2) Structure and functions in living organisms - excretion Flashcards

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1
Q

Waste products in plants

A

-oxygen
-carbon dioxide
-water/ water vapour
-other unwanted chemical substances

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2
Q

Plants - Waste products in the day

A

-when there is sufficient light
-rate of photosynthesis > rate of respiration
-more oxygen released by photosynthesis than used in respiration
-less carbon dioxide released by respiration than used in photosynthesis
-oxygen is in access and a waste product

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3
Q

Plants - Waste products in the night

A

-when there is inefficient light
-no photosynthesis, only respiration
-no carbon dioxide used
-carbon dioxide is in excess and is a waste product

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4
Q

Plant waste products - water vapour

A

-water that has been drawn up from the roots in the transpiration stream
-not a waste product of metabolism

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5
Q

Plant waste products - chemical substances

A

-plant cells can break down molecules into chemical substances no longer required by the plant
-some of these substances cannot be converted into another useful compound and should be removed from the plant
-chemical waste materials - can be stored in dying tissues of a plant
-dying tissue falls off the plant the substances are removed

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6
Q

The kidney functions

A

-regulate water content of the blood
-excrete toxic waste products of metabolism (urea, salts)

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7
Q

Urinary system functions

A

-filter waste products from the blood, expel it from the body as urine
-control water levels of the body - osmoregulation

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8
Q

Structure of the urinary system

A

-two kidneys
-joined to the bladder
-by two tubes - ureters
-urethra - carries urine from the bladder to outside the body
-renal artery - from aorta, delivers oxygenated blood to the kidney
-renal vein - delivers deoxygenated blood from kidney to the vena cava

-draw it

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9
Q

Structure of the kidney

A

Cortex - the outermost region
Medulla - the inner section of the kidney
Renal pelvis - the tube linking the kidney to the ureter
Nephrons - start in the cortex, loop down into medulla, back up the cortex
-contents of the nephron drain into the renal pelvis and collects there before it flow into the ureter to the bladder

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10
Q

The nephron structure

A

Made up of a kidney tubule which has several sections:
-Bowman’s capsule
-proximal convoluted tubule
-loop of Henle
-distal convoluted tubule
-collecting duct

-surrounding tubule is a network of capillaries with a knotted section - sits inside the Bowman’s capsule

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11
Q

Ultrafiltration

A

-Arterioles branch off the renal artery and form the glomerulus inside the Bowman’s capsule
-capillaries get narrower further into the glomerulus
-increases blood pressure
-causes smaller molecules (glucose, water, urea, salts) in the blood is forced out of the capillaries and into the Bowman’s capsule and form a filtrate

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12
Q

Process through the nephron

A

Bowman’s capsule - glucose, water, urea, salts form a filtrate
Proximal convoluted tubule - glucose reabsorbed
Loop of henle - salts, water reabsorbed
Distal convoluted tubule - filtrate travels to collecting duct
Collecting duct - remaining fluid forms urine, leads to the ureter

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13
Q

Kidney - reabsorption of glucose

A

-glomerular filtrate enters Bowman’s Capsule
-glucose reabsorbed at the proximal convoluted tubule by active transport
-nephron has many mitochondria to do this

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14
Q

Kidney - reabsorption of water

A

-filtrate drips through loop of henle
-necessary salts reabsorbed back into the blood by diffusion
-water reabsorbed by osmosis in different amounts depending on how much water the body needs at the time

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15
Q

Importance of osmoregulation

A

-cytoplasm of all cells and blood plasma largely composed of water
-maintaining water levels is vital to prevent harmful changes in cells
-too much water in the blood - cell lysis (bursting)
-too little water in the blood - cells lose water

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16
Q

Need for ADH

A

-control of water reabsorption in the nephron is negative feedback
-water content of blood is too high, less water reabsorbed
-if too low, more water reabsorbed
This is controlled by the hormone ADH, released by the pituitary gland in the brain
-affects the permeability of the tubules to water

17
Q

ADH - water content of blood is too high

A

-pituitary gland releases less ADH
-collecting ducts become less permeable to water
-less water reabsorbed into collecting ducts of the kidney by osmosis
-kidney produces large volume of dilute urine

18
Q

ADH - water content of blood is too low

A

-pituitary gland releases more ADH
-collecting ducts become more permeable to water
-more water reabsorbed into collecting ducts of the kidney by osmosis
-kidneys produce a small volume of concentrated urine