LS 11 - Life Sciences > Excretion > Flashcards

Excretion Flashcards

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0
Q

Example waste products of metabolisms

A
  • CO2
  • Excess water
  • Salts
  • Nitrogenous wastes (e.g. Urea, uric acid, creatinine)
  • Bile pigments
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1
Q

Metabolism

A

All chemical reactions taking place in a cell

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2
Q

Excretion definition

A

Removal of metabolic wastes from the body

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3
Q

Egestion definition

A

Removal of undigested substances from the alimentary system

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4
Q

Secretion

A

Release of useful substances produced by cells for important functions

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5
Q

Where do waste products first go when they leave cells?

A
  • Diffuse from cells into tissue fluid
  • From here they are moved to the blood stream
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6
Q

Excretory organs

A
  • Lungs
  • Kidneys and bladder
  • Liver and intestines
  • Skin
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7
Q

Origin of CO2 as a waste

A
  • Product of cellular respiration
  • All cells in the body
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8
Q

Origin of excess water as a waste

A
  • Product of cellular respiration
  • Also from intake of fluid and food
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9
Q

Origin of urea as a waste

A
  • Formed largely in the liver
  • from deanimation of excess amino acids
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10
Q

Origin of uric acid as a waste

A
  • End product of metabolism of nucleic acids
  • e.g. DNA and RNA
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11
Q

Origin of creatinine as a waste

A

Formed from creatinine phosphate in the cells

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12
Q

Origin of bile pigments as a waste

A
  • Formed in liver with haemoglobin breakdown.
  • Haemoglobin from red blood cells
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13
Q

Main parts of the urinary system

A
  • Two kidneys
  • Two ureters
  • The bladder
  • The urethra
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14
Q

Blood vessels associated with the kidneys

A
  • Renal artery carrying oxygenated blood and rich in wastes
  • Renal vein carrying deoxygenated blood and purified of wastes
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15
Q

What is the urinary bladder

A
  • Thin walled muscular sac
  • Urine is temporarily stored here
  • Urine enters trough the two ureters
  • Exits through the urethra
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16
Q

Function of the ureters

A

Transport urine from the kidneys to the bladder

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17
Q

Function of the urethra

A

Transport urine from the bladder to outside the body

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18
Q

Function of the sphincter muscle

A
  • Found at the base of the bladder
  • it controls the flow of urine to the urethra
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19
Q

External structure of kidney

A
  • Dark bean shaped organ
  • Kidneys enclosed in fat for insulation and protection
  • Hilum - renal artery, vein and ureter enter/leave
  • Renal capsule - membrane surrounding kidney
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20
Q

Internal (macro) structure of kidney - what you see when you dissect a kidney

A
  • Renal capsule (outer membrane)
  • Cortex (directly under capsule, dark red brown colour)
  • Medulla (inner region, lighter in colour)
  • Collecting tubes form pyramid (broad bases face cortex)
  • Renal papilla (inner tips of pyramids)
  • Renal calyx (renal papilla open into renal calyces)
  • Renal pelvis (calyces open into this widened region of ureter)
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21
Q

Nephron

A

Structural and functional unit of kidney

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22
Q

Two main parts of a nephron

A
  • Malpighian body
  • Renal tubule
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23
Q

