Summary The excretory system grade 11 Life Science (B&W printable version)
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Course
Life Sciences
Institution
11th Grade
This summary contains study notes on the following topics for grade 11 Life science: excretion in humans, excretory organs, metabolic wastes and their origins, structure of the urinary system, structure and functions of the kidneys, homeostatic control, and diseases that affect the kidneys.
EXCRETION IN HUMANS
• Metabolic wastes → diffuses from cells via tissue fluid into blood.
• Metabolic waste in blood → to various excretory organs →removes waste from
bloodstream & excreted out of the body.
EXCRETORY ORGANS
LUNGS:
Excretes CO2, water vapour, & heat
KIDNEYS & BLADDER:
• Excretes urine.
• Urine: excess water, mineral salts, nitrates (urea, uric acid, creatine).
• Urea: transports via blood to kidneys + excreted in urine.
• Gall pigments: end up in small intestine as bile salts in faeces.
SKIN:
• Sweats via sweat glands
• Sweat: excess water, salt, small amount of urea
Metabolic wastes and their origins
• CO2 → product of cellular respiration
• Excess water → product of cellular respiration & ingestion of fluids + food
• Urea → formed through deamination of excess amino acids in liver.
• Uric acid → end product of metabolism of nucleic acid.
• Creatine → formed in cells by creatine phosphates.
• Gall pigments → formed during breakdown of haemoglobin in liver
, STRUCTURE
• Consists of the two kidneys, two ureters, bladder, & urethra
• 2 types of blood vessels, renal arteries & veins
• 2 kidneys → in abdominal cavity, either sides of spinal column, just underneath
diaphragm.
• Kidneys receive oxygenated blood, rich in metabolic wastes, through renal
artery.
• O2 -rich blood → transported away from kidneys through renal veins once
filtered from all the metabolic wastes.
• 2 thin tubules, the ureters, each connect separately to bladder.
• Bladder → thin-walled, muscular sac that temporarily stores urine.
• Urethra → tube that transports urine from bladder to external environment.
• Sphincter → at base of bladder, controls flow of urine to urethra.
STRUCTURE OF THE KIDNEYS
EXTERNAL STRUCTURE
• Kidneys → dark red, bean-shaped organ, concave side towards spinal column.
• Indent in middle of concave side, called the hilum (renal port), where renal artery
enters kidney & where renal vein + ureter exits kidney.
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