excretory system

Question 1

what is excretion?

Answer 1

removal of metabolic wastes produced by chemical activities of an organisms cells

Question 2

what are the excretory organs?

Answer 2

lungs, liver, sweat glands, kidneys, alimentary canal

Question 3

why is excretion essential?

Answer 3

metabolic wastes are toxic and if left in the body they can cause sickness.

Question 4

what is deamination and the word equation?

Answer 4

• removal of an amino group of a molecule
• the remaining part of the amino acid is converted to carbohydrate to release energy
• amino acid + oxygen > carbohydrate (energy) + ammonia (toxic)

Question 5

what happens after deamination?

Answer 5

once the amino group is removed, it is converted by the liver cells to ammonia then to urea where it is eliminated in urine

Question 6

describe the role of skin in excretion

Answer 6

removes excess water and salts via sweat glands.

Question 7

what is a nephron?

Answer 7

• the filtering unit of the kidney, where urine is formed.

Question 8

what is glomerular filtration?

Answer 8

• takes place in the renal corpuscle
• when fluid is forced out of the blood in the glomerulus due to blood pressure and is collected by the Bowman’s/glomerular capsule

Question 9

what is filtrate?

Answer 9

• contains everything except blood cells and plasma proteins as they are too big
• contains = water, urea, salt, glucose, amino acids.

Question 10

what is tubular secretion?

Answer 10

• adds materials to the filtrate from the blood like potassium, hydrogen ions and creatinine.
• the process maintains blood pH and urine pH

Question 11

what are kidney stones and how are they formed?

Answer 11

• formed from solid crystals that build up inside the kidneys.
• usually form when urine becomes too concentrated - urine is too acidic or basic, too much oxalate in diet
• small crystals can pass unnoticed or crystals may form stones which can get stuck in ureter, bladder or urethra causing pain

Question 12

what are the symptoms of kidney stones?

Answer 12

blood in urine, burning while urinating, nausea, extreme pain when the stone passes

Question 13

what are the treatments for kidney stones?

Answer 13

laser pulses
sound waves
surgically removed
medication
increase water, activity, improve diet

Question 14

what is kidney failure and the causes?

Answer 14

• kidneys lose ability to excrete waste and control the level of fluid in the body.
• high sugar and salt intake, lack of water, diabetes, high blood pressure

Question 15

what are the treatments for kindey failure

Answer 15

• dialysis

transplant

Question 16

what is liver disease and the causes?

Answer 16

• liver is not able to function effectively - it is unable to process toxins ready for elimination
• can be caused by infections, viruses, autoimmune problem

Question 17

the function of the kidney?

Answer 17

• get rid of body wastes

- regulate the balance of fluid, salt + Ph in blood

Question 18

what are the tubule pathways?

Answer 18

• Bowmans capsule
• proximal convoluted
• loop of henle
• DCT
• collecting duct

Question 18

what are the tybule pathways?

Answer 18

• Bowmans capsule
• proximal convoluted
• loop of henle
• DCT
• collecting duct

Question 19

what are the blood vessels pathway?

Answer 19

• renal artery
• afferent arterioles
• glomerulus
• effective arterioles
• network of capillary
• renal vein

Question 20

describe the structure and function of a nephron

Answer 20

• Bowman capsule surrounds the glomerulus > collects fluid filtered out of capillary
• efferent arterioles has a smaller diameter than afferent arteriole > raise blood pressure = more fluid filtered out of the blood
• tubule has PCT + DCT + loop of henle > large SA for reabsorbtion + secretion
• each kidney has 1 million nephrons+ > total SA for reabsorbtion + secretion is extremely large

Question 21

what are the 3 steps of urine formation?

Answer 21

glomerular filtration, selective reabsorbtion, tubular secretion

Question 22

what is glomerular filtration?

Answer 22

blood > tubule

• occurs in renal corpuscle
• fluid is forced out of the blood and collected by Bowmans capsule
• 2 membranes (both 1 cell thick)
• high-pressure forces substances out of blood differentially permeable membranes into capsule = filtrate
• size determines what is filtered
• filtrate produced by renal capsule (only 1% leaves as urine = most is absorbed into blood)

Question 23

what is selective reabsorption?

Answer 23

tubule > blood

• many of the components of the plasma that are filtered from the capillaries of the glomerulus of use to the body and their excretion would be undesirable
• occurs in PCT (renal tubule) > materials are reabsorbed from PCT into capillary network
• materials reabsorbed = amino acids, glucose, sodium, water ( active transport = except urea + wastes)
• Large SA required

Question 24

what is tubular secretion?

Answer 24

blood/capillary network > tubule

• occurs in DCT
• materials are secreted into tubule from capillary
• materials secreted = excess H ions, ammonium ions, penicillin, the heroine
• effects = remove certain unwanted substances from body + maintain PH of blood