To Maintain Homeostasis
Class 9th Biology Kerala Board Solution
Let Us Assess
Question 1.Water reabsorption in kidney takes place in the
A. Glomerulus
B. Renal tubules only
C. Efferent vessel
D. Renal tubule and collecting duct
Answer:
Glomerulus
Function
1. Development of Filtration pressure
It occurs because of 2 reasons
a. The diameter of efferent arteriole is smaller than that of afferent arteriole
b. Pressure of blood flow due to heart
2. Ultrafiltration
It occurs because of 2 reasons
a. Filtration pressure
Small sized pores
Renal Tubule
Renal Tubule comprises of
1. Proximal Convoluted tubule
-reabsorbs all glucose, amino acids, 2/3 Na and water
2. Loop of Henle
-ascending loop – impermeable to water, reabsorbs Na
-descending loop – impermeable to Na, reabsorbs water
3. Distal Convoluted tubule
-actively reabsorbs Na and Cl,
Impermeable to water, Reabsorption of water can only occur in presence of ADH/vasopressin hormone.
Efferent vessel
It carries the filtered blood out of the glomerulus
Collecting duct
Route of urine flow
Glomerulus (filtrate)
Bowman’s Capsule Proximal Convoluted tubule Descending loop of henle ascending loop of henle Distal Convoluted tubule Collecting tubule collecting duct (urine) duct of belleni papillary duct minor calyx major calyx Ureter
Impermeable to water, Reabsorption can occur only in presence of ADH/vasopressin hormone
Question 2.
The steps involved in the formation of urine are given below. Arrange them in the correct sequence.
• Collects urine.
• Ultrafiltration takes place.
• Reabsorption of ions takes place towards this part from renal tubules.
• Collects glomerular filtrate.
• Excess urea is secreted here from peritubular capillaries.
Answer:
First Box
•Collects glomerular filtrate
•Ultrafiltration takes place
Second Box
•Reabsorption of ions takes place towards this part of renal tubule
Third Box
•Excess urea is secreted here from peritubular capillaries
Fourth Box
•Collects urine
Question 3.
Why are blood cells and proteins not seen in the glomerular filtrate?
Answer:
To form the glomerular filtrate, blood passes through 3 layers
1. Endothelium of glomerular blood capillaries
2. Basement membrane of glomerular blood capillaries
3. Inner wall of Bowman’s capsule
The pores at each passage are small, hence do not allow large blood cells and protiens to pass.
Extended Activities
Question 1.Conduct a seminar in the class on 'Lifestyle and kidney diseases'.
Answer:
