Excretion and Osmoregulation

Question 1

Excretion

Answer 1

Excretion is the process by which waste and harmful substances, produced by chemical reactionsoccurring inside body cells, i.e. the body’s metabolism, are removed from the body

Question 2

Is excretion important?

Answer 2

Excretion is important in living organisms because many WASTE products are HARMFUL and if these BUILDUP in cells, they DAMAGE and KILL the cells.

Question 3

Excretion and Egestion

Answer 3

Excretion IS removal of undigested dietary fibre OR UNDIGEST FOOD MATERIAL and other materials (bile pigments, dead bacteria mucus) from the body in the form of FAECES. This dietary fibre is NOT produced in the body’s metabolism, so its removal cannot be classed as excretion.

Question 4

Products excreted by plants

Plants produce the following waste substances during metabolism:

Answer 4

• Oxygen is produced in photosynthesis and is excreted duringthe day when the rate ofphotosynthesis is higher than the rate of respiration.
• Carbon dioxide is produced in respiration and is excreted duringthe night when no photosynthesisis occurring.
• Water is produced in respiration and is excreted duringthe night when no photosynthesis is occurring.
• ORGANIC WASTE PRODUCTSs such as tannins, alkaloids, anthocyanins, and salts of organic acids such as calcium oxalate.

Question 5

Products excreted by animals

Animals produce the following waste substances during metabolism:

Answer 5

• Carbon dioxide is produced in respiration.
• Water is produced in respiration.
• Nitrogenous compounds are produced by the deamination of amino acids in the liver, e.g. urea, ammonia which is very toxic, and uric acid which is the least toxic.
• **Bile pigments, e.g. bilirubin, are produced by the breakdown of haemoglobin from red blood cells in the liver. **
• Heat is produced in general metabolism.

Question 6

Excretory organs in humans

Humans have several organs that excrete waste products.

Answer 6

• The kidneys excrete water, nitrogenous waste (mainly urea) and salts as urine.
• The lungs excrete carbon dioxide and water vapour during exhalation.
• The skin excretes water, urea and salts as sweat. It also excretes heat.
• The liver excretes **bile pigments. **It also makes nitrogenous waste.

Question 7

Osmoregulation in humans

Answer 7

Osmoregulation is the regulation of the concentration of blood plasma and body fluids. It is essential to prevent water moving into and out of body cells unnecessarily.

Question 8

If the body fluids become to dilute or concentrated

Answer 8

1. If the body fluids become too dilute, water enters body cells by osmosis. The cells swell and may burst.
2. If the body fluids become too concentrated, water leaves body cells by osmosis. The cells shrinkand the body becomes dehydrated. If toomuch water leaves cells, metabolic reactions cannot take place and cells die.

Question 9

Water gain by the human body

Answer 9

• In drink.
• In food.
• Metabolic water is produced by cells duringrespiration.

Question 10

Water loss by the human body

Answer 10

• From the kidneys inurine.
• From the skin insweat.
• From the respiratory system during exhalation

Question 11

The kidneys and osmoregulation

Answer 11

The kidneys regulate the concentration of body fluids by controlling how much water is reabsorbed into the blood plasma during selective reabsorption. This determines how much water is lost in urine.

Question 12

NEPHRON THREE SECTIONS

Answer 12

first convoluted tubule (in the cortex)
loop of henle (in the medulla)
second convoluted tubule (in the cortex)

Question 13

urinary system

Answer 13

• thousands of kidney tubules and nephrons
• renal artery (away from heart to kidney supply it with oxygen)
• renal vein
• ureter; carries urine from the kidneys to the bladder
• sphincter muscle; relaxes to allow urine to leave the bladder. keeps the bladder closed
• bladder: bag with muscular walls stores urine
• urethra: tube which carries urine out of the bladder

Question 14

glomerulus

Answer 14

intertwined cluster of capillaries

an arteriole which branches from the renal artery, leads into each glomerulus. blood capillaries wrap around each nephron which leades from the glomerulus and then joins into a venule and renal vein.

Question 15

mechanisms of excretion in plants

Answer 15

oxygen, carbon dioxide and water vapour diffuse through the stomata and lenticels in stems and roots

organic waste products stored in dead permanent tissue (leaves bark petals) which the plants sheds

Question 16

glucose in urine

Answer 16

Normally, urine contains very little or no glucose. But if you have too much glucose in your blood, your kidneys will get rid of some of the extra glucose through your urine. So, a high level of urine glucose may mean that your blood glucose is high, too, and that could be a sign of diabetes

Question 17

blood in urine

Answer 17

Bloody urine may be due to a problem in your kidneys or other parts of the urinary tract, such as: Cancer of the bladder or kidney. Infection of the bladder, kidney, prostate, or urethra. Inflammation of the bladder, urethra, prostate, or kidney (glomerulonephritis)

Question 18

Glomerulonephritis

Answer 18

Glomerulonephritis is inflammation and damage to the filtering part of the kidneys (glomerulus). It can come on quickly or over a longer period of time. Toxins, metabolic wastes and excess fluid are not properly filtered into the urine. Instead, they build up in the body causing swelling and fatigue.

Question 19

FUNCTION OF KIDNEYS

Answer 19

• remove waste products from the body such as urea
• remove drugs from the body
• balance the body’s fluids and water content
• sercetes hormones (such as RAS)
• produce an active form of vitamin D that promotes strong, healthy bones
  *** control the production of red blood cells as bile is secreted by the kidney which breaks down haemoglobin from red blood cells
• conatins bile pigments from bile which is stored in the gall bladder and secreted by the bile duct is an excretory products**

Question 20

Kideny failure and dialysis

Question 21

ADH

Answer 21

Antidiuretic hormone (ADH) is a chemical produced in the brain that causes the kidneys to release less water, decreasing the amount of urine produced. A high ADH level causes the body to produce less urine. A low level results in greater urine production.