysis fluid has the same concentration of solutes as normal
1.5 The dialysis machine 2 The dialysis fluid has the same concentration of solutes as normal plasma but no metabolic waste. This allows metabolic waste to diffuse from the patient’s blood to the dialysis fluid while glucose and other useful substances are retained in the blood.

1 Why may a person die quickly if the kidneys fail to function?
When the kidneys fail to function, the body cannot keep the water content in blood stable for cells to function properly.

1 Why may a person die quickly if the kidneys fail to function?
Besides, metabolic waste builds up in blood which can cause death.

2 How does a kidney machine treat kidney failure?
A kidney machine removes metabolic waste from the patient’s blood by haemodialysis.

3 Why can’t people with kidney
failure take in too much fluid and high-protein food? Excess proteins in the body are converted to urea by the liver.

failure take in too much fluid and high-protein food? The failed kidney cannot remove excess fluid and urea from the body.

failure take in too much fluid and high-protein food? Therefore, excessive intake of fluid and high-protein food must be avoided.

Osmoregulation urinary system water content in blood kidneys
is the maintenance of a stable done by urinary system water content in blood main parts include kidneys detected by hypothalamus

hypothalamus kidneys antidiuretic hormone nephrons urine
controls secretion of functional units antidiuretic hormone nephrons form controls concentration and volume of urine

urine kidneys ultrafiltration dialysis machine reabsorption
fail to function can be treated by contains by ultrafiltration dialysis machine reabsorption helps body remove metabolic waste

When the kidneys fail People with kidney failure (腎衰竭) must be treated immediately.

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When the kidneys fail People with kidney failure (腎衰竭) must be treated immediately.

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Presentation on theme: "When the kidneys fail People with kidney failure (腎衰竭) must be treated immediately."— Presentation transcript:

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