Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biology > Excretion > Flashcards

Excretion Flashcards

(134 cards)

Start Studying
1
Q

What are the major forms of nitrogenous wastes excreted by animals?

A

Ammonia, urea, and uric acid

These substances are produced either by metabolic activities or through excess ingestion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Which nitrogenous waste is considered the most toxic?

A

Ammonia

Ammonia requires a large amount of water for its elimination.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the term for the excretion of ammonia?

A

Ammonotelism

Ammonotelism is common in bony fishes, aquatic amphibians, and aquatic insects.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How is ammonia primarily excreted by ammonotelic animals?

A

By diffusion across body surfaces or through gill surfaces

In fish, ammonia is excreted as ammonium ions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What type of animals are called ureotelic?

A

Mammals, many terrestrial amphibians, and marine fishes

These animals primarily excrete urea.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How is ammonia converted into urea in ureotelic animals?

A

In the liver

Urea is then released into the blood and filtered out by the kidneys.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What role do kidneys play in the elimination of urea?

A

They filter and excrete urea out of the body

Some urea may be retained in the kidney matrix to maintain osmolarity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the term for animals that excrete nitrogenous wastes as uric acid?

A

Uricotelic animals

These include reptiles, birds, land snails, and insects.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the advantage of excreting uric acid?

A

Minimum loss of water

Uric acid is excreted in the form of pellets or paste.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Fill in the blank: Animals accumulate ammonia, urea, uric acid, carbon dioxide, water, and ions like Na+, K+, Cl–, phosphate, and sulphate due to _______.

A

[metabolic activities or excess ingestion]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

True or False: Ammonia requires less water for elimination compared to uric acid.

A

False

Ammonia is the most toxic and requires a large amount of water for its elimination.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the excretory structures in Platyhelminthes?

A

Protonephridia or flame cells

These structures are primarily involved in osmoregulation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the primary function of nephridia in annelids?

A

Removal of nitrogenous wastes and maintenance of fluid and ionic balance

Nephridia are tubular excretory structures found in earthworms and other annelids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are Malpighian tubules and their function?

A

Excretory structures in most insects, including cockroaches, that help in the removal of nitrogenous wastes and osmoregulation

Malpighian tubules are crucial for insect excretion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What excretory function do antennal glands serve?

A

Excretory function in crustaceans like prawns

Also known as green glands.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What components make up the human excretory system?

A

A pair of kidneys, ureters, urinary bladder, and urethra

These components work together to remove waste from the body.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe the shape and location of human kidneys.

A

Reddish brown, bean-shaped structures located between the last thoracic and third lumbar vertebrae

They are close to the dorsal inner wall of the abdominal cavity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the average size and weight of an adult human kidney?

A

10-12 cm in length, 5-7 cm in width, 2-3 cm in thickness, weighing 120-170 g

These dimensions can vary slightly among individuals.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the hilum in the kidney?

A

A notch through which the ureter, blood vessels, and nerves enter

It is located towards the center of the inner concave surface of the kidney.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the renal pelvis?

A

A broad funnel-shaped space inside the kidney that connects to the ureter

It is located inner to the hilum and has projections called calyces.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the two zones inside the kidney?

A

Outer cortex and inner medulla

The medulla contains conical masses called medullary pyramids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Fill in the blank: The outer layer of the kidney is a tough _______.

A

capsule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the shape of Henle’s loop in the nephron?

A

Hairpin shaped

Henle’s loop consists of a descending and an ascending limb.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the next part of the tubule after the hairpin shaped Henle’s loop?

A

Distal convoluted tubule (DCT)

