excretory products and their elimination Flashcards
what do animals accumulate in their body by metabolic activities or excessive ingestion?
ammonia, urea, uric acid, carbon dioxide, water and ions like Na+, K+, Cl-, phosphate and sulphate
what are the major forms of nitrogenous waste?
ammonia, urea and uric acid
what is the most toxic and least toxic form of nitrogenous waste?
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
what is ammontelism? how is the process done? and what are the examples?
-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
what is ureotelism? what is the process of it. and it’s examples
-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.
which organism maintains desired osmolarity?
ureotelic organisms. some amount of urea maybe maintained in the kidney matrix of some of the animals to maintain desired osmolarity.
what are uricotelic organisms? what is the process and some examples.
-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
platyhelminthes excretory structure
protonephridia or flame cells maintain osmoregulation( fluid and ionic balance)
e.g. planaria, rotifers, some annelids and the cephalochordate : amphioxus
earthworms and other annelids excretory structure
nephridia. helps remove nitrogenous waste and maintains osmoregulation
insects excretory structure
malphigian tubules
helps remove nitrogenous waste and maintains osmoregulation
crustaceans ( prawn ) excretory structure
antennal gland or green gland
what does the human excretory system consist of?
a pair of kidneys, a pair of ureters, a urinary bladder and a urethra
kidneys color,shape and location?
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
kidneys measurement and weight
length : 10-12 cm
width : 5-7 cm
weight : 120-170g
hilum location and function
-located towards the center of inner concave surface of the kidney
-ureter, blood vessels and nerves enter through this
what is renal pelvis
inner to the hilum is broad funnel shaped space called renal pelvis. their projections are called calyces.
what is the outer layer of kidney?
tough capsule
what are the 2 zones inside kidney?
outer cortex
inner medulla
the medulla is divided into?
medullary pyramids with projections called calyces
what are columns of bertini?
they are renal columns which extend between medullary pyramids
what are nephrons 2 parts
glomerulus and renal artery
glomerulus is formed by
it is a tuft of capillaries formed by afferent arteriole
what is afferent arteriole
a fine branch of renal artery
who carries blood away from gloumerulus?
efferent arteriole
the renal tubule begins with?
a double walled cup like structure called bowmans capsule which encloses the glomerulus
what is the malpighian body or renal corpuscle?
glomerulus along with bowmans capsule
nephron order
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
what are corticle nephrons?
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.
what are juxta medullary nephrons?
when loop of henle is too long and runs deep into the medulla these nephrons are called juxta medullary nephrons
what and all are situated in the cortical region of the nephron?
PCT, DCT and malphigian corpuscle
what are peritubular capillaries?
efferent arteriole forming network around renal tubule
what is vasa recta?
when peritubular space runs parallel to henles loop forming u shaped vasa recta.
where is vasa recta absent or highly reduced?
cortical nephrons
what are the 3 main processes of urine formation
glomerular filtration, reabsorption and secretion
how much blood is filtered by the kidney per minute?
1100-1200ml
what are the 3 layers of filtration of blood
- endothelium of glomerular blood vessels
- basement membrane
- epithelium of bowmans capsule
what are podocytes?
epithelial cells of bowmans capsule which are arranged in an intricate manner as to leave filtration slits
what is the only constituent from the plasma that does not filter through the membranes
proteins
this filtration is also called?
ultra filtration
what is glomerular filtration rate ( GFR )?
the amount of filtrate formed by the kidney per minute
GFR of a healthy individual
125 ml/minute or 180 liters per day
what is the built in mechanism for regulation of GFR
JGA mechanism
JGA is formed by the cellular modifications of?
DCT and afferent arteriole
what is the JGA mechanism
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.
What is the percentage of filtrate that has to be reabsorbed by the renal tubules?
99%
What performs active or passive mechanisms of reabsorption
tubular epithelial cells
What are the substances from the filtrate that get reabsorbed by active mechanism
glucose, amino acids, Na+
What are the substances from the filtrate that get reabsorbed by passive mechanism
nitrogenous waste and water (initial segment of nephron)
During urine formation what do the tubular cells secrete into the filtrate
H+, K+ and ammonia
what does tubular secretion do
help maintain ionic and acidic base balance of body fluids
function of PCT
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.
