Life Processes- Excretion

LIFE PROCESSES

Hello everyone! I hope you are keeping well and taking good care of yourself!

After the completion of today’s class, you will be able to

a)     Define excretion

b)    Study various excretory organs in humans

c)     Learn the process of urine formation

d)    Know about various excretory products in plants.

Important instruction: Copy the text given in red in your biology note book.

EXCRETION

It is the biological process of removal of harmful nitrogenous wastes from the body.

The various excretory organs in humans are:

1. Kidney –i.  removes nitrogenous waste (urea and uric acid) from the body in the form of urine

                ii. helps in osmoregulation ( maintaining the water level in the body)

(If the body has more amount of water then the urine produced is dilute and if the body lacks water, the urine produced is concentrated.)

Each kidney is made of number of filtration units called nephrons.

              (not to be drawn)

2. Lungs- removal of carbon dioxide takes place here.

3. Skin – also removes excess water and minerals in the form of sweat.

                           HUMAN EXCRETORY SYSTEM

1. The excretory system of human beings includes a pair kidney, a pair of ureters, a urinary bladder and a urethra.

Location of Kidney: Kidneys are located in the abdomen one on either side of the backbone.

Urine produced in the kidneys passes through the ureters into the urinary bladder where it is stored until it is released through the urethra.

Draw a neat labelled diagram of human excretory system – page 110 ,fig 6.13

     STEPS OF URINE FORMATION

https://youtu.be/O8_206fULo0     video explains urine formation

you may pause the video at 2.12 s and draw the basic structure of nephron from here. Later you can cover it up with blood vessels as shown in fig 6.14 page 111.

       Urine formation occurs in three steps:

    1)    Ultra filtration – it takes place at the glomerulus part of nephron, and the wastes such as urea, uric acid along with some useful substances like amino acids, glucose minerals and water move into nephron from blood.

   2)    Selective reabsorption – the useful substances that form the initial filtrate (or have entered the nephron) are selectively reabsorbed by the blood capillaries that surround the tubular part of the nephron.

   3)    Tubular secretion – more ions and water (depending upon the amount of water present in the body) are secreted into the tubular part to finally form urine.

(read page 111)

(not to be drawn)

DIALYSIS  (ARTIFICIAL KIDNEY)

The diagram below explains how filtration of harmful substances occur outside the body. Read more to know part on page 111 for  better explanation. This diagram is not to be drawn.

(not to be drawn)

EXCRETION IN PLANTS

read page 112

   1)    Plants remove excess water through transpiration.

   2)    Some waste products are stored in barks of trees and leaves which fall off.

   3)    In some plants, the waste is stored in the form of crystals such as calcium carbonate in the leaves. Eg fig plant

4)    Several plant products such as resins and alkaloids such as morphine are plant wastes and useful to us. 

 latex

 gum

 resin

DEAR STUDENTS, WE END THIS CHAPTER, LIFE PROCESSES TODAY.

PLEASE FEEL FREE TO ASK ANY DOUBT THROUGH THE COMMENTS BELOW.

COMPLETE YOUR BIOLOGY NOTEBOOKS WITH ALL NOTES AND DIAGRAMS.

YOU SHOULD NOW BE ABLE TO ANSWER QUESTIONS THAT ARE GIVEN ON PAGE NO. 113 OF YOUR NCERT.

ATTEMPT QUESTION NUMBER 5, 6, 10, 12 AND 13 IN YOUR NOTEBBOKS.

WE SHALL BEGIN WITH CHEMISTRY CHAPTER 1 ON 15^th APRIL. UTILISE YOUR EASTER HOLIDAYS TO FINISH THE ABOVE TASK.

HAPPY LEARNING !

TAKE CARE !!!