The DCT continues from the ascending limb of Henle’s loop.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Where do the DCTs of many nephrons open into?
Collecting duct ## Footnote Many collecting ducts converge and open into the renal pelvis through medullary pyramids in the calyces.
26
Which parts of the nephron are located in the cortical region of the kidney?
Malpighian corpuscle, PCT, DCT ## Footnote These components are situated in the cortical region, while the loop of Henle dips into the medulla.
27
What are nephrons with short loops of Henle called?
Cortical nephrons ## Footnote These nephrons have loops that extend only very little into the medulla.
28
What are nephrons with long loops of Henle that run deep into the medulla called?
Juxta medullary nephrons ## Footnote These nephrons have a significant portion of their loop in the medulla.
29
What is the fine capillary network around the renal tubule called?
Peritubular capillaries ## Footnote This network emerges from the efferent arteriole of the glomerulus.
30
What is the U-shaped vessel running parallel to Henle’s loop called?
Vasa recta ## Footnote Vasa recta is absent or highly reduced in cortical nephrons.
31
What are the three main processes involved in urine formation?
* Glomerular filtration * Reabsorption * Secretion ## Footnote These processes occur in different parts of the nephron.
32
What is the first step in urine formation?
Glomerular filtration ## Footnote This process is carried out by the glomerulus.
33
How much blood is filtered by the kidneys per minute on average?
1100-1200 ml ## Footnote This constitutes roughly 1/5th of the blood pumped out by each ventricle of the heart in a minute.
34
What causes the filtration of blood in the glomerulus?
Glomerular capillary blood pressure ## Footnote This pressure causes blood to be filtered through three layers.
35
What are the three layers through which blood is filtered in the glomerulus?
* Endothelium of glomerular blood vessels * Epithelium of Bowman’s capsule * Basement membrane ## Footnote These layers work together in the filtration process.
36
What are the epithelial cells of Bowman’s capsule called?
Podocytes ## Footnote Podocytes are arranged to leave minute spaces called filtration slits or slit pores.
37
What is the process of blood filtration through the nephron considered?
Ultra filtration ## Footnote This process allows almost all constituents of plasma except proteins to pass into Bowman’s capsule.
38
What is the glomerular filtration rate (GFR)?
The amount of filtrate formed by the kidneys per minute, approximately 125 ml/minute or 180 litres per day.
39
What mechanism regulates the glomerular filtration rate?
The juxta glomerular apparatus (JGA) regulates GFR.
40
What happens when there is a fall in GFR?
JG cells release renin, which stimulates glomerular blood flow and normalizes GFR.
41
What percentage of the filtrate is reabsorbed by the renal tubules?
Nearly 99 percent of the filtrate is reabsorbed.
42
What is the process called when substances are reabsorbed by the renal tubules?
The process is called reabsorption.
43
How are glucose and amino acids reabsorbed in the nephron?
They are reabsorbed actively.
44
How are nitrogenous wastes reabsorbed in the nephron?
They are absorbed by passive transport.
45
What role does tubular secretion play in urine formation?
It helps maintain ionic and acid-base balance of body fluids.
46
What is the function of the Proximal Convoluted Tubule (PCT)?
PCT reabsorbs nearly all essential nutrients and 70-80 percent of electrolytes and water.
47
What is the role of Henle’s Loop in urine formation?
It maintains high osmolarity of medullary interstitial fluid and concentrates the filtrate.
48
What occurs in the Distal Convoluted Tubule (DCT)?
Conditional reabsorption of Na+ and water, and selective secretion of hydrogen and potassium ions.
49
What is the collecting duct?
The collecting duct is a long duct that extends from the cortex of the kidney to the inner parts of the medulla.
50
What is the role of the collecting duct in urine concentration?
Large amounts of water can be reabsorbed from the collecting duct to produce concentrated urine.
51
How does the collecting duct contribute to osmolarity?
The collecting duct allows the passage of small amounts of urea into the medullary interstitium to maintain osmolarity.
52
What is one of the functions of the collecting duct regarding blood balance?
The collecting duct plays a role in maintaining pH and ionic balance of blood by selectively secreting H+ and K+ ions.
53
What mechanism allows mammals to produce concentrated urine?
Mammals produce concentrated urine through the mechanisms involving Henle's loop and vasa recta.
54
What is the flow direction of filtrate in Henle's loop?
The flow of filtrate in the two limbs of Henle's loop is in opposite directions, forming a counter current.
55
What is the flow direction of blood in the vasa recta?
The flow of blood through the two limbs of the vasa recta is also in opposite directions.
56
What is the role of the proximity between Henle’s loop and vasa recta?
It helps maintain an increasing osmolarity towards the inner medullary interstitium, from 300 mOsmolL–1 in the cortex to about 1200 mOsmolL–1 in the inner medulla.
57
What substances primarily cause the osmolarity gradient in the inner medulla?
NaCl and urea.
58
How is NaCl transported in the nephron?
NaCl is transported by the ascending limb of Henle’s loop and exchanged with the descending limb of vasa recta.
59
What happens to NaCl in the vasa recta?
NaCl is returned to the interstitium by the ascending portion of vasa recta.
60
How does urea contribute to the osmolarity gradient?
Small amounts of urea enter the thin segment of the ascending limb of Henle’s loop and are transported back to the interstitium by the collecting tubule.
61
What is the counter current mechanism?
It is the transport of substances facilitated by the special arrangement of Henle’s loop and vasa recta.
62
What is the role of the interstitial gradient in the kidneys?
