Biology - 4BI1 PearsonEdexcel

Excretion

Gbogbo ọrọ náà

Every metabolic reaction in your body generates waste. Some of these waste products are toxic and must be removed before they accumulate to dangerous levels. Excretion is the process that gets rid of them, and the kidneys are the organs that do most of the heavy lifting, filtering your entire blood volume roughly 40 times every day.

In this lesson you will learn what excretory products the body makes and which organs remove them, how the nephron filters blood and produces urine, and how ADH regulates the water content of the blood. Kidney function is a favourite topic for structured questions on both Paper 1 and Paper 2.

Ebumnobi

Understand the origin of carbon dioxide and oxygen as waste products of metabolism and their loss from the stomata of a leaf
Know the excretory products of the lungs, kidneys and skin (organs of excretion)
Understand how the kidney carries out its roles of excretion and osmoregulation
Describe the structure of the urinary system, including the kidneys, ureters, bladder and urethra
Describe the structure of a nephron, including the Bowman's capsule and glomerulus, convoluted tubules, loop of Henle and collecting duct
Describe ultrafiltration in the Bowman's capsule and the composition of the glomerular filtrate
Understand how water is reabsorbed into the blood from the collecting duct
Understand why selective reabsorption of glucose occurs at the proximal convoluted tubule
Describe the role of ADH in regulating the water content of the blood
Understand that urine contains water, urea and ions

Akọmọ Ojú-ẹkọ

After a long run you produce dark, concentrated urine. On a cold day when you have been drinking water all morning, your urine is almost colourless. The difference is your kidneys adjusting how much water they retain, balancing what you take in against what you lose. This constant fine-tuning is one example of excretion at work, and it keeps the internal environment stable enough for enzymes and cells to function.

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Ayẹwo Ẹkọ

Ekele diri gi maka imecha ihe karịrị na Excretion. Ugbu a na ị na-enyochakwa isi echiche na echiche ndị dị mkpa, ọ bụ oge iji nwalee ihe ị ma. Ngwa a na-enye ụdị ajụjụ ọmụmụ dị iche iche emebere iji kwado nghọta gị wee nyere gị aka ịmata otú ị ghọtara ihe ndị a kụziri.

Ị ga-ahụ ngwakọta nke ụdị ajụjụ dị iche iche, gụnyere ajụjụ chọrọ ịhọrọ otu n’ime ọtụtụ azịza, ajụjụ chọrọ mkpirisi azịza, na ajụjụ ede ede. A na-arụpụta ajụjụ ọ bụla nke ọma iji nwalee akụkụ dị iche iche nke ihe ọmụma gị na nkà nke ịtụgharị uche.

Jiri akụkụ a nke nyocha ka ohere iji kụziere ihe ị matara banyere isiokwu ahụ ma chọpụta ebe ọ bụla ị nwere ike ịchọ ọmụmụ ihe ọzọ. Ekwela ka nsogbu ọ bụla ị na-eche ihu mee ka ị daa mba; kama, lee ha anya dị ka ohere maka ịzụlite onwe gị na imeziwanye.

Where is urea produced? A) Kidneys B) Liver C) Lungs D) Bladder Answer: B
Which process forces small molecules out of the blood in the glomerulus? A) Osmosis B) Active transport C) Ultrafiltration D) Diffusion Answer: C
Glucose is reabsorbed in the proximal convoluted tubule by: A) Diffusion B) Osmosis C) Ultrafiltration D) Active transport Answer: D
When a person is dehydrated, what happens to ADH levels? A) They increase B) They decrease C) They stay the same D) ADH is not involved Answer: A
Which substance should NOT be found in the urine of a healthy person? A) Urea B) Water C) Glucose D) Ions Answer: C