Excretion Flashcards
(123 cards)
1
Q
Excretion
A
the removal of waste products of metabolism from the body
2
Q
egestion
A
the removal of undigested material from the gut
3
Q
is egestion an example of excretion?
A
no
4
Q
why do plants not have as great a need for excretion as animals?
A
because they make there own food (photosynthesis)
5
Q
what do plants lose during the day?
A
oxygen and water vapour
6
Q
through what are CO2, oxygen and water vapour excreted in the plant
A
the stomata and the lentils of the stem
7
Q
what do plants lose at night?
A
CO2
8
Q
what are lenticles
A
small pores in the stems
9
Q
some carbon dioxide produced in photosynthesis
A
used in respiration by the plant
10
Q
some carbon dioxide used in respiration
A
used in photosynthesis by the plant
11
Q
where are waste products stored in the plant
A
in the vacuoles in the leaves
12
Q
how do the plants get rid of the waste products
A
when the leaves fall off
13
Q
meaning of homeostasis
A
staying the same
14
Q
definition of homeostasis
A
the maintenance of a constant internal environment in an organism
15
Q
2 roles of excretion in homeostasis
A
removing of waste products of metabolism from the body
control of water and salt balance in the body
16
Q
osmoregulation
A
the maintenance of water and salt balance in body fluids
17
Q
4 excretory organs in the human
A
kidneys
skin
lungs
liver
18
Q
what do the kidneys excrete
A
water salts and urea
19
Q
what does the skin excrete
A
water and salts in the form of sweat
20
Q
what does the lung excrete
A
carbon dioxide and water
21
Q
what does the liver excrete
A
bile pigments
22
Q
what are bile pigments a product of
A
the breakdown of haemoglobin
23
Q
urea
A
formed when excess amino acids are broken down in the liver
24
Q
where are the kidneys located
A
in the abdominal cavity in the small of the back
25
2 functions of the kidney
excretion
| osmoregulation
26
urine formed in
the kidneys
27
urine passes to bladder via
the ureters
28
urine released via
urethra
29
blood enters kidneys through
the real arteries
30
blood in renal arteries
high in waste products
31
what do the kidneys do to the blood
filter out waste and reabsorb useful materials
32
blood leaves kinky via
renal veins
33
blood in renal veins
purified blood
34
3 sections of kidney
cortex
medulla
pelvis
35
cortex
outer part of kidney
36
4 things in the cortex
glomeruli, Bowman's capsule, distal and convoluted tubules
37
2 things in the medulla
loops of Henle and collecting ducts
38
Pelvis
the space int which the urine is collected from the collecting ducts
39
ureters
the tubes that carries the urine from the kidneys to the bladder
40
how many ureters do we have
2
41
nephron
functional unit of the kidney
42
nephrons are also called
kidney tubules
43
kidneys are made up of
millions of nephrons and their blood supply
44
nephrons carry out 2
excretion
| osmoregulation
45
what does the great number of nephrons provide?
a large surface area for exchange of materials with the blood
46
blood flow in the kidneys
renal artery -> many afferent arterioles -> glomerulus -> efferent arteriole -> capillaries around the tubule -> venules -> renal vein
47
where is the glomerulus located
in bowman capsule
48
2 functions of kidney carried out by
the production of urine
49
composition of urine, water
96%
50
composition of urine, urea (nitrogen waste)
2.5%
51
composition of urine, salts
1.5%
52
3 processes in urine formation
Filtration of blood
Selective reabsorption
Secretion
53
Filtration of blood
small molecules are filtered out of blood leaving large ones behind
54
where does Filtration of blood occur
in the cortex
55
Selective reabsorption
as the filtrate flows along the tubule, useful substances are removed from it and taken back into the blood
56
where does Selective reabsorption occur
the cortex and the medulla
57
Secretion
some substances are actively transported by the cells of the nephron from the blood into the filtrate
58
2 examples of substances in secretion
H+ and K+
59
where does Secretion occur
the cortex
60
where do unwanted substances go?
flow from the kidney into the ureter and onto the bladder as urine
61
does Filtration occur under high or low pressure
high pressure
62
exact places of Filtration
through the glomerulus in bowman capsule
63
site of filtration
glomerulus
64
3 reasons why blood is under high pressure in the glomerulus
renal artery is branched off from the aorta, which is under high pressure from the heartbeat
efferent arteriole is much narrower than the afferent arteriole
arterioles present at both ends
65
what is the glomerulus
a network of capillaries which acts as a filter
66
1 feature of the glomerulus
has a large surface area
67
what does the high pressure in the glomerulus cause?
forces part of the blood plasma to leak through the one cell thick wall of the glomerulus into the lumen of bowmans capsule
68
liquid that comes out of the glomerulus
glomerular filtrate
69
cells of bowmans capsule
one cell thick
70
glomerular filtrate contains (6)
```
water
salts
urea
glucose
amino acids
vitamins
minerals
```
71
what do the substances in bowmans capsule all have in common
they are all very small, small enough to pass through bowman's capsule
72
3 larger substances that cannot enter the glomerular filtrate
red and white blood cell
| large plasma proteins
73
entering arteriole
afferent arteriole
74
exiting arteriole
efferent arteriole
75
what type of substances are reabsorbed into the blood
useful substances
76
what process is used in selective reabsorption
osmosis and active transport
77
how much glomerular filtrate is reabsorbed
99%
78
2 waste products not reabsorbed into blood
urea and uric acid
79
2 locations of selective reabsorption
proximal convoluted tubule
| loop of henle
80
where does most reaborption take place
proximal convoluted tubule
81
how much water is rebsorbed by osmosis
80%
82
3 things reabsorbed by active transport (and some diffusion)
glucose, amino acids and vitamins
83
by what process is salt reabsorbed
active transport
84
4 ways the proximal convoluted tubule is adapted for reabsorption
thin walled
long
has microvilli
a lot of mitochondria
85
why is it important that the proximal convoluted tubule has a lot of mitochondria
to provide energy for active transport
86
how thin are the walls of the proximal convoluted tubule
1 cell thick
87
how long is the proximal convoluted tubule
14mm
88
function of microvilli in the proximal convoluted tubule
more surface area
89
what occurs in the descending loop of henle
H2O reabsorbed by osmosis
90
what occurs in the ascending loop of henle
salt reabsorbed by difussion near the bottom and active transport at the top
91
where does salt move out of during reabsorption
nephron
92
where does salt move into during reabsorption
the fluid of the medulla
93
what does the addition of salt do to the medulla
makes it more concentrated (low water conc.) than the fluid in the tubule (high water conc.)
94
what happens when the fluid of the medulla is more concentrated than the fluid in the tubule
water is removed from by osmosis from the descending loop of hence and the collecting duct
95
osmosis
the diffusion of water molecules across a semi-permeable membrane
down a concentration gradient
no energy needed (passive process)
96
what part of reabsorption happens in the distal convoluted tubule
the precise control of water and salt concentration in the blood
97
what controls the reabsorption of water into the blood
ADH
98
ADH
anti diuretic hormone
99
function of ADH
controls the osmoregulatory role of the kidney
100
what controls the reabsorption of salt into the blood
the hormone aldosterone
101
what part of reabsorption happens in the collecting duct
H2O can be reabsorbed by osmosis under the control of ADH
102
2 places where ADH acts
distal convoluted tubule
| collecting duct
103
Where does selective secretion take place
in the distal convoluted tubule
104
what happens in selective secretion
some substances pass from the blood into the nephron e.g. drugs and H+ ions
105
what is the distal convoluted tubule important for?
adjusting the pH balance of the blood
106
the bladder
a sac with an elastic muscular wall that stores urine
107
what happens when urine starts to fill the bladder
it stretches the walls of the bladder
108
plasma
blood minus blood cells, liquid part of the blood
109
glomerular filtrate
filtrate made in bowman's capsule, initially contains small molecules e.g. glucose and it travels through the nephron
110
urine
the liquid passing from the collecting ducts
111
2 ways in which glomerular filtrate differs from urine
has more water
| contains useful molecules e.g..glucose that are not normally found in urine
112
other name for ADH
vasopressin
113
is concentration of urea higher in plasma or urine and why
urine because a lot of water gets reabsorbed out of it
114
H2O reabsorption in PCT
most
115
salt reabsorption in PCT
most
116
H2O reabsorption in descending limb of LoH
a little
117
salt reabsorption in descending limb of LoH
none
118
H2O reabsorption in ascending limb of LoH
none
119
salt reabsorption in ascending limb of LoH
a little
120
water reabsorption in DCT
some
121
salt reabsorption in DCT
some
122
water reabsorption in CD
some
123
salt reabsorption in CD
none
