excretory products and their elimination

Question 1

what do animals accumulate in their body by metabolic activities or excessive ingestion?

Answer 1

ammonia, urea, uric acid, carbon dioxide, water and ions like Na+, K+, Cl-, phosphate and sulphate

Question 2

what are the major forms of nitrogenous waste?

Answer 2

ammonia, urea and uric acid

Question 3

what is the most toxic and least toxic form of nitrogenous waste?

Answer 3

ammonia is the most toxic form and requires large amount of water for its elimination. uric acid is the least toxic form and requires minimum amount loss of water

Question 4

what is ammontelism? how is the process done? and what are the examples?

Answer 4

-the process of excreting ammonia is ammonotelism.
-ammonia as it is readily soluble is generally excreted by diffusion across body surfaces or gill surfaces as ammonium ions. kidneys do not play a significant role in its removal.

EXAMPLES: bony fishes, aquatic amphibians and aquatic insects

Question 5

what is ureotelism? what is the process of it. and it’s examples

Answer 5

-excretion by urea is ureotelism.
-ammonia produced by metabolism is converted into urea in the liver and released into the blood which is filtered and excreted out by the kidney.

EXAMPLES: mammals, terrestrial amphibians and marine fishes.

Question 6

which organism maintains desired osmolarity?

Answer 6

ureotelic organisms. some amount of urea maybe maintained in the kidney matrix of some of the animals to maintain desired osmolarity.

Question 7

what are uricotelic organisms? what is the process and some examples.

Answer 7

-excretion of uric acid is called uricotelism.
- they excrete uric acid in the form of pellets or paste with minimum loss of water.

EXAMPLES: reptiles, land birds, snails and insects

Question 8

platyhelminthes excretory structure

Answer 8

protonephridia or flame cells maintain osmoregulation( fluid and ionic balance)
e.g. planaria, rotifers, some annelids and the cephalochordate : amphioxus

Question 9

earthworms and other annelids excretory structure

Answer 9

nephridia. helps remove nitrogenous waste and maintains osmoregulation

Question 10

insects excretory structure

Answer 10

malphigian tubules
helps remove nitrogenous waste and maintains osmoregulation

Question 11

crustaceans ( prawn ) excretory structure

Answer 11

antennal gland or green gland

Question 12

what does the human excretory system consist of?

Answer 12

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

Question 13

kidneys color,shape and location?

Answer 13

it is reddish brown and bean shaped. it is located in the last thoracic and third lumbar vertebra located near the dorsal inner wall of the abdominal cavity

Question 14

kidneys measurement and weight

Answer 14

length : 10-12 cm
width : 5-7 cm
weight : 120-170g

Question 15

hilum location and function

Answer 15

-located towards the center of inner concave surface of the kidney
-ureter, blood vessels and nerves enter through this

Question 16

what is renal pelvis

Answer 16

inner to the hilum is broad funnel shaped space called renal pelvis. their projections are called calyces.

Question 17

what is the outer layer of kidney?

Answer 17

tough capsule

Question 18

what are the 2 zones inside kidney?

Answer 18

outer cortex
inner medulla

Question 19

the medulla is divided into?

Answer 19

medullary pyramids with projections called calyces

Question 20

what are columns of bertini?

Answer 20

they are renal columns which extend between medullary pyramids

Question 21

what are nephrons 2 parts

Answer 21

glomerulus and renal artery

Question 22

glomerulus is formed by

Answer 22

it is a tuft of capillaries formed by afferent arteriole

Question 23

what is afferent arteriole

Answer 23

a fine branch of renal artery

Question 24

who carries blood away from gloumerulus?

Answer 24

efferent arteriole

Question 25

the renal tubule begins with?

Answer 25

a double walled cup like structure called bowmans capsule which encloses the glomerulus

Question 26

what is the malpighian body or renal corpuscle?

Answer 26

glomerulus along with bowmans capsule

Question 27

nephron order

Answer 27

afferent arteriole -> glomerulus along with bowmans capsule
->PCT -> Henles loop -> ascending limb -> DCT of many nephrons -> collecting duct which converge and open into -> renal pelvis

Question 28

what are corticle nephrons?

Answer 28

in majority of nephrons the loop of henle is too short and dips only very little into the medulla such nephrons are called cortical nephrons.

Question 29

what are juxta medullary nephrons?

Answer 29

when loop of henle is too long and runs deep into the medulla these nephrons are called juxta medullary nephrons

Question 30

what and all are situated in the cortical region of the nephron?

Answer 30

PCT, DCT and malphigian corpuscle

Question 31

what are peritubular capillaries?

Answer 31

efferent arteriole forming network around renal tubule

Question 32

what is vasa recta?

Answer 32

when peritubular space runs parallel to henles loop forming u shaped vasa recta.

Question 33

where is vasa recta absent or highly reduced?

Answer 33

cortical nephrons

Question 34

what are the 3 main processes of urine formation

Answer 34

glomerular filtration, reabsorption and secretion

Question 35

how much blood is filtered by the kidney per minute?

Answer 35

1100-1200ml

Question 36

what are the 3 layers of filtration of blood

Answer 36

1. endothelium of glomerular blood vessels
2. basement membrane
3. epithelium of bowmans capsule

Question 37

what are podocytes?

Answer 37

epithelial cells of bowmans capsule which are arranged in an intricate manner as to leave filtration slits

Question 38

what is the only constituent from the plasma that does not filter through the membranes

Answer 38

proteins

Question 39

this filtration is also called?

Answer 39

ultra filtration

Question 40

what is glomerular filtration rate ( GFR )?

Answer 40

the amount of filtrate formed by the kidney per minute

Question 41

GFR of a healthy individual

Answer 41

125 ml/minute or 180 liters per day

Question 42

what is the built in mechanism for regulation of GFR

Answer 42

JGA mechanism

Question 43

JGA is formed by the cellular modifications of?

Answer 43

DCT and afferent arteriole

Question 44

what is the JGA mechanism

Answer 44

a fall in the GFR can activate the JG cells to release renin which can stimulate glomerular blood flow and bring GFR back to normal.

Question 45

What is the percentage of filtrate that has to be reabsorbed by the renal tubules?

Answer 45

99%

Question 46

What performs active or passive mechanisms of reabsorption

Answer 46

tubular epithelial cells

Question 47

What are the substances from the filtrate that get reabsorbed by active mechanism

Answer 47

glucose, amino acids, Na+

Question 48

What are the substances from the filtrate that get reabsorbed by passive mechanism

Answer 48

nitrogenous waste and water (initial segment of nephron)

Question 49

During urine formation what do the tubular cells secrete into the filtrate

Answer 49

H+, K+ and ammonia

Question 50

what does tubular secretion do

Answer 50

help maintain ionic and acidic base balance of body fluids

Question 51

function of PCT

Answer 51

PCT is lined by simple cuboidal brush border epithelium which increases the surface area of a reabsorption. nearly all the essential nutrients and 70 to 80% of electrolytes and water are reabsorbed by the segment . PCT also helps to maintain the pH an ionic balance of the body fluids by selective secretion of hydrogen ions ammonia and potassium ions into the filtrate and absorption of HCO3 minus from it.