Two main parts of the Malpighian body

A
  • Bowmans capsule
  • Glomerulus
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24
Parts of the renal tubule
* Bowman's capsule * proximal convoluted tubule * loop of Henle * distal convoluted tubule * collecting duct
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Parts of the glomerulus
* Wide afferent arteriole * Capillary network * Narrow efferent arteriole
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Parts of the loop of Henle
* Descending limb * Ascending limb
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Parts of the nephron in the cortex
* Malpighian body * Proximal convoluted tubule * Distal convoluted tubule
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Parts of the nephron in the medulla
* Loop of Henle * Collecting duct
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Structure of the Bowman's capsule
* Inner lining of cells are specialised (called podocytes) * Tiny slit pores between podocytes * pores open into hollow capsular space
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Structure of the renal tubule
* Long and twisted to increase surface area * Lined by cuboidal epithelial cells * Cells have many mitochondria for active reabsorption * Cells have microvilli to increase surface area
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Composition of blood plasma
* Water * Dissolved gases * Dissolved useful substances (glucoce, salts, amino acids etc.) * Dissolved waste substances (urea, uric acid and creatinine) * Large plasma proteins
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Where does the efferent arteriole lead to?
* A network of capillaries running closely alongside the renal tubules * This is called the peritubular capillary network. * these link up with other capillaries to join a branch of the renal vein.
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The three main processes taking place in the nephron
* Glomerular filtration / ultrafiltration * Tubular re-absorption * Tubular excretion
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Glomerular filtration
* Blood in glomerulus under great pressure (narrower efferent arteriole) * small substances forced out through pores into capsular space * i.e. Water, glucose, amino acids, glycerol, fatty acids, salts as well as waste products urea, uric acid and creatinine * blood cells and plasma proteins stay behind in blood vessels * this filtrate called glomerular filtrate * process is not selective, contains waste and useful substances.
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Tubular re-absorption
* As glomerular filtrate passes proximal convoluted tubule * water reabsorbed by osmosis into peritubular capillaries * other useful substances re-absorbed actively * cuboidal cells of the tubule have mitochondria for active transport and microvilli to increase surface area. * filtrate with useful substances removed is now called dilute urine
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Tubular excretion
* Wastes actively transported from the blood into the renal tubule * e.g. Creatinine, drugs, ammonia, potassium, hydrogen and bicarbonate ions
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How water is conserved (tubular reabsorption process)
* Sodium and chlorine ions pumped out of loop of Henle * dilute urine leaving the loop of Henlee has a very high water potential * because of a steep concentration gradient, water leaves the distal convoluted tubule by osmosis * depending on the water levels of the body, urine is either more dilute or concentrated
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Hormone that regulates how much water is reabsorbed
Anti-diuretic hormone (ADH)
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The action of ADH on the distal convoluted tubules and collecting ducts
* It's presence reduces the permeability of the distal convoluted tubules and collecting ducts * this reduces water reabsorption * urine is more diluted
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Kidney tubule response if blood becomes too alkaline
* Hydrogen ions concentration in blood is too low (high pH) * cells of tubules remove more bicarbonate ions * Various ions act as buffer in filtrate (resists pH change) * pH in blood returns to normal
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Homeostasis
* a process that keeps the amounts of substances and conditions of the body within narrow limits. * maintained by constantly adjusting these to prevent any large changes.
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Homeostasis of water
Osmoregulation
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Osmoregulation process (shortage of water in body)
* osmoreceptors in hypothalamus stimulated * pituitary stimulated to produce more ADH * ADH via blood increases permeability of distal convoluted tubules * more water passes from tubules into blood by osmosis * less water remains in tubules * concentrated urine is excreted
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Osmoregulation process (excess of water in body)
* osmoreceptors in hypothalamus stimulated * pituitary stimulated to produce less ADH * less ADH decreases permeability of distal convoluted tubules * less water passes from tubules into blood by osmosis * more water remains in tubules * dilute urine is excreted
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What is aldosterone
* A hormone * regulates the salt concentration of the blood and tissue fluid * secreted from the cortex of adrenal glands
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Homeostasis of salt balance (e.g. when sodium in the body is too low)
* Sodium levels on the blood drop * More aldosterone secreted from the adrenal glands * The renal tubules are stimulated to increase active reabsorption of sodium ions from the filtrate into the blood * Sodium levels in the blood increase
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Causes of kidney failure
* Overuse of painkillers * Chronic high blood pressure * Type 2 diabetes * Injury * Infection e.g. Bilharzia
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Kidney dialysis
* A short term treatment for those with kidney failure * Entire blood volume is passed through a series of filters * cleaned blood is returned to the body * Done mainly in hospital with a dialysis machine * several times per week * expensive
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Long term solution for kidney failure
* Kidney transplant * Dysfunctional kidney removed * Replaced by a healthy donated kidney
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Process of dialysis
* Blood is removed from an artery * A substance is added to prevent the blood from clotting * It is pumped into semi-permeable tubes in the dialysis machine * On the other side of these tubes is dialysis fluid * This contains water, glucose and salts of same concentration as the blood * Waste molecules move through the membrane into the dialysis fluid by diffusion * useful molecules don't move through (no concentration gradient) * cleaned blood returned to a vein of the person
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Issues with kidney transplants
* Risk of rejection (immune system attacks foreign cells) * Finding a donor hard - often a close relative required * shortage of donors * Immuno-suppressants required for life * Expensive * public health system in SA will not treat those over 50 years old due to its cost
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Kidney stone
* A solid formed from minerals in the diet * E.g. Calcium, uric acid
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Increased risk for getting kidney stones
* Dehydration * Excess animal protein * Sodium (salt) * Sucrose * Fructose * High fructose corn syrup (e.g. In Coke)
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Getting rid of kidney stones
* Small ones pass with urination * Larger ones need treatment as they can cause blockages * ultrasound to shatter them * surgery
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Effect and symptoms of kidney stones
* Blockage of different parts of the renal system * Renal colic - intense pain * Sometimes nausea and vomiting
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Kidney failure caused by medicines
* Analgesic nephropathy * Irreversible damage * Damage builds up through time * Leads to kidney failure
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Common medicines causing kidney damage
* Paracetamol (e.g. Panado) * Ibuprofen (e.g. Neurofen)
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Risk of damage to kidneys by medicines increases...
* With dehydration * With large amounts of exercise (e.g. long distance runners) mainly due to dehydration
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An example parasite that affects the urinary system
Schistosomiasis / bilharzia
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Symptoms of bilharzia
* Painful urination * Blood in urine
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Portal of entry for Bilharzia
* Schistosomiasis flatworms * Burrow into skin from infected waters * Female lays eggs in blood vessels lining the bladder
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Place of exit by bilharzia from humans
* Eggs have spike that cuts blood vessel * They enter bladder * Exit body with next urination
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Secondary host of bilharzia
A snail
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Complications from bilharzia infection
* Eggs or larvae can obstruct different part of the system * If not treated, can lead to chronic kidney failure
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Ureters
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Urinary bladder
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Urethra
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Renal pelvis
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Adrenal glands
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Renal capsule
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Renal cortex
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Renal pyramids
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Renal calyces
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Renal pelvis
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Renal artery
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Renal vein
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Renal medulla
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A: Collecting duct B: Malpighian body
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* A nephron * Structural and functional unit of the kidney
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A: Afferent arteriole B: Bowmans capsule C: Glomerulus (capillaries) D: Distal convoluted tubule E: Collecting duct F: Loop of Henle G: Proximal convoluted tubule
LS 11 - Life Sciences
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