excretory products and their elimination Flashcards
most toxic form of nitrogenous waste
ammonia
least toxic form of nitrogenous waste
uric acid
process oof excreting ammonia and examples of ammonotelic animals
aquatic amphibians, aquatic insects, bony fishes, amoeba, crayfish, hydra, sponges, tadpole of frog
how is ammonia excreted out of the body
through simple diffusion across body surfaces or through gills as ammonium ions
process of excretion of urea and examples of ureotelic animals
mammals, terrestrial amphibians, marine fishes
how and where is urea synthesized in ureotelic animals
ammonia produced by metabolism is synthesized into urea in the liver and released into blood where it filtered out of the kidneys
some amount of urea is maintained in the kidney matrix of ureotelic animals - ?
to maintain desired osmolarity
how many times less toxic is urea than ammonia
1,00,000 times less toxic
process of excretion of uric acid and its examples
uricotelism ; reptiles, birds, land snails, insects
uric acid is excreted in the form of
pellet or paste
excretory structures in vertebrates
complex tubular structures called kidneys
invertebrates excretory structures
simple tubular forms
protonephridia or flame cells are the excretory structure in
platyhelminthes(flatworms) - planaris, some annelids, rotifers, cephalocorddates - amphioxus
protonephridia function
maintaining ionic and fluid volume- osmoregulation
nephridia is found in
earthworms, other annelids
function pf nephridia
ionic and fluid volume balance, excretion of nitrogenous wastes
malphigian tubules are found in
insects like cockroach
antennal or green glands are found in
crustasceans like prawns
excretory system in humans contains
a pair of kidneys, pair of ureters, urinary bladder, urethra
location of kidneys
between last thoracic vertebrae to 3rd lumbar vertebrae
dorsal inner wall of abdominal wall
dimensions of kidneys
10-12 cm in length, 5-7 cm in width, 2-3cm in thickness, 120-170 g
describe location of kidneys in humans
the left kidney is a little higher than the right one as the right kidney needs to be a little lower to accomodate the liver
concave notch towards the inner surface of kidneys
hilum
what passes through hilum
nerves, veins, arteries,ureters
outer most covering of kidney
tough capsule made up of white fibrous connective tissue
kidney is divided into two regions
outer cortex, inner medulla
what arrangement does kidney have with peritoneal cover
peritoneal cover is only present on the ventral side of the kidneys as the dorsal side is fused with abdominal wall - retroperitoneal arrangement
medulla is divided into
medullary pyramids
medullary pyramids extend into the
calyx
the cortex extends in between medullary pyramids as
columns of bertini
osmolarity of medullary interstitial fluid is
1200mOsm/L
urinary bladder is divided into
neck and body region
lenth of ureters
25-3o cm
sphincters of urinary bladders
internal involuntary sphincter, external voluntary sphincter
where is urine stores
urinary bladder
signal to release urine is initiated by
walls of the urinary bladder being stretched
stretch receptors on urinary bladder wall send signal to ; nature of signal
voluntary signals to CNS
what messages does CNS pass ; outcome ?
motor messages to initiate the contraction of smooth muscles of bladder
what muscles contract during micturition
detrusor muscles
sphincters of urinary bladder during micturition
sphincter undergo relaxation
process of passing of urine is called
micturition
neural mechanisms causing micturition is called
micturition reflex
adult human excretes
1-1.5 litres of urine per day
nature of urine
characteristic odour, light yellow watery fluid, pH of 6.0 ( slightly acidic
how much urea is excreted out per day
25-30 gm
presence of glucose in urine
glycosuria
glycosuria is caused by
low levels of insulin which cause blood glucose levels to increase leading to less reabsorption of glucose and increase in glucose in urine
presence of ketone bodies in urine
ketonuria
ketonuria is caused by
hyposecretion of insulin, glucose cannot be used for energy, breakdown of fat creating ketone bodies in blood
glycosuria and ketonuria are indicative of
diabetes mellitus
inflammation of glomeruli and symptoms
glomerulonephritis
presence of proteins(albumin) in urine
jaundice
bile salts and pigments
hyperthyroidism, starvation
creatinine
what is nephron
complex tubular structural units of kidneys
what is nephron
complex tubular structural units of kidneys
parts of nephron
glomerulus and renal tubule
what is glomerulus
a tuft of capillaries formed from afferent arterioles, a fine branch of renal artery
blood from glomerulus is carried away by
efferent arterioles
what is nephron also called
uriniferous tubules
the renal tubule begins with
double walled cup like structure called bowman’s capsule
what does bowman’s capsule enclose
glomerulus
glomerulus and bowman’s capsule is called
malphigian tubules or renal corpuscle
the malphigian body continue as
a highly coiled network called proximal convoluted tubules
PCT is lined by
brush bordered cuboidal epithelium
pct descend into
loop of henle
loop of henle consists of
an ascending arm and descending arm
the ascending limb continues as
a highly coiled tubular structure called distal convoluted tubule
the DCTs of many nephrons open into a straight tube called
collecting duct
the collecting ducts converge
and open into the renal pelvis throught m medullary pyramids in the calyx
collecting ducts open enter throught the medulla region and form
ducts of belllinii
collecting ducts open enter throught the medulla region and form
ducts of belllinii
what structures lie in the cortical region of nephron
malphigian corpuscles pct, dct
what structures lie in the medulla
loop of henle
cortical nephrons
loop of henle is short, does not dip into medulla, 80% of all nephrons, malphigian body is in cortex
juxta-medullary nephron
20%, loop of henle is long and dips into medulla, Vasa recta is present, helps in concentrated urine formation
the efferent arterioles emerging from glomerulus forms a fine capillary network around renal tubule called
peritubular capillaries
3 main processes of urine formation
glomerular filtration, reabsorption, secretion that rahe place in different parts of nephron
net pressure that causes fluid to filter out of glomerulus into capsule
20mmhg
first step in urine formation
blood filtration-glomerular filtration
how much blood is filtered by kidneys per minute
1100-1200 ml it constitutes roughly 1/5th of the blood pumped out by each ventricle i in a minute
what causes filtration of blood
glomerular capillary blood pressure
what causes filtration of blood
glomerular capillary blood pressure
3 layers of glomerular filtration layer
endothelium of glomerular blood vessels, epithelium of bowman’s capsule, basement substance in between
epithelial cells of bowman’s capsule
podocytes
arrangement of podocytes
arranged in an intricate manner so as to leave some minute space called filtration slits or slit pores
GFR in a healthy individual
125ml/min, 180 litres per day
what is JGA
a special sensitive region formed by cellular modifications of dct and afferent arterioles at the place of their concact
a fall in gfr activates jg cells to release
renin; increase glomerulus blood flow and gfr
how much urine is formed in a day
1.5 litres
how m much filtrate has to be reabsorbed by renal tubules
99%
what cells perform reabsorption
tubular epithelial cells of nephron by active or passive mechanism
substance reabsorbed actively
glucose, amino acids, Na+
substances reabsorbed passively
water and n2 wastes
where does reabsorption of water take place
in initial segments of nephron
tubular secretion
tubular secretion helps in ionic and acid base balance of body fluids
tubular cells secrete
H+,K+ and ammonia into filtrate
why is pct lined by brush bordered epithelium
to increase surface area for absorption
what is absorbed by pct
nearly all essential nutrients, 70-80% of electrolytes and water
selective secretion of pct
selective secretion of H+,K+, ammonia into filtrate and absorption of HCO3- from filtrate
selective secretion of pct maintains
pH and ionic balance
where does conditional reabsorption of na+ and water take place
dct
reabsorption in dct
HCO3-
selective secretion in dct
maintains ph and sodium potassium balance in blood, H2,K+,NH3
where is reabsorption minimum in loop of henle
ascending limb
role of ascending limb
Significant role in maintenance of high osmolarity of medullary interstitial fluid
the descending limb is permeable to
water, almost impermeable to electrolytes
effect of descending limb on filtrate
concentrate filtrate as it moves down
the ascending limb is permeable to
electrolytes, impermeable to water
the ascending limb is permeable to
electrolytes, impermeable to water
effect of ascending limb on filtrate
dilutes filtrate as it moves up due to passage of electrolytes actively or passively
where does collecting ducts extend to
from cortex to inner parts of medulla
large amounts of water is absorbed by
collecting duct to produce concentrated urine
how does collecting duct play role in maintaining osmolarity
collecting ducts allow passage of small amounts of urea into medullary interstitium
selective secretion of collecting ducts
H+ and K+
selective secretion of collecting ducts
H+ and K+
who has the ability to produce concentrated urine
mammals
segments of nephron playing a significant role in concentration of urine
vasa recta, henle loop
the capability of concentration of urine relies on the
length of the henle loop
the flow of filtrate in both limbs of henle loop is
is in opposite directions
