Excretory System Flashcards
Immunological filter
Spleen and lymph nodes
Physiological filter
Kidney
Most toxic waste in humans
Ammonia
Do humans excrete ammonia?
No. They convert it into less toxic urea in the liver.
Why is ammonia toxic?
Amino acids cannot be used directly in energy production. So they are broken down and ammonia ion is released whereas the carbon and hydrogen can be metabolised. This ammonia ion when enters the cell it combines with free proton and forms ammonium ion which disturbs the pH of the cell making it alkaline/basic from acidic where outside the cell environment is acidic.
Ammonotelism is seen in ?
Bony fishes, aquatic amphibians, aquatic insects
Because Approximately 0.5 L of water is required per 1 g of nitrogen to keep ammonia levels in excretory fluid below the level in body fluids to avoid toxicity.
Ureotelism is seen in ?
Terrestrial amphibian, marine fishes
Uricotelism is seen in ?
Reptiles, birds, insect, land snails
Excretory structure of platyhelminthes?
Protonephridia or flame cells
Nephridia are excretory structure found in ?
Earthworm and annelids
Excretory structure of cockroach?
Malphigian tubules
Antennal or green glands are found in?
Crustaceans like prawns
What are the parts of human excretory system
- A pair of kidney
- Pair of ureter
- Urinary bladder
- Urethra
What is the position of kidney ?
Between last thoracic and third lumbar in the dorsal side of the abdominal cavity
The medial border of kidney is concaved and the center of the concavity is called _________ from which the ureter enters
Renal hilus /hilum
Inner to the hilum is a broad funnel shaped space called ?
Renal pelvis
Renal pelvis is not smooth. It has projections called ?
Calyces
The cortex region of kidney extends in between the medullary pyramid as renal column called ?
Column of bertini
How many nephron are present in each kidney ?
1.2 million in each
Each nephron has 2 parts ?
Renal corpuscle/malphigian body and renal tubule
The renal corpuscle is composed of
A glomerulus and a bowman’s capsule
Does kidney help in removal of ammonia?
No.
Renal tubule is composed of
Pct , Loh, dct and collecting duct
Which parts of nephron are under conditional control?
DCT and CD
Filtration slit of bowmans capsule is composed of which cells ?
Podocytes
What are the 2 parts of Pct ?
Pars convolute - initial major convoluted portion
Pars recta - distal smaller straight portion
Where does maximum reabsorption takes place?
PCT
Why does maximum reabsorption take place in PCT
Because it has epithelial cells with extensive folding of the apical memberane containing microvilli .
Descending limb of loop of henle is more thick or thin portion?
Thin
Descending limb of loop of henle is permeable to only ?
Water
Descending limb of loop of henle is composed of which cells?
Simple squamous epithelium
How much absorption occurs in loop of henle?
15%
Ascending limb of loop of henle has more thick or thin portion?
Thick
Ascending limb of loop of henle is composed of which cells?
Simple cuboidal epithelial
Ascending limb of loop of henle is permeable for ?
Sodium and other electrolytes
What modification exists in the loh of desert animals?
Longer loop of henle
Dct is impermeable to water but when stimulated by these two hormones, they conditionally absorb water.
Aldosterone and ADH
Dct and CD help in balancing?
pH and water-electrolyte levels
Collecting duct opens into ?
Renal pelvis —-> ureter
Which 2 important cells are present in collecting duct?
P cells (principle cells) and I cells (type A intercalated cells) .