The interstitial gradient helps in the easy passage of water from the collecting tubule, thereby concentrating the filtrate (urine). ## Footnote Human kidneys can produce urine nearly four times concentrated than the initial filtrate formed.
63
How is kidney function regulated?
Kidney function is monitored and regulated by hormonal feedback mechanisms involving the hypothalamus, JGA, and to a certain extent, the heart.
64
What activates osmoreceptors in the body?
Osmoreceptors are activated by changes in blood volume, body fluid volume, and ionic concentration.
65
What happens when there is excessive fluid loss from the body?
Excessive fluid loss activates osmoreceptors, stimulating the hypothalamus to release antidiuretic hormone (ADH) or vasopressin.
66
What is the function of ADH?
ADH facilitates water reabsorption from the latter parts of the tubule, preventing diuresis.
67
How does an increase in body fluid volume affect ADH release?
An increase in body fluid volume switches off osmoreceptors and suppresses ADH release.
68
How does ADH affect blood pressure?
ADH has constrictory effects on blood vessels, causing an increase in blood pressure.
69
What is the role of the JGA in kidney function?
The JGA releases renin when there is a fall in glomerular blood flow, blood pressure, or GFR.
70
What does renin convert angiotensinogen into?
Renin converts angiotensinogen in blood to angiotensin I and further to angiotensin II.
71
What is the effect of angiotensin II?
Angiotensin II is a powerful vasoconstrictor that increases glomerular blood pressure and GFR.
72
What does angiotensin II stimulate in the adrenal cortex?
Angiotensin II activates the adrenal cortex to release Aldosterone.
73
What is the function of Aldosterone?
Aldosterone causes reabsorption of Na+ and water from the distal parts of the tubule, increasing blood pressure and GFR.
74
What is the Renin-Angiotensin mechanism?
The Renin-Angiotensin mechanism involves the regulation of blood pressure and GFR through renin, angiotensin, and aldosterone.
75
What triggers the release of Atrial Natriuretic Factor (ANF)?
An increase in blood flow to the atria of the heart triggers the release of ANF.
76
What is the effect of ANF on blood pressure?
ANF causes vasodilation, thereby decreasing blood pressure.
77
What initiates the micturition process?
Micturition is initiated by the stretching of the urinary bladder as it fills with urine.
78
How does the CNS respond to bladder stretching?
The stretch receptors on the walls of the bladder send signals to the CNS, which passes on motor messages.
79
to initiate the contraction of smooth muscles of the bladder and
80
simultaneous relaxation of the urethral sphincter causing the release of
81
urine. The process of release of urine is called micturition and the neural
82
mechanisms causing it is called the micturition reflex. An adult human
83
excretes
on an average
84
is a light yellow coloured watery fluid which is slightly acidic (pH-6.0)
85
and has a characterestic odour. On an average
25-30 gm of urea is
86
excreted out per day. Various conditions can affect the characteristics of
87
urine. Analysis of urine helps in clinical diagnosis of many metabolic
88
discorders as well as malfunctioning of the kidney. For example
presence
89
of glucose (Glycosuria) and ketone bodies (Ketonuria) in urine are
90
indicative of diabetes mellitus.
91
16.7 ROLE OF OTHER ORGANS IN EXCRETION
92
Other than the kidneys
lungs
93
of excretory wastes.
94
Our lungs remove large amounts of CO2
95
(approximately 200mL/
96
minute) and also significant quantities of water every day. Liver
the largest
97
gland in our body
secretes bile-containing substances like bilirubin
98
biliverdin
cholesterol
99
Most of these substances ultimately pass out alongwith digestive wastes.
100
The sweat and sebaceous glands in the skin can eliminate certain
101
substances through their secretions. Sweat produced by the sweat
102
glands is a watery fluid containing NaCl
small amounts of urea
103
acid
etc. Though the primary function of sweat is to facilitate a cooling
104
effect on the body surface
it also helps in the removal of some of the
105
wastes mentioned above. Sebaceous glands eliminate certain
106
substances like sterols
hydrocarbons and waxes through sebum. This
107
secretion provides a protective oily covering for the skin. Do you know
108
that small amounts of nitrogenous wastes could be eliminated through
109
saliva too?
110
16.8 DISORDERS OF THE EXCRETORY SYSTEM
111
Malfunctioning of kidneys can lead to accumulation of urea in blood
a
112
condition called uremia
which is highly harmful and may lead to kidney
113
failure. In such patients
urea can be removed by a process called
114
hemodialysis. During the process of haemodialysis
the blood drained
115
from a convenient artery is pumped into a dialysing unit called artificial
116
kidney. Blood drained from a convenient artery is pumped into a dialysing
117
unit after adding an anticoagulant like heparin. The unit contains a coiled
118
cellophane tube surrounded by a fluid (dialysing fluid) having the sam
119
composition as that of plasma except the nitrogenous wastes. The porous
120
cellophane membrance of the tube allows the passage of molecules based
121
on concentration gradient. As nitrogenous wastes are absent in the
122
dialysing fluid
these substances freely move out
123
blood. The cleared blood is pumped back to the body through a vein
124
after adding anti-heparin to it. This method is a boon for thousands of
125
uremic patients all over the world.
126
Kidney transplantation is the ultimate method in the correction of
127
acute renal failures (kidney failure). A functioning kidney is used in
128
transplantation from a donor
preferably a close relative
129
chances of rejection by the immune system of the host. Modern clinical
130
procedures have increased the success rate of such a complicated
131
technique.
132
Renal calculi: Stone or insoluble mass of crystallised salts (oxalates
133
etc.) formed within the kidney.
134
Glomerulonephritis: Inflammation of glomeruli of kidney.

Biology (